用正演数值计算方法开展双侧向测井对裂缝的响应研究

采用有限元分析软件ANSYS对裂缝的双侧向测井视电阻率与裂缝孔隙度、泥浆电阻率、裂缝倾角和基岩电阻率的关系进行了计算. 在大量正演数据的基础上得出双侧向测井响应反演公式和裂缝孔隙度计算公式，提出更为精细的裂缝倾角的弹性划分模型，用双侧向视电阻率值近似估算裂缝倾角的方法，提高了利用双侧向测井求裂缝产状与裂缝孔隙度（裂缝宽度）的精度.

A study on the dual laterolog response to fractures using the forward Numerical modeling

We use ANSYS, a large general finite element method software, to compute the dual laterolog response to parallel fractures of equal spacing in the carbonate formation crossing a borehole. The relationship between the dual laterolog response and fracture porosity, fracture dip-angle, base rock resistivity and fluid resistivity are discussed. Based on the analysis of numerical simulation results and the characterizations of dual laterolog response to fractures, a new method is developed to classify the forms of fractures, which can dynamically change the definition of fracture dip-angle range to fit different instances. The technique to obtain the approximate dip-angles of fractures with dual laterolog response is realized. It can greatly prove the estimation of fracture porosity (aperture of fracture). With the condition of constant fracture dip-angles, the inversion model of the dual laterolog response and formula for computing fracture porosity are presented.