Microbial and Waterflooding of Fractured Carbonate Rocks: An Experimental Approach

Fractures and fractured zones require special reservoir development plan. They may improve or hider the oil production. Conductive fracture rocks may provide the required permeability to drain an oil saturated low permeability rock matrix. Low sweep efficiency of many oil reservoirs may be the result of channeling of injected water through high permeability zones that normally associated with fracture system in heterogeneous reservoirs. In this case substantial amount of work focused on improving the distribution of injected water in the wellbore through different treatments: using gelling agents, cements, cross-linked polymer and emulsions. Other alternatives such as microbial and surfactant based methods have been proposed. This paper presents the results of research conducted on thermophilic bacteria that were obtained from UAE local environment. Coreflooding experiments were conducted on single fractured cores to show the effectiveness of microbial treatment. Different fracture angel orientations 45°, 90°, and 180° of the axis of the flow were investigated. The effect of matrix permeability on the treatment was also studied. A comparison between water flooding and microbial flooding of fractured systems were investigated. Non-invasive imaging technique such as Scanning Electron Microscopy (SEM) was employed to visualize changes on the surface of the fracture as a result of bacteria flow through the system.