生物气研究新进展与勘探策略

Advances in biogenic gas studies and play strategies

生物气是厌氧环境下特殊的生物产甲烷菌的代谢产物,形成途径主要有乙酸发酵和CO2还原两种。对于生物气形成,沉积有机质的丰度、类型并不重要,同生水溶解有机碳及无机碳均可为微生物活动提供碳源和能源,因此,需重新建立生物气源岩评价体系。在总结生物气形成有利地质因素的基础上初步分析认为,生物气勘探成功的关键是识别生物气聚集过程并建立合适评价方法;地质构造和地下水流动与生物气化学分析相结合,可以有效确定勘探目标。

Biogenic gas is important end-product of methanogenesis in an anoxic environment. Methanogenesis mainly occurs through acetate fermentation and CO2 reduction. Because those methanogens obtain carbon and energy sources mainly from organic and inorganic carbons dissolved in native water, the type and abundance of organic matters in the sediments are not important for the formation of biogenic gases, thus the evaluation system for biogenic gas source rocks should be re-built. Exploration strategies for biogenic gases are analyzed based on the conclusion of the favorable geologic conditions for the biogenic gas formation. The keys of the play strategy are to recognize the process of biogenic gas accumulation and to build an appropriate evaluation method. Through synthesizing the geochemical, geological, and hydrological information, the targets could be efficiently predicted.