固井清洗剂DQQX-2及其冲洗液体系的研制与应用

The Development and Application of Well Cementing Cleaning Agent DQQX-2 and Flushing Fluid Formulated with It

为解决油基钻井液在套管壁及井壁形成不易冲洗的胶凝结构影响固井质量的问题,该研究重点进行了固井冲洗液用清洗剂的研制,通过对助剂体系各项物性指标的考察,筛选出具有高效清洗及助悬浮能力的清洗剂体系,同时根据固井前置液所要求的技术指标优选固井冲洗液用悬浮剂及其他助剂的种类及加入量,得到了一套具备高效清洗能力的固井冲洗液体系。室内实验发现,在清洗剂加入量达到3%~6%,悬浮剂加入量达到3%时,冲洗液可抗温180℃,加重密度可在1.2~2.0 g/cm^(3)范围内调节,23℃静止24 h冲洗液上下密度差小于0.03 g/cm^(3),冲净油基钻井液的时间不大于7 min,与钻井液和水泥浆相容性优异。现场试验表明,应用该冲洗液体系,现场施工顺利,固井质量优质,水平段优质井段比例大于93%。说明该冲洗液体系可提升冲洗顶替效率,从而提升固井质量,具有较高推广价值。

Residual oil based drilling fluids retained on the surfaces of casing strings and on the borehole walls become gels that are difficult to wash away,hence affecting the job quality of well cementing.To solve this problem,efforts were made on the development of flushing fluids for well cementing.By studying the physical properties of various cleaning agents for use in well cementing,a cleaning agent system with high cleaning performance and suspending capacity is developed.Based on the technical requirements for the well cementing pre-pad fluids,the suspending agent and other additives for a high efficiency flushing fluid are engineered.Laboratory study shows that in the flushing fluid when the concentration of the cleaning agent is in a range of 3%to 6%and the concentration of the suspending agent is 3%,the flushing fluid can function normally at 180℃,the density of the flushing fluid can be adjusted between 1.2 g/cm^(3)and 2.0 g/cm^(3),and the difference between the density of the top fluid and the density of the bottom fluid is less than 0.03 g/cm^(3)after the flushing fluid stands for 24 h at 23℃.The time for the flushing fluid to clean completely the residual oil-based drilling fluids is within 7 min.This flushing fluid has good compatibility with the drilling fluids and the cement slurries.Field operation results show that in wells cleaned with this flushing fluid,the cementing job is performed smoothly,and the excellent job quality of cementing the horizontal section of a well is more than 93%of the total.Field operation achievements prove that this flushing fluid can be used to better clean the wellbores drilled with oil-based drilling fluids and enhance the efficiency of displacing the cement slurries,thereby improving the job quality of well cementing.