提高水泥环二界面胶结质量方法的探讨

Discussion on measures to improve the interface cementation quality of cement sheath.

通过控制钻井措施、钻井液和前置液以及固井液性能 ,保证井身质量、井眼轨迹平滑、顶替效率高、固化井壁泥饼等 ,可以达到提高二界面胶结质量的目的。在钻井措施方面 :直井段要防斜打直 ,造斜段要增斜平稳 ,避免井斜度大于 5°/ 30m以及狗腿度大于 3°/ 10m ,使井眼轨迹平滑 ;使用近平衡技术钻井 ,并控制滤失量小于 5mL ,保证井壁稳定。在钻井液方面 :建议使用聚合醇 正电胶钻井液 ,因为该体系有很好的抑制防塌性和较强的降滤失性 ,能很好地防止缩径、垮塌掉块。固井方面 :在固井前使用表面活性剂使井壁润湿反转 ;通过加双弓弹簧扶正器提高套管居中度 ;在下完套管大排量循环时及在固井时均要上下活动套管 ;用冲洗液 +CMC溶液 +药水作为前置液 ,该前置液对井壁疏松泥饼具有一定的浸透力 ,将前置液与地层的接触时间提高到 7min以上 ;在固井液中加入PZW增强剂 ,使水泥浆直角稠化 ,并要求矿渣浆凝结顺序为从下到上和保持正压差。通过实施以上几个方面的措施 ,收到了良好的效果 ,VDL电测显示第二界面合格率达 10 0 %。

The target of good interface cementation quality may be realized by drilling properly, controlling properties of drilling fluid, pad fluid and MTC slurry in good condition, ensuring stable hole, smooth well trajectory, high displacement rate and solidified mud cake as preconditions. Details are as follows: 1) drilling measures. In the vertical section, the hole should be drilled straightly without any inclination; in the deflecting section, the inclination should increase steadly, with no inclination more than 5°/30 m or dog-leg degree no more than 3°/10 m; try to drill the hole trajectory as smooth as possible, use approximate balanced drilling technology and control the filtrate less than 5 mL to ensure the hole in good condition. 2) drilling fluid. Polycol-MMH drilling fluid is recommended, because it has prominent inhibition and anti-collapse properties. 3) Cementing. Employ some surfactant to reverse the wetting characteristic of the well wall prior to cementing; centralize the casing by using dual-bow spring centralizer, rotate and move casings up and down after casing and during cementing operation; use flushing fluid(+CMC solution + additives) as the pad fluid, and prolong the interacting time of the pad fluid and the formation to more than 7 min; add enhancing agent PZW in the cementing slurry to make the slurry condensate in right-angle-thickening style. Above measures were verified successful with VDL logging result of 100% qualification rate in the second interface.