Development of Maximum Efficient Rate Model and Improvement of Erosional Velocity-Based Correlation for Vertical Oil Wells in the Niger Delta

Maximum efficient rate (MER) and erosional velocity are known to be vital concepts in oil and gas production, and producing a well at a maximum efficient rate remains a critical concern to the oil and gas operators, the production engineer and the regulator. Well testing and equilibrium concept are commonly used by oil and gas players to determine the MER of a well. However, little adjustment of the plot axes of the production rate, choke size and tubing head pressure can affect the accuracy of the MER determination. Additionally, there are no known generalized correlations to compare results with that of the MER tests. Furthermore, oil regulatory bodies in Nigeria have no known published models for estimating the technical allowable rate, unlike other regulatory bodies in other countries. This work therefore presents the outcomes of the formulation of MER and the improved erosional velocity-based correlations for vertical oil wells, using MER test data from the Niger Delta region of Nigeria. Multiple linear regression (MLR) and probabilistic modeling approaches were considered. The