渭河盆地生物气生成条件

Biogas generation conditions in Weihe Basin

张云翠

ZHANG Yuncui

中国石化华北油气分公司勘探开发研究院，河南 郑州 450006

Research institute of Exploration and Development, North China Oil and Gas Company, SINOPEC, Zhengzhou 450006, China

文中利用钻测录井资料，结合前人研究成果，通过野外地质调研、气体化验分析、岩石地化分析等方法，对渭河盆地生物气的地球化学特征及生成条件进行了研究。研究表明：渭河盆地张家坡组天然气具有典型的生物成因特征，其适宜甲烷菌存活的地层温度、水介质矿化度和pH值及新生代快速沉积形成的缺氧还原环境，为生物气的生成提供了有利条件；固市凹陷快速沉积形成的半深湖相未成熟—低成熟暗色泥岩是生物气良好的母质来源。参考沉积有机质降解生成甲烷的生物化学反应机理，结合区域地质条件，文中明确了张家坡组生物气的生气模式，预测主产气带埋深为1 300～1 600 m，并指出固市凹陷沉积中心张家坡组断块和岩性圈闭发育区是生物气富集有利区。 

 Using drilling and logging data, and combined with the previous research results, the geochemical characteristics and generation conditions of biogas in Weihe Basin are studied by means of field geological survey, gas laboratory analysis and rock geochemical analysis. The study shows that the natural gas of Zhangjiapo Formation in Weihe Basin has typical biogenic characteristics. The strata temperature, water medium salinity and pH value suitable for the survival of methane bacteria and the hypoxic reduction environment formed by rapid deposition of the Cenozoic provide favorable conditions for the generation of biogas. The lacustrine immature to low mature dark mudstone formed by rapid deposition in Gushi sag provides good source of parent material for biogas. Based on the biochemical reaction mechanism of methane generation from sedimentary organic matter degradation, and combined with the regional geological conditions, the biogas generation mode of Zhangjiapo Formation is clarified, and the buried depth of main gas producing zone is predicted to be 1,300 to 1,600 meters. The fault block and lithological traps of the Zhangjiapo Formation in the deposition center of Gushi Sag are favorable areas for biogas enrichment.

10.6056/dkyqt202105007