Y国J区块主力油气田G为中孔、中渗、带边底水和薄油环的砂岩凝析气藏,针对油环开发已进入高含水阶段、剩余油比较分散和油藏压力保持低的问题,提出了CO2吞吐提高油环采收率的方法。通过开展数值模拟研究优化CO2吞吐过程中注采参数,进行动态跟踪分析,明确了补充地层能量和控抑底水是吞吐致效的主要机制;总结出非混相驱、超稀饱和原油直井开发、吞吐前地层能量亏空严重和施工过程中注入不连续且焖井时间过长是影响吞吐试验效果的主要因素;以生产保障、增产增效和碳埋存为目标,建立了研究区不同含水率下的合理吞吐参数图版。研究成果可为CO2吞吐技术在复杂断块砂岩气顶边水油气藏的应用提供借鉴。

The major oil and gas field G in J block of country Y is a sandstone condensate gas reservoir characterized by medium porosity and permeability, with edge-bottom water and thin oil rims. To address challenges such as high water content during oil rim development, dispersed remaining oil, and low reservoir pressure, a method involving CO2 huff and puff to enhance oil recovery is proposed. Numerical simulation studies were conducted to optimize the injection and production parameters of the CO2 huff and puff process, and dynamic tracking analysis clarified that replenishing reservoir energy and controlling bottom water are the key mechanisms for the success of CO2 huff and puff method. Factors affecting the effectiveness of the CO2 huff and puff test were identified, including immiscible displacement, development of over-saturated crude oil using vertical wells, severe reservoir energy deficit before CO2 huff and puff, and discontinuous injection along with excessively long soaking periods. With the triple objectives of production security, increased production efficiency, and carbon sequestration, optimal CO2 huff and puff parameters were established under varying water content in the study area. The research results can provide valuable experience for the application of CO2 huff and puff technology in complex faulted sandstone reservoirs with gas cap and edge-water.