摘要
油气井钻井过程中井筒液柱压力变化,作为主要漏失通道的裂缝发生应力敏感性,裂缝张开而使工作液固相颗粒粒径与裂缝宽度不匹配,导致井漏发生并恶化。孔洞存在及沟通性质影响裂缝的应力敏感程度,选用致密碳酸盐岩露头岩样,制取不同洞径、不同沟通情况的单一孔洞、双孔洞(不沟通)和双孔洞(沟通)6类裂缝岩样开展应力敏感性实验。实验结果表明,单孔洞(5mm)、单孔洞(10mm)、双孔洞(5mm,不沟通)、双孔洞(5mm,沟通)、双孔洞(10mm,不沟通)、双孔洞(10mm,沟通)6种缝洞类型岩样的平均应力敏感系数分别为0.66、0.59、0.47、0.24、0.66、0.43,其应力敏感程度分别为中等偏强、中等偏强、中等偏弱、弱、中等偏强、中等偏弱。孔洞加剧了裂缝宽度变化幅度,其应力敏感性更为强烈。孔洞的沟通虽弱化了裂缝的应力敏感性,但易导致堵漏封堵层失稳而堵漏失效,从而加剧了井漏。
Due to the changes of pressure, fractures intersected with borehole open and stress sensitivity happens in the progress of drilling, which make the diameters of solid materials unmatched to the loss channels and aggravates mud loss controlling. The existence and connectivity of vugs affect the variation range of fracture width. Carbonate outcropping core samples with different vug types are taken as laboratory subject. Experimental results including 6 groups rock samples shows that stress sensitive coefficients of the single vug（5 mm）, single vug（10 mm）, double vugs（5 mm, disconnected）, double rugs （5 mm, connected）, double vugs（10 mm, disconnected）, double vugs（10 mm, connected） core samples are respectively 0. 66, 0. 59, 0. 47, 0. 24, 0. 66, 0. 43, and the degree of stress sensitivity is respectively medium to strong, medium to strong, medium to weak, weak, medium to strong, medium to weak. It shows that the vugs intensify the rangeability of fracture width and the stress sensitivity. Though thevuggy connectivity weakens the stress sensitivity of fractures, it destabilizes the plugged zone and fails in lost circulation controlling, which causes severe lost circulation.
出处
《重庆大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2012年第5期115-120,125,共7页
Journal of Chongqing University
基金
国家重点基础研究发展计划(973计划)资助项目(2010CB226705)
国家科技重大专项资助项目(2011ZX05005-006-008HZ)
关键词
碳酸盐岩
缝洞型储层
应力敏感
孔洞沟通
渗透率
裂缝宽度
carbonate
fractured vuggy reservoir
stress sensitive
vuggy connectivity
permeability
fracture width
