论文部分内容阅读
欠平衡钻井采用低密度钻井液,中子孔隙度的测井响应和常规井眼流体有一定差异。通过对双层介质扩散方程解析解的分析以及蒙特卡罗数值模拟,研究了低密度钻井液条件下中子孔隙度测井响应的变化规律。低密度井眼流体会对补偿中子孔隙度测井产生井眼挖掘效应,使视孔隙度值低于真孔隙度,且井眼流体密度越小,井眼尺寸越大,地层孔隙度越大,井眼挖掘效应越明显。利用数值模拟结果计算得到了井眼挖掘效应的孔隙度校正公式及不同密度泡沫钻井液时的中子孔隙度校正图版。
Underbalanced drilling using low-density drilling fluid, neutron porosity logging response and conventional wellbore fluid have some differences. By analyzing the analytic solution of the two-layer medium diffusion equation and the Monte Carlo numerical simulation, the variation of neutron porosity logging response under low-density drilling fluid is studied. Low-density wellbore fluids can cause borehole excavation effects on compensated neutron porosity logs, leaving apparent porosity below true porosity and with lower borehole fluid density, larger borehole size, and greater formation porosity , The more obvious the hole digging effect. The porosity correction formula for borehole excavation effect and the neutron porosity correction plate for different density foam drilling fluids are calculated by numerical simulation results.