四川盆地高陡构造碳酸盐岩钻井技术发展方向

DEVELOPING DIRECTION OF DRILLING TECHNIQUE FOR CARBONATE ROCKS IN HIGH AND STEEP STRUCTURES IN SICHUAN BASIN

川东高陡构造带是四川盆地主要的天然气产区。但区内陡构造碳酸盐岩钻井地质条件特别复杂。主要表现在 :浅—中层恶性井漏 ,上部泥页岩及膏盐层垮塌 ,纵向上多产层、多压力系统 ,压力系数悬殊大、横向上储层分布不稳定 ,储层类型多样化 ,地层压力变化大 ,对比性差、中靶难度大和天然气H2 S含量高。造成钻井复杂情况多 ,事故风险大 ,严重制约深井钻井速度的提高。文中根据目前技术发展趋势 ,针对高陡构造钻井难点 ,提出了今后一段时期应重点组织攻关并尽快推广的几项钻井实用技术 ,包括深化地质规律特性的认识 ,防漏治漏、防斜打快、井身结构挖潜 。

The high and steep structure belt in east Sichuan is a main gas producing area in Sichuan basin;however the geological condition of the carbonate rocks in the steep structures in the area is very complex,which is mainly expressed as follows:the pernicious lost circulation occurs in shallow medium formations;the argillutite,anhydrocks and salt rocks at the upper part collapse;there are multiple pays and pressure systems longitudinally;there is a great disparity in the pressure coefficient;the distribution of the reservoirs is not stable horizontally;the types of the reservoirs are various;the change of the formation pressure is great;the stratigraphic correlativity is poor;the difficulty in hitting the target is great and the content of H 2S in natural gas is high,which cause many complicacies and accidents in drilling,seriously restricting the drilling rate of deep wells.In view of the existing developing trend of the technique and the difficulty in drilling high and steep structures,several practical drilling technologies which should be emphatically surmounted in the future and spreaded as soon as possible (including deepening knowledge of the characteristics of the geological law,leak protection and control,deviation control,raising drilling rate,tapping the latent power in casing program,directional drilling and under balance pressure drilling,etc.) are proposed in this paper.