淡水钻井液侵入对双感应和双侧向测井响应的影响

钻井液侵入储集层将导致储集层含水饱和度、地层水矿化度、地层电阻率等的径向变化。由于双感应和双侧向测井测量原理的不同，地层电阻率的径向变化对其测井响应特征影响也不同。实测资料统计和数值模拟计算结果均证实，水层双侧向测井受淡水钻井液增阻侵入影响较大，钻井液愈淡，水层的侧向测井值愈高；而在好油层双感应测井受淡水钻井液减阻侵入影响较大。针对目前勘探较多的低电阻率油层，结合淡水钻井液侵入对双感应和双侧向测井响应特征影响的差异，建立了应用双感应测井或双感应、双侧向测井联合的油、水层识别方法，并在此基础上建立了油层含油饱和度的定量评价方法，提高了低电阻率油层的测井识别评价能力。图7参19

Effects of fresh drilling mud invasion on logging responses of dual induction and dual lateral to reservoirs

The invasion of drilling mud can cause the radial variation of reservoir parameters such as water saturation, salinity of formation water and formation resistivity etc. The effects of radial variation of formation resistivity on the logging responses of dual induction logging and dual lateral logging to reservoirs are different due to their different measuring principles. Statistics of measured data and numerical simulation results verify that the increased resistance invasion of fresh mud exerts more influence on dual lateral logging in water formation and the decreased resisance invasion of fresh mud does more influence on dual induction logging in oil formation. Methods of identifying water or oil formation applying dual induction logs or combination of dual induction logs and dual lateral logs are established for low resistivity oil reservoirs according to the effect differences of fresh mud invasion on the responses of dual induction logging and dual lateral logging to reservoirs, and the corresponding evaluation method of oil saturation is also established.