【摘要】 井壁稳定是钻井的关键技术之一 ,而且是世界性的钻井难题。根据不稳定地层的特性 ,给出相应的防范措施 ,对钻井工程中保持井壁稳定起着举足轻重的作用。井壁失稳问题不仅在砂泥岩剖面中存在 ,而且在碳酸盐岩剖面中也司空可见 ,但碳酸盐岩剖面井壁失稳的地层主要集中在地应力不平衡的地层、具有塑性和蠕变特性的盐膏岩地层、裂缝性地层及胶结性差的易破碎地层等。针对碳酸盐岩地层实际钻井过程中所遇到的各种引起井壁失稳的因素 ,对地应力因素引起井壁失稳控制技术、钻遇盐膏层预防措施、裂缝较发育的地层及胶结性差的破碎性地层井壁失稳对策进行了研究 ,并对保持井壁稳定的唯一可控因素 ,即安全钻井液密度窗的确定进行了探讨。这一整套对策对碳酸盐岩地层安全、经济、快速地钻探具有科学的指导作用更多还原

【Abstract】 It is one of the key techniques for well drilling, and also is a drilling problem worldwide to keep borehole stability. According to the features of the instable formations, the corresponding precautions should be proposed, which will play an important role for drilling to keep the borehole stability. The issue of borehole instability exists not only in sand-mud formations, but also in carbonate formations. The borehole instability happens mainly in the following carbonate formations. They are the formations with unbalanced formation stress; the salt and anhydrite formations with plasticity and creep property; the fractured formations; and the week bonding and friable formations etc. According to the factors causing borehole instability in carbonate formations, the control techniques of borehole instability caused by formation stress, the precautions of drilling salt and anhydrite formations, the countermeasures to deal with borehole instability for fracture-developed formations and the week bonding and friable formations are studied. Also, it is discussed how to determine the only controllable factor to keep the borehole stability, i.e. the density window of secure mud, The all countermeasures have guiding significance for carbonate formations to drill safely, economically and rapidly.更多还原