神狐海域天然气水合物成藏系统数值模拟与试采矿体优选

    Numerical simulation of gas hydrate migration-accumulation system and trial mining optimization of orebodies in the Shenhu area

    • 摘要: 为了进一步了解南海北部陆坡神狐海域勘探区天然气水合物成藏系统特征,优选天然气水合物优势矿体,基于经过矿体的地震剖面资料,结合区域成藏地质条件,分别构建了勘探区W17和W18两个矿体的二维地质模型,从天然气水合物成藏的稳定域、气源形成、运移输导及储集成藏进行了系统数值模拟。结果表明:①神狐勘探区成矿气源丰富,来自浅层的生物成因气和深层的热成因气都可作为天然气水合物成藏的气源;②神狐勘探区流体输导条件良好,深部大断裂可以作为油源断裂沟通深部源岩,是连接深部热成因气的主要通道,浅部调节性断裂和渗透性砂岩一起作为横向+垂向复合输导;③在神狐勘探区稳定域内,区域构造部位相对高、断块封闭性相对好、渗透率相对大的区域为天然气水合物成藏的有利储集层;④综合分析认为,W17矿体比W18矿体在气源、运移及储层特性上更具优势,应作为优先考虑的试采矿体。

       

      Abstract: Based on seismic profile data of natural gas hydrate exploration in Shenhu area in the north of South China Sea, combined with geological conditions of regional accumulation, the 2D geological models for the W17 and W18 orebodies in the exploration area were constructed respectively to further understand the gas hydrate accumulation system in Shenhu exploration area of the northern continental slope of South China Sea.A systematic simulation was carried out to test gas hydrate stability zone, gas source formation, migration and accumulation.The results show that: a.the Shenhu exploration area is rich in gas sources, and both the shallow biogenic gas and the deep thermogenic gas can be used as gas sources for hydrate accumulation; b.the Shenhu exploration area has excellent transport system where the deep fault can be used as source fault to connect the deep source rocks and serves as the main channel connecting the deep thermal gas, and the shallow regulatory fracture and permeable sandstone serve as transverse and vertical transportation; c.the areas with relatively good sealing property of fault blocks and relatively high permeability are favorable reservoirs for gas hydrate accumulation.According to the comprehensive analysis, the orebody W17 has more advantages than the orebody W18 in gas source, migration and reservoir characteristics, so it should be considered as a priority for trial mining.

       

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