缝洞油藏注气吞吐优选和技术界限优化设计

缝洞型油藏一直以来都是开发过程中十分具有挑战的课题,在我国也已发现大型底水整装缝洞型油藏。由于底水十分发育,水平井快速见水,油藏整体采收率20%左右。首先通过实验对比注入N_2和CO_2进行吞吐的效果分析,研究证实针对缝洞底水油藏的特殊情况,高含水水平井中进行注气吞吐时,虽然注入N_2可以有效保持储层压力,但是注入CO_2能够更加有效的降低含水率和提高采收率(相比较注N_2,提高了10%以上),同时CO_2吞吐效率(50%)要高于底水驱效率(30%)。仿真数值模拟结果表明,针对TK907井,最佳工艺为注气速度50 t/d,注气量481 t,焖井22天和吞吐2轮次。

Optimization and Design of Gas Huff-Puff and Technical Limits for Fractured Reservoirs

Developing fractured-vuggy reservoirs is a very challenging subject, large bottom water integrated fractured-vuggy reservoirs have been found in China. Because of the live bottom water, water content is rising fast and overall recovery rate is about 20%.In this paper, effect of injection of N2 and CO2 was analyzed by experiments. The research results confirmed that, according to the special conditions of fracture cave reservoir with bottom water, during gas huff and puff in high water cut horizontal well, injection of N2 can effectively maintain the reservoir pressure, but the injection of CO2 can effectively reduce the water cut and enhance oil recovery; The CO2 huff and puff efficiency (50%) was higher than that of bottom water drive efficiency (30%).Simulation results show that, the optimum process is that gas injection rate is 50 t/d, gas injection amount is 481 t, soak time is 22 days and cycle of huff and puff is 2 rounds.