埕岛油田沙河街地层强抑制性海水钻井液技术

为了解决胜利浅海埕岛油田沙河街地层硬脆性泥岩易剥蚀掉块、垮塌等问题,对埕岛油田沙河街地层的井壁不稳定问题进行了分析,找出了该地层坍塌的主要原因是钻井液及滤液沿层理和微裂缝渗入地层内部,进而引起硬脆性泥页岩剥落坍塌所致。针对沙河街地层特点,研制了强抑制性海水钻井液,对该钻井液的防塌性能、封堵性能、抗污染性能、环保性能进行了室内评价试验和防塌机理分析,并在埕岛油田6口井上进行了现场应用,试验表明:强抑制性海水钻井液具有较好的抑制性能和流变性、较强的抗海水和劣质土污染能力,环境可接受性好,维护处理简单,有效解决了沙河街复杂地层钻进中出现的技术难题,避免了复杂情况的发生。

Study and application on drilling fluid in Shahejie formation of Chengdao Oilfield

In order to prevent the collapse of Shahejie formation in Chengdao Oilfield during drilling,a new seawater drilling fluid with strong inhibition was developed.According to analysis for instability mechanism,main reasons that result in well bore instability in Shahejie formation were found.Experimental results and field applications showed that new inhibitive drilling fluid is characterized by good rheology,low filtrate loss,superior collapse-preventing effectiveness,strong seawater and clay resistance.Satisfactory anti-collapse effectiveness has been achieved from the tested wells in Shahejie formation.