China's petroleum exploration enterprises and geological survey organizations invested more in oil and gas exploration in 2022 to cope with complicated situations like global profound changes unseen in a century and shock in international energy markets. And a lot of new exploration discoveries and breakthroughs were found and made. For the high-quality and sustainable development of China's petroleum exploration in the coming future, situations about conventional and unconventional oil and gas resources in China were expounded, main features and fresh highlights in this exploration in 2022 were reviewed, and exploration prospects in 2023 were put forward in combination with resource potential. Results show that (i) China' petroleum exploration in 2022 exhibited obvious turnaround of both capital investment and petroleum production, new discoveries mainly founded around or in the deep part of proved reservoir-forming assemblies, outstanding findings of unconventional oil and gas exploration in mature fields, and guidance of advanced geological theories and technologies to make new exploration breakthroughs; (ii) significant exploration breakthroughs have been made in fault-controlled high-energy shoal at the Ordovician of Fuman oilfield in Tarim Basin, the Permian natural gas and deeper shale gas in southeastern Sichuan Basin, and shale oil in old oilfields of east China; and (iii) China's petroleum exploration in 2023 is expected to witness novel breakthroughs in the deep or the deep waters, periphery of large petroliferous basins, as well as marine shale oil/gas and shale gas with marine-continental transitional in north China.

Although in 2022, frequent COVID-19 outbreak appeared across China, economic development faced triple pressure of pullback in demand, vulnerable supply and weaker expectation, and global oil and gas prices were on the rise due to geopolitical conflicts, China's natural gas development rolled back and forth but held stable supply and demand as well as lot of resilience. Moreover, it presents the following characters. First, major achievements were remade in gas exploration, and proved reserves kept growing at the peak rate. Second, gas production still increased like an upward arrow, but with continuous decline in growing output and rate. Third, the import price of natural gas rose whereas the imports fell; and the imports of LNG emerged as a negative growth for the first time. Fourth, its consumption dropped due to feeble demand. Fifth, the infrastructure construction of natural gas advanced energetically. Sixth, its marketization went ahead. In conclusion, in 2023, both social and economic development momentum will be enhanced in China, and natural gas development will welcome a stable and progressive year after variations of COVID-19 control and prevention strategy. It is expected that, with shale gas as the leading gas, the natural gas will exceed one trillion cubic meters of proved reserves again. Its production should move forward steadily with the output staying an increase around 10 billion cubic meters. LNG imports will continue their up trend, and those of natural gas will rebound by cooperating with Gazprom. The demand of natural gas will pick up strongly and the supply-demand market will be steady. And some latest progress will be made in system and mechanism reforms on natural gas.

Holding the decisive essence leading to some regional variations in the carbon emission from energy consumption and taking relevant emission-reduction measures are the prerequisites for achieving the dual-carbon goal. Therefore, taken Sichuan-Chongqing area as an example, a carbon-emission inventory which regarded both fossil-fuel combustion and power allocation in different areas was constructed, and the effect of multiple influential factors was discussed on the basis of the Kaya Identity and LMDI model in order to figure out both temporal-spatial characteristics and influential factors of this emission. Results show that (i) a decreasing trend emerged in the carbon emission from energy consumption in Sichuan Province from 2015 to 2022 while an increasing trend in Chongqing City due to the endowment diversity among renewable energy resources. The emission from energy processing and conversion is rooted in thermal power generation and heating sectors. In terms of terminal expenditure, the largest emission source comes from industrial field, followed by transportation and residential life, then business and other services, and both agriculture and building industry making a small contribution to the emission. Sichuan advances the low-carbon strategy in addition to ensuring the energy's supply-demand security through transporting large amount of water and electricity resources, while Chongqing indirectly raises its carbon contribution via relying on external power output; and (ii) as an inhibiting factor, the structure of energy use makes the incremental contribution to the Sichuan's emission year by year while little impact in Chongqing. For the energy intensity as a key factor for emission reduction, its inhibition peaked in 2016-2017 due to benefits from the dual control in the energy use. The industrial structure in Sichuan is an inhibition factor as well, and its influence is slowly diminishing, while that in Chongqing increases first and then decreases with changes of secondary industries' proportion. The economic growth whose effect is on the decease each year under the new pattern of low carbon is also a critical factor in emission acceleration. The effect of population development is affected by population size, social culture, and resource allocation comprehensively.

The fifth member of the Ordovician Majiagou Formation (Ma 5 Member) in Daniudi gasfield is standing in regression. Vertically, it is divided into 10 submembers (Ma 5¹ to Ma 5¹⁰), among which Ma 5¹⁺² is still in relative regression. Numerous dissolved pores, vugs and fractures induced from fresh water leaching and karstification are extended into Ma 5¹⁺² where gray dolomite is dominantly developed with a little limestone to accumulate hydrocarbon. Therefore, cores, well- and mud-logging data from over 580 wells drilling through the target were analyzed to predict geological sweetspots of Ma 5¹⁺² in this field. And that there developed 4 types of sedimentary microfacies, including calcareous dolomite flat, dolomite flat, dolomitic limestone flat, and argillaceous dolomite flat, was pointed out. Furthermore, combined with paleogeomorphological natures, the thickness distribution of Ma 5¹⁺² reservoirs on the plane was characterized. By referring to production data of gas wells, the extension of quality reservoirs was predicted, and the sweetspots were delineated. Results show that (i) 7 episodes of sedimentary cycle are developed vertically in Ma 5¹⁺² where shale content increases from below, meaning the decreasing trend of waterbody depth and salinity while this content decreases from north to south on profile, implying the increasing trend of waterbody depth and salinity; and (ii) Ma 5¹⁺² reservoirs overall get thicker to the west, and their thickness varies greatly along north to south, with the maximum thickness difference of 24 m, but gently along east to west, with the maximum difference of 8 m. Six geomorphological units are identified, i.e., karst platform mound, monadnock, slope, highland, low-lying land and trough, and the reservoirs are mainly located in the first two units. In conclusion, the quality reservoirs are mainly deposited in both calcareous dolomite flat and dolomite flat. Rich in dolomite extended from northeast to southwest, the residual reservoirs are thick. This thickness often exceeds 4 m in both platform mound and monadnock, and that from 2 to 6 m in slope. Additionally, three sweetspot zones are selected on the basis of predominant microfacies, lithofacies and paleogeomorphological units. With the porosity exceeding 2.5%, the quality reservoirs are over 4 m in thickness. Imaging logging presents that fractures, dissolved pores and vugs are well developed, indicating better physical properties. Both gas saturation and total hydrocarbon content are over 15% and 20%, respectively. The testified cumulative production is more than 2000×10⁴ m³.

