杭州湾地区超浅层生物气充注与成藏模式研究

Based on the previous research results, detailed geological and chemical analyses of the ultra-shallow biogenic gas and its potential gas source sediments in the Hangzhou Bay area, as well as the physical simulation experiment, this study aims to 1) determine the characteristics of the effective gas source sediments and the main phase state of biogenic gas migration, and 2) investigate the patterns and laws of ultra-shallow biogenic gas charging and migration, including the way of the biogenic gas migration from the muddy gas source sediments to the sandy reservoirs, within the sandy reservoirs, and from the sandy reservoirs to the muddy gas source sediments. Then we evaluate comprehensively the generation, migration, accumulation process and model of ultra-shallow biogenic gas by comparing with the other typical ultra-shallow biogenic gas reservoirs in the world. This study will provide a typical research example for the ultra-shallow biogenic gas reservoirs, enrich the migration and accumulation mechanism of biogenic gas, and fill up the blankness in this area around the world, which has great realistic significance in the exploration and exploitation of ultra-shallow biogenic gas.

本项目将在以往研究的基础上，对杭州湾地区超浅层生物气藏的潜在烃源岩和生物气进行精细的地质解剖和地球化学分析，从而确定其烃源岩特征、气体来源、运移相态等；利用室内物理模型试验对杭州湾地区超浅层生物气从泥质烃源岩充注到砂质储层中、在储层内、以及从砂质储层向周围，特别是上覆泥质地层运移的过程进行模拟再现；两者相互配合印证，进一步明确杭州湾地区下切河谷型超浅层生物气藏的有效烃源岩、气体充注方式和聚集过程等，分析其主要控制因素；与国内外其它地区典型超浅层生物气藏进行对比，综合评价超浅层生物气的生成、运移、成藏过程和成藏模式。该项目的实施将在一定程度上丰富生物气运聚机制、填补该领域的国内外空白，同时对超浅层生物气勘探开发有着重大的现实意义。

对江浙沿海平原浅层生物气藏的潜在烃源层泥质沉积物和生物气进行精细的地质解剖和地球化学分析，从而确定其烃源层沉积物特征、气体来源、运移相态等。利用室内物理模型试验和地球化学资料等，分析了晚第四纪地层生物气烃源层泥质沉积物生烃、 运移和聚集过程等，探讨了生物气的主要控制因素、成藏过程和成藏模式。研究区自下而上河漫滩、古河口湾相粉砂质黏土及近岸浅海相淤泥质黏土生气能力强，为江浙沿海平原浅层生物气有效气源层沉积物。有机质特征和沉积环境是研究区晚第四纪沉积物中生物气形成的最重要因素。有机质丰度主要受原始有机质的输入和后期微生物的生物降解两个因素控制。生物气主要是向上运移，而难以向下运移，成藏模式属于自生自储型。该项目的实施将在一定程度上丰富生物气运聚机制、填补该领域的国内外空白，同时对超浅层生物气勘探开发有着重大的现实意义。