“Exploring petroleum inside source kitchen”: Shale oil and gas in Sichuan Basin

The Sichuan Basin is rich in shale oil and gas resources,with favorable geological conditions that the other shale reservoirs in China cannot match.Thus,the basin is an ideal option for fully"exploring petroleum inside source kitchen"with respect to onshore shale oil and gas in China.This paper analyzes the characteristics of shale oil and gas resources in the United States and China,and points out that maturity plays an important role in controlling shale oil and gas composition.US shale oil and gas exhibit high proportions of light hydrocarbon and wet gas,whereas Chinese marine and transitional shale gas is mainly dry gas and continental shale oil is generally heavy.A comprehensive geological study of shale oil and gas in the Sichuan Basin reveals findings with respect to the following three aspects.First,there are multiple sets of organic-rich shale reservoirs of three types in the basin,such as the Cambrian Qiongzhusi Formation and Ordovician Wufeng Formation-Silurian Longmaxi Formation marine shale,Permian Longtan Formation transitional shale,Triassic Xujiahe Formation lake-swamp shale,and Jurassic lacustrine shale.Marine shale gas enrichment is mainly controlled by four elements:Deep-water shelf facies,moderate thermal evolution,calcium-rich and silicon-rich rock association,and closed roof/floor.Second,the"sweet section"is generally characterized by high total organic carbon,high gas content,large porosity,high brittle minerals content,high formation pressure,and the presence of lamellation/bedding and natural microfractures.Moreover,the"sweet area"is generally characterized by very thick organic-rich shale,moderate thermal evolution,good preservation conditions,and shallow burial depth,which are exemplified by the shale oil and gas in the Wufeng-Longmaxi Formation,Longtan Formation,and Daanzhai Member of the Ziliujing Formation.Third,the marine,transitional,and continental shale oil and gas resources in the Sichuan Basin account for 50%,25%,and 30%of the respective types of shale oil and gas geological resources in China,with great potential to become the cradle of the shale oil and gas industrial revolution in China.Following the"Conventional Daqing-Oil"(i.e.,the Daqing oilfield in the Songliao Basin)and the"Western Daqing-Oil&Gas"(i.e.,the Changqing oilfield in the Ordos Basin),the Southwest oil and gas field in the Sichuan Basin is expected to be built into a"Sichuan-Chongqing Daqing-Gas"in China.

Characteristics of shale gas reservoirs in Wufeng Formation and Longmaxi Formation in Well WX2,northeast Chongqing

To further understand shale reservoir characteristics of Wufeng Formation and Longmaxi Formation in the Wuxi area,northeast Chongqing,based on drilling data of Well WX2,and taking the graptolite biostratigraphy as the standard marker of stratigraphic division and comparison,the geochemistry,petrology,reservoir space and properties of organic-rich black shale were well investigated,and its gasbearing capacity and controlling factors were also analyzed.The result shows that in the Wufeng Formation and Longmaxi Formation of Well WX2,the organic-rich shale is 89.8 m thick and is characterized by good kerogen type,high organic abundance,moderate maturity and favorable hydrocarbongeneration condition,and the graptolite sequence is developed completely and continuously;the organic abundance is influenced by depositional rate,and the slow depositional rate is favorable for accumulation of organic matter in the black graptolite shale;from top to bottom,content of siliceous minerals increases and content of clay minerals decrease,therefore the brittleness increases;the organicrich siliceous shale and clay siliceous shale are favorable lithofacies for development of shale reservoirs;the nanopore is dominated by the parallel-plate pore with four open sides and has good connectivity;the pore size distribution curve has the multimodal characteristic,and the pore diameter mainly is in the range of 0.42e0.62 nm and the range of 3e5 nm;organic pores and interlayer pores of clay minerals make the greatest contribution to the total pore volume,while pores of brittle minerals have the least contribution;from top to bottom,organic pores gradually increase while interlayer pores of clay minerals gradually decrease;the on-site core gas content exceeds 8 m3/t,and the gas-bearing capacity is jointly controlled by hydrocarbon generation,reservoir and preservation conditions;and the WF2-LM6 biozone of the Katian to the early Aeronian is the high-quality shale reservoir,where the LM1 biozone of the Hirnantian was the best“sweet spot”which is the target of horizontal well drilling.

全面落实 提高疫情防治人员薪酬待遇关键点及应对建议

本文基于我国新冠肺炎疫情发生及防治现状,根据目前防疫人员薪酬待遇相关政策,针对不同区域医疗人力资源投入,分区域、分层次地分析、探讨如何合理确定和提升疫情防治人员薪酬待遇,阐述了在落实薪酬待遇中应注意的问题和应关注的焦点,提出了提高疫情防治相关人员薪酬待遇的若干建议。