Characteristics Of The Lower Cretaceous Shales And Cap Rock Of Eastern Basin Group To Songliao Basin

In recent years,Lower Cretaceous mud shale of the eastern basin group of Songliao basin is a favorable exploration target strata.In the Tonghua Basin,we find that the good oil and gas shows in the mud shale and tight sandstone of TongD1 well,which indicates the region with conventional oil and gas and unconventional oil and gas exploration prospect.As a result,the mud shale of lower cretaceous in the study area has a long-term research significance.At present,the definition of mud shale has not yet unified.Mud shale in this paper is a general designation,mainly including mudstone and shale.Because of the special concept of mud shale,collected and measured a large number of geochemical data and petrology characteristics data of Lower Cretaceous mud shale of the eastern basin group of Songliao basin,the paper attempts study the hydrocarbon generation capability of the mud shale,the possibility of formation of unconventional reservoirs and the sealing ability,through the petrology characteristics,geochemical characteristics of the mud shale and seal ability.The results showed that the Lower Cretaceous mud shale in the study area is mainly developed in Marina shallow lake and semi-deep lake facies.The sedimentary water of the north of Lower Cretaceous is shallow,the variation in thickness of the shale with a high content of silty.In the south,the sedimentary water is deep,little change in thickness of the shale with a low content of silty.By XRD and scanning electron microscopy(SEM)experiments of the mud shale.Brittleness mineral content of the Lower Cretaceous mud shale(?40%)is high,that is beneficial to formation of cracks under the action of external force.Under the influence of quartz mineral content,total tender has the very good neighbor with mineral content of Barnett shale.The cracks of the Lower Cretaceous mud shale developed,and has positive correlation with organic matter maturity,and have a certain critical value.Pore throat is mainly microporous-middle hole.The microporous holes for the most probable,with the possibility of formation of unconventional reservoir.Through the analysis of geochemical data,the mud shale of Lower Cretaceous in the study area has a certain hydrocarbon-generating ability,and the north of the shale is batter than the south one.The Lower Cretaceous mud shales in the north of the study area reache moderate deviation organic matter abundance.These source rocks resulting gas contain type ?2 kerogen and ? kerogen at mature to over-mature stages.The Lower Cretaceous mud shales in the south of the study area are easy to generate gas and oil with a high abundance of organic matter.These source rocks mainly contain type I-?2 kerogen at low-mature to mature stages.Compared to the geochemical characteristics of the mud shale at home and abroad,the most of mud-shale samples of Lower cretaceous falling in the area of TOC = 1.0%~24.0% and Ro=0.4%~1.0%,has the potential of generating shale gas.In the study area,the local cap rocks and regional cap rock lithology of the Lower Cretaceous is not only a mud shale,as well as volcanic rock and tuff,but this article mainly discuss the mud shale,mainly including silty mudstone,tuffaceous shale,mudstone and shale.The diagenetic stage of mud shale is mainly at the rock middle stage A1 and A2.D Displacement pressure is bigger.Sealed performance is mainly in good,well and good in three levels with good sealing capacity.According to the source control theory preservation condition control theory knowledge,combined with the result petrology characteristics,geochemical characteristics and characteristics of closed of mud shale of Lower Cretaceous in the study area,the discussion of shows that the exploration and development of the south area has more value in the study area.