Reservoir Characteristics Of The Fifth Member Of Majiagou Formation In Sulige East District

Located in the North of the Ordos Basin,Sulige gas field is one of the largest gas fields discovered in China so far.Gas reservoir development of the upper Paleozoic He 8 and Shan 1 have developed a stage of stable,strengthen the research of the lower Paleozoic reservoir characteristics to find out the law of gas reservoir distribution,which is an effective measure to realize productivity superseding.Focus on Mawu1-5(M1-5)sub-segment and based on the predecessors,with theoretical guidance of the reservoir geology and sedimentology,using logging information as foundation,combining with core observation,thin section identification,the paper conducted an intensive research on the zone of interest in regarding of its reservoir lithology,reservoir type,pore texture characteristics and controlling factors.Also the paper evaluated and forecast the reservoir's range of profitability.The stratum of objective interval was divided by stratigraphic correlation and electrical characteristics of the rock.The M1-4 sub-segment reservoirs in this area is identified to made up of denudation vug dolomite,crystalline dolomite and other types of carbonate rocks with the help of cores,flakes and logging data.The main ingredients filled in the reservoir space is gypsum concretion dissolved pore.The reservoir is low porosity and permeability.Effective reservoir is mainly distributed in M41a,followed by M13 and M2.The M5 sub-segment is made up of microcrystalline limestone,micrite dolomite and crystalline dolomite.The main ingredients filled in the reservoir space is intercrystal pore.The reservoir is low porosity and permeability either.The data of porosity and permeability increase exponentially and the favorable reservoir develop discontinuously.The effective reservoir of M1-4 is based on the large area of distribution of gypsum concretion on the superatidal zone.The greater the stratum is intact,there is the possibility of gas reservoir exists,Micro highlands and micro platform of transition zone and the both sides of groove are favorable for gas reservoir distribution,and structure affects gas water distribution.Reservoir of M5 is mainly controlled by the burial diagenesis has transformed penecontemporaneous dolomite into intercrystal pore dolomite.The effective reservoir distributes into the bank body is due to the distribution of dense limestone.Considering manipulating factors of the reservoir,combined with pore throat structure and physical properties of each production formation,to establish the evaluation criteria for the area,the favorable reservoir of the M1-a and M5 sub-sections in this area is divided into ?,?,? categories.By restoring micro morphological characteristics of pre-sedimentation basement of M5 sub-segment and looking for sedimentary micro upheaval to predict the distribution of dolomite and the favorable reservoir.