Abstract
A multi-tank model is presented that was used to evaluate the volume of gas produced from an undeveloped gas reservoir as a result of sand-to-sand juxtaposition with a developed oil rim reservoir. An innovative approach of using Microsoft Excel via OpenServer to link MBAL model to history match reservoir pressures in a multi-tank model, while considering all the reservoir uncertainties was adopted. The process helps to save time in Reservoir Management.
An oil rim reservoir with future gas development seemed to be communicating with an undeveloped gas reservoir via sand to sand juxtaposition based on the pressure data taken during the drilling of one of the wells and fault seal analysis. This clearly showed depletion in the undeveloped gas reservoir.
Through a multidisciplinary approach, the two reservoirs were built into tank models and connected using a transmissibility model. The resultant model was history matched using an experimental design approach and contacts calibrated prior to running simulation and prediction.
The result showed the quantity of Gas Initially in Place (GIIP) in the undeveloped reservoir that has flowed into the developed reservoir and has possibly been produced already. This insight provides a quick analytical understanding on the resource volume impact of this phenomenon on both reservoirs with respect to their future gas development. This has led to the need for a revised development plan for both reservoirs with respect to future gas production.
The novelty of the use of experimental design with MBAL multi-tank model in this scenario is in the ability to history match the model in reasonable time. This is achieved while effectively managing reservoir uncertainties. This is critical for key business decisions on reserves booking, business planning, general reservoir management and production.
