伊朗雅达油田S4井水平井钻井液技术

伊朗Y油田水平井水平段长在900～1000m,平均钻井周期为69d.该工区水平井施工存在二开井段盐膏层污染严重,潜在异常高压盐水层；Ph、Iam和Lf地层泥灰岩、页岩易水敏剥落,造成井壁失稳；斜井段漏失,滑动钻进“托压”严重,斜井段井眼清洁困难等技术问题.为此,对水平井钻井液体系配方和工程技术措施进行优化,改善钻井液抗污染、封堵防塌及润滑防卡性能,加强井眼净化及摩阻控制.“多元协同”防塌技术解决了井壁失稳问题;随钻防漏与细颗粒堵漏技术解决了定向段渗漏地层措施受限问题；液体润滑剂、固体润滑剂、乳化石蜡和聚合醇复配使用润滑效果显著,该井滑动钻进摩阻小于10kN,未出现明显的“托压”现象,并从现场验证了液体润滑剂最佳加量应小于3％.S4井现场试验表明,优化后钻井液技术措施效果显著,钻井过程无复杂事故发生,钻井周期缩短至57d.

Drilling Fluid Technology for Horizontal Well S4 in Yadavaran Oilfield of Iran

Horizontal section length of the horizontal well in Y Oilfield of Iran is 900-1000m.Its average drilling cycle is 69 days.A lot of technical difficulties encountered during drilling operation in Yadavaran oilfield：the pollution of salt and gypsum bed in second well section,latent abnormal high pressure saltwater zones;wellbore collapse and expansion by water sensitive muddy limestone and shales in Ph,Iam and Lf formation;mud losses in deviated well sections;serious phenomenon of backing pressure while sliding drilling;and difficult borehole cleaning in the deviated well section.Therefore,drilling fluids formula and technical measures used in the horizontal well are optimized.The performance of antipollution,blocking and slough resistance,lubrication and pipe stuck prevention is improved.And hole cleaning and friction control capability are reinforced.Multi-coordination anti-sloughing technology solves the problem of wellbore instability.Preventing loss while drilling and fine particles leak stoppage formula solve the issues of lost circulation in directional drilling of the low permeability formation.The lubricate property can be better when the fluid and solid lubrication and wax emulsion match with polyalcohol.The friction resistance is less than 10kN while sliding drilling.There is no obvious ＂back pressing＂ phenomenon and the optimal fluid lubrication concentration is less than 3% according to the field test.Field application in S4 well shows that the optimized technical measures of drilling fluid have remarkable effect.No complex downhole accidents occurred during drilling,and the drilling cycle is shortened to 57 days.