泾河油田水平井固井难点与对策研究

Challenges and Countermeasures of Well Cementing Operations for Horizontal Wells in the Jinghe Oilfield

泾河油田地层承压能力低,固井过程中易发生水泥浆漏失,导致水平井固井质量较差。在分析固井技术难点的基础上,通过室内和现场试验优化了GSJ水泥浆体系,基于地层压力与破裂压力确定了环空浆体结构,优选了扶正器类型并优化了其加放位置,采用了加长胶塞、树脂滚轮刚性旋流扶正器和关井阀等工具,并采用"紊流+塞流"复合顶替工艺,以降低漏失风险、提高固井质量。室内试验表明,GSJ水泥浆体系具有良好的性能,尾浆API滤失量小于20mL,过渡时间15min,水泥石12h抗压强度达19.0 MPa,模拟套管居中度大于72.5%。该固井技术在泾河油田18口水平井进行了现场应用,水泥浆全部返至地面,固井优良率达100%。现场应用表明,该固井技术解决了泾河油田水平井固井难题,提高了固井质量,为后期分段压裂提供了良好的井筒条件。

With low pressure bearing capacity of the formation,the Jinghe Oilfield is characterized by the poor quality of cementing operations in horizontal wells because cement slurry is susceptible to lost circulation.With consideration to the challenges in cementing operations,a GSJ cement slurry system was developed and optimized through lab tests and field applications.Based on formation pressures and fracturing pressures,the annular structure of slurry was determined,wherein the types and positions of centralizers were optimized.In addition,prolonged rubber plugs,resin wheel rigid swirl centralizer and shut-in valves were adopted.Laboratory tests and field applications showed the innovative GSJ cement slurry system had outstanding performances with an API loss of tail slurry of less than 20 mL,a transition time of 15 minutes,and 12 hcompressive strength of set cement up to 19 MPa.At the same time,software simulation results show that casing center degree is greater than 72.49%.The"turbulent flow+slug flow"compound displacement technology was adopted to minimize the risk of lost circulation.The cementing technology was applied in 18 horizontal wells in the Jinghe Oilfield.With all the cement slurry returned to the ground,all cementing operations were performed successfully.Field application results showed the cementing technology could effectively solve problems in cementing operations of horizontal wells in Jinghe Oilfield.In addition to enhance cementing quality,the innovative cementing technology could provide high-quality wellbores for fracturing operations in later staged fracturing.