柴达木盆地腹部晚期构造带成藏模拟实验研究

柴达木盆地腹部晚期构造带成藏条件优越，但勘探一直未取得突破。为了深入研究该区天然气成藏机理与成藏模式，在以实际模型为基础建立的3种不同封闭体系之下，进行了2个阶段的成藏模拟实验，并根据实验结果提出了有利勘探方向。研究结果表明：①开放体系下，天然气分散运聚，有限的资源难以到达距离最远的高部位；②半开放—半封闭体系下，气藏内势能的变化造成了高部位砂体含气饱和度优于低部位，与物性关系不明显；③封闭体系中，气藏整体充注，含气性普遍较好。在晚期构造带中天然气主要沿断层进行运移，气藏垂向上叠置成串、平面上成带分布，具有高部位含水、薄砂层含气的特殊性。保存条件较好且圈闭较为完整的深层及浅层滑脱断层的下盘是下一步勘探的主要领域。

Physical simulation experimental study on gas accumulation in the late tectonic belts of the northern border of Qaidam Basin

The late tectonic belts in the north margin of Qaidam Basin have favorable conditions for hydrocarbon accumulation,but the exploration has not made a breakthrough. In order to further study the natural gas accumulation mechanism in this area,the simulation experiment of natural gas accumulation has been carried out. The paper takes the Eboliang Ⅲ play as an example. Two stages of simulation experiment of reservoir formation under three different sealing systems were carried out,and the favorable exploration direction according to the experimental results is put forward. The results show that: (1) The natural gas migrated and accumulated separately under the open system,the limited resources are difficult to reach the structure high of the farthest distance;(2) Under the semi-open and semi-closed system,the change of sealing property leads to the change of potential energy in the gas reservoir,and the gas saturation of sand-body in the high position is better than that in the low position,and has little relation with the physical property;(3) In the closed system,the natural gas is charged integrally with better gas content. The natural gas mainly migrated along faults in the late tectonic belts,the gas reservoirs has the characteristics of “clustered distribution in vertical and zonal distribution in horizontal”,and these reservoirs have special reservoir forming characteristics with water-bearing in high position and gas-bearing in thin sand layers. Therefore,the footwalls of deep and shallow decollement faults with better preservation and more complete traps are the next major exploration areas.