致密油体积压裂水平井CO_2吞吐实践与认识

PRACTICE AND UNDERSTANDING OF THE CO_2 HUFF-PUFF FOR THE VOLUME FRACTURED HORIZONTAL WELL IN TIGHT OIL RESERVOIRS

针对致密油体积压裂水平井弹性开发采收率低的问题,运用室内实验和数值模拟方法,以增油量和换油率为评价依据,结合水平井数据,优化了吞吐时机、注入总量、注入速度等吞吐参数。应用CO_2吞吐优化参数,选取YP1-7井进行现场试验,该井累计注入二氧化碳9 900 t,初期日增油17.4 t,增油效果明显。研究表明:致密油水平井体积压裂储层改造体积大、裂缝复杂,吞吐过程中不能实现混相;增膨、降黏是扶余致密油藏CO_2吞吐增产的主要作用因素。该技术在扶余致密油藏开发中具有较好的适应性,是提高致密油藏采收率的一项有效手段。

For the problem of the low recovery factor for tight-oil volume fractured horizontal wells in the elastic development,using the laboratory experiments and numerical simulation method,referred by the oil incremental amount and oil change rate evaluations,integrated with the horizontal well data,the parameters such as the huff-puff opportunity,injection volume,injection rate and so on were optimized. With the help of the optimized parameters of the CO2 huff-puff,Well YP1-7 was selected to operate the field test. The well was totally injected 9 900 t CO2,the initial increase of the oil was up to 17. 4 t,the effect was pretty obvious. The study shows that the fracturing was characterized by the huge volume and complex fractures,the mixed phase could not be realized in the huff-puff process; the increasing expansion and reducing viscosity are the main acting factors for the incremental production of the CO2 huff-puff in Fuyu tight oil reservoir. The technique possesses much better adaptability in the development of Fuyu tight oil reservoir,so it can be the effective method of enhancing the recovery of the tight oil reservoir.