| The YW area is located in Zhidan county of Shaanxi province which belongs to the middle and western area of Shanbei Slope in Ordos Basin.Chang 6 oil formation is the main reservoir and production,which is delta front sedimentary facies that have poor permeability and porosity,strong heterogeneity,it is considered as low porosity and extra low permeability reservoir.since water flooding carries out in the area,the contradictions between the planes,the inter-layers and the inner-layers are increasing,output are decreasing,production stabilization is difficult and residual oil content is high,to solve these problems,this paper detailedly evaluates geological characteristics reconnition and development effects of the area,and proposes technical countermeasures to have important significance for adjusting exploit,production stabilization and mproving reservoir recovery efficiency of the oil field.Based on vast drilling,logging,well logging,experimental analysis,production and injection,etc,using the theory and method of principles of sedimentology,Reservoir Geology,reservoir engineering,etc,this paper synthetically analyzes stratigraphic characteristics,entonic features,edimentary and evolutionary characteristics and reservoir features,the result shows that four subgroups(Chang 64,Chang 63,Chang 62,Chang 61)of Chang 6 oil formation have oil shows,according to depositional cycle combination and the actual development and production,Chang 62 and Chang 61 is detailedly divided into Chang 62-3,Chang 62-2,Chang 62-1,Chang 61-3,Chang 61-2,Chang 61-1 six layers,the main oil producing is Chang 61-1,Chang 61-3and Chang 62-1.The local places of the area grow nose-like uplift;the type sedimentary microfacies have underwater distributary channel,mouth bar,distal bar and distributary bay microfacies;reservoir rock type is fine-grained feldspar sandstone,average porosity is 10.9%and permeability is 0.96×10-3μm2,which have poor permeability and porosity and microthroat,so it is considered as low and extra low permeability reservoir;the reservoir type is mostly lithological reservoir,which have no gas cap,edge waterand bottom water and typical the elastic-soluble gas driving oil.On the basis of the recognition of geological characteristics,further from production performance characters,well pattern and density,production and injection proration of the single well,injection-production relation,the non-correspondence of injection and production,etc,this paper makes a systematic analysis.the study shows that the reasonable oil/water wellquantity ratio is 3.2,well pattern form is invert nine-spot method and its part is not imperfect;well density is 15.9kou/ km2,well array distance is 450×150m,single well productivity is1.74t/d,water flooding amount is 11 m3,injection-production ratio is 1.3,rate of oil production is 1.15%,formation pressure is from 14.8MPa to 18.8MPa,flow pressure of oil well is from3 MPa to 5MPa,flow pressure of water well is from 26.4MPa to 28.1MPa;oil layer of wells are developmental and its connectivities are good,but actual injection-production relation is not well;reserves producing degree is integrally higher and average value is 90%,the water drive reserves control degree is bad and is 50%,water flooding reserves producing level is medium ang is 74.8%;injection-production ratio of the oil is high at present and is 77%,injected water utilization ratio is also high and 80%,but water flood effect is worse because of the non-correspondence of injection and production.from upper analysis of several aspects,it summarizes the main contradictions and problems development of the area and proposes corresponding technical countermeasures-layer-adjusting,Pattern perfect and the measures of increasing yield. |
PDF Full Text Request