库车山前固井质量风险评价研究

塔里木山前构造油气资源丰富，但其气藏埋深在7 000 m左右，应用油基钻井液可有效地解决盐膏岩、泥页岩层段钻进过程中井下复杂问题，但在此环境下油基钻井液影响了水泥石与井壁/套管的胶结能力。为此，以已施工井的相关数据为参考依据，分别从液固界面润湿反转能力、防漏条件下提高顶替效率的施工排量、固井井筒浆体性能匹配以及套管扶正器安放情况为研究对象，系统分析影响固井质量的主要因素。研究结果表明，在用隔离液中表面活性剂/水大于30%可实现胶结界面处于亲水状态、在未发生漏失条件下排量达到塞流流量以上均有助于提高顶替效率，每2个套管安放一个扶正器能确保套管居中度大于67%；综合分析表明，影响部分井固井质量不理想的主要原因是套管居中度差与部分井段井筒内的浆体匹配性差。基于本论文理论与现场相结合的针对性研究，为提高区域固井质量提供了切实可行的方法与依据。 

Risk Evaluation of Cementing Job Quality of Wells Drilled in Kuche Piedmont Structure

The Kuche piedmont structure in Tarim Basin is abundant in oil and gas which, unfortunately, are buried at depth of about 7 000 m. Oil base muds can be used to overcome the drilling challenges such as salt and gypsum contamination, borehole instability through mudstone and shale formations. On the other hand, oil base muds negatively affect the bonding between set cement and borehole wall, and the bonding between set cement and casing string. To minimize these negative effects, researches were conducted based on the data from drilled wells to systematically analyze the main factors affecting well cementing job quality from several aspects, i.e., wettability reversion on liquid-solid interface, flow rate to increase displacement efficiency while avoiding lost circulation, compatibility between drilling fluid in hole and cement slurry, as well as the placement of centralizers along casing string. The research work showed that percentage of surfactants/water in spacer fluid above 30% makes the interfaces (cement sheath-casing string and cement sheathborehole wall) water wet. Flow rates enough to realize plug flow while lost circulation is avoided help increase displacement efficiency. One centralize every two singles of casing ensures that casing centricity is greater than 67%. It can be concluded that poor cementing job quality in some wells is resulted from poor casing centricity and poor compatibility of cement slurry with drilling fluid in hole. This study provides a feasible and reliable method and basis for the enhancement of well cementing job quality in the piedmont structure.