水平井随钻电阻率与双侧向响应差异影响因素分析

Influence factors analysis of response characteristics difference between dual laterolog resistivity and LWD resistivity in horizontal well

在大斜度井和水平井中,不同电阻率测井系列测量的结果并非完全一致,测量结果的差异性分析对于正确认识和评价地层非常重要.依据双侧向测井和随钻电磁波测井原理,采用三维有限元素法模拟双侧向在水平井中的测井响应特征,采用积分方程法模拟随钻电磁波电阻率在水平井中的测井响应特征,通过对比分析值模拟结果,造成大斜度井和水平井随钻电阻率与双侧向电阻率测井响应差异的主要因素有:井斜、各向异性、地层界面以及泥浆侵入.随钻电阻率一般受泥浆侵入影响小,但是它在水平井中容易产生极化现象,有助于地层界面识别,同时受各向异性影响明显;而双侧向电阻率在水平地层中对地层界面不敏感,且受各向异性影响相对较弱,但会受泥浆侵入影响严重;正确认识这些差异,可以有效指导水平井的合理解释.

The measurement results of different resistivity logging series is not completely consistent in high angle and horizontal well due to the different measuring principle,the response characteristics difference analysis is very important for the correct understanding and evaluation of formation. Based on the logging principle of the dual laterolog and electromagnetic wave Logging While Drilling（ LWD）,adopted the 3-D finite element method to simulate the dual laterolog response characteristics in horizontal wells, and adopted the integral equation method to simulate the LWD resistivity response characteristics in horizontal wells. Through the comparison and analysis,the results showed that the response differences may be caused by the deviation,anisotropy,formation interface and mud intrusion. The LWD resistivity is little influenced by the mud invasion,but it is easy to produce polarization in horizontal wells which will help to formation interface recognition,at the same time it is severely affected by the anisotropic. The dual laterolog resistivity is not sensitive to the formation interface in horizontal well,and the affect by the anisotropic also relatively weak,but the affect by mud invasion is seriously. The correct understanding of these differences,can effectively guide the reasonable explanation of horizontal well.