塔中高含硫碳酸盐岩储层密闭循环安全钻井技术

塔里木盆地塔中高含硫碳酸盐岩储层钻井主要难点为:储层压力敏感、H2S含量高,导致采用常规欠平衡钻井技术风险很大,而利用密闭循环钻井技术则可以有效降低钻井风险。通过分析国外密闭循环钻井技术的工作原理、系统构成,针对塔中高含硫碳酸盐岩储层的特点,充分考虑国内现有装备水平,提出了使用气液二相分离器加密闭振动筛替代四相分离器的实用化密闭循环系统方案。在此基础上,完成了具有自主知识产权的密闭振动筛的结构设计,进行了高含硫天然气燃烧排放对大气环境的影响实验和氨洗脱硫效果实验,对实用化的密闭循环系统方案进行了充分的论证。研究表明:破解塔中高含硫碳酸盐岩储层面临的钻井难题最合适的技术就是密闭循环钻井技术;实用化的密闭循环系统是密闭循环钻井技术的关键装备。实验结果也证明了实用化的密闭循环系统方案具有很好的针对性和适用性。该成果对于高效勘探开发塔中高含硫碳酸盐岩储层有着重要的意义。

Closed-circulation safe drilling technology for high-sulfur carbonate reservoirs in the Middle Tarim Basin(Tazhong)

Many drilling difficulties exist in high sulfur carbonate reservoirs of the Middle Tarim Basin (Tazhong), which are featured by stress sensitivity and a high H2S content, leading to a high risk in routine unbalanced drilling work. The closed circulation drilling technology can effectively reduce the drilling risk and is of significance to the highly efficient exploration and development of Tazhong high sulfur carbonate reservoirs. Based on the investigation of the working principles and system components of the closed circulation drilling technology used overseas, with the equipment now available in China being taken into account, a practical closed circulation system is recommended with a gas/liquid separator plus closed shale shakers instead of the 4 phase separator being applicable for drilling through high sulphur carbonate reservoirs at Tazhong. On the basis of this, the structure design is then completed for a closed shale shaker with independent intellectual property awarded. Experiments regarding the effects of sour gas flaring on atmospheric environment are performed and a sulfur scavenging experiment by ammonia washing is done to testify this practical closed circulation system. The results show that the closed circulation drilling is the most appropriate technology for high sulfur carbonate reservoirs at Tazhong, and the practical equipment proposed herein is critical for this technology with good applicability and pertinence.