基于叠前AVO同步反演的特低渗储层流体性质识别方法及其应用——以大庆长垣敖南鼻状构造敖158井区为例

Identifying methods of the fluid properties in ultra-low permeability reservoirs based on prestack AVO simultaneous inversion and their applications:A case of Well Block Ao-158 in Aonan nose structure of Daqing Placanticline

特低渗岩性油藏具有储层薄、与围岩阻抗差异小、油水分布横向变化快、流体响应特征不明显的特点,导致常规叠前阻抗反演方法对流体性质识别精度不高。利用叠前AVO同步反演获取拉梅阻抗、剪切阻抗数据体,结合拉梅阻抗—剪切阻抗油水层交会定量识别图版,建立了一套特低渗储层流体性质识别方法,并将其应用于松辽盆地大庆长垣敖南鼻状构造敖158井区扶余油层特低渗油水层识别中。结果表明:拉梅阻抗与剪切阻抗交会可消除岩石骨架参数的影响,突显出孔隙流体响应,可最大限度体现流体性质,适合于特低渗岩性油藏储层孔隙流体性质的识别。

The ultra-low permeability lithologic oil reservoirs are characterized by thin layers,small impedance difference with the host rock,fast lateral variation of the oil and water distribution and indistinct fluid response properties,which lead to the poor identification accuracy of the fluid properties by the conventional prestack impedance inversion method.With the help of the prestack AVO simultaneous inversion,Lame-impedance and shear-impedance data body are obtained;combined with Lame impedance and shear impedance oil and water layer quantitative identifying chart,a set of the fluid-property identifying methods of ultra-low permeability reservoirs are established,and are applied in Fuyu oil and water layer identification in Well Block 158 of Aonan nose structure in Daqing Placanticline of Songliao Basin.The results show that the crossplot between Lame impedance and shear impedance can eliminate the influences of rock matrix parameters,highlight the response of pore fluids,and reflect the fluid properties to the maximum extent,which is feasible to identify the fluid properties in the sand-shale oil reservoirs with ultra-low permeability.