| Shale gas is a kind of unconventional natural gas existing in shale,mainly in adsorption and free state.It has advantages such as wide distribution and large resources,Has not only attracted the attention of many countries in the world,And a few countries,including China,have invested in active mining.Research shows,China’s shale gas resources have great potential,wide distribution range,and many types,Good exploration and development prospects,Is an important supplement to the shortage of conventional natural gas.As China’s marine shale gas exploration and development has made substantial progress in a basin——Sichuan Basin,four blocks——Fuling（Shale gas reserves exceed 800 billion cubic meters）,Weiyuan,Changning（Weiyuan Changning shale gas reserves exceed trillion cubic meters）,Weirong（Shale gas reserves exceed 100billion cubic meters）,it has been put into commercial development.According to the latest data,as of the end of 2022,China’s cumulative proven shale gas reserves exceed3.0×1012m3,Cumulative shale gas production exceeds 300×108m3.It is estimated that in the next ten years,China’s shale gas production capacity will exceed 1000×108m3Scale of.Thereby leading the world.Then,China’s marine terrestrial transitional shale gas,From the current exploration data and understanding level,South North China Basin is one of the most favorable areas.The research of the thesis is carried out to further understand the present distribution and preservation of the shale in the basins of the southern part of North China,especially in the Upper Paleozoic marine-terrestrial transitional facies o f Zhongmu block,the generating capacity of gas and scale of shale,the formation mechanism and mode of shale gas reservoirs,indicate which vertical distribution and planar areas are relatively rich in shale gas,and realize the exploration breakthrough of marine-terrestrial transitional shale gas in our province as soon as possible,especially the commercial development and utilization.Based on the analysis and research of previous data and achievements,Utilizing new seismic and drilling data from Zhongmu Block and Mouye1,Weican1,Zhengdongye1,2,1HF,And through detailed observation of the core,And statistics on the development and distribution of fractures in rock cores,Especially based on experimental tests such as mineral composition analysis,organic geochemical testing,Porosity and permeability measurement,scanning electron microscopy,High pressure mercury injection,methane isothermal adsorption,on-site desorption,etc.To better analyze and explore the geological conditions and accumulation and distribution laws of oil and gas formation in this area.The geological conditions of oil and gas formation in South North China Basin are analyzed,and Zhongmu Depression is selected as the foundation to study the structural background,sedimentary environment and distribution characteristics of marine-terrestrial transitional shale.With the organic geochemical analysis of shale as the key,the thesis quantitatively analyzes the abundance,type and maturity characteristics of organic matter,focuses on shale composition and physical properties,and analyzes mineral composition,proportion,all kinds of primary pores,secondary pores and fracture development.On the basis of the above research,the hydrocarbon migration,source-reservoir communion,gas content,dissociation and adsorption,and preservation conditions are comprehensively analyzed.and the formation conditions and enrichment laws of marine-terrestrial transitional shale gas in Zhongmu Depression are comprehensively obtained.（1）Structurally:the basins of the southern part of North China feature subdivision of blocks in the east-west direction and subdivision of belts in north-south direction,which commonly forms the present tessellated,piling-up and compounding structure of the basins of the southern part of North China.Zhongmu block spans Kaifeng depression and Taikang uplift.（2）From Kaifeng Depression to Taikang Uplift,From Late Carboniferous to Middle Permian,This region presents a wide range of marine and terrestrial transitional environments,Deposited organic rich shale including Taiyuan Formation and Shanxi Formation,Its thickness can reach 377～568m,The existence of these rocks,Greatly enriched the material basis for shale gas formation,Is also a prerequisite for shale gas development.（3）The important strata of shale gas resource distribution involve the Carboniferous and Permian systems,While Taiyuan group and Shanxi group are relatively optimal,Specifically,their dark shale is relatively thick,The distribution range is also wide,And has a high organic content,Generally speaking,their organic content ranges from 0.07%～4.54%,And generally belongs to excellent hydrocarbon source rocks.The results of laboratory analysis indicate that,The reflectance of vitrinite in the Upper Paleozoic coal measure source rocks significantly exceeds 3.5%,This indicates that they have entered a high evolutionary stage,However,it is still in the angry stage.（4）Reservoir:Quartz is the main brittle mineral in shale,and illite is the highest in clay minerals.The shale reservoir in Zhongmu Block is mainly composed of clay minerals and quartz,The content of quartz is between 6～55%,The content of clay minerals ranges from 32%～64%.In addition,the porosity of this area is between 0.3%～8.8%,Generally2.2%;Permeability is between 0.023～0.92×10-3μm2,The average value is 0.045×10-3μm2.（5）Gas Content:The average gas content of the core sample found in desorption is 1.8m3/t,which indicates that Zhongmou Block has great shale gas potential.Accumulation:Self-generated and self-stored gas-bearing system.There are many factors that affect shale gas content.Based on sedimentary environment and geological analysis,Zhongmu Block studies organic geochemistry,reservoir physical properties,mineral composition and their relationship with gas content,the thesis analyzes the influence of different factors on gas content and shale gas accumulation.（6）Zhongmu Block covers an area of 1400km2,The average thickness of the three favorable geological structure layers reaches 50m,he density of shale reaches2.6g/cm3,with an average gas content of 1.5m3/t.Calculated q50 resource amount:2860×108m3.Vertically,it is mainly influenced by sedimentary facies.Taiyuan Formation and Shanxi Formation are valuable strata for shale gas generation and storage,and Taiyuan Formation is better than Shanxi Formation.On the plane,it is mainly affected by the late differential rise and fall,and Kaifeng Depression,Taikang Uplift and Luyi Depression in the north of Zhoukou Depression are all valuable.The research of the thesis is expected to provide guidance for further deepening shale gas exploration,finding favorable enrichment areas and breaking through industrial gas flow in this area. |
