泥浆侵入低电阻率环带对斜井感应测井响应影响分析

Effect of Mud Invasion on Induction Logging Response in Deviated Hole with Low Resistivity Annulus

依据斜井几何因子理论,通过数值计算研究了泥浆侵入低电阻率环带环境下井斜角度对双感应测井响应的影响,以及泥浆侵入深度对斜井双感应测井响应的影响。深感应测井和中感应测井在井斜角度0°～90°之间会有2个敏感角度段,并且仪器在这2个响应敏感变化倾斜角度段内响应特性有较大的差异。在低电阻率环带电阻率与地层电阻率比较接近时,敏感角度段1消失。深感应测井在敏感角度段2与中感应测井的敏感角度段2有明显的角度差,角度差随着侵入带电阻率与地层真电阻率的对比度值的减小而增大。不同井斜角度,中、深感应测井响应随侵入深度变化趋势与在垂直井基本相同。为感应测井更好地应用于油水层识别中消除侵入低电阻率环带的影响提供理论依据。

Based on induction log geometrical factor in deviated hole, studied are the effect of inclination angle and mud invasion depth on dual induction log responses in deviated hole with low resistivity annulus by numerical calculation. Analysis results show that deep induction log and middle induction log has two sensitive angle sections within 0°to 90° inclination angle, and re- sponse characteristics are quite different in sensitive angle section; When resistivity is close with formation resistivity in low resistivity annulus, sensitive angle section 1 disappears; In sensitive angle section 2, there is obvious angle difference between deep induction log responses and middle induction log responses, and the angle difference increases with the ratio decrease of invaded zone resistivity and formation true resistivity; Under different inclination angles, the middle and deep induction log response changes with depth is the same as that in vertical wells. The above analysis provides a theoretical basis for induction log in oil and water reservoir identification and removing the effect of low resistivity annulus.