复杂断块油藏水平井二氧化碳吞吐注采参数优化研究

Study on Injection-production Parameters Optimization of Horizontal Well CO_2 Huff and Puff Technology in Complex Fault Block Reservoir

水平井是冀东油田浅层复杂断块油藏的主要开发方式,随着水平井的持续开发,含水快速上升,严重影响了开发效果。采用CO_2吞吐可进一步提高增油效果和产能,降低含水上升速率。为优化CO_2吞吐的注采参数、提高现场试验效果,利用矿场岩屑设计制作了CO_2吞吐三维物理模型(尺寸30 cm×30 cm×12 cm,水测渗透率1.160μm^2,孔隙度31%),使用该模型开展了注入量、焖井时间等注采参数优化研究。结果表明,CO_2吞吐增油效果明显,采收率较衰竭开采增加幅度为1.97%~9.47%,换油率为1.14~3.62 m^3/m^3;为达到最佳的增油效果,宜采用的CO_2吞吐注采参数为:注入量0.3~0.4 PV、焖井时间12~15 h、注入速率4~6 mL/min、采液速率480~600 mL/h。

Horizontal well is the main development way in the shallow complex fault block reservoir of Jidong oilfield. During the process of horizontal well continual production, the water cut go up quickly, resulting in the poor development effects of oil field. The CO2 huff and puff technology can improve horizontal well productivity and reduce the water cut. In order to optimize the injection-production parameters and improve the effect of the field oil recovery, three-dimensional physical model of CO2 huff and puff was made of cuttings, the size being of 30 cm×30 cm×12 cm, the water permeability being of 1.160 μm^2, and the porosity being of 31%. The experiment of injection-production parameters optimization, such as injection volume, soaking time and so on, was carried out using the model. The experimental results showed that the effect of increasing oil production was obvious, degree of reserve recovery rose by 1.97%-9.47% more than the development way of depletion and oil exchange ratio was 1.14-3.62 m^3/m^3.In order to achieve the best effect of increasing oil, the production injection-production parameters were optimized as follows, the rate of injection was 0.3-0.4 PV, the time of well shut was 12-15 h, the velocity of injection was 4-6 mL/min and the liquid withdrawal rate was 480-600 mL/h.