Characteristics Of Clastic Reservoirs And Favorable Areas Prediction Of Yingcheng Formation In The Dehui Fault Depression Of Songliao Basin

Songliao basin is located in the northeast of China.It has been explored for more than half a century and has great potential for deep gas exploration in the basin.The object of this research is the clastic reservoirs in Yingcheng Formation of Dehui Fault Depression and we used casting thin slice,X-ray diffraction analysis of the whole rock composition,scanning electron microscopy and other technical means to study the reservoir characteristics based on the perspective of sedimentology and diagenesis,and then selected the favorable areas.The results of the research show as follows:The reservoir of Yingcheng Formation in central part of Dehui Fault Depression is characterized by semi-deep lake facies,while fan delta sedimentary system is widely developed on both sides of the fault depression.The sand bodies of the reservoir have good transverse continuity,and each single well presents multi-superimposed fan bodies in the vertical direction.The lithology of the reservoir in study area is mainly feldspar lithic sandstone and lithic feldspar sandstone.The particles have medium sorting,and the particles are mostly in point and linear contact with each other.The overall component maturity is low,and the cementing materials in the interstitial materials are mainly of pore type and contact type cementing.The pores are mainly secondary dissolution pores and the sortings of pores and throats are good,but the connectivity between pores is poor.The average porosity of the reservoir is 9.41%,the average permeability is 0.207 m D and the reservoirs belong to extra-low porosity and extra-low permeability reservoir.The main diagenetic stage of the clastic reservoirs in the study area is at the middle diagenetic stage A,and in some areas to the middle diagenetic stage B.The whole diagenetic evolution sequence is: compaction(whole process)-early carbonate cementation-siliceous cementation-dissolution-late carbonate cementation.Combined with the analysis of logging data,the logging curves of natural gamma ray,compensated neutron,compensated density,acoustic time difference and resistivity were selected for semi-quantitative calculation,in order to study the logging characteristics of each diagenetic facies.The clastic reservoirs in the study areas are divided into four diagenetic facies: compacted tight facies,carbonate consolidated facies,clay mineral filled facies and unstable component dissolution facies.In combination with the comprehensive analyses of the sedimentology and diagenesis,according to the geological factors,reservoir physical parameters,geophysical parameters,the reservoirs based on reservoir performance are divided into four types: Type ?(good),Type ?(medium),Type ?(poor),Type ?(very poor).It is concluded that the favorable reservoirs(? and ?)in the study area are: Northwest of Baojia Dustpan-shaped Sag,area around Well Deshen 8 in the south of the Baojia Dustpan-shaped Sag,area in the middle of Lanjia Dustpan-shaped Sag,area around Well Wan 17 in the north of Nong'an Graben,area in the north of Huajia Slope Belt and area around Well Deshen 20 in the north of Longwang Dustpan-shaped Sag.