Under the background of "dual carbon" goal, the industrial development of new energy resources generates the endogenous demand for the construction of talent team, and it is urgent to break the restrictions of imbalanced talent supply and demand and other problems. So, the status and difficulties in the construction of talent team were analyzed for the new resources, and the idea, model and mechanism guarantee were also made clear for this construction. Results show that (i) there exist some problems in this talent team construction, including that foreign experiences are hardly applicable to China's situations, the promotable and duplicable modeling experiences have not been formed in China, and the existing mechanisms are lack of systematic and collaborative construction and exploration; (ii) this construction shall follow the idea of keeping up with the needs of market change and industrial development, focusing on the scarce talent team and attracting multiple participants to generate the collaborative linkage effect. The construction modes include the multi-dimensional goal led planning mode, the multi-party collaboration based promoting mode, multi-advantage integrated implementing mode; and (iii) the mechanism guarantee for the construction includes four mechanisms in innovating the all-type "talent cultivation", planing the all-round" talent gathering", creating the whole-process "talent management" , and constructing the full-guarantee "talent utilization". These results provide beneficial reference for the construction of talent team in new energy sources and new functions for the development of new energy industry under new situations.

In April 2022, FB1 well in Qijiang area of southeastern Sichuan Basin achieved the gas production of 6.42×104 m3 /d from the second member of Qixia Formation (Qixia 2 Member) after acid-fracturing test. It was the first considerable exploration breakthrough for the Qixia Formation in this basin made in intra-platform and platform-depression margin shoals followed by major commercial top in both marginal platform shoal and intra-platform shoal around paleouplift. So, in order to comprehend sedimentary and reservoir characteristics of the Qixia Formation, Qijiang area, ascertain favorable exploration zones and guide the next exploration deployment, both sedimentary-facies distribution and reservoir extension were explored for this formation by making full use of field survey, core observation, thin-section identification, assay analysis and well-logging data. Results show that (i) during the deposition of the Qixia Formation, a sort of uplift-depression pattern was inherited in this area before the Permian deposition to further grow up the stable deposition of carbonate platform where platform-depression margin shoal, inter-shoal and intra-platform depression were developed. Qixia 1 Member belongs to the inter-shoal deposition, and high-energy shoal deposits were extended at the top of the upper submember of Qixia 2 Member and the top of the lower submember; (ii) reservoir rocks are mostly composed of sparry grainstone, aplite dolomite and limy dolomite, and reservoir space can be classified into two types, i.e., pore (vug) and fracture. Imaging well-logging and physical property data indicates the overall reservoir characteristics of low porosity and extra low permeability; and (iii) with an obvious facies control, Qixia reservoirs get better under karstification. The transitional belt of platform-depression margin during the deposition of Qixia Formation is regarded as a favorable exploration area. It is deemed that these results offer a scientific decision-making basis for the following deployment in the Qixia Formation of Qijiang area.

In order to accurately characterize both occurrence laws and physical parameters in multiple thin CBM reservoirs and provide guidance for CBM development, the upper Longtan Formation in Panzhihua mine of western Guizhou Province was taken as an objective to comprehensively organize some data on both mud logging and core analysis, standardize the interpretation on logging curves, and analyze a relation of physical parameters to logging curves. Then, one relation was established quantitatively by means of linear regression fitting, and a 3D geological model was built for the multiple thin CBM reservoirs through one method called facies-controlled stochastic modeling. In addition, one structural model and the other lithofacies model were developed, and the spatial distribution of physical parameters such as dry-ash-free content, permeability, density and ash was simulated. With the help of the other approach to compute CBM reserves, the original CBM in place in the upper Longtan Formation in this mine was calculated by 3.91×10⁸ m³ from the established 3D geological model. Results show that (1) taking lithofacies as the constraint of the distribution and change of physical parameters and performing variation function analysis, the multiple thin CBM reservoirs may be figured out more effectively under theoretical guidance of facies-controlled modeling, (2) the characterization on physical parameters based on logging curves can be effectively conducted through correlation analysis and linear fitting; and (3) reliable data can be gotten from the facies-controlled stochastic modeling, the modeling process is well available for the multiple thin CBM reservoirs, and the established model can provide better guidance for the following exploration and development of CBM reservoirs.

Being a globally recognized technology to reduce carbon emission with the greatest commercial potential, carbon capture, utilization and storage (CCUS) plays an important role in helping the achievement of China's dual-carbon goal on schedule. Moreover, CCUS-enhanced gas recovery (CCUS-EGR), as a feasible path for petroleum enterprises to enhance gas recovery in old gasfields, can achieve carbon peaking and carbon neutrality simultaneously. It is of great significance to reserve and production increment as well as carbon peaking. To set up an economic evaluation method for the whole industrial chain of CCUS-EGR is the foundation for the demonstration and future industrial development of CCUS-EGR projects. So, based on this whole chain process, one economic evaluation model has been developed for this chain which is composed of five modules, such as capture & compression, transportation, injection & storage, separation & reinjection, and risk monitoring. In addition, the model was verified through one whole industrial chain project on Chongqing Hechuan Power Plant and WLH Gasfield. Results show that (i) natural-gas price, production condition, carbon-trading price and operation cost have great influences on the revenue of the whole industrial chain. Among them, production condition and carbon-trading price are the most sensitive, followed by operation cost and natural-gas price; (ii) resource earnings contributed by CCUS-EGR can substantially increase the total chain revenue; (iii) the carbon-emission right trading price is crucial to the chain revenue, and introducing the net emission reduction of CCUS-EGR into carbon-trading markets can effectively raise the return rate. Three suggestions are made in an effort to increase the whole industrial chain economic benefits of CCUS-EGR projects, including to further discuss the effective CO₂ storage, to accelerate the research and development of CCUS-EGR, and to deliver standards and policies to quantitatively certify CCUS-EGR and support this industry.

