Study On Differential Reservoir Quality Of Channel Sandbody In Shahejie Formation, Qinan Depression

Reservoir geology is a major project in the petroleum exploration.It requires understanding reservoir horizon,geognosy character,sedimentary environment, tectonism and its effect,origin type,reservoir properties,pore structure, oilness,rock body geometry, distribution regulation,and distribution and prediction about advantageous reservoirs.With the petroleum exploration development,reservoir geology is more progressional, and more significant.Qinan ramp region-Chengning uplift,locates in the South part of Dagang tectonic belt,is the stress area of lithostratigraphy reservoirs.The north of the ramp region is Qinan depression,which is a long-term growing hydrocarbon depression. Tertiary stratum uplifts and forms ramp belt in the west,Zhang Juhe tectonic belt in the east, and Yang Erzhuang fault belt in the south.The western ramp belt reveals well exploration success in lithostratigraphy reservoir of recent two years,and YouYi oil field discovering in the southern Yang Erzhuang fault belt and ZhangDong oil field discovering in the eastern Zhang Juhe Tectonic belt,became major product region,the main hydrocarbon reservoir assemblage includes Esl segment and Es3 segment in Tertiary.Predecessors have analyzed sedimentary system in Tertiary, factors controlling reservoir development,and generation condition of lithostratigraDhy reservoirs. The previous research indicates that the Esl segment and Es3 segment stratum develops bank and dam deposition,and offshore underwater fan sediment in the control of palaeotectonics background,like as the major reservoir of YouYi oil field in the south of Yang Erzhuang fault belt belonging to offshore underwater fan sandbody.With the exploration development of YouYi oil field,people recognize that rapid variation of reservoir lateral change in the region and scarcity of sedimentary facies research causes to the difficulty of advantageous reservoi prospect.Because the exploration well such as Qinan2,Qinan6,Qinan7,QinanS,shows good oil and gas,and reservoir property is low.Recently the most important task is looking for advantageous sandbody,so sediment reservoir appraisal, sediment microfacies subdivide,research about factors controlling reservoir attribute,summarization about reservoir geology pattern,sandbody distribution regulation,and advantageous reservoir prospect,will became the geology base of oil and gas exploration.This paper bases on the sediment facies research in Qinan depression,utilizes rock core observation,logging,and geologic control datum,and then uses 3D seismic to pursuit channel sandbody,in the end comprehensive research reservoir of Esl segment with modern laboratory analysis technique.In the aspect of reservoir lithology,this paper analyzes the pore organization and reservoir property in Sha Hejie formation,discusses the control of original mineral composition and diagenesis, and then indicates the distinction and effect of differential channel sandbody reservoir property,combine secondary pore distribution regulation and seismic inversion technique,divide advantageous reservoir distribution.Seismic attribute channel sandbody pursuit reveals that channel sandbody develop well,with typical morphological characteristic and clear internal structure,it is multisystem composed by multi-lenticular sandbodys.The background of Qinan depression make for fault block-lithologic reservoirs trap and updip pinchout reservoirs lithologic trap,exploration potential is great.Analysis of deposition environment indicate that in the Sha Hejie formation, research region locates lowland area between Zhang Juhe and Yang Erzhuang tectonic belt,the steep depositional gradient,intensely synsedimentary faulting movement including Yang Erzhuang faults and Zhaobei faults,offer beneficial palaeogeographic background for gravity flow channel.In the bottom of up-Esl and mid-Esl gravity flow channel group well.Through Diagenesis research,the paper indicates that channel sandbody is in A stage of late-diagenesis,it benefits the secondary pore development,and the sequence of diagenesis includes feldspar leacheate(?)clay membrane(?)micrite calcite cement(?)quartz overgrowth(?)dissolution of limestone debris and feldspar,kaolinite fill(?)deposition of par calcite,chlorite,ferrocalcite and ankerite deposition.Differential analysis of reservoir property shows the property of reservoir is effected by below factors:In the diagenesis,dissolution of limestone debris and feldspar is the major factors accelerating secondary pore development;calcite cementation,quartz overgrowth,kaolinite deposit is main factors decreasing secondary pore,and calcite cementation is much obvious.In the sediment,matrixes fill is the main factors declining low pore,low permeability.Though dissolution of limestone debris is the major origin of calcite cementation,limestone debris is not the direct factors effecting pore development because of its intensive anti-pressure property. From the sediment diagenesis feature in Sha Hejie formation,composing reservoir attribute characteristic,the paper summarize four pore evolution patterns.â‘ Lakeshore bank and bar type,includes the characteristics:good separation and sideways connectedness of sandbody,much development original pores, general denudation,more secondary pores,good reservoir property;â‘¡main gravity flow channel type,includes the characteristics:good sideways connectedness of sandbody,much development original pores,general denudation,more secondary pores;â‘¢flank distal sandbody of gravity flow channel type,includes the characteristics:bad sideways connectedness of sandbody,much development original pores,weak pore fluid movement,general carbonatite cementation and kaolinite deposition,universally metasomatism,bad secondary pores;â‘£underwater fan inter-bay type,includes the characteristics:high content of matrix,weak pore connectedness,intensive compaction,weak pore fluid movement,bad secondary pores.Base on the above research,the paper draw the conclusion: gravity flow channel sandbody is the major exploration region.Reservoir property of main gravity flow channel and flank distal sandbody of gravity flow channel is distinctive.It interprets why the reservoir attribute of Qinan2,Qinan6,QinanT,and Qinan8 is weak in the early exploration.The paper emphasize that the center part of the main gravity-flow channel sandbody is potential targets.