埕岛油田埕北1区钻井液工艺

Drilling fluid technology in Block Chengbei-1 of Chengdao oilfield

埕岛油田埕北1区由于注水量偏大造成下部地层压力系数偏低,钻井中常引起长裸眼井段反复划眼、卡钻,甚至井眼报废等复杂事故。介绍了该地区不同井段的钻井液配方、维护处理措施以及斜井段岩屑床的控制方法。该井复配使用K-PHP和PAC-141,控制pH值为8.0～8.5,有效地稳定平原组、明化镇组井壁,减少井眼缩径、钻头泥包现象的发生;保证钻井液具有“低粘度、低密度、低切力和适当的滤失量”性能;严格控制钻井液固相含量小于7％,含砂量小于0.3％;通过在条件允许的情况下调整环空返速为0.85～1.10m/s,提高钻井液的动切力、塑性粘度,在定向钻进阶段定时、定井段进行短程起下钻,用起钻前充分循环、起下钻分段循环钻井液的方法破坏岩屑床的形成,达到净化井眼、稳定井壁的目的。应用结果表明,该钻井液体系抑制页岩膨胀、防塌、携岩能力强,井眼净化、井壁稳定等性能均满足该地区不同井段施工要求,并具备无毒、无害、无污染、无荧光特点,在具有良好润滑性的同时,满足海上环境保护的要求。

Due to the low pressure factors in block Chengbei-1 of Chengdao oilfield because of excessive water injection, such troubles as repeated whipping, pipe sticking and as worse as well abandonment frequently take place. Drilling fluid formations for different sections, field maintenance and conditioning, as well as controlling of cutting beds in the slant section were presented. Such additives as K-PHP and PAC-141 were added into this well, to control the pH value between 8. 0 - 8. 5, this effectively stabilized the borehole, minimized bore shrinkage and bit balling; the drilling fluid kept such features as low viscosity, low weight, low shearing force and suitable filtration; the solids content was strictly controlled within 7%, and sand content within 0.3%; the annular return velocity was adjusted between 0. 85-1. 10 m/s, to improve the dynamic shearing force and plastic viscosity; during directional drilling, by applying short tripping, sufficient circulation before tripping out, and sectional tripping to break the forming of cutting beds, so that to clean the borehole and stabilize the borewall. Using of this system showed that its properties of shale inhibition, sloughing control, good cuttings transportation, hole cleaning and hole stabilization all meet the requirements of drilling in this area, furthermore, it is free of toxicity, pollution and fluorescence, which are good for offshore environment protection.