摘要
礁灰岩漏失地层是一类结构脆弱 ,并含有大量孔洞和气体的特殊地层 ,常常是严重井漏与天然气的井喷井涌并存。解决这类地层的漏失问题对中国海相地层各种严重漏失地层钻井技术的发展有借鉴作用。讨论了礁灰岩漏失地层的特点 ,综述了国外 4个油田的礁灰岩漏失地层的钻井技术。礁灰岩漏失地层的流体通道是孔洞和岩石碎裂的裂缝 ,流体易出易进 ,渗透率极高 ,气体上窜速度快 ;岩石本体强度低 ,易碎裂 ,可钻性好 ;采用普通的堵漏工艺无法制服礁灰岩漏失地层的井漏。采用浮动钻井液帽 (floatingmudcap)技术钻礁灰岩漏失地层 ,能够快速穿过漏失地层 ,降低钻井成本。该技术的工艺要点为 :用清水作钻井液、高粘度钻井液稠浆作清扫液 ,边漏边钻 ,将钻屑带入漏失地层 ;在钻井、起下钻、电测和下套管等全部现场作业中连续不断地灌入具有适当密度的高粘度稠浆作为环空压井液。运用floatingmudcap技术的关键是井控技术的可靠性和水源。
Biolithite loss zone is a kind of special reservoirs where rock structure is frailish and lot of pore spaces and gas exist, while severe circulation loss and well blowout and well kick occur. It is important reference to development of drilling technology for overcoming severe circulation loss zone of marine reservoir in home oilfields that overcomes loss problems in the above reservoirs. Characteristics of biolithite loss zone were discussed and the drilling technology in four oilfields abroad were reviewed. As the channels of fluid in biolithite loss zone are pore space and fractures of reservoir, the fluids easily flow in or out the reservoir with its high permeability; drillability of the rock is good because of its low strength and fragility and conventional plugging technology cannot prevent circulation loss in the reservoir. Thus, drilling fluid technology using floating mud cap was used in drilling biolithite loss zone to drill lost layers rapidly and decrease drilling cost. Key points of the technology are following: drilling while fluid loss using fresh water as the drilling fluid and high viscosity thick fluid as the sweep fluid, so that makes cutting into lost layers; continuously injecting high viscosity thick fluid with appropriate density into borehole as annular killing fluid during drilling, tripping, logging and casing. Reliability of well control device and repertory of water and high viscosity mud used in annulus must be assured in using floating mud cap technology.
出处
《钻井液与完井液》
CAS
北大核心
2004年第1期45-49,共5页
Drilling Fluid & Completion Fluid
关键词
礁灰岩
漏失地层
钻井
浮动钻井液帽
堵漏
biolithite
loss zone
plugging
circulation loss
drilling
review
