川西新场地区中深丛式定向井防卡技术

川西新场构造沙溪庙气藏的主要开发手段是应用丛式定向井组,但在开发中期发生了7次卡钻事故,严重影响了该地区的勘探开发进程。对该地区卡钻井的情况进行了详细调研,确定卡钻的性质是黏附压差卡钻,借助相关数值模拟技术对该地区黏附压差卡钻原因进行了研究,得出卡钻的主要原因是该地区目前施工压差大、钻井液性能不稳定、井眼净化不良、轨迹控制和施工操作不当,提出了合理设计钻井液密度、控制合理井底压差、优选钻井液类型和性能、严格控制钻具在井内的静停时间、钻进和其下钻的过程中监控记录其摩阻与扭矩情况、优化井下钻具组合等现场技术对策。经过现场应用,获得了一套适合当前川西新场地区中深丛式定向井快速、安全钻进的防卡技术,取得了较好的应用效果,加快了新场地区的勘探开发步伐,同时对川西和其他老油气田防止卡钻事故具有借鉴意义。

No-wall-stick technology of medium-deep directional cluster wells in Xinchang region west of Sichuan

Shaximiao gas pool of Xinchang Formation is a gas pool mainly developed in Xinchang gas field. It is the major method that applies directional cluster wells to develop the gas pool. However, there have been seven sticking accidents happened during the mid stage of development, which has great effect on the exploration and development of the region. Based on the exact survey and study of the sticking problems of the region, the property of sticking is identified as differential pressure sticking. Then the causes of differential pressure sticking are analyzed by using relevant numerical modeling techniques. Finally, the main causes of sticking are identified, that is, the big operation pressure differential, the unstable drilling fluid properties, the poor borehole cleaning, poor trajectory control and construction operation. Some techniques are brought forward to prevent the differential pressure sticking in the construction field, such as rational design of the density of drilling fluid, optimal control of bottom-hole pressure differential, optimization of the types and performance of drilling fluid, strict control of the time of drilling tool stopped in wells, the monitoring and recording the friction and torque during drilling, and optimization of downhole drilling assemblage. Through field application, a set of non-wall-stick technologies suitable for safe and fast drilling of the mid-deep directional cluster wells in Xinchang region are developed. Good results are obtained from the field application, which accelerates the exploration and development of the region. What's more, it may be a good reference to preventing sticking accidents in western Sichuan and other old oil and gas fields.