A Practical Approach to History-Matching Water-recycling in Waterflood Reservoir Simulation - Method and Case Studies in South Belridge Diatomite Waterflood

Abstract

Premature water breakthrough (water recycling) negatively affects waterfloods in low permeability, naturally fractured reservoirs such as the South Belridge Diatomite. Water recycling reduces the effectiveness of waterflooding by partially or entirely bypassing the reservoir matrix where most of the reservoir fluids are stored. Reservoir simulation is handicapped by the inability to accurately characterize the architecture and dynamic nature of the natural and induced fractures that yield high conductivity flow paths between injectors and producers. Generally, reservoir simulation can only represent the effective fluid flow by ignoring the ineffective water production that bypasses the matrix. Detailed production performance analysis yields a practical approach to history-match the waterflood process under premature water breakthrough conditions. Basic reservoir rock-fluid flow characterization parameters must be tuned by history-match of primary production before water injection related effects dominate fluid flow under waterflooding. An analytical waterflood method is used to diagnose premature water breakthrough on a well-to-well basis and to calculate the volume of ineffective water injection. Effective injection and water production volumes are recalculated and used to achieve a history-match that honors oil production, reservoir pressure and injection/production volume balance. A field-scale case study is presented to demonstrate the application of the proposed approach.