深盆气藏勘探方法及其应用

Exploration method for deep basin gas trap and its application

深盆气藏是天然气勘探与研究的一个发展方向,深盆气藏的勘探须基于地质理论、勘探方法和工程技术三者“一体化”的综合研究。“一体化”综合研究主要包括:①强调油气勘探过程中,深盆气藏地质理论的研究与应用;②针对深盆气藏地质特征,开展与之相配套的多学科综合勘探方法研究;③钻井和试采工程技术的改进。这3方面的研究内容相辅相成,缺一不可。在四川盆地通南巴构造带,以深盆气藏地质理论为指导,进行了深盆气藏综合勘探方法的探索性应用。结果表明,利用该方法识别深盆气藏是可行的。地质、地震资料显示,尺溪向斜生储盖条件配置完好,已形成“压力封存箱”,为该区深盆气藏勘探的前景区。基于深盆气藏系统要素分析,提出了适合于通南巴构造带的深盆气藏地质模型。构造向斜部位、区域性压力转换带以下、陆相地层中的上沙溪庙组下部到下沙溪庙组上部局部异常高压区是深盆气藏勘探的重点位置,建议进一步论证后部署探井。

Deep basin gas trap is considered as the prospective target of gas exploration and research in recent decades. The exploration methods for deep basin gas trap are based on integrative study of geological theory, exploration strategy and engineering techniques. In detail, the integrative study consists of the following three indispensable aspects: (1) Emphasis on study and application of geological theory for deep basin gas trap during the exploration process; (2) Multi-subject integrative study on the exploration method based on the specific geological features of deep basin gas trap; (3) Improvement of drilling and production techniques. The application of the integrative exploration method for deep basin gas trap in Tongnanba Structural Belt of Sichuan Basin proved the feasibility of this method for identifying the deep basin gas trap. The geological and seismic data indicated that Chixi Syncline has formed pressure compartment with favorable source-reservoir-cap rock assemblage and become the prospective area for exploration of deep basin gas trap. The systematic factors/elements of deep basin gas trap were analyzed, and a geological model suitable for deep basin gas traps of Tongnanba Structural Belt was proposed. It is suggested that under the condition of regional geo-pressure transforming zone in the syncline of the structure, and the terrestrial formation from the bottom of Upper Shaximiao Formation to the top of Lower Shaximiao Formation, the local overpressure areas are the important spots for exploration of deep basin gas traps. It is recommended to make further study and to design a wildcat well in this area.