Smart logging technologies have been increasingly applied to petroleum companies with the digital and intelligent advancement. Especially remote skills emerge as the times require to resolve difficulties in conventional logging, such as long well occupation time, big logging costs, low efficiency and high labor intensity. Remote control of logging equipment can be attained by means of wireless transmission, so that experts as well as technical and safety personnel can examine and analyze data, and regulate parameters to guarantee all logging operation in high quality, efficiency and safety. Results show that (i) the established new remote control system is well applicable to logging operation; (ii) its application acquires real-time monitoring and transferring logging curves from numerous wells, solves on-site abnormalities in time, reduces well occupation time and logging costs, and optimizes human resources; and (iii) promoting this system is of guiding significance for next breakthrough made in core online logging technologies, and collaborative innovation across well areas and departments.

Natural gas, a sort of transitional resources for energy transition, is growing rapidly. However, its storage and transportation are in the face of multiple challenges, such as poor storage facilities, not very good connectivity among pipelines, and safety and environmental risks. Therefore, the path to the high-quality development in the natural-gas storage and transportation was proposed in terms of ensuring national energy security and stable gas supply, improving natural-gas utilization, and reducing a negative impact of carbon emission. Results show that (i) this quality development driven by energy revolution should emphasize four revolutions and one cooperation, with the promotion of energy transition and upgrading as the goal, the optimal allocation and integration of storage and transportation resources as the core, the value creation as the premise, the innovation as the fundamental driving force, and the sustainability as the essential path. And it is necessary to adhere to both quality and efficiency the first, and encourage the digital, informationized, international and sustainable development of the storage and transportation; and (ii) it is essential to fix on the application and innovation of green and intelligent technologies to the storage and transportation domain, to strengthen the construction and upgrading of gas pipelines, underground gas storages and peak-shaving facilities, to make better the networking infrastructure like storage, transportation and pipelines, to build an efficient gas market monitoring system and an information exchange platform; to establish the international energy corridor cooperation and innovation mechanisms based on the Belt and Road Initiative, and actively cultivate the storage and transportation globally-oriented talents. These measures are conducive to the development of the natural-gas storage and transportation toward safety, green, information, intelligence and efficiency, so as to achieve the smooth and stable energy transition and advance the flourishing and sustainable development of energy industry.

In order to sufficiently clarify the casing deformation laws of shale gas wells, make the effectively preventive and control measures, and reduce the economic loss caused by casing deformation, Weirong shale gasfield was taken as an objective to study the effects of fracture development, horizontal section trajectory, cementing quality, casing load, and fracturing parameters on casing deformation after analyzing the deformation in early appraisal wells. In this way, a technology integrated geology with engineering to prevent and control the casing deformation was developed. Results show that (1) the main deformation cause is that the casing is compressed by fracturing-induced stratigraphic shear slide, so casing deformation is aroused by the integrated factor of geology and engineering; (2) whole-process prevention and control in the development stage of single well may be realized by fine fracture identification, hole trajectory, cementing quality improvement, casing wall thickening, specific fracturing parameter design of “one strategy for one stage”, and construction pressure control; (3) after casing deformation happens, long-hole section multi-stage temporary plugging fracturing can be adopted for remedy. And fracture monitoring indicates that the application of staged remedy measures obtained remarkable effect; and (4) after adopting these preventive and control measures, both deformation ratio and section missing ratio are reduced significantly, so as to meet production demand. They are the main technological measures available for the efficient development of deep shale gas.

There often exist well-developed fractures in Lower Paleozoic carbonate rocks, Ordos Basin, which function as one of the key factors affecting high yield and enrichment of natural gas. In order to precisely predict plane distribution laws of fractures with different sizes as well as provide reference for selecting exploration areas and deploying development wells, the Ordovician in Daniudi gasfield of Ordos Basin was taken as an objective to analyze development characteristics of the fractures in the Ordovician Majiagou Formation by using core and imaging logging data. Then, seismic response characteristics were analyzed for fracture zones and seismic attributes sensitive to fracture prediction were chosen dependant on quality analysis on seismic data and forward modeling. In addition, one method was established to predict multi-scale fractures based on seismic poststack attributes. Results show that (1) for developed fractures in the study area, their logging characteristics are featured by high interval transit time, low resistivity, compensation density and wave impedance, while implicit in seismic response characteristics only emerging as worsening continuity and differential torsion of waves; (2) the boundary of great fractures can be depicted by using dip angle and coherence, and the distribution of small fractures and the intensity in a certain zone with these small ones can be predicted by using high-accuracy Likelihood fusion attributes. Results predicted from those three sorts of fractures can prove each other, and the depicted accuracy is improved a lot; and (3) these results are in line with actual geological situations and better accordant with lost-circulation points. They are conducive to selecting areas and deploying development wells. In summary, the comprehensive fracture prediction method used in Daniudi gasfield is of guiding significance to other blocks with similar geological situations and seismic data.

Taking the development of coalbed methane (CBM), X block, northwestern Qinshui Basin, as an example, based on gas-producing situation of some drainage wells, we implemented a study on the main factors influencing the CBM accumulation and high output. Moreover, we discussed the effect of coal measure conditions, structural movement, and hydrological conditions on the accumulation and high output. Results show that one area with high yield must be located at CBM accumulation belts, which is affected by both engineering conditions and drainage system; and one accumulation and high-output belt should be influenced by multiple factors. So, in the next exploration and production, it's essential to analyze comprehensively the influencing factors with various conditions when optimizing these belts.

In 2020, global economy was plunged into severe recession and energy industry was suffered from hard hit due to joint influence of extreme natural disasters and global COVID-19 pandemic. However, domestic oil and gas enterprises might firmly seize favorable opportunities of China's leading position in achieving economic positive growth in the world and low-carbon transformation and development, and adhere to careful budget, intensive production, meticulous management, and technical excellence, bringing about fruitful exploration and development achievements on natural-gas resources. In addition, in order to guarantee that China's oil and gas industry will maintain quality and sustainable development in the future, the achievements in 2020 were summed up and analyzed. Combined with domestic natural-gas resource potential, the natural-gas development trend in 2021 was expected. Results show that (1) new breakthroughs of natural-gas exploration have been made continuously, and new proved reserves exceed one trillion cubic meters per year once again and set the second largest in history; (2) natural-gas production increases quickly, especially strong growth in shale-gas production. Shale gas will become the main force in increasing production and plenty of gasfields may achieve milestone leap; and (3) along with further promotion on the strategies of carbon peak and carbon neutral, it is predicted that the natural-gas demand will rise significantly, the production and reserves will remain increasing at high level, the natural-gas industry will step into an era when conventional and unconventional resources are both regarded important and shale gas will be a fresh force for the multiplication.

