Waterflooding is a common practice recovery method in West Siberia oil fields. SPD started water injection in Dec 2005 and, since then, there are more than 100 injectors operating in the field. It is well established already that a successful waterflooding can only be achieved with a proper well and reservoir surveillance and management. Field observations indicate that injection is taking place under fracturing conditions. In order to manage and control this process SPD has put a surveillance plan in place which include performing regularly (modified) Hall-plot analysis, temperature and production logging (TLP/PLT), pressure fall-off (PFO) tests, and step-rate tests.
The case study, presented in this paper, describes the approach of induced fracture modeling of one of injectors in the field. An in-house coupled fracture/flow simulator (FRAC-IT) is used for this purpose. First, data assimilation/history match is performed by calibrating FRAC-IT simulation model with the fracture size and BHP data based on PLT/PFO analysis. This covers the historical period of injection. Subsequently, forward simulations are run to predict fracture sizes for a number of future infill and waterflood pattern conversion scenarios. Finally, since water quality influnces on fracture dimensions and containment, recommendations related to injection water quality specifications are made.
An important outcome of the study is establishing an approach and the workflow required for modeling induced fracture for complex field operations.