长岭断陷深层气井岩石可钻性计算方法

CALCULATING ROCK DRILLABILITY FOR DEEP GAS WELL DRILLING IN CHANGLING FAULT DEPRESSION

长岭断陷沉积岩段2500m以下钻井事故较多,下部火山岩岩石硬度大,岩石研磨性强,钻井速度慢。为了提高长岭地区钻井的机械钻速,开展了该地区的岩石可钻性计算方法研究。针对研究区上、下部岩性相差大,深层火山岩硬度大等特点,制定了分段研究岩石可钻性的方案:上部的沉积岩层采用常规测井资料求取岩石可钻性的方法,下部的火山岩层段采用钻速方程反求法。以长深103井为例,将试验结果和利用钻速方程计算的岩石可钻性进行了对比,两者的相对误差小于5%,说明利用钻速方程计算该地区火山岩岩石可钻性是可行的。

Drilling accidents occur rather frequently after the depth of 2500 m below the sedimentary rocks at Changling fault depression,and the lower igneous rocks are very hard and abrasive,making drilling ROP rather low.To improve the drilling ROP there,study was conducted on rock drillabilty.Because the upper and lower rocks in that block varied a lot,and deeper igneous rock was hard,staging study program was chosen.For upper sedimentation rocks,conventional logging data was used to calculate the rock drillability.For lower igneous rocks,ROP equation was used for calculation.And the well Changshen-103 was taken as an example.The comparison between the test results and the ROP equation calculation results showed relative error are below 5%,which proved the feasibility to use ROP equation for calculating the drillability of igneous rocks.