Study Of The Wells And Layers With Low Efficiency Circle Identiifcation And Remaining Oil Distribution In Ying-8Block

Waterflooding is adopted in most oilfields worldwide. Especially in China, more than90%of the fields are waterflooding oilfields. After a long time of waterfloodingdevelopment,because of immersing and washing of injection water to formation,the porestructures and physical characteristics of formation changed,inefficient circulation emergedand various types of remaining oil formed.Based on the investigation of remaining oil at home and abroad,in view of actualsituation that the ShengLi oilfield is in high water cut period,considering distributioncharacteristics of edge water and bottom water,φ function theory was adopted to simulate thepetroleum reservoir performance in high water cut period.φ function is the derivative of waterfractional flow and water saturation, which is numericallyequal the reciprocal of injectionpore volume magnification.Based on this theory, the relationship between remaining oilsaturation and the pore volume magnification of cumulative inflow amount at any point inone-dimensional homogeneous reservoir model was obtained,which can be expanded tothree-dimensional anisotropic reservoir.In study of the influences on simulation result offactors such as gas phase, the viscosity and density of oil and water,water saturation weretaken into consideration.A simple and practical numerical simulation forecasting method ofremaining oil distribution was established.The error between the simulation results of thismethod and that of Eclipse commercial software is less than1%.The inefficient circulation of injection water in underground formation caused theinefficiency of waterflooding displacement,which leads to the formation of various types ofremaining oil. Dynamic and static factors that have great influence on the formation ofinefficient circulation were optimized through level analysis method.Static factorsinclude:effective thickness, permeability,monolayer breakthrough coefficient;Dynamic factorsinclude:daily water injection rate, head pressure of injection well,apparent water injectivityindex,cumulative water injection volume of unit thickness,daily fluid production rate,watercontent,bottom hole flowing pressure of producing well and cumulative fluid production ofunit thickness.Parameters have been confirmed for the determination of wells with lowefficiency circle.Evaluation method has been used in this thesis to establish the mathematicalmodel based on three-leveldistinct comprehensive evaluation.A software that used for remaining oil research and ineffective circulation well layersrecognition was programmed and applied in remaining oil calculation of25sedimentary unitsin Ying8region, the calculation results agree well with the actual data; this software wasapplied to the calculation of Ying8region for3days,which multiply up to more than10timesfaster than artificial determination methods.