松辽盆地北部生物气成藏特征和资源潜力

Accumulation characteristics and resource potentials of biogas in the northern Songliao Basin

对松辽盆地北部生物气形成的地质条件、成藏特征和有利分布区进行了深入研究,认为该盆地北部未熟—低熟源岩分布广,生物气主要分布在源岩有机质丰度高、类型好和泥岩厚度大的地区。松辽盆地北部浅层温度低、压力小、盐度低和NaHCO_3型水介质有利于生物气的生成。生物气成藏一般为低丰度、高产的小型气藏,平面上可能具有广泛的分布特征。综合地球化学、地质、录井和测井研究成果,确定了松辽盆地北部生物气的3个有利勘探区带:一是西部斜坡的萨尔图油层;二是古龙和长垣南部的黑帝庙油层;三是三肇凹陷和朝阳沟—长春岭地区的葡萄花油层。

The Daqing Oilfield speeds up to explore deep gas reservoir,at the same time the study of shallow gas is propelled for latest years. Biogas was often discovered when the shallow strata in the Songliao Basin was drilled. Based on the numerous statistical data by the authors,geologic conditions of generation, accumulation characteristics and favorable distribution area of biogas were deeply studied in the northern Songliao Basin. The study thought that immature and lowmature source rocks had a wide distribution, biogas was mainly distributed in some zones with organic matter having a higher abundance,better type and more thickness of mudstone. Biogas had the beneficial generation conditions in the shallow strata of the Songliao Basin, such as low temperature,low pressure,low salinity and neutral aqueous medium. The biogas reservoir was generally, characterized by small, less abundant and high-yielded, and probably with a wide distribution horizontally. According to the geochemical,geological,logging and well-logging re- suits,we confirmed that there were three potential zones of biogas and low maturity gas for exploring in the Songliao Basin： one being Saertu oil layer in the West Slope,the second being Heidimiao oil layer in Gulong and the southern Daqing Placanticline areas, and the third one being Putaohua oil layer in Sanzhao-Chaochang area. Taking the trap resource quantity of Heidimiao layer in Aonan reservoir for the reference section,the paper calculated gas trap resource quantity of Heidimiao oil layer being 3 315.5 × 10^8 m^3 in the northern Songliao Basin.