强抑制成膜封堵钻井液在长南气田的应用

APPLICATION OF HIGH INHIBITION FILMFORMING PLUGGING TYPE DRILLING FLUID IN CHANGNAN GASFIELD

靖平69-12井目的层马五^(1-3),埋藏深度3 700 m,属长南气田第一口三开结构水平井,刘家沟组漏层和"双石"层与山西组、太原组以及本溪组等煤层处于同一裸眼井段,裸眼段长,防漏与防塌的安全密度窗口窄,是典型的塌漏同段井。针对该区块地层特点,研制出了抑制性强、封堵性好等特点的强抑制成膜封堵钻井液体系。现场应用结果表明,该体系表现出良好的抑制防塌性、润滑防卡性和成膜封堵特性,滤饼薄而韧。在整个斜井段施工过程中井壁稳定,起下钻不阻不卡,克服了上部裸眼段长时间浸泡所带来的井壁不稳定风险,防止了地层漏失,解决了长裸眼段下存在的井壁坍塌、润滑防卡等技术难题,保证了3 460 m多的长裸眼井段的井眼稳定和177.8mm技术套管一次性下到预定位置。

Well Jingping 69- 12 was the first 3-spud horizontal well in Changnan gasfield,target zone at Majiagou formation,with burial depth at 3700 m. LJG thief zone and SS formation were in the same section with coal seams like SX,TY and BX formations,featured with long open hole,narrow safe density window for loss control and sloughing control,and typical well with loss and sloughing hazards. There are micro crack in Liu jiagou formation and coal seams in this section. A high inhibition film-forming plugging type drilling fluid system was thus developed. Its application results showed that this drilling fluid had excellent inhibition to prevent slough,good lubricity to avoid pipe sticking and high film-forming ability for plugging. The filter cake formed was thin and tough. When drilling the deviated section,the borehole was kept stable and no sticking occurred,eliminating any potential wellbore unstability problem which might take place due to long time soaking of the long upper open hole.And the well loss,well sloughing and pipe sticking were prevented,ensuring 3460 m open hole kept stable and φ177. 8 mmcasing run to the preset location in one running.