碳酸盐岩溶孔溶洞型储层双侧向测井响应数值模拟

碳酸盐岩溶孔溶洞型储层的测井识别、有效性评价和流体性质判别等非常困难,其主要原因之一是双侧向电阻率测井的响应特征复杂。为了深入研究碳酸盐岩溶孔溶洞型储层不同储集空间特征与双侧向电阻率测井响应之间的关系,根据双侧向电阻率测井恒流式工作原理,基于有限元数值模拟技术,建立了双侧向电阻率仪器模型和碳酸盐岩地层模型,并分别对不同尺寸的溶孔型储层、圆形溶洞型和椭圆溶洞型碳酸盐岩储层的双侧向电阻率进行了模拟。结果表明：(1)有限元方法可实现双侧向测井的连续测量模拟,使用全局常微分方程可满足监督电极间的电位平衡；(2)深侧向电极系系数Kd为0.693m、浅侧向电极系系数Ks为1.222m；(3)溶孔型储层、圆球状溶洞储层、椭圆球状溶洞储层段深浅双侧向电阻率在围岩电阻率的基础上大幅度下降,但电阻率值下降程度、电阻率形态、深浅双侧向差异特征等受储层类型、溶洞尺寸的影响而差异较大。

Numerical simulation of dual lateral logging resistivity of carbonate solution-vuggy reservoir

The logging identification, validity evaluation and fluid identification of carbonate solution-vuggy reservoirs are very difficult. One important reason is that the response characteristics of dual lateral resistivity logging are complex. The aim of this research is to investigate the relationship between the reserving space characteristics of different reservoirs and the resistivity response of dual lateral logging in carbonate solution-vuggy reservoirs. Based on the constant flow principle and the finite element numerical simulation technology, the instrument and formation models for dual lateral logging resistivity simuation were constructed. The resistivity of dual lateral logging of dissolved pore reservoir, spherical cave reservoir and elliptical spherical cave reservoir with different sizes were simulated. The result show that continuous dual lateral logging simulation is feasible by using the finite element method. The electrical balance of the supervisory electrodes can be obtained by using the global ordinary differential equations (ODE). The system coefficient of deep lateral electrode (Kd) is 0.693m and the system coefficient of shallow lateral electrode (Ks) is 1.222m. The resistivity of dual lateral logging in dissolved pore reservoir, spherical cave reservoir and elliptical spherical cave reservoir decreases greatly on the basis of the resistivity of bedrock. Due to the influence of the reservoir type and the size of cave, the decrease degree of resistivity, the shape of resistivity curves, and the diffence characteristics between deep and shallow lateral logging are very different.