南中国海东沙海域水合物成藏动力学模拟

Simulation of Reservoir Dynamic of Gas Hydrates of Dongsha Area of South China Sea

基于南中国海东沙海域某地震剖面资料,利用Basin2二维模拟软件,结合研究区有关地温场、热流探测资料和ODP184航次调查的岩心数据,重塑了研究区沉降史、有机质生烃史、古地温场与热史变迁。进而利用＂生物成因天然气水合物成藏动力学模拟系统＂（Hydrate Dynamics）软件,模拟了水合物聚集的过程与分布范围。模拟结果表明,研究区水合物稳定域较厚（200~250 m）,有机质含量适中,生物成因甲烷主要在海底1 km以浅范围内形成。稳定域之下早先埋藏的沉积物中有机质形成的生物成因甲烷在压实流的作用下能够向浅部层位中运移聚集,从而对现在的矿层有所贡献。水合物主要赋存于稳定域底部以上50 m的层位内,富集带中水合物的平均含量约为5%。

Based on the seismic profile data of Dongsha of the South China Sea,using a two-dimensional simulation software,Basin2,combining with the data of the geothermal field,heat flow and core of leg 184 of ODP,this paper rebuilt the subsidence history of the study area,the hydrocarbon-generating history of the organic matter,and the change history of the ancient geothermal field and thermal.The paper simulated the process of hydrate accumulation and distribution with ＂Biogenic Gas Hydrate Reservoir Dynamics Simulation System＂（Hydrate Dynamics）.Simulation results show that the thickness of the hydrate stability region is large（200~250 m）,and organic matter content is moderate,biogenic methane is generated 1 000 mbsf.Biogenic methane generated by the organic matter in the sediments buried previously under the stability region can migrate and accumulate in the shallow strata because of the compaction flow,and contribute to the current mineral deposit.Hydrates occur in the stable region mainly for the thickness of 50 m,and average saturation of hydrate is about 5%.