To construct a natural (shale) gas base with the production capacity of one hundred billion cubic meters (10¹²-m³-scale) in China is a great strategy for securing the energy security and supporting the rapid development of regional social economy. So, based on numerous successful practices in petroleum industry, a co-constructing and sharing mode was built for the national natural (shale) gas base with this scale, and some implementation routes were proposed. Results show that (i) this base construction involves an enormous industrial system and interest demands of plural subjects. Thus, guided by many co-constructing and sharing concepts, the mode should be established in plural subjects integrated with multiple elements; and (ii) there are five routes proposed, such as, to reinforce the top-level strategic design for this co-construction and sharing, to set up more modes between the government and enterprises, to perfect the co-constructing and sharing mechanisms among enterprises, to smooth the communication and negotiation channels for plural subjects, and to strengthen the early-warning system of this mode. It is concluded that the proposed co-constructing and sharing mode in a strategic view can plan the base construction as a whole, collaborate the benefits of plural subjects with effect, and promote not only development and utilization of natural (shale) gas but industrial chain's value, thereby driving the evolution of regional social economy and providing powerful support for advancing common prosperity.

The natural-gas chemical industry in Sichuan-Chongqing region focuses on the production of basic chemicals like methanol, synthetic ammonia and carbamide. To encourage it with the high-quality and sustainable development, some research visits were conducted in relevant enterprises inside this region. Moreover, opportunities and challenges for this industry were discussed according to some analysis on policy orientation as well as domestic and international situations. Results show that (i) the state invests more in natural-gas exploration and development and is stepping up the construction of natural-gas production capacity, causing an increase in resource supply. Meanwhile, the natural-gas consumption in Sichuan-Chongqing region tends to rise evidently following the economic growth together with the support of national and local policies, which may provide guarantee of raw materials for the sustainably industrial development; (ii) the cost gap between natural gas-based and coal-based chemical enterprises is narrowing. In the natural-gas chemical industry, management is optimizing and technologies are improving in addition to complex and ever-changing international situations, which may offer opportunities to this industry with the high-quality development in the region; and (iii) the natural gas-based chemical industry in China only accounts for a smaller share and weaker discourse power of the whole chemical industry, new and expanded chemical projects are limited, and raw gas is short supply in heating seasons, which may also restrict its industrial development. It is concluded that the natural-gas chemical industry in Sichuan-Chongqing region will hold a high growth rate in the 14th Five-Year Plan period.

In order to make a demonstrative exploration breakthrough of coalbed methane (CBM) resources in coal-bearing basins, western Inner Mongolia, this paper took the principal coal bed of Heishan coalfield as an example to analyze its basic geologic conditions. Then, some standards to select and evaluate CBM resource areas in this field were formulated based on exploration norms. Results show that (1) the principal coal bed is thick and extensive. Its coal metamorphic degree is moderate, rock types are mainly bright coal and semi-bright coal, and vitrinite content is high, all presenting strong hydrocarbon-generating potential; (2) on the whole, it's in a hydrodynamic environment which is relatively detained. Both top and bottom coal bed is mainly composed of thick mudstone and siltstone with strong sealing capacity available for CBM accumulation and preservation; (3) the coal bed is generally 600~1000 m deep with better porosity and developed fracture systems, which is favorable for a cost-effective development; and (4) the position and range of plays and the favorable targets of CBM resources in Heishan coalfield are defined according to these evaluation standards. The predicted CBM resources and abundance are 810×10⁸ m³ and 0.98×10⁸ m³/km², individually. In conclusion, the key parameters of gas content, reservoir pressure, pressure gradient, gas saturation, and permeability can be measured further by deploying parameter wells in the selected target areas.

In Dongfang block, Yinggehai Basin, the gas-water relationship in high-temperature and high-pressure gas reservoirs of Huangliu Formation is complex, which makes it difficult to carry out well deployment. So, combined with some drilling, well logging, seismic, pressure measurement, and testing data, the Huangliu gas reservoirs in this block were taken as objectives to analyze three types of gas-water distribution and their geneses based on sedimentary microfacies, fine sandbody description, and connectivity evaluation. Then, according to the geneses of various waterbody, its spatial location and scale of contacted gas reservoirs, two gas-water distribution modes were pointed out. Finally, several corresponding development suggestions were made. Results show that (1) the complex sedimentation mechanisms and process of gravity-flow submarine fan in the Huangliu Formation may complicate sandbody superposition and connection relationship, so as to affect gas and water distribution; and (2) there are two gas-water distribution modes in the study area, including the structure- and lithology-controlled large-scale monoblock gas reservoirs with edge water and the small-scale gas reservoirs of lithological trap. In conclusion, the former is the main type of gas reservoirs in the study area. And these gas reservoirs are mainly distributed in the part where large erosion channels are developed continuously. The principle reasons for their formation are thick sandbody, better connectivity and physical properties, and obvious gas and water differentiation, so development wells shall be deployed at the structural high and middle position, away from edge water. In addition, the small-scale gas reservoirs of lithological trap belong to the secondary ones, which are mainly distributed at the front end and side of deposit. Most sandbody in these gas reservoirs has complex connectivity and is mostly isolated. Therefore, to develop this type of gas reservoirs, it is necessary to deploy horizontal wells at the structural high position of sandbody as much as possible.

In southern Sichuan Basin, there are abundant resources of shale gas. For these shale-gas reservoirs, the burial depth varies from 3 600 m to 4 100 m, and many risks of incorrect casing running and poor cementing quality often appear during a cementing. So, a suite of key technologies conducive to increasing cementing quality were developed, such as strengthening a drifting, optimizing string structure, optimally selecting a center device, and adopting four-class cleaning ways. After their successful application to three wells including JY1HF well, high cementing quality was obtained, over 92.5 % especially occurring at horizontal and deviation sections.

