致密油藏体积压裂水平井数值模拟及井底流压分析

NUMERICAL SIMULATION AND BOTTOMHOLE PRODUCING PRESSURE ANALYSIS FOR THE VOLUME-FRACTURED HORIZONTAL WELL IN TIGHT OIL RESERVOIRS

致密油藏储层渗透率极低,大规模水平井体积压裂已成为其最有效的开发手段。体积压裂明显区别于常规压裂所形成的双翼对称裂缝,可沟通天然裂缝,形成错综复杂的裂缝网络,这使体积压裂井与常规压裂井的数值模拟方法迥异。为对天然裂缝发育储层的体积压裂水平井进行有效的数值模拟,采用了"双重介质+缝网加密"的方法,即将SRV区(体积压裂改造区)建为双渗模型,并对SRV区进行缝网加密,分别模拟人工主缝、二级缝网和天然裂缝。再由试井解释结果预估一组缝网参数,然后通过自动历史拟合进行反演、修正,获得等效缝网。该模型生产预测参数与油田实际生产数据符合程度较高,具有可行性。利用该模型进行了井底流压分析,并划分出了5种流态。

Because of the extreme low permeability tight oil reservoir,large-scale horizontal-well volume fracturing has become the most effective developing method. Comparing with the two-wing symmetrical fractures resulted from the conventional fracturing,the volume fracturing is obviously different,for it can communicate the natural fractures and form a complex fracture network which results in the different numerical simulation from the conventional one.In order to effectively numerically model the volume fractured horizontal well penetrated the well-developed natural fracture reservoirs,with the help of 'dual media + fracture network infilling',i. e. the bi-permeability model isbuilt in the SRV,and moreover the above infilling is conducted for the block,and then the artificial main fractures,two-level fracture network and natural fractures are respectively modeled. And furthermore,by means of the well test interpreted results,a group of the fracture network parameters are predicted,and the inversion and correction are performed by the automatic history match,finally the equivalent fracture network is achieved. Much higher coincidence between the model-performance predicted parameters and actual production data,thus the feasibility of the model is proven. In fact,the bottomhole producing pressures are analyzed with the help of the model,and at the same time,five states of the flow are divided.