致密油水平井压裂数值模拟及裂缝参数优化

水平井压裂是致密油藏开发的必要技术手段。为了给出致密油水平井压裂的合理裂缝参数,以大庆油田致密油储层为例,使用油藏数值模拟软件Radial-X建立模型,模拟了致密油水平井压裂生产过程。结果表明,致密油仅在井、缝附近发生渗流,水平井开发的控制范围由水平段长度和压裂改造的缝长、缝密决定。通过水力压裂的裂缝参数敏感性分析得出:裂缝导流能力增加到一定程度即可达到增加水平井产能的目的;增加裂缝数量能提高水平井产能,但是水平井多条裂缝会互相干扰,大庆油田致密油高台子储层2 km井长模型5 a的最优裂缝条数约为20条,扶杨储层5 a的最优裂缝条数约为15条;增加裂缝长度对压后生产有利,但随着裂缝长度增加,产量增加幅度会减小。

NUMERICAL SIMULATION AND FRACTURE PARAMETER OPTIMIZATION FOR THE HORIZONTAL WELL FRACTURING IN TIGHT OIL RESERVOIRS

Horizontal well fracturing is the necessary technical method of the development of tight oil reservoir.In order to give the proper parameters of the fracturing in horizontal wells,taking the tight oil reservoir in Daqing Oilfield as an example,with the help of Software Radial-X in the reservoir numerical simulation,the model was established to simulate the productive process of the horizontal well fracturing in the tight oil reservoir.The results show that the seepage of the tight oil only occurs near the wells and fractures,and the controlled development range by the horizontal well is determined by the length of the horizontal section and the length and density of fractured cracks.The sensitivity analysis of the hydraulic fracturing parameters shows that when the fracture productivity increased to a certain extent,the incremental productivity target of the horizontal well can be achieved;the increase of the fracture number can enhance the productivity of the horizontal well,but the multi-fractures will interfere with each other,the model with 2 000 m well length shows that the five-year optimal fracture number is about 20 in Gaotaizi tight oil reservoir in Daqing Oilfield,while the five-year optimal fracture number is about 15 in Fuyang reservoirs;the increased fracture length is favorable to the post-fracturing production,but with the rise of the fracture length,the incremental amplitude of the production will be reduced.