南海北部边缘盆地生物气/亚生物气资源与天然气水合物成矿成藏  

Bio-genetic and sub-biogenetic gas resource potential and genetic types of natural gas hydrates in the northern marginal basins of South China Sea

作　　者：何家雄[1] 颜文[1] 祝有海[2] 张伟[1] 龚发雄[1] 刘士林[1] 张景茹[1] 龚晓峰[1] 

机构地区：[1]中国科学院边缘海地质重点实验室 [2]中国地质科学院矿产资源研究所

出　　处：《天然气工业》2013年第6期121-134,共14页Natural Gas Industry

基　　金：国家自然科学基金项目(编号:41176052);国家重点基础研究发展计划(973计划)项目(编号:2009CB219501)

摘　　要：南海北部边缘盆地天然气资源丰富,迄今在该区浅层及中深层除发现大量成熟—高熟偏腐殖型气(煤型气)资源外,在浅层还发现了大量生物气与亚生物气显示和单独成藏的生物气与亚生物气气藏。为弄清该区生物气与亚生物气资源前景、天然气水合物成因及成矿成藏模式等关键性地质问题,根据历年来天然气勘探所获得的大量地球化学资料,结合该区油气成藏地质条件,深入分析和阐明了南海西北部莺—琼盆地及东北部珠江口盆地生物气与亚生物气的地质、地球化学特征和新近纪及第四纪生物气与亚生物气烃源岩的展布特点。在此基础上,初步预测和估算了莺—琼盆地和珠江口盆地生物气的生成量与资源量。评价结果表明:该区生物气与亚生物气资源丰富,完全可作为南海北部深水区天然气水合物的主要气源;同时,通过南海北部深水区天然气水合物成因类型的地球化学分析,亦进一步证实该区目前勘查发现的天然气水合物,应属"自源扩散型"生物成因成矿的水合物类型,其气源供给主要来自原地或其附近以生物气为主的混合气,而水合物成矿成藏模式则属于原地及其附近近源运聚的"自源扩散型"成因模式,具有巨大的资源潜力。Abundant natural gas resources have been found in the marginal basins of the South China Sea. Besides a huge amount of mature and highly mature （humic types） coal-formed gas in the shallow and middle deep strata there, a great quantity of biogenetic and subgiogenetic gas displays as well as their reservoirs have been discovered in shallow formations. Therefore, this paper aims to make clear many essential geological issues in this study area： the resource potential of biogenetic and sub-biogenetic gas, the origin of natural gas hydrates and its mineralization and accumulation modes, and so on. First, based on a number of geochemical data col lected from the exploration over the past years, this paper analyzed the geological conditions of hydrocarbon pooling and then made a deep investigation into the geological and geochemical characteristics of biogenetic and sub-biogenetic gas and the distribution features of hydrocarbon source rocks in Neogene and Quaternary bed layers in the northwestern Yinggehai Qiongdongnan basins and the northeastern Pearl River Mouth Basin. On this basis, the generation amount and resource extent of biogenetic gas in the above-men- tioned basins were preliminarily predicted and estimated. The following findings were obtained. First, the rich biogenetic and sub- biogenetic gas in this study area can completely be regarded as the main gas source of natural gas hydrate in the deep water of north- ern South China Sea. Second, through the geochemical analysis of the genetic types of gas hydrate in this deep water area, it is con firmed that the gas hydrate discovered so far belongs to self-source diffusion mode, the source of which comes from a kind of mixed gas dominated by biogenetic gas in situ or nearby, while the mineralization and accumulation mode of gas hydrate can be classified into a near source migrated and accumulated self-source diffusion genetic model, which has tremendous resource potential.

关 键 词：生物气与亚生物气 资源潜力 天然气水合物 成因类型 成矿成藏模式 勘探前景 沉积速率 南海北部边缘 

分 类 号：P618.13[天文地球—矿床学]