含裂缝地层的过套管电阻率测井响应特征研究

由于石油压裂开采等开发措施的实施,会使在套管周围存在着许多被油气等高阻流体填充的微裂缝.尽管这些裂缝或孔隙可能很小,但对套管井电阻率测量会有非常大的影响,甚至会改变原地层的电阻率测井特征,因此裂缝测井响应的计算及考察对过套管电阻率测井十分重要.为解决裂缝测井响应的计算问题,本文提出了计算等效电阻的电流通量管模型,利用该电流通量管模型给出了含垂直裂缝地层横向电阻的计算方法,基于传输线方程法及地层电阻的过套管测量方法实现了含裂缝地层的过套管电阻率测井响应的数值计算,通过计算实例考察了地层裂缝对过套管电阻率测井响应的影响.算例表明:裂缝中的高阻流体对地层视电阻率测量结果会有较大的影响;环形裂隙比垂直裂缝有更大的电阻率测井响应.本文的研究为解决微裂缝过套管电阻率测井响应的计算这一关键技术问题提供了一种可行的计算与考察方法.

Characteristic research on the resistivity logging response of formation with fracture through casing

The implementation of hydraulic fracturing in oil exploration generates a lot of micro-fractures, which are filled with high-resistant fluid around the pipe. Although these micro-fractures and pores are very mall, they have large impacts on the measurements of resistance around casing. It may even change the resistivity logging characteristics of the stratum. So it's very important to study the impacts of micro-fractures on the resistivity logging characteristics in through casing log. In order to solve this problem, a new model with current flux piping was brought forward in this paper. With this model, a method is introduced to calculate transverse resistance in the formation with vertical fractures. The resistivity logging responses in through casing log was calculated with this proposed method. Real through casing log data was also used to investigate the effects of fractures in the formation on resistivity log responses. Numerical results show that the existence of high resistant fluid in fractures have large influences on the measurements of resistivity logging responses. Annular fracture generates larger resistivity log response than planar fracture. The study of this paper presents a feasible computational and investigational method for solving resistivity logging response of micro-fractures in through casing log.