基于岩相约束的砂岩油藏渗透率表征新方法

A new method of permeability characterization in sandstone reservoir based on petrographic constraints

渗透率是油藏工程中一项重要的基础参数。常规获取渗透率的方法通常是首先根据电性测井解释得到孔隙度,然后根据室内岩心实验获得的孔隙度和渗透率,建立岩石物性解释模型,进而求取渗透率。分析渤海Y油田300多块岩心样品的孔隙度和渗透率室内实验数据发现,利用统一的孔、渗回归关系无法准确确定多层砂岩油藏的渗透率,表现为测井解释的渗透率往往与生产动态响应不一致。为此,提出基于岩相约束,利用相渗曲线、吸水剖面和初期产能资料验证的渗透率定量表征新方法。微观上,通过扫描电镜、铸体薄片、常规测井和取心等资料明确孔隙度和渗透率关系的主控因素;宏观上,利用岩相约束,根据室内岩心相渗曲线、吸水剖面和初期产能等资料进行动态验证。研究结果表明,利用基于岩相约束的砂岩油藏渗透率表征新方法计算的渗透率与初期吸水剖面的吻合度从65%提高至91%。

Permeability is an important basic parameters in reservoir engineering. First step of conventional method for ob?taining permeability is usually to get porosity according to the electric logging interpretation. Second step is to establish pet?rophysical interpretation model according to the relationship between porosity and permeability obtained from the core labo?ratory test. And then the permeability is gained. Experimental data of porosity and permeability in 300 pieces of cores of Bo-hai Y oilfield shows that the permeability in the multi-layer sandstone reservoir cannot be accurately described by unifiedregression relationship between porosity and permeability,and the permeability from well logging interpretation is often in-consistent with production performance. Therefore,a new method of quantitative characterization based on petrographic constraint,relative permeability test and dynamic agreement was put forward. Microscopically,main factors controlling therelationship between porosity and permeability were known by scanning electron microscope(SEM),cast thin section,log-ging and core data. Macroscopically,it was verified dynamically by laboratory relative permeability curve,water injectionprofile and initial productivity using petrographic constraints. The results show that the permeability gained by the newmethod based on petrographic constraints can improve the alignment with initial injection profile from 65% to 91%.