Solution to Limited Pressure BHP Data in Brown Fields; Material Balance Equation Approach

Abstract

Reservoir performance analysis and forecasting poses a challenge in brown fields with limited Bottom Hole Pressure (BHP) data. Most brown Oil Fields in Nigeria have the problem of limited BHP data. Most fields from 1960 to 1970 are having the problem because they were not properly managed from inception as per their data storage and recording systems. In Nigeria, many farm-out assets to the Marginal Operators from the International Oil Companies are having such challenges and managing such assets is daunting and time-consuming because of limited BHP data. Reservoir management is central to the effective exploitation of any hydrocarbon asset and is heightened for the development of brown fields. The problem of limited BHP data also makes reservoir pressure history matching difficult. This study proposes a workflow implemented on an Excel VBA program for a brown field in Niger Delta region of Nigeria with limited pressure (BHP) data. The program, which was validated, was used to history match the observed field production data, the limited reservoir BHP data, predict reservoir performance and production profile within the specified timeframe. The tool is built on Material Balance Equation which is a zero-dimensional-tank model created for the reservoir. Pressure Volume Temperature (PVT) properties with correlations, fractional flow models and Corey correlation for relative permeability estimates were incorporated in the algorithm. The matched model calculates the likely parameters of the reservoir and aquifer, then the production history calibrates the pressure model. The following approach is used in resolving the problem for the field case study. Production data aggregation; Calibration of PVT laboratory data; Calibration of reservoir pressure model; Development of fractional flow model for the system; Calibration of the reservoir's last production date. This approach gives an accurate reservoir pressure history prediction, and also good production forecast in field with limited BHP data.