松辽盆地北部浅层气成藏主控因素及勘探有利区

浅层气是埋深相对较浅的天然气，世界范围内资源丰富，也是中国重要的潜在勘探领域。由于受中浅层找油、深层找气的二元勘探思想指导，松辽盆地北部浅层气的勘探和研究工作开展相对较少，浅层气分布、成因类型和成藏主控因等方面缺乏系统性研究。针对上述问题，笔者系统地研究了松辽盆地北部浅层气的分布和成因类型，总结了不同类型浅层气成藏控制因素，并预测了浅层气勘探有利领域。研究表明：①松辽盆地北部浅层气分布广泛，平面分区，纵向分层;②松辽盆地北部浅层气总体可分为与生物作用相关的浅层气和与热成因相关的浅层气两大类，其中与生物作用相关的浅层气包括浅层生物成因气（Ⅰ）、浅层生物-热催化过渡带气（又称低熟气）（Ⅱ），与热成因相关的浅层气包括浅层热成因油型气（Ⅲ₁）、浅层热成因煤成气（Ⅲ₂）;③松辽盆地北部与生物作用相关的浅层气和与热成因相关的浅层气具有不同的成藏主控因素：浅层生物成因气、低熟气成藏主要受未熟-低熟烃源岩或降解原油的分布，岩性和构造相关的圈闭以及盖层控制;浅层热成因气成藏主要受腐泥型或煤系成熟气源岩，构造和断层遮挡相关的圈闭，盖层和断层控制;④松辽盆地北部浅层资源丰富、潜力巨大，浅层生物成因气、低熟气比浅层热成因气具有更广阔的资源前景，其中西部斜坡区和中央坳陷区浅层是浅层生物成因气和低熟气的勘探有利区域。该研究对松辽盆地北部浅层气勘探具有重要的理论和现实指导意义。

Main controlling factors in the shallow-gas reservoir formation and its favorable exploration area in the northern Songliao Basin

The exploration for shallow gas that has a relatively shallower burial depth has been carried out all over the world, especially in North America. Shallow gas is also considered as an important potential resource in China. Guided by the binary exploration thought of looking for oils in shallow-medium layers and for gases in deep layers, researches on and exploration for shallow gas in the northern Songliao Basin are rarely carried out, so shallow gas distributions, genetic types and main controlling factors in the gas-reservoir formation in the basin lack systematical studies. Aiming at the above-mentioned problems, we firstly studied shallow gas distributions and genetic types, then discussed main controlling factors for different shallow gases, and finally forecasted favorable areas of gas exploration. The research result indicates that：①shallow gas is widely distributed in different horizontal areas and vertical formations in the northern Songliao Basin;②shallow gas in the northern Songliao Basin can be generally divided into biogenic gas and thermogenic gas, the former includes shallow biogenic gas（Ⅰ）and shallow bio-thermocatalytic transitional zone gas (so-called low-maturity gas)(Ⅱ), while the latter includes shallow oil-type gas（Ⅲ₁）and shallow coal-formed gas（Ⅲ₂）;③both biogenic gas and thermogenic gas have different main controlling factors in reservoir formation: for instance, shallow biogenic gas and low-maturity gas are mainly controlled by immature and low-maturity source rocks or distributions of degraded crude oils, lithologhic and tectonic traps and caprocks; while shallow thermogenic gas is mainly controlled by matured sapropel or coal-measures source rocks, fault-screened and tectonic traps, caprocks and faults;and ④ the northern Songliao Basin is very abundant in shallow gas, of which shallow biogenic gas and low-maturity gas have a greater resource prospect than shallow thermogenic gas, the west slope area and shallow layers of the central depression are favorable areas of the exploration for shallow biogenic gas and low-maturity gas in the northern Songliao Basin. The present study is of great significance both in theory and in realistic guidance for the shallow gas exploration in the northern Songliao Basin.