成品油管道定向穿越通明海峡泥浆性能控制技术

Control technology of drilling fluid performance in horizontal directional crossing of Tongming Strait by product pipeline

通明海峡周边海域环保要求较高,穿越地层复杂多变,地下淡水、海水交互出现,穿越井段长且摩阻大,地层松散致使保孔非常困难,极易造成冒浆、泥浆性能变化、钻头泥包、地层漏失等钻井难题。基于此,研选出环保型泥页岩抑制剂、抗盐降滤失剂及润滑剂,并研制了极浅层环保固壁泥浆体系,其具有优异的泥岩抑制、润滑、抗固相污染及固壁性能。在定向穿越通明海峡工程中的应用表明:新研制泥浆性能稳定,润滑效果突出,能有效降低泵压和摩阻,井壁稳定性强,且无钻井复杂事故发生,缩短定向穿越钻井周期87天,为顺利拖管提供了可靠保障。

As the environmental protection requirements for surrounding sea areas of Tongming Strait are high, the crossing strata are complex and changeable, the underground fresh water and sea water appear alternately, the crossing section is long with large friction, the stratum is loose, and it is difficult to maintain the stability of borehole, which is very easy to cause drilling problems such as drilling fluid over-spilling, variation of drilling fluid performance, bit balling and lost circulation, et al. In view of the above problems, environment-friendly shale inhibitor, salt-resistant filtrate reducer and lubricant were selected by research, and on this basis, an environment-friendly wellbore stabilizing drilling fluid system was formed for the very-shallow strata, which has excellent performances of shale inhibition, lubrication, solid contamination resistance and wellbore stability. Application of the system in directional crossing project of Tongming Strait shows that, the performance of the drilling fluid is stable with good lubrication effect, capable of effectively reducing the pump pressure and friction resistance, and the wellbore stability is strong with no complex drilling accidents occurring, so that the directional drilling cycle is shortened by 87 days, which provides a reliable guarantee for smooth pipe dragging.