摘要
地层裂缝发育状况对井壁坍塌压力及井周失稳区域的分布方位和深度存在一定影响,但常规井壁稳定分析方法将地层视为各向同性介质,未考虑到破碎地层的裂缝特征。为研究破碎地层井壁坍塌压力及井周失稳区域变化规律,文中结合修正的MC强度准则和三向应力作用下的裂缝面强度准则,建立了破碎地层井壁坍塌压力和井周失稳区域预测模型,研究了裂缝数量及井眼轨迹对井壁稳定的影响。研究发现:三向应力作用下,破碎地层井壁坍塌深度主要受裂缝倾角的控制,与裂缝倾向无关,而井壁的坍塌方位与裂缝倾角无关,仅随裂缝倾向的变化而改变;井壁坍塌主要受某条特殊产状裂缝的控制,可通过调整井眼轴向与该裂缝面的相对夹角,达到减轻或控制井壁失稳程度的目的。
The development of stratigraphic fractures has a certain impact on the collapse pressure and the distribution azimuth and depth of the instability area around the wellbore.However,conventional wellbore stability analysis methods treat the formation as an isotropic medium without considering the fracture characteristics of the broken formation.In order to study the variation laws of wellbore collapse pressure and instability area around the wellbore in broken formation,this paper combines the modified MC strength criterion and the fracture surface strength criterion under triaxial stress to establish a prediction model for wellbore collapse pressure and instability area around the wellbore in broken formation.The effects of fracture number and wellbore trajectory on wellbore stability are studied.The study found that under triaxial stress,the collapse depth of the wellbore in broken formation is mainly controlled by the fracture dip angle,which is unrelated to the fracture tendency,while the collapse azimuth of the wellbore is unrelated to the fracture dip angle,and only changes with the change of the fracture tendency;The collapse of the wellbore is mainly controlled by a fracture with special occurrence.The relative angle between the axial direction of the borehole and the fracture surface can be adjusted to reduce or control the degree of wellbore instability.
作者
张明明
李大奇
范翔宇
ZHANG Mingming;LI Daqi;FAN Xiangyu(Research Institute of Petroleum Engineering Co.,Ltd.,SINOPEC,Beijing 100101,China;State Key Laboratory of Shale Oil and Gas Enrichment Mechanism and Effective Development,SINOPEC,Beijing 100101,China;Southwest Petroleum University,Chengdu 610500,China)
出处
《断块油气田》
CAS
CSCD
北大核心
2024年第5期916-921,共6页
Fault-Block Oil & Gas Field
基金
海相深层油气富集机理与关键工程技术基础研究子课题“高温高压油气安全高效钻完井工程基础理论与方法”(U19B6003-05)
国家重点研发计划课题“井筒稳定性闭环响应机制与智能调控方法”(2019YFA0708303)。
关键词
破碎地层
坍塌压力
井周失稳区域
强度准则
裂缝数量
broken formation
collapse pressure
instability area around wellbore
strength criterion
number of fractures
