Study On Petroleum Geological Conditions Of Jurassic In Dahongqi Fault Depression Of Western Liaoning And Its Adjacent Areas

In recent years,Study on petroleum geology of Jurassic has been achieved great progress made in Dahongqi fault depression and its adjacent areas.In particular,2-D seismic data and drilling of Hei 1 and Hei 2 wells are carried out in Dahongqi fault depression.Which Completely reveals stratigraphic characteristics and distribution of Jurassic Tuchengzi Formation,Beipiao formation,Haifanggou formation,Lanqi formation and the Tuchengzi formation.Yingcheng Formation.The Beipiao formation is a potential hydrocarbon source rock layer,which are widely distributed in Dahongqi fault depression and adjacent areas,and have good exploration prospects.However,there are still some problems in the exploration process:(1)The distribution of hydrocarbon source rocks is not clear,which restricts oil and gas explorationWhen drilling in Hei 1 wells,we can see 8m fluorescent display in Haifanggou formation.Hydrocarbon potentia of Beipiao formation can not be evaluated correctly because the formation of Beipiao formation is too shallow(only 35m).The Beipiao formation is a better hydrocarbon source rocks in the region.Therefore,Sinopec drilled the Hei 2 well around Hei1 well about 5km.It is found that there are no oil and gas shows in the Beipiao formation and Haifanggou formation.(2)The fault is not clear with regard to the formation and evolution of Dahongqi fault depression and adjacent areas and the preservation of hydrocarbon source rocksThe Dahongqi fault depression is a double fault small basin,which is composed of two sets of relatively fractured faults,near North East.The interior also have complex small fractures,How do these complex small fractures in the interior control the formation and evolution of Dahongqi fault depression and its adjacent areas? In particular,several stretches and several stages are critical for the formation and preservation of hydrocarbon source rocks.To solve the above problems,this paper takes Jurassic of Dahongqi fault depression and its adjacent areas in western Liaoning as the studying object.Through stratigraphic research and field geological survey in western Liaoning,based on the datas of two drillingss and fifteen 2-D seismic data profiles in Dahongqi fault depression.Whiche Comprehensive analysis The lithology and lithofacies characteristics and regional structure setting of Jurassic strata.The thickness map of potential source rocks in Dahongqi fault depression and adjacent area is established.According to the characteristics of sedimentary facies distribution and organic geochemistry of hydrocarbon source rocks,Comprehensively analysing the prospect in Dahongqi fault depression and adjacent area.1.Comparison of The Dahongqi fault depression and its adjacent basins about Lithology and lithofaciesThrough the contrast between the Dahongqi fault depression and its adjacent areas,The Beipiao formation is a clastic rock and a coal seam,which is a better hydrocarbon source rock series.The Haifangou formation is the main component of polymictic conglomerate of alluvial fan facies.Lithology and lithofacies of Dahongqi fault depression is diffirent from adjacent basin's on lithology and lithofacies,Lanqi formation is a set of volcano rock in area.however,Lanqi formation is a hydrocarbon source rock series in the Dahongqi fault depression and its adjacent areas.Which may be related to regional strike slip.The Tuchengzi formation is a set of clastic rock,depositional environment is made up mostly of fan delta facies.2.The characteristics and distribution of sedimentary facies in Dahongqi fault depression and its adjacent areasThrough the core,logging and seismic data,identification criteria of the single well facies and seismic facies and their corresponding relations are established.Recognizing the alluvial fan facies,fan delta facies and lacustrine sedimentary environment characteristics.The distribution characteristics of sedimentary facies in Beipiao formation of Dahongqi fault depression and its adjacent areas: The littoral and shallow lacustrine facies are generally developed in the whole area,and the connectivity is better among regions;The fan delta facies is mainly developed in the southeastern and northwestern margin of the study area;The semi deep lake is mainly located in the southeast and southwest study area.3.Tectonic evolution history of Jurassic in Dahongqi fault depression and its adjacent areasDuring the deposition of the Beipiao formation,Dahongqi fault depression entered the initial stretch,the extension amount was about 2.45 km,the extension rate was 5.03%.Meanwhile,the top erosion of the Beipiao formation was obvious.During the Haifangou formation deposition period,Dahongqi fault depression Start from stretch to extrusion,the overall amount of extrusion is small,only 1.05%.Stretching is weak and stretching rate is only 0.02% during the deposition Lanqi formation period.At this time,the paleo Pacific plate suddenly began to subduction to Eurasia,a large number of volcanic eruptions were triggered on the region.The Tuchengzi Formation Period is in the transitional period of the thinning of lithosphere in eastern China.The tension is mainly in the fault depression,and the extension rate is 5.52%.Generally speaking,the tectonic environment of Dahongqi fault depression in Jurassic period is relatively stable,which is favorable for hydrocarbon generation.4.Resource potential analysis of The Dahongqi fault depression in Jurassic periodThe total area of Dahongqi fault depression and its adjacent area are 5398.3km2,The potential source rock of thickness is generally 40-120 m and the maximum thickness is 200 m.Which is Mainly distributed in the former Dahongqi fault depression and the new peripheral area of The Dahongqi fault depression(Xinlitun Town periphery)With "South thick,North thin" characteristics.Through the comparative analysis of organic geochemistry of the Chaoyang-Beipiao basin,Jinlingsi-yangshan basin and Dahongqi fault depression.organic matter abundance is generally higher in Liaoxi area.Organic type II-III is the main type,Maturity of organic matter are Basically in the mature stage.The organic abundance and organic matter types of Hei 2 well are basically the same as those in western Liaoning.Which is different in the maturity of organic matter.The maturity of organic matter in Hei 2well is in high mature stage,which may be related to the samples located in the tectonic zone.The tectonic environment in the depression is relatively stable,and it's organic abundance and organic type should be better.The comprehensive analysis shows that Dahongqi fault depression and it's adjacent area have a good prospect of exploration.