The "dump flood completion" (DFC) is a mechanism conceived to inject water from a reservoir with an active aquifer into a depleted reservoir using a drilled well with marginal production or closed due to low pressure. This innovative mechanism allows for saving the costs of drilling an injector well as well as expenses associated to building additional surface facilities, and water treatment procedures.
This study includes using dynamic models to evaluate scenarios linked to different DFC schemes, with the goal of increasing the net present value (NPV), while maintaining/increasing pressure in the reservoir.
A multidisciplinary team developed a detailed static model to better represent within the dynamic model, the sedimentary bodies dimensions, fluids flows, and the corresponding pressure changes.
The static model build used an exhaustive structural framework comprehensively coupled to the reservoir sedimentology model: facies and rock types, bodies' preferential directions, and bodies' dimensions. Before populating properties, sensitivitiess were performed to obtain an optimum grid and better represent facies lateral changes. The facies distribution model was created from the discrete curve of facies proportionality and using bodies dimensions defined in the sedimentology model. The netgross model was based on Vshale/porosity cutoffs. The porosity and NetGross characterizations were generated based on the facies modeling, and using the Sequential Gaussian Simulation (SGS) technique. The P50 of the stochastic simulations was used to establish the OOIP value.
The resulting static model was input into a black oil simulator to history match production and pressure, and obtaining a base case for prediction purposes. Subsequently, the sensitiy of the reservoir performance on most significant paramters, i.e. water injection rate, bottom-hole pressure, and number and location of injector wells, was analysed. The procedure was assisted by an optimization simulation tool to obtain optimum values of net present value (NPV). The final result was considered the most optimium injection pattern applicable to the current reservoir conditions.
Methodology and modeling techniques applied in this study can easily be extended to reservoirs in the basin with similar features.