Dual-Porosity Model for History Matching and Production Forecast for an Oil Reservoir at Cuu Long Basin, Offshore Vietnam

Abstract

This article presents the reservoir simulation method to accurately evaluate the reservoir performance, thus providing the forecast and optimal plan of reservoir development. It uses the dual-porosity model for an oil basement reservoir. The model concepts are fractured reservoirs which are divided into macrofractures and microfractures. Macrofratures can contain and transfer reservoir fluids, whereas microfractures transfer fluid only. Although it is difficult to separate the porosity into two different types, this model run-time is significantly reduced compared to traditional models.

The dual-porosity model in the paper uses actual data of an oil reservoir at CuuLong basin, offshore Vietnam, and has been proven that it is more accurate than the traditional ones. Each cell in the simulation process contains two separate systems of parameters such as permeability, porosity, saturation, etc. In addition, the matching for an oil reservoir is made from history production data based on uncertain variables. The results of history matching for oil rates, reservoir pressure, GOR, and watercut in 1P-ST1, 2P, 3P and 4XST wells show that the dual-porosity models are more reliable. Then production forecast from this model has been matched with drilling the new well plan to assess the economy comparing with the base case. The oil basement in Vietnam is highly heterogeneous, so this dual-porosity model reduces the model run-time and make better history matching. As a result, the production forecast has increased its reliability, which makes the reservoir development more convenient and suitable for practical production.