南海西部特低渗油气藏储层特征及流体识别方法探讨

Discussion on Reservoir Characteristics and Fluid Identification Methods of Extra Low Permeability Oil&Gas Reservoirs in the Western South China Sea

南海西部海域中深部地层广泛存在特低渗致密油气藏,该类储层气测和含油显示好,孔隙度中等且高阻特征,但测压以干点和致密点为主,测压流度和岩心渗透率很低,常规取样难以取到原状地层流体,给测井流体识别和储层评价带来很大困难。因此,以岩心分析资料为基础,结合测井曲线和测压、测试成果,重点对储层特低渗的成因开展分析,通过已证实的特低渗致密油层,建立一套基于措施条件下的储层参数下限标准。基于不同钻井液体系下泥浆侵入在测井曲线中的特征,分析储层渗透性并指导判别流体性质。最后,结合相渗、半渗透隔板等资料,建立区域束缚水、残余油饱和度模型,开展储层精细评价,寻找储层甜点,为开发生产奠定基础。

Extra low permeability tight oil&gas reservoirs widely exist in middle-deep formation of the western South China Sea.This type of reservoirs presents good gas measurement and oil bearing display,medium porosity and high resistance characteristics.But the pressure measuring points are mainly dry points and tight points.The pressure fluidity and core permeability are very low.So it is difficult to obtain undisturbed formation fluids through conventional sampling,which brings great difficulties to logging fluid identification and reservoir evaluation.Therefore,based on core analysis data,this artical focuses on analyzing of the cause of extra low permeability reservoirs combined with logging curves,pressure measurement and formation testing.Through the proven extra low permeability tight oil layers,a set of lower limit standards about reservoir parameters based on measures is established.Based on logging curve characteristics of mud invasion under different drilling fluid systems,the reservoir permeability is analyzed and the fluid properties are ascertained.Finally,combined with the data of phase permeability and semi-permeability diaphragm,the regional irrestrictable water and residual oil saturation model is established,and the fine evaluation of the reservoir is carried out to find the sweet spot of the reservoir,which lays the foundation for development and production.