In order to evaluate the fracability of some shale reservoirs with burial depth over 3500 m, many cores sampled from deep shale reservoirs of Wufeng-Longmaxi Formation in Yongchuan block were taken as objectives to analyze the uniaxial and triaxial rock mechanical parameters, and X-diffraction composition and study the effects of brittleness index, horizontal stress difference coefficient, diagenesis, and fracture toughness on this fracability. The weight of these four affecting factors was determined by means of analytical hierarchy process (AHP). And one model to evaluate the fracability was established and then verified by using pump-off pressure in five shale gas wells during fracturing. Furthermore, this model was used to guide a 24-staged fracturing for YY5-2 well. Results show that (1) this established model based on brittleness index, horizontal stress difference coefficient, diagenesis, and fracture toughness can not only better reflect the fracability of deep shale in Yongchuan block but also be used to classify the fracability so as to guide on-site fracturing; and (2) it is only 83.13% correlated with the pump-off pressure. Therefore, in order to improve its accuracy to evaluate the fracability in Wufeng-Longmaxi Formation, it is necessary to further consider other factors affecting the fracability.

Recently, Sinopec Southwest Oil & Gas Company has been strengthening its exploration on lacustrine Da'anzhai Member of Jurassic Ziliujing Formation, Zhongjiang slope, western Sichuan depression. And industrial oil and gas flow has been obtained from many wells, showing promising exploration potential. In order to further determine shale oil and gas resource potential in this member, its sedimentary setting and areal distribution characteristics were analyzed, including geochemical features (e.g. total organic carbon (TOC) and its areal distribution, and organic-matter type and maturity), reservoir characteristics, gas content, preservation condition, and engineering physical characteristics. Then, it was pointed out that the Da'anzhai Member in the study area has good geological condition to form shale oil and gas. Results show that (1) the high-quality shale of Da'anzhai Member has some characteristics of great thickness, extensively areal distribution, higher TOC, and better organic-matter type and maturity, better physical property, and higher content of brittle mineral; and (2) this member is characterized by shallow burial depth and high formation pressure coefficient available for stimulation. In conclusion, Fuxing, Huilongchang, and Yongtai regions in the eastern to southeastern study area are the favorable target ones of shale oil and gas.

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.

It is hardly to identify lithology of igneous rock via mud logging. So, the Permian igneous rock, Sichuan Basin, was taken as an objective to analyze both lithological and element mud-logging characteristics. Then combined with wireline well logging, thin-section identification, and regional geological understandings, it was pointed out that one technology of element mud logging can be used for lithological identification. Based on the application of element mud-logging technology, it is shown that the Permian in Sichuan Basin is dominated by basic and ultrabasic igneous rock and it is overall alkalinity leaning. For the igneous rock, its lithologic identification chart established on the basis of element mud-logging data can effectively reveal geochemical characteristics of different types of rock, e.g. clastic, carbonate, and igneous rock. Single-well practice demonstrates the reliability of lithological interpretation chart. In conclusion, TAS chart shows that the element mud-logging technology and other conventional petrochemical analysis technologies are accordant in the understanding on igneous-rock lithology, also indicating that this element mud-logging technology can reflect igneous-rock chemical composition correctly. In addition, this technology based on lithological identification chart of Permian igneous rock in Sichuan Basin can effectively define limestone in Maokou Formation, clastic rock and different types of igneous rock in Longtan Formation, and the position of different lithology in the chart is essentially the reflection of mineral content. What's more, in essence, the chart method is also a kind of probability statistics method. In the currently established chart, only two wells are taken as analysis points. Along with more and more wells have been drilled into igneous rock, the chart shall be updated and improved further.