Water-soluble gas is a kind of unconventional resources dissolved in groundwater. Its solubility increases with temperature and pressure. When the groundwater is extracted to the surface, some associated gas dissolved in water may be separated out due to a decrease of pressure and temperature, and then becomes an industrial fuel or material as same as conventional energy. Geothermal water-soluble gas（helium）is a new type of unconventional resources, named for associated gas dissolved in geothermal water. It not only contains abundant water-soluble flammable gas and helium, but also possesses geothermal energy, a renewable one which can be used for heating and power generation. At present, in Weihe Basin, the exploration of water-soluble flammable gas and water-soluble gas（helium）resources makes a great breakthrough while geothermal development begins to take shape. This multi-resource basin is being revealed, and a mystery of “one heat two gases” resources is gradually removed. According to the research on previous achievements, and the recent re-exploration, re-evaluation and re-understanding for the resources, this paper describes the occurrence and potential of geothermal water-soluble gas（helium）in macro view, forecasts its development prospects, and proposes some suggestions for the comprehensive utilization.

Heichiliang area is located at the frontal Micangshan Mountain, northeastern Sichuan Basin. And it was also located at the northeastern Kaijiang-Liangping continental shelf during the Changxing-Feixianguan formations. Moreover, with a developed platform marginal oolitic deposition, this area and Puguang area are situated at the same platform marginal oolitic facies belt. After an analysis on some outcrop, drilling, and seismic data, it is shown that in Heichiliang area, there are successively continental shelf, slope, platform margin, open platform, and restricted-evaporite platform facies developed from west to east. In addition, a spatial-distribution feature of sedimentary facies was discussed for Changxing-Feixianguan formations. After another analysis on reservoir, such as rock type, space, and physical property, it is deemed that (1) the studied area is developed dominantly by a platform marginal oolitic reservoir of Feixianguan Formation, which is not only characterized by vertical aggradation, large thickness, stable distribution, and better physical property, but also similar to oolitic reservoir in Puguang area; (2) the favorable platform marginal oolitic reservoir appears a NW-SE-trending distribution and further expands to Puguang area; and (3) the platform marginal oolitic reservoir of Feixianguan Formation between Heichiliang and Puguang areas should be one favorable exploration target.

In Daniudi gasfield, Ordos Basin, production differs greatly in porous carbonate reservoirs even after hydraulic sand fracturing due to strong reservoir heterogeneity. Thus, a model was established to compute the production contribution of each layer, and a heat map matrix chart was created on both geology-engineering parameters and production data. Moreover, the major geology-engineering factors influencing on the production were analyzed to evolve into a formula for evaluating double sweetspots and calculating productivity. Results show that (i) the production contribution in fifth submember of Majiagou 5 Member (Ma 5⁵, hereinafter same) negatively correlates with gamma ray and positively with interval transit time, bulk density and gas saturation. While that of Ma 5⁶⁺⁷ is positively correlated with reservoir thickness, bulk density and neutron porosity; (ii) the production in Ma 5^5-7 is in high correlation with reservoir thickness, maximum total hydrocarbon, porosity, gas saturation, and injected fracturing-liquid, and acid proppant volume; (iii) the established double-sweetspot index calculation model for Ma 5^5-7 is dependent on multiple factors, and the calculated index has the correlation of 0.937 5 with the production; and (iv) the created production prediction model is on the basis of the double-sweetspot index, and the error between the predicted and actual production is less than 2%. In conclusion, with high coincidence with reality, both geology-engineering sweetspot and productivity prediction models which provide active guidance for selecting staged fracturing and designing optimal fracturing are worth popularizing.

The growth of compressed natural gas (CNG) in Sichuan-Chongqing area slows down in the context of the dual carbon. Thus, the main challenges in the CNG business were analyzed for this area in order to follow the energy trend and push CNG stations in the high and sustainable development. Results show that (i) the impact of new energy resources leads to fiercer industrial competition and there exists limit expansion space of CNG market in this area; (ii) for the CNG business in Sichuan-Chongqing area, its own industrial base is weak and the driving force is fatigue. Additionally, some suggestions on the development and transformation of CNG business have been made for Sichuan-Chongqing area, including to accelerate the construction of CNG filling stations, to install electricity-charging replacement and hydrogen filling in CNG stations, to expand the station refueling, and to push the sales of non-gas products. It is concluded that the transition of vehicle fuel to electricity and hydrogen is inevitable. But in Sichuan-Chongqing area boasting mature natural-gas industrial chain and promising CNG business, gas companies will certainly develop towards service providers integrating oil, gas, hydrogen, electricity and service.

Daniudi gasfield is located at Yishan slope in northeastern Ordos Basin, where the Upper Paleozoic structure is relatively gentle and no faults are developed. It is a tight sandstone gas reservoir featured by strong heterogeneity and proximal oil and gas accumulation. Da 28 well area just lies in northern gasfield, in which He 1-1 submember of the Permian Lower Shihezi 1 Member is one of the principal development reservoirs and presents obvious sedimentary characteristics of braided river. In order to clarify the sedimentary characteristics of the principal development reservoirs in this well area, the sedimentary microfacies of He 1-1 submember was taken as objectives to analyze outcrop, core, and logging data. And three principal microfacies were identified, including braided channel, point bar, and flood plain. Results show that (1) this submember can be subdivided into He 1-1-1 and He 1-1-2. There is four-phase channel developed, and vertical and lateral superposition represents the nature of positive rhythm. Single-phase sandbody is preserved completely without obvious denudation. Frequent channel scouring leads to a few thick argillaceous sediments with some thin fine-grained interbed, which belong to high-energy braided channel deposits; and (2) the sandbody advances continuously southward along provenance, and the main channel stays in the same place, presenting the characteristics of thick in the middle and thin on both sides. The sandbody in the north is more developed and dominated by coarse sediments. In conclusion, the sandbody of He 1-1 submember is characterized by complex superposition and clear difference between thickness and gas content. The effective sandbody thicknesses of point bar and braided channel are 6.5 m and less than 4.0 m, respectively. what's more, gas layers are developed in the microfacies of point bar and braided channel, especially in their evolution zones, where sand is purer due to the effect of current scouring. Shale content is less than 15%, Gamma-ray value ranges from 45 API to 70 API, the sandbody's physical property is better and gas content is higher, which can be used as reference and basis for the late development and measured well deployment.

