论文部分内容阅读
川南三、二迭系气藏,属碳酸盐岩不均质裂缝性气藏。它在纵向上具有多产层、横向上具有多裂缝系统的特征。在同一气藏内存在着有水裂缝系统和无水裂缝系统。而地层水是受裂缝系统控制的封闭型的水,它与外界不连通,没有供水区。在开采过程中,随着采出量的增加,水产量会越来越小,因此水体是有限的。裂缝系统内的地层水有弹性能量。这是由于在地层条件下水中溶解有天然气的缘故。但是单位体积的水溶解的天然气是有限的,因此,水的弹性能量也是有限的。从以上认识出发,对位于不同构造部位的井采取不同的开采方法,可以提高有水裂缝系统的采收率。如在同一裂缝系统内的不同构造部位的井,在构造高部位的井采气,低部的井排水采气;处于构造高部位单独裂缝系统的井,控制合理的采气速度以延长无水采气期;在构造低部位气水界面附近的井,一开始就进行排水采气。然后根据不同的生产阶段,优选出“三稳定” (产量稳定、压力稳定和气水比稳定)的生产制度,求得较长时期的稳产。总之,针对各井的不同情况,采取适合该井的开采方法,可以提高有水裂缝系统的采收率。
The Third and Second Diego Gas Reservoirs in South Sichuan Basin belong to an inhomogeneous fractured gas reservoir of carbonate rocks. It has a prolific layer in the longitudinal direction, with multi-fracture system features. In the same gas reservoir exists a water crack system and an anhydrous crack system. The formation water is controlled by the crack system closed water, it is not connected with the outside world, there is no water area. In the mining process, with the increase of production volume, the production of water will be smaller and smaller, so the water body is limited. Formation water in the fracture system has elastic energy. This is due to the fact that natural gas is dissolved in the water under formation conditions. However, the volume of water per unit volume of dissolved natural gas is limited, so the elastic energy of water is also limited. Based on the above understanding, adopting different mining methods for wells located in different tectonic parts can improve the recovery rate of water-fractured systems. For example, wells with different tectonic positions in the same fracture system may have well gas in the high part of the structure and water in the lower part of the well drained for gas recovery. The wells in the high-position separate fracturing system control the reasonable gas recovery rate to prolong the water- During the gas recovery period, wells near the gas-water interface at the lower part of the structure will be drained for the first time. Then, according to different production stages, the production system of “three stability” (stable output, stable pressure and stable gas-water ratio) is preferable and long-term stable production is obtained. In short, according to the different conditions of each well, adopting the mining method suitable for the well can improve the recovery ratio of the water-fractured system.