耐温抗盐聚合物钻井液在中原油田水平井的研究与应用

Study and application of the temperature tolerant and salt resistant polymer drilling fluid for horizontal drill-ing

根据中原油田地层具有高温、高盐、易塌、易漏失的特点,研究了水平井用耐温抗盐聚合物正电胶钻井液。优选出的新型阳离子流型调节剂SPJ-1和SPJ-2,抗温达120℃,抗盐可达尥和。同时SPJ-2又是一种理想的抗温原油乳化剂,SPJ-2乳化的钻井液原油不分层,在120℃时钻井液不增粘。室内试验结果表明,耐温抗盐聚合物正电胶水基钻井液具有良好的井眼净化、摩阻控制、井壁稳定及油层保护等性能。现场应用表明,该钻井液悬屑携砂能力强,流变性能易于控制,在大井眼段排量不能满足要求的情况下,结合短起冲砂能满足水平井及高难度定向井井眼净化的要求;抗盐污染能力强,钻进盐膏层后性能变化小;抑制性能好,井壁稳定,实验井的平均井径扩大率明显低于邻井;井下摩阻小,循环开泵摩阻为30～40 kN;保护油气层效果好,岩心静态渗透率恢复值在85％以上。

In accordance with such characteristics as high temperature, high salt content, hole collapse and lost circulation in the formations of Zhongyuan Oilfield, the high temperature tolerant and salt resistant polymer positive colloid drilling fluid is developed for horizontal drilling. The optimized cationic plow pattern adjusting agent SPJ-1 and SPJ-2 have a temperature tolerance of 120 ℃and salt resistance to fully saturated. Meanwhile, SPJ-2 is an ideal temperature tolerant crude oil emulsifier, when it is used, no separation of drilling fluid and crude oil is detected and no increasing on drilling fluid viscosity even in 120 ℃. Laboratory tests show that the high temperature tolerant and salt resistant polymer positive colloid drilling fluid has good hole cleaning, good friction control and wellbore stability, and good formation protection capability. Field using shows its additional advantages on good cuttings suspension and transportation, and easy control of rheology; when in the large hole section of insufficient flow rate, combining with short tripping and sand washing, this drilling fluid can meet the requirements of hole cleaning in the horizontal well and difficult directional well; its has good salt resistance and there is little change on drilling fluid performance as drilling through the gypsum salt bed; it has good shale inhibition and wellbore stability, and the hole enlargement ratio of the testing well is obviously lower than that of the offset well; the downhole friction is minimum, and the pump start-up friction is 30-40 kN when in circulation; good formation pro- tection results are achieved by using this drilling fluid, and the core static permeability recovery can reach to over 85%.