Research On Remaining Oil Characteristics Of Kalamkas Oilfield At Later Stage Of High Water Cut

With Kalamkas Oilfield in the Buzachi Peninsula in the north of the Republic of Kazakhstan as the research object,this paper made fine reservoir research.Located within Mangistau District,Mangistau State,Kalamkas Oilfield structurally lies in the north of North Buzachi Arch,to the northwest of tail of Duran Platform,and is overall an anticlinal fold composed of 20 fault blocks divided by 21 faults.The oil-gas-bearing target stratum is divided into 13 sandstone groups and 24 sublayers at the bottom of Middle and Upper Jurassic,and Lower Crataceous.Lithologically based on siltstone and fine sandstone,Kalamkas Oilfield belongs to delta plain intrafacies and delta front intrafacies.With good reservoir properties,the reservoir is the reservoir with high porosity and medium high permeability,and the porosity is generally 20~30%;and the permeability is generally 10~3000×10-3?m2.The interlayer,in-layer and plane heterogeneity is quite strong.The oil-bearing area is 80.8km2,average effective net sand 30.6m,stock tank oil viscosity at 50?within 26.3~40.1m Pa·s,and initial oil in place 6.38×108t.The hydrocarbon distribution is controlled by both structure and lithology,the lithologic-structural hydrocarbon reservoir is developed at the high-structure location;the median lamina edge water hydrocarbon reservoir is developed at the relatively low location.Currently,Kalamkas Oilfield,a large-scale multi-layer water flooding development oilfield,enters the late stage development of high water content after more than 30-year development,and the development contradiction is becoming more and more prominent.In order to further exploit the resource potentials and improve oilfield recovery rate,it is necessary to conduct the fine research of oil reservoir.Based on the geological research and comprehensively using fine stratigraphic correlation,geological structure recognition,thin layer sedimentary microfacies research,three-dimensional geological modeling,numerical simulation,remaining oil research and other technical means,this paper conducted the fine oil reservoir description of Kalamkas Oilfield.Under the control of the marker layer,we conducted the oil layer division and the thin layer contrast according to the sedimentary cycle;well drilling and earthquake fine structural interpretation results were used to conduct fracture restructuring and geologic structure recognition,and rediscover the complex oil-water relations of the large-scale multilayer sandstone oilfield after the water flooding development for many years;Based on petrology and sedimentology,and by applying drilling,well logging,and well logging information,we researched the sedimentary microfacies vertical evolution of each thin layer and the plane distribution law;Based on structure research and reservoir characteristics research,and with the assistance of the site production test and dynamic analysis of oil and water wells,we established the three-dimensional geological models,further clarified the distribution pattern of oil and gas and controlling factors by combing the numerical simulation,studied the spatial distribution characteristics of the remaining oils,which provides the technical support to further explore the remaining resource potentials of the oilfield and realize the scientific and effective development of oilfield,and also provides technical reference for the oil reservoir researches of the same oil reservoir in Buzachi oil region.