高酸性活跃厚沥青层复杂碳酸盐岩油田钻完井关键技术

A key technology for drilling and completion in complex carbonate oilfields with highly acid and active thick asphalt layers

典型的高酸性复杂碳酸盐岩油藏——YD油田的碳酸盐岩储层厚度达3km,具有活跃厚沥青层漏喷同存、地层多腐蚀介质、多套地层压力体系并存等特点,钻井过程中存在碳酸盐岩地层孔隙压力预测困难、沥青侵入严重、多腐蚀介质导致井筒完整性难以保障、钻井周期长、长井段均匀改造难度大等难题,通过技术攻关研究,形成了碳酸盐岩地层孔隙压力预测、监测和检测技术,揭示了沥青与钻井液置换机理,提出了以堵代压的活跃厚沥青层安全钻井技术,形成了高酸性多腐蚀介质并存条件下井筒完整性保障和长井段均匀酸化改造等为核心的高酸性活跃厚沥青层复杂碳酸盐岩油田钻完井关键技术。该技术在YD油田55口井进行了现场应用,平均机械钻速提高了45.5%,钻井周期缩短了44.5%,大大降低了钻完井成本,有力保障了该油田一期产能建设的完成,也为国内外类似碳酸盐岩油田的高效勘探开发提供了借鉴。

With the thickness of carbonate reservoirs up to 3000 m,the YD oilfield is characterized by coexistence of blowout and lost circulation in active thick asphalt layers,multiple corrosive media in the formation,and coexistence of multiple formation pressure systems.There are problems such as severe bitumen intrusion,long drilling cycles,and difficulties in predicting pore pressure,guaranteeing wellbore integrity due to multiple corrosive media,and uniformly transforming long well sections in carbonate formations during drilling.Through technical research,this study has established the prediction,monitoring and detecting technology of the pore pressure in carbonate formations,reveals the replacement mechanism of asphalt and drilling fluid,and proposes a safe drilling technology for active thick asphalt layers with plugging instead of well killing,forming a key technology for drilling and completion in complex carbonate oilfields with highly acid and active thick asphalt layers,which focuses on wellbore integrity and uniform acidification transformation of long well sections under the coexistence of highly acid and multiple corrosive media.The technology was applied on-site in55 wells of the YD oilfield.The average rate of penetration was increased by45.5%,and the drilling cycle was shortened by 44.5%,which greatly reduced the cost of drilling and completion and effectively guaranteed the completion of the firststage productivity construction of the oilfield.It provides a reference for the efficient exploration and development of similar carbonate oilfields at home and abroad.