This paper reviews some difficulties, problems and successful practices in the process of promoting natural-gas price reform in China, and puts forward policy suggestions on further deepening this reform and improving price-forming mechanisms. And some conclusions are made as follows. First, both difficulties and problems faced in this reform include the continuously increasing dependence degree of natural gas on foreign countries, the high usage cost of imported gas, the insufficient ability of domestic market to pay for imported gas, the unbalanced regional economic development, and the low final consumption rate of residents, which will be the focus to be considered in deepening China's natural-gas price reform for a long time in the future. Second, successful reform practices include establishing the price system on natural-gas production, transportation, storage and marketing with gate station price management as the core, steadily advancing with the first easy and then the difficult in accordance with the goal orientation, combining government control and market regulation, and firming up price supervision of natural monopoly links, which will be of importance for a considerable period of time in the future. Third, perfecting the gate station price management focuses on improving the release and control combined policy, reducing the scope of controlled gas, expanding the scope of non-controlled gas, as well as clarifying the scope of supply and the responsibilities and obligations of all parties. Fourth, improving the price management of natural-gas infrastructure concentrates on further reasonably determining the allowable rate of return, establishing the standard cost system, and accelerating the promotion and implementation of the two-part charging price. Fifth, making the city-gas price management better is to set this price in accordance with international practices, further reasonably ascertain the allowable rate of return and the depreciation period of pipelines when approving gas distribution prices, and establish and upgrade the upstream and downstream price linkage mechanisms. Finally, it is essential to quicken the construction of natural-gas trading hub and the encouragement of natural-gas energy metering and pricing.

When single-layer production used in one gas well, the production rate is often low and the productivity declines fast. Whereas when commingled production used in some layers with high or low pressure, there is interlayer interference and the contribution rate in gas-producing layers is not made clear. So, Xushen volcanic gasfield, Xuzhong structure belt, Xujiaweizi rift in deep structure of northern Songliao Basin, was taken as an objective to study the separate-layer fracturing-testing integrated technology for deep wells after comprehensive analysis on field development. Then, by means of multidisciplinary study on physics, chemistry, material and mechanics, some fracturing-testing tools which are China's leading ones were developed, and separate-layer fracturing and testing in one trip was realized. Results show that, the separate-layer fracturing-testing integrated technology can not only realize fracturing, completion, and testing in one trip, but also meet the requirement for separate-layer fracturing and testing on 2-4 layers in 3000-m-deep wells. The material of soluble ball seat is selected through multiple experiments and its surface is treated specially, so it has strong erosion and corrosion resistance to meet the insoluble requirement during fracturing or quick solution after fracturing. In conclusion, after successful application of this integrated technology, the contribution rate in each producing layer during commingled production is tested clearly, the operation cycle is shortened, and both construction risk and cost are reduced. As a result, the integrated technology is reliable to realize efficient development in Xushen gasfield.

Carbon capture, utilization and storage (CCUS) is an all-inclusive technology for fossil energy to achieve large-scale carbon emission reduction and ultimately achieve the goal of carbon neutrality, but its problems of high cost and low income restrict the demonstration and large-scale development of CCUS industry. In order to promote the development of CCUS industry in the Sichuan-Chongqing area, this paper systematically sorts out domestic and foreign CCUS industrial development policies. Then, with a hypothetical CCUS-ERG demonstration project as an example, the investment cost is analyzed, and the project economy under different government subsidies and carbon prices is calculated, so as to provide reference for the support policy level of CCUS demonstration project in the Sichuan-Chongqing area. And the following research results are obtained. First, in the case of medium carbon price, the government subsidy level to reach the break even point is 145.50 yuan/t-285.50 yuan/t. Second, increasing the scale of geological storage is conducive to the decrease of the subsidy level. In the case of medium carbon price, the government subsidy level to reach the break even point can be reduced by 30-80 yuan/t if the CO₂ reinjection scale is doubled. Finally, in order to better promote the demonstration and large-scale development of CCUS industry, expand the scale of CCUS projects and reduce costs, three suggestions are put forward: First, Sichuan's and Chongqing's local governments shall accelerate the formulation of government subsidies, industrial funds, low interest loans and other policies to support the development of CCUS industry; Second, it is necessary to promote the link between CCUS and carbon trading market, and realize the carbon price benefits of CCUS projects through CCER or local CER; Third, it is suggested to link internal and external carbon sources and sinks through source-sink match , and expand the scale of CCUS projects to reduce costs.

As the main process in most LNG terminals, discharging not only ensures safe receiving and unloading, but also meets the demand of LNG ship’s demurrage time. Taking the Qingdao LNG Terminal as an example, we found out some common problems during discharging, including operation time over planned time, uneven pre-cooling speed for discharging leg, rapid increase of tank pressure, and unstable operation of BOG recondenser. And then, their reasons were analyzed. Finally, some countermeasure were made, including（1）to optimize the condensate discharge,（2）to keep the ship pressure at 0.3 MPa during precooling process, and（3）to accelerate the controllable discharge speed. After adopting these measures, discharge time might be shortened by over 2 hours, and some facilities such as recondenser and storage tank also became more stable and flexible.

Many older wells in Daniudi gasfield emerged two questions of downhole liquid and near-wellbore water locking along with their development entering into later stage. So, taking three diseased and older wells as examples, we carried out some pilot tests on integrated recovery of both foam discharge + forced discharge and water unlocking. Results show that, these integrated technologies bring clear gains, incremental gas yield and accumulative output respectively come to 2 720 m³/d and 393 179 m³, and the test’s period of validity is as long as 126~193 d. Additional, economic accounting displays that, after technological application to these three wells, certain economic profit has been got, such as daily benefits of ￥3200 and accumulative benefits of ￥456100, total investment of ￥434400, and input-output ratio of 1:1.05, individually. In general, their application has a brighter future.

