泥页岩层不规则井眼环空注水泥顶替理论与技术

泥页岩层油气井井眼往往不规则,固井注水泥环空顶替效率低,严重影响着固井质量。目前国内外对之研究非常少,缺乏成熟的理论与技术。对井眼不规则影响固井质量的原因进行了分析,提出了有效解决不规则井眼环空钻井液在作业允许范围内被有效"替净"问题关键在于掌握不规则井眼几何形状及其与井斜角、套管偏心度、浆体性能、施工排量、旋流强度等对顶替界面的稳定性的影响规律; 在不规则井段,顶替液对被顶替液的作用机制,涡流强度与"替净"之间的关系,被顶替液的涡流结构变化规律等,亚滞留钻井液( 暂存于不规则段但能够不断流出的钻井液) 进入下游的扩散与迁移规律。因此,重视对不规则井眼固井环空顶替理论与方法前瞻性的研究具有重要意义。

THEORY AND TECHNOLOGY ON CEMENTING DISPLACEMENT IN IRREGULAR WELL BORE ANNULUS ACROSS SHALE SECTION

The wellbore of oil and gas well is often irregular across shale section which seriously affects cementing displacement efficiency,further affecting cementing quality.So far,the mature theory of guiding operations of cementing such well is very lacking at home and abroad.This paper analyzed the effects of the irregular wellbore on cementing quality and put forward that it was necessary to remove mud completely by mastering the affecting law of wellbore shape,deviation angle,casing eccen-tric,fluid properties,pump rate and swirl intensity on displacement interface stability.The relationships between vortex intensity and adequate hole cleaning,the vortex range change and residence time of the replacement fluid in the irregular hole annulus were discussed.The research on irregular well bore cementing displacement theory has important significance for similar well cementing.