鄂尔多斯盆地东部区块强抑制性钻井液研究及应用

STUDY AND APPLICATION OF STRONG INHIBITIVE DRILLING FLUIDS IN EAST BLOCK OF ORDOS BASIN

鄂尔多斯盆地东部延长组岩性复杂,钻进过程中常伴有严重的井壁失稳,表现为掉块、缩径、部分井段井径扩大等井下复杂情况,极不利于提高该区块的钻井速度。为解决这一技术难题,在室内对地层岩样的组构特征进行了详细分析。在此基础上,对多种无固相钻井液体系进行了优化,最终提出两套无固相聚合物钻井液配方。现场应用证明,设计出的无固相聚合物钻井液配方具有较强的抑制能力,能使该区块的井壁失稳问题得到缓解,复杂时效平均值由上年的5.66%,降至应用后的1.74%;电测一次成功率由上年的74%上升到95%,收到较理想的效果。目前,该体系正在气田东部钻井现场进一步推广应用。

The formation lithology of Yanchang group is complicated in East Ordos Basin, and the serious hole-instability, including serious sloughing, tight hole sections and unfavorable hole enlargement, often happens in drilling process, which is very unfavorable to improve penetration rate in the block. To solve the technical problem, the composition features of the formation samples are analyzed carefully indoors. Based on the analysis, the optimization of several systems of solid free drilling fluids is conducted and two kinds of drilling fluids with solid free polymer are selected. Field applications show the newly developed drilling fluids with solid free polymer have strong inhibiting ability, which can alleviate the problem of well-bore instability. The average percentage of down-hole problem prescription decreases significantly from 5.66% to 1.74%, and the primary successful rate of well-logging increases from 74% to 95%. Good results have been achieved. The drilling fluid systems are being popularized now in East Ordos Basin.