不同充注方式下致密砂岩气藏的成藏效率探讨

Discussion on Accumulation Efficiencies of Tight Sandstone Gas Reservoir under Different Manners of Migration

中国中西部地区致密砂岩气藏发育面积广,深部勘探潜力巨大;但由于储层孔渗条件差和充注方式不同,既有上气下水的常规致密气藏,也有气水倒置的深盆气藏。因此亟需探讨不同充注方式下致密砂岩气藏的成藏效率。利用理论推导结合物理模拟试验的方法,对断裂充注与致密储层底部烃源岩面式充注这2种不同充注方式的成藏效率进行探讨。结果表明,储层底部面式充注的成藏效率高于断裂疏导,表现为单位时间内的充注量前者较高;致密储层内部一般具有多种裂缝,发育裂缝带的致密储层的成藏时间相对较短,但储层内部气水关系复杂。本文模拟试验验证了理论推导的合理性,虽然试验温压条件与实际地质条件仍有一定的差距,但可为勘探实践提供有价值的理论参考。

In the mid-west part of China, tight sandstone gas is reserved in a large area. The potential gas and oil source in deep reservoir is tremendous; however as a result of low reservoir porosity and permeability with different manners of migration, both tight gas reservoir with conventional gas-water relation and deep basin gas reservoir with gas-water inversion are developed. It is necessary to discuss the accumulation efficiencies of tight sandstone gas reservoir with the different manners of migration in order to provide valuable references to exploration and practice. For the sake of exploration practice direction of tight sandstone gas reservoir, the methods of theoretic argumentation and physical simulative experiments are used to discuss the accumulation efficiency of tight sandstone gas reservoir which is migrated by faults and by an interface of source rock and tight sandstone, respectively. The results are as follows： Firstly, the accumulation efficiency of migration of an interface of source rock and tight sandstone is better than the efficiency of faults migration and the gas filling volume is higher in a unit time. Secondly, tight sandstone gas reservoir located at the developing belt of fractures needs shorter time to accumulation; however the relation between water and gas is complex in the reservoir. The rationality of the inference is verified by the simulation test. Nevertheless, there are still differences with the temperature and pressure conditions between the laboratory and the actual geological conditions, the results could provide the valuable theory reference for the exploration in the future.