塔北轮南地区油气成藏年代与成藏模式

通过包裹体分析法、伊利石测年法、露点压力 /饱和压力法、油气水界面追溯法等多种成藏年代分析方法研究认为 ,轮南地区油气藏具有多期成藏、晚期调整的特点 ,且早期油藏在晚期的调整改造十分强烈 .其中古生界特别是奥陶系油藏主要为晚海西期充注、喜山期受到调整改造而形成的残余原生油藏 ,三叠—侏罗系油藏主要为奥陶系古油藏在晚喜山期调整形成的次生油藏 .造成古油藏普遍发生调整的主要原因 ,一是后期强烈的构造变动和断裂活动 ,二是晚期高—过成熟气强烈的气侵作用 .因此 ,轮南地区大中型油气田的勘探应以轮南古隆起的斜坡部位 (包括轮南西斜坡和南斜坡 )为重点 ,它们是轮南地区大中型油气田形成和保存的最有利部位

Geological age and mode of hydrocarbon accumulation in Lunnan region,north Talimu Basin

The geologic age of hydrocarbon accumulation in Lunnan region is analyzed according to inclusion enclave, illite, dew point pressure/saturation pressure, interfaces among oil, gas and water, and it is held that hydrocarbon accumulation in Lunnan region of Talimu Basin is multiple stages and it is transformed in later period. The transformaton is very strong and quite common in this region. Ordovician reservoirs are mainly the remained primary hydrocarbon reservoirs accumulated and formed in the late Hercynian and transformed in Himalayan. Triassic—Jurassic reservoirs are the secondary hydrocarbon reservoirs formed in Ordovician and transformed in the late Himalayan period (Neogene). There are two factors to cause the strong adjustment and re-distribution of earlier hydrocarbon accumulations, one is the strong tectonic changes including faulting in the late Himalayan; another is the strong intrusion of high to over—maturated natural gas in the Neogene. In addition, the lower amplitude of traps, which is a common phenomenon in Talimu craton, is also an important reason for the widespread adjustment and transformation of hydrocarbon accumulation. The strong tectonic movements and gas intrusion make the hydrocarbon accumulation in lower traps adjusted rather easily. Therefore, structurally stable regions such as the west and the south slopes in the Lunnan ancient uplift ought to be most favorable for middle and giant hydrocarbon accumulation.