四川盆地中部上三叠统排水找气可行性论证

Feasibility of Gas Finding by Water Withdrawal in Sandstone Reservoir in Upper Triassic,Central Sichuan Basin

四川盆地中部上三叠统砂岩储层裂缝系统之间在开发动态上表现出相互分隔性,不存在连通范围较大的边底水体,其自生自储的成藏特征决定了裂缝系统中必然气水共存。测试产水井是由于井孔储层位处裂缝系统的含水部位,产水能量主要依靠水体上方的天然气膨胀驱动。低产量排水过程将使裂缝系统中的气水界面按照排水找气理论模式缓慢下降,而高产量排水将使水体上方高流度的天然气尽早突破水体窜入井底产出。建议对川中上三叠统水井开展连续强排水,加大井底与上方天然气的压力差,以较快实现水井变成气水同产井的目的。

The fracture systems in Upper Triassic sandstone reservoir are separated in the performance development. There are no large-scale connectivity edge and bottom water in the systems. Gas and water certainly coexist in the single fracture system because gas in the reservoir is self-generated. The expansion of the nature gas above the water is mainly the driving energy of water-production while a well is drilled in the water body in a system. The low productivity of water drainage makes the gas-water contact slowly, declining according to the model of gas finding by water withdrawal. The high productivity of water drainage will make the gas with the higher mobility above the water body, channeling into the well bottom through the water body. This well would change into gas and water co-production from water production. It is proposed that the method of continuous and intensive water withdrawal for some wells of water production in the Upper Triassic, central Sichuan Basin would increase different pressure between the well bottom and the gas above the water body, and accomplish quickly the goal of changing water production to gas-water co-production.