A better relation among enterprises, local government and community stakeholders is one of the key elements in the great development of natural gas, Sichuan Basin, so that the government and all sectors of the community can be mobilized to serve for increasing both reserves and production in an effort to build the production-capacity base hitting 1,000×10⁸m³ and clean-energy demonstration base as well as promote the regional economy. Taken PetroChina Southwest Oil & Gasfield Company as an example, the vital function, principle ways and obtained achievements of the enterprise-locality relation were analyzed for the great development of natural gas, some solutions of both collaboration were proposed with consideration of existing problems. Results show that (i) oil and gas exploration and development activities are exactly constrained to both subsurface and surface resources. As the exploration and development technological process, technical conditions do no longer serve as bottlenecks, and non-technical contradictions between enterprises and local entities are increasingly prominent and become one of the main factors governing this great development; (ii) enterprises and local entities should be work together to set a coordination and communication platform through deliberate planning and coordination across industrial chains, the central enterprises should build joint ventures with provincial, municipal or other local entities to initially form enterprise-locality co-sharing and co-construction mechanisms; and (iii) functions of various platforms in resource allocation and interest-sharing balance will be fully activated in order to realize mutual prosperity, and an active cooperation between petroleum enterprises and local entities will be enhanced so as to bring about favorable conditions.

Along with the development of Hubuzhai gasfield enters a later stage, and the problems of sand burial appear in most gas wells, which may lead to productivity decline and further influence a stable production. Many common-used sand-surface treatment technologies are unavailable to a good effect due to long sand-buried time, long length of sand-buried interval, impervious sand particle, and high compaction. So, an investigation was carried out on the basis of some successful experience from other foreign gasfields, a technology of nitrogen foam sand washing was optimized and used to be a tool for sand-surface treatment, and a method of snubbing process was presented to overcome defects in easy failure in wellhead BOP during a coiled-tubing sand washing. Meanwhile, an assembly of sand-washing rod string including drag bit, screw drill, and coiled tube was designed. Moreover, their application to Bu 1-X well shows that, due to operation time shorting about 37 % under the same sand-washing footage, both the snubbing process and the assembly of sand-washing are better than conventional hydraulic sand washing.

In the Lower Jurassic, 1057 block, South Turgay Basin, on the basis of sedimentologic, well-logging geologic, and seismic stratigraphic principles, a suite of fan body was identified by lot of 3D seismic, well-logging, mud-logging data and some tools including seismic-facies characteristics analysis, multiple seismic-attribute acquisition, and 3D visualization subpart engraving. In addition, both space distribution and inner structure of the fan body were also presented. With about 4 km², this fan body appears an ellipse shape with NNW-SSE trend in plane, and fan-body deposits came from the bulge belt northwestward.

As a peak-shaving power source with low carbon, environmental protection, and high quality, natural-gas power generation plays a vital supporting role in ensuring power security. However, its profitability is greatly affected by several elements, including on-grid electricity price, gas price, gas consumption for power generation, and government subsidy. Therefore, these elements and the profitability from gas-power projects that are in operation or being constructed in Sichuan and Chongqing areas were discussed so as for gas power in the rapid growth. And some suggestions were made to promote the profitable gas-power growth in these two areas. Results show that (i) the key to fuel cost reduction is to raise electricity price and further improve gas-power price linkage mechanisms, ensure stable gas supply, control gas price within a reasonable range, and lessen gas consumption in power generation; (ii) efficient and advanced H-class gas turbine equipment can actively improve power generation efficiency and overall profitability; (iii) the coordination among the five major entities related to gas power is also a fundamental way to enhance this profitability; (iv) for gas-power stations, their individual advantages, such as rapid start and stop, clean and low carbon, short construction period, low investment, and large output, can complement other peak-shaving forms to achieve integrated growth; and (v) during the 15th Five-Year Plan period, it is in urgent need to construct a batch of clean and efficient coal- and gas-power projects, and add a certain scale of regulating and supporting power sources, like new energy storage, to fill power gap and enhance regulating and supporting abilities in power system.

Some investigation and professional discussion have been carried out in an effort to estimate the development potential of carbon asset from natural-gas residual pressure power generation and make this generation's methodology meeting filing requirements of the Ministry of Ecology and Environment of the People's Republic of China. Furthermore, the key to work out this methodology was analyzed according to methodological compilation needs through reference on a carbon-credit system of CDM. In addition, the decisive elements were proposed for the compilation of such generation methodology, and an additional and monitoring management was designed. Results show that (i) via the evaluation on the potential of both residual pressure power generation and carbon-asset development in different links such as oil and gasfields, long-distance pipelines, and gate stations, these two sorts of potential achieved are 145.73×10⁸ kWh/a and 811.44×10⁴ tCO₂e/a, respectively; (ii) as for the additional methodological design, baseline scenarios are made certain to contrast the additionality. And it is proposed to directly adopt exemption from demonstration based on the potential analysis on power generation and practical work; and (iii) as for the monitoring design of methodology, the principles of credibility, accuracy and conservation should be followed, and monitoring projects' boundaries are described. Parameters and data which should be relatively surveyed in not only design but implementation stages, and the method to ensure surveying quality is defined by using emission-reduction calculations.

Zhongba gasfield, discovered in 1972, has entered into the later development stage. It’s necessary to explore new replacement strata. So, based on previous study, the oil and gas geological conditions of Xujiahe 3 Member were analyzed. Results show that (1) there are two kinds of gas reservoirs including shale-gas ones and tight sandstone gas ones; (2) for the shale-gas reservoirs, the effective shale is featured by large thickness, stable distribution, and big gas-generating capacity; and (3) for the tight sandstone gas reservoirs, which are composed of underwater ditributary channel, mouth bar sandbody, and reservoir sandbody with the assembly of intercrystalline pore, dissolution pore and fracture as the reservoir space, they connect with large-scale source rock and belong to self-generating and self-preserving ones. Furthermore, part oil and gas generated from Xujiahe 1 Member migrated vertically to Xujiahe 3 Member. Our study demonstrates that in Zhongba area, the Xujiahe 3 Member has the better association of source, reservoir, and caprock; and there is a plenty of source rock with large exploration potential. So, this member should be another important exploration stratum since Xujiahe 2 Member and Leikoupo 3 Member.

For pneumatic-hydraulic valves, a sort of key devices on long-distance gas pipelines, its normal run decides downstream gas safety. Pneumatic-hydraulic actuators, however, have frequently suffered from abnormal shutdown with high failure in recent years since most devices early constructed and put into operation in both domestic gas distribution stations and long-distance pipelines become worse, further to greatly affect production safety for numerous enterprises. Thus, the abnormal shutdown of the Shafer pneumatic-hydraulic actuator caused by device failure was discussed, and failure mechanisms were pointed out for some key parts, including LineGuard electronic line break detection controller (hereinafter refer to as LineGuard controller), power supply equipment, pressure sensor, electromagnetic valve and hydraulic circuit. Results show that (i) incorrectly triggering the LineGuard controller is the main cause of abnormal shutdown; (ii) the power supply equipment in failure generates abnormal control signal; (iii) the data distortion of the pressure sensor results in misjudgment; (iv) the abnormality of the electromagnetic valve creates emergency failure; and (v) both blockage or leakage in the hydraulic circuit lessen the driving force in this actuator. In conclusion, it is recommended to establish a multi-level protection system and improve the lightning grounding, shielding grounding, cathodic protection, and insulation joint installation in these devices according to regulatory requirements; to establish redundant mechanisms for the power supply equipment and strengthen the calibration and maintenance of pressure equipment; to regularly check the electromagnetic valve and the circuit sealing; and to incorporate the LineGuard controller into the prevention system and check its integrity and function periodically.

Taking America, the first country developing shale gas, as an example, the paper describes the shale gas development process in America and some key factors promoting the successful shale gas reform in America, introduces the development history and current situation of Chinese shale gas reform, lists some opportunities and challenges for Chinese shale gas development and gives suggestions on current shale gas development of China, for example, carrying out shale gas development activities in scientific and reasonable way, relying on the government to have certain policy guidance and development supervision, establishing a shale gas development information sharing platform, enhancing development technology introduction and innovation, reducing the consumption of water for fracturing and treating fracturing flow-back fluid.

As the accelerating market-oriented natural-gas reform in China, such fair and open infrastructures as pipelines and their connectivity have reinforced the competition in natural-gas upstream and downstream markets after the establishment of PipeChina. However, mechanisms to form previous segmented price is not able to mirror a competitive relation between gas price and source under market conditions. So, changes in China's natural-gas industrial chain and value chain after the pipeline network independence were investigated and the price transmission was examined from the perspectives of industrial chain and value chain. Then, integrating these two chains, a "dual-chain" mode was proposed. Furthermore, both price formula and natural-gas competitiveness analysis model (NGCAM) were constructed. At last, the competition among national and regional natural-gas markets was analyzed by this model. Results show that (i) the newly-constructed model can, to some extent, represent operating mechanisms on these markets after opening the pipeline network, imply the price transmission in the natural-gas industrial chain, and highlight the competition among gas-gas, gas-liquid and liquid-liquid in this chain; (ii) in terms of national market competitiveness, this model presents the competition among gas sources such as domestic gas, imported pipeline gas and LNG, and the distribution of preferential markets, namely, LNG resources in coastal areas gradually infiltrating into inland and unconventional gas like coal gas into mid-eastern China with the help of the pipeline network, resulting in an increasingly prominent collaborative development among gas sources; and (iii) in terms of regional market competitiveness, the model assumes competitive results among various sources and many changes of supply structure in the next markets, indicating that as a sort of flexible regulatory resources, LNG is supportive to pipeline gas each other, and its source has became more competitive than before.

Gas reservoirs of Suining Formation, Luodai gasfield, western Sichuan Basin, were taken as examples to analyze reservoir characteristics and microscopic seepage mechanism. And then a rational development mode was built for them, also providing guidance for similar tight sandstone gas reservoirs with ultra-low porosity, low abundance and multiple thin layers in the efficient development. Results show that (i) featured with poor physical properties, these reservoirs exhibit frequent interbedding and superimposition of sandstone and mudstone, which assumes as tight ones with ultra-low porosity. Their pore structure is mainly composed of fine pores to microscopic throat with relatively small pore-throat volume ratio; (ii) their original irreducible water boasts moderate saturation and they have larger area of gas-water dual-phase co-seepage, and core experiments under pressure depletion represent middle to higher recovery efficiency; (iii) without bottom and edge water, they belong to constant volume, closed, elastic gas-drive dry gas reservoirs with normal pressure; and (iv) they are characterized by low well-controlled reserves, short period of stable production, fast decline in pressure and production, and long-term low yield under low pressure. It is concluded that (i) geologically, this kind of gas reservoirs feature multiple thin sandbodies interbedded each other, presenting the lenticular extension. And they should be appraised and then developed progressively for enhanced recovery to increase development benefits; (ii) in the initial production stage, the highly productive and enriched zones will be preferentially developed under normal pressure if necessary; (iii) in the stable production stage, multiple layers will be co-exploited through vertical wells, and additional wells will be drilled to conduct interwell replacement for productivity; and (iv) in the production decline stage, some techniques, such as changing payzone in old wells, pressured exploitation, and foaming drainage gas recovery, may be employed to delay this decline. Meanwhile, development adjustment wells will be deployed to further enhance the recovery.

With abundant oil and gas resources, Central Asia has long been a prominent source for China to import natural gas. In recent years, some new situations on natural-gas markets, however, have presented in Central Asian countries. For example, these countries trim their natural-gas export to meet local demand and promote the long-term goal of carbon neutrality. Accordingly, it is predicted that the problem on insufficient gas sources will highlight in China-Central Asia natural-gas pipelines in the future. With the energy transformation and steady advancement of the "dual-carbon" goal in China, natural-gas demand presents a strong growth, which needs more much gas source support from overseas. In order to maintain China's strategic pattern of energy import diversification and satisfy the strongly growing demand, some suggestions on the "Belt and Road Initiative" energy cooperation with Central Asia have been made on the basis of extensive investigation and in-depth analysis. Results show that (i) Central Asia boasts not only superior base of renewable energy such as wind, solar and hydropower, but favorable national policies for related industries. So, promoting the cooperation with Central Asian countries in this field can seize opportunities of renewable energy markets in these countries and push their renewable energy industrial development, while restraining the local natural-gas demand to a certain extent; and (ii) Kazakhstan enjoys strong base and great potential in coalbed methane resources. Grasping chances to develop related industries through the cooperation with this country can strengthen its natural-gas base and meet its need in energy transformation, which is of great significance to firm overseas gas sources for China to import natural gas and maintain the pattern of diversified energy imports.