油气分段捕获原理在天然气成藏研究中的应用——以柴达木盆地南翼山和开特米里克地区为例

油气分段捕获原理是基于油气生成与聚集的阶段性提出的一项动态分析油气成藏过程的理论，从现今圈闭中油气地球化学性质反推油藏形成过程是其最大的特色，在构造活动较为复杂的地区尤为适用。以构造活动较为频繁的柴西北区南翼山和开特米里克地区天然气成藏研究为例，根据天然气碳同位素差异，确定了气藏捕获的阶段性。阐述了2个构造形成期的不同，是其分别形成凝析气藏和干气藏及其成藏规模存在较大差异的主要原因，指出开特米里克构造期形成晚于气源岩生烃高峰，它仅捕获源岩演化阶段晚期生成的天然气，而南翼山构造则捕获了源岩生烃高峰期的油气。油气捕获阶段性的差异是造成2个构造气藏规模与类型存在较大差异的主要原因。

Natural Gas Accumulation by Phased Capture Principle:Taking North-West Area of Qaidam Basin as an Example

The theory of “Phased Capture Principle” is a method to analyse oil and gas accumulation based on the segment process of hydrocarbon generation and accumulation.Inferring the accumulation process from the oil and gas geochemical characteristics in the current traps is the bright spot of this theory,which is fit to area with frequent tectonic activities.Take the North-West area of Qaidam Basin as an example,we confirm the formation time of gas reservoir according to the analysis of carbon isotopes.Different formation time of Nanyishan structure and Kaitelimike structure is the reason that why they accumulated condensate and gas respectively.Kaitelimike structure formed later than the E²₃ source rock reaching the hydrocarbon generation peak,just captured the later mature stage gas,while,Nanyishan structure captured the product of hydrocarbon generation peak,which always lead to the difference of hydrocarbon characteristic and scale of the two structures.