论文详情
电测井是评价洞穴型储层的主要手段之一,洞穴型储层非均质性强,电测井仪器响应复杂,评价难度大。利用二维有限元数值模拟方法对洞穴型储层中的高分辨阵列侧向测井(resolution laterolog array,RLA)响应进行正演模拟,分析了测井响应随洞穴半径、洞穴填充物种类、填充程度以及洞穴形状变化的规律。阵列侧向测井仪器对半径不小于0.2 m的洞穴具有良好的识别能力,同时能反映填充物电阻率。当洞穴半径大于6 m时,仪器响应基本反映了洞穴填充物的电阻率。阵列侧向测井仪器对填充物分层界面敏感,且RLA1和RLA5的视电阻率值能较好地指示填充物的电阻率,当填充物为多种物质分层填充时,洞穴处的仪器响应会出现明显的阶梯状特征。阵列侧向测井曲线形态受洞穴形状影响大,洞穴径向延伸时,仪器响应明显降低,洞穴纵向延伸时,洞穴处的RLA5逐渐增大而RLA1逐渐减小。该研究结果对洞穴型储层的定性识别和定量评价具有指导意义。
Electrical logging is one of the primary means to evaluate a cavernous reservoir.The strong heterogeneity and anisotropy in the cavernous reservoir lead to a complex response of the electrical logging,which makes its evaluation difficult.The array laterolog response (RLA1-RLA5) in cavernous reservoirs is studied using the 2D finite element numerical simulation method.The regularity of logging responses with cave radius,cave filling type,filling degree,and cave shape is verified.Research shows that the array laterolog can successfully recognize caverns with a radius of more than 0.2m,and provides a good reflection of the resistivity of the fillings.When cave radius is larger than 6 m,the instrument’s response primarily reflects the resistivity of the cave fillings.Array laterolog tools are sensitive to the presence of a layered interface,and RLA1 and RLA5 apparent resistivity are good indicators of the resistivity of the filling.When the fillings are layered with various substances,the response of the instrument in the caverns will have distinct step-like features.The shape of the array laterolog curve is greatly affected by the change in the cavernous shape.The instrument’s response decreases significantly with radial extension of caverns.When the caverns extend longitudinally,RLA5 increases gradually while RLA1 decreases.The findings of this study provide significant guiding principles for qualitative identification and quantitative evaluation of cave reservoirs.
国家自然科学基金项目“地层条件下富有有机质页岩电磁响应机理与应用基础研究”(U1562109)资助。