胜利坨826区块裸眼内转化合成基钻井液技术

Conversion Technology of Synthetic Based Drilling Fluid in Open Hole in Block Tuo 826,Shengli Oilfield

胜利油田坨826区块油井在钻至储层时需将井内钻井液转化成合成基钻井液,以保护储层,提高油井产能。由于井下安全的需要,转化成合成基钻井液时需要多下一层技术套管,从而增加了钻井成本,为此,胜利油田进行了裸眼内转化合成基钻井液技术研究。在合成基钻井液基本配方基础上,优化油基封堵材料DF-1用量,确定了封堵型合成基钻井液配方,并与现场施工工艺相结合,形成了裸眼内转化合成基钻井液技术。通过可视砂床试验和封堵能力测试、抗污染试验及滤饼破坏试验,对封堵型合成基钻井液的封堵性能、抗污染性能及其对水基钻井液滤饼的影响进行了评价。结果表明:封堵型合成基钻井液的承压能力大于7.5 MPa;钻屑、井场水、水基钻井液和隔离液侵入量达到15.0%时,该钻井液的流变性和电稳定性符合设计要求;可以压缩已形成的水基钻井液滤饼,使滤饼质量提高。坨826区块3口井应用了裸眼内转化合成基钻井液技术,均在裸眼内顺利转化成封堵型合成基钻井液,稳定了井壁,保护了储层。这表明,在裸眼内转化合成基钻井液是可行的,能够有效降低钻井成本。

During the drilling of Block Tuo 826 in the Shengli Oilfield,synthetic based drilling fluid should be used to protect the reservoir,but one more technical casing must be used for drilling fluid conversion.In order to avoid running another technical casing and reduce drilling costs,the conversion technology of synthetic based drilling fluid in open hole was researched.Based on the basic formula of synthetic based drilling fluid,a formula of plugging synthetic based drilling fluid was determined by optimizing the amount of oil based plugging material DF-1.And combined with field operation technologies,the conversion technology of synthetic based drilling fluid in open hole was developed.Evaluation was conducted on the plugging capacity and anti-contamination capacity of the plugging synthetic based drilling fluid and its effect on water based mud cake by means of visual sand-bed test,plugging capacity test,anti-contamination test and filter cake breaking test.It was shown that its pressure bearing capacity was over 7.5MPa.When the invasion amount of the cuttings,well site water,water base drilling fluid and spacer？fluid reached 15%,its rheological property and electrical stability could also meet the design requirements.And this system could improve the quality of the existing cake by means of compression.The technology was successfully applied in 3wells in Block Tuo 826 and the goals of wellbore stability and reservoir protection were realized.It was shown that the conversion of synthetic based drilling fluid in open hole was feasible.Based on this technology,drilling cost could be reduced significantly.