加蓬G4-188区块钻井液技术难点与对策

Gabon Block G4-188 Drilling Fluid Technology Difficulties and Countermeasures

加蓬G4-188区块存在表层严重漏失引起基础沉降、UPC井段缩径严重阻卡、LPC和ANG井段垮塌掉块扩径、地层承压能力分布不均引起的井漏等钻井液技术难点。为此,提出不同开次采用不同钻井液体系及不同工程技术措施的技术对策:一开采用加入随钻堵漏材料的高黏高切钻井液;二开采用强包被抑制性钻井液;三开采用抑制防塌钻井液;钻进坍塌掉块缩径井段采取防阻卡和防扩径技术措施;钻至预计漏层前采取防漏技术措施;钻进高压地层时采取控制流变性和膨润土含量的技术措施。这些技术措施在SAWZ-5井、SAWZ-6(2)井和SAWZ-7井的现场施工中取得了良好的应用效果。

There exist a lot of technical difficulties in Gabon Block G4-188,including foundation settlement caused by serious surface circulation lost,pipe stuck in UPC formation caused by tight hole,LPC and ANG section wellbore collapse and expansion,circulation lost caused by uneven distribution of formation loading capacity.Therefore,different drilling fluid systems and different technical measures for different well sections were proposed.Plugging materials were added to the high shear and high viscosity drilling fluid in first spud.Strong inhibition drilling fluid was used in second spud.Strong inhibition and anti-collapse drilling fluid was used in third spud.Anti-pipe-stuck and anti-wellbore-expansion techniques were used in section with hole shrinkage and slough problem.Anti-circulation-lost technique was used in circulation lost formation.When drilling high pressure formations,the bentonite contents and rheological property are controlled properly.All these measures were used in wells SAWZ-5,SAWZ-6（2） and SAWZ-7,and excellent results were obtained.