| The Y14 well area of XW Oilfield is located in the north Shaanxi slope of the Ordos Basin.Now the main mining layers are the Chang 2 oil layers group and the Yan'an oil layers group.The initial mining stage is based on the natural energy attenu ation until 2012 adopts the small-scale water injection mining.At present,the strata pr essure in the study area continues to decrease,the strata energy decreases rapidly,the oil production rate and the yield is low,the water content is as high as 88.4%.More over,there is no perfect water injection well network in the mining layer,result the d egree of water flooding control is low,and the water injection utilization rate is low.In order to further improve the development degree of the reservoir,this paper studies and improves the water injection development plan of the Chang 2 reservoir of the main production layer in the Y14 well area.Based on the existing data in the study area,this paper conducts basic geological research and comprehensive evaluation of the existing injection and production system on the Chang 2 reservoir in the Y14 well area.Through the well logging data,the Y2 well zone Chang 2 stratum is subdivided into Chang 222,Chang 221,Chang 21 sm all layer and Chang 222 small layer is stable in the all study area.The Chang 221 and Chang 21 have partial erosion in the study area,and there are unconformity contact with the overlying stratum;combined with the elevation data of the well site,the top structural features of the Chang 2 small layers are studied,and the overall structural change is gentle,shows the east high and low west tendency,the partial have small a mplitude nose bulges.With coring observation and particle size analysis combined and logging phase characteristics,it is considered that the Chang 2 is river facies,and th e Chang 222 is braided river sediment,Chang 221 and Chang 21 as a meandering river sediment.Through the analysis of sandstone thin sections of the 222 reservoir sandsto ne in the Y14 well area and of the mercury intrusion data study found that the Chan g 222 reservoir mainly have fine-grained feldspar quartz sandstone,which is dominated by iron-containing calcite cement with an average porosity of 13.5%and an average permeability of 5.25×10-3um2,the whole is ultra-low-medium-hole special low-permeabi lity reservoir;combined with oil test data and logging data,analyzes the four-relations hip relationship of reservoirs,establishes logging interpretation model,and discovers th e Chang 222 reservoir's interlayer heterogeneity is strong,and the plane pore permeabil ity distribution is affected by the sedimentary and sand body distribution.It is determi ned that the lower limit of the effective thickness of the Chang 222 reservoir is the fi ne oil sandstone with a lower permeability limit of 1.41×10-3um2 and the lower limit of porosity is 9.8%,the lower limit of resistivity is 11.0?.m,and the oil saturation i s 30%.On this basis,it is determined that the oil area of Chang 222 reservoir is 15.86 km2,and the geological reserves are 737.99×104 t.Combined with production data a nd dynamic data analysis,the strata pressure in the Y14 well area is attenuated,and t he oil recovery rate continues to decrease.Water-flooding is needed to maintain forma tion energy and improve recovery ratio.Through five sensitive data,analysis of format ion crude oil data,Chang 2 reservoir is weak speed sensitive,medium weak water se nsitive reservoir,crude oil is low specific gravity,low viscosity crude oil,combined with reservoir lithology and physical property analysis,Chang 2 reservoir is suitable f or water-flooding.The degree of water flooding control of the Chang 222 reservoir is55.84%,the degree of water flooding control is low,the comprehensive moisture cont ent is 88.4%,and the water injection utilization rate is low.It is necessary to improv e the injection and production well network.Finally,the comprehensive geological res earch is put forward.The water injection well network adjustment scheme of the Y14well area in XW oilfield.Combined with the reservoir geological research and histori cal production.The reasonable injection-production well ratio is determined to be 1:2.49,and the reasonable pressure is calculated to be 8.43Mpa.The degree of water flood ing reserve control can reach 72.7%,and the recovery rate can reach 12.09%. |
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