Fuyu Layer Reservoir Evaluation And The Role Of Reasonable Development In Daqing Talaha Oilfield

The oil-bearing area of Fuyu layer in Daqing Talaha oilfield is 84.9 km²,and the forecast reserves is 2956×10⁴t.But in the southern development zone with conventional water flooding method,oil well is flooding or low output extraction.There is a lack of effective energy supplement in the northern development zone with tight oil development method,the production of oil wells decreased rapidly.In view of the invalid use of reserves in Talaha oilfield,with the unclear geological understanding and the unreasonable development mode,this paper takes sedimentary rock science,reservoir geology,petroleum development geology and so on as the guide.This paper also combines model experiments,thin section analysis and production test data with macro-micro method.This paper also researched formation distribution,lithology,physical property and brittle plastic characteristics.On the basis of water flooding and reservoir capacity sensitive parameter analysis,reservoir classification evaluation has been established and researched the role of reasonable development mode.Through research,several understandings are obtained:（1）Talaha oilfield Fuyu layer is mainly controlled by the northwest source,widely developed distributary channel sand bodies and underwater distributary channel sand bodies.The sandstone is near east-west and north-west spreading.（2）The average effective porosity of Fuyu layer is 10.3%,and the average permeability is 1.02×10^-3μm²,Fuyu layer belongs to the low-porosity and ultra-low permeability reservoir.Through high-speed centrifugation experiments,the core of the Fuyu layer determined into three types of seepage channels at micron,submicron and nanometer.The proportion of submicron and above in more than 1×10^-3μm²reservoir was greater than 40%,the proportion of submicron and above in 0.5～1.0×10^-3μm²reservoir is about 25%,the proportion of submicron and above in 0.2～0.5×10^-3μm²reservoir is about20%,reservoir less than 0.2×10^-3μm²are mainly nanometer seepage channels.The brittleness index of Fuyu layer is between 25%and 49%,and the compressibility is well.（3）On the basis of comprehensively research water flooding capacity sensitive parameters and classification evaluation criteria,the"six parameters"reservoir evaluation standard has been established.In reservoir evaluation standard,the classification limits of effective porosity are11.7%and 10.3%,the classification limits of permeability are 0.8×10^-3μm²and 1.4×10^-3μm²,the classification limits of oil saturation are 52.5%and 59.0%,the classification limits of brittleness index are 37%and 44%,The lithology of Class I reservoirs is medium sandstone and fine sandstone,the lithology of Class II reservoirs is fine sandstone and siltstone,the lithology of Class III reservoirs is siltstone.The proportion of submicron and above seepage channels in Class I reservoir is greater than 40%,Class II reservoir submicron and above seepage channels accounts for 30～40%,and the proportion of submicron and above seepage channels is less than 30%for Class III reservoir.Most of the reservoir in the FI group are Class I and II oil reservoir,only south of the Ying27-2—Ying15 well are Class III reservoir.Most of the reservoir in the FII group are Class II and III oil reservoir,and only north of the Ha1—Gu14-2 well is Class I reservoir.（4）Class I reservoir can be developed in conventional water flooding method,Class II reservoir can be developed in tight oil development methods,and Class III reservoir can be undeveloped in existing technology conditions economically.The EOR of reservoir classification project designs respectively are 3.4 and 3.7 percentage points higher than unclassified project designs,which clarified the role of reasonable development in Talaha oilfield with reservoir classification evaluation.This paper provides technical support for the economical and effective development of Talaha oilfield Fuyu layer.