塔里木盆地天然气系统划分

DIVISION OF NATURAL GAS SYSTEMS IN TALIMU BASIN

天然气系统实质上特指那些富气的含油气系统。塔里木盆地是一个既富油也富气的盆地，划分天然气系统的目的是为了寻找天然气富集区，并从中发现大中型气田。通过对盆地中油气系统的评价，划分出库车、叶城两个天然气系统及塔中、塔北、巴楚油气系统中的一些富气区。其中前陆盆地中的库车天然气系统属过充注、高阻抗、网状运移的整体富气的天然气系统，是盆地中天然气资源潜力最大的地区；克拉通盆地中富气区受寒武系—下奥陶统生气中心控制；塔中油气系统中东部富气区气藏形成具多期、多阶连续聚集的特点，发育多套成藏组合，保存条件好，是台盆区资源潜力最大的地区；塔北隆起东部及巴楚隆起玛扎塔格富气区区域盖层受构造运动和断裂的破坏，保存条件不如塔中地区，主要聚集了晚期高—过成熟干气，天然气聚集期短，属阶段聚气区；逼近寒武系—下奥陶统生气中心，特别是寒武系膏盐层下有可能形成较大规模的原生干气藏。

Essentially, the natural gas system is the hydrocarbon system rich in gas. Talimu Basin is rich in not only oil but also gas. The goal of dividing natural gas systems is to survey gas accumulation regions from where the medium and large sized gas fields will be found. Through the evaluation of the hydrocarbon systems in the basin, two natural gas systems (Kuche and Yecheng) and some rich in gas regions in the Tazhong, Tabei and Bachu hydrocarbon systems are divided. In these systems, the Kuche natural gas system in foreland basin belongs to the whole rich in gas one with overinjection, high impedance and reticulated migration, being the region with the greatest potentialities in gas resources in the basin; the rich in gas regions in craton basin are controlled by the gas generation centers in Cambrian Lower Ordovician; the east rich in gas region in Tazhong hydrocarbon system, in which the gas reservoirs are of the properties of successive multistage accumulation, multiple source reservoir cap assemblages and good preservation conditions, is the one with the greatest potentialities in resources in platformal basin region; the east part of Tabei Uplift and the Mazatage rich in gas region in Bachu Uplift, where the preservation conditions were not as good as those in the Tazhong region because of regional caprocks' destruction by faults, mainly accumulated the late high and post maturity dry gas with a short accumulation period, belonging to staged gas accumulation regions; and some larger original dry gas reservoirs might be formed near the gas generation centers in Cambrian Lower Ordovician especially under the anhydrocks and salt beds in Cambrian.