旋流扶正器井眼清洁效率规律研究

STUDY ON WELL CLEANING EFFICIENCY OF SWIRL CENTRALIZER

水平井段注水泥过程中,为有效清洗底边环空的钻井液滤饼和岩屑床,通常使用旋流扶正器来改变顶替流场,提高井眼清洗效率。为研究旋流扶正器对钻屑的运移及钻井液滤饼清洗的效果,文章通过流动模拟试验对比了旋流扶正器对注水泥过程井眼流场的影响,分析了钻屑运移机理,推导了钻屑起动速度。研究表明旋流流场具有更强的钻屑运移能力,其原因是旋流产生的切向流速提高了环空流体对钻屑的举升能力。但旋流效果和钻屑清除效率与旋流扶正器肋片高度、安放距离等因素有关。旋流扶正器必须有合理的形状结构与安放间距,才能获得有效的井眼清洗效果。

In order to effectively clean the mud cake and cuttings bed at the low side of the horizontal wellbore during thecementing job,the swirl centralizer is often used to change the flow field of the cement displacement so as to improve well cleaning. By flow simulation test, how the swirl centralizer changed the flow field during cementing was compared,the drilling cuttings migration mechanism and the speed the cuttings got stirred were analyzed. The study shows that the swirl flow is stronger for removing cuttings,because its tangential velocity improves the cuttings lifting of annulus fluid. However,the swirl flow effects and cuttings removal are affected by factors like the centralizer rib height and the distance centralizers installed. The swirl centralizer must have a reasonable shape,structure and spacing to have an effective well cleaning. This study result can provide some theoretical support for the design and application of swirl centralizers.