断控气藏的动态成藏物理模拟与启示——以柴达木盆地西北地区典型气藏为例

天然气成藏过程的动态物理模拟是揭示天然气运聚成藏机理、总结其分布规律的重要手段，然而由于天然气本身特性，使得“易泄漏、难动态、难观察”成为天然气运聚动态成藏物理模拟的最大问题。为了揭示断控气藏运聚成藏机制，总结其气藏形成序列和分布模式，以柴达木盆地西北地区东坪、马海—南八仙典型气藏为例，在建立各个典型气藏成藏演化地质模式基础上，针对气藏模拟存在的问题，设计了既能实现构造动态变化过程，同时又能清晰观察气体充注、运移、聚集现象的“一种可调式天然气运聚成藏模拟装置”。运用该装置成功模拟了东坪、马海—南八仙等典型气藏形成过程，明确了断层不仅作为气体运移和传递动力的通道，还控制了演化序列和分布模式；建立了“晚期成藏”和“长期成藏”两种不同类型天然气藏的形成演化序列模式，揭示了“断传高压驱动”天然气运移成藏机理，明确“深浅共存、浅差深好”的天然气藏纵向保存系列，提出了“有浅(浅层气藏)必有深(深层气藏)”，据“浅”寻找“深”的天然气勘探新理念。 

Physical simulation of dynamic accumulation of fault-controlled gas reservoirs and its implications: a case study of typical gas reservoirs in northwestern part of Qaidam Basin

The dynamic physical simulation of natural gas accumulation process is one of the important means to reveal the mechanism of natural gas migration and accumulation and to summarize its distribution law. However, due to the characteristics of natural gas itself including “easy to leak, difficult to move and difficult to observe” have become holdbacks for the physical simulation of natural gas migration and accumulation. In order to reveal the migration and accumulation mechanisms of fault-controlled gas reservoirs, and to summarize the formation sequence and distribution pattern of gas reservoirs, typical reservoirs in Dongping, Mahai and Nanbaxian areas in the northwestern part of Tarim Basin were taken as examples to establish a geological evolution model for each reservoir. Aiming at the problems of gas reservoir simulation, an adjustable simulation device for gas migration and accumulation was designed, which could realize the dynamic process of structural change and clarify the phenomenon of gas charging and migration, and the formation process of typical gas reservoirs such as Dongping, and Mahai-Nanbaxian, etc. was successfully simulated. It is clear that the fault not only acts as a channel for gas migration and power transmission, but also controls the evolution sequence and distribution pattern. The formation and evolution sequence models of two different types of natural gas reservoirs, named “late accumulation” and “long-term accumulation”, were proposed, the mechanism of natural gas migration and accumulation driven by “fault transmission and high pressure” was revealed, and the vertical preservation sequence featured by “co-existence of natural gas in both deep and shallow formations, and the deeper formations are more favorable for preservation” was concluded. A new concept of natural gas exploration was put forward that “if there are shallow gas reservoirs, there must be deep ones”, and we can find natural gas from shallow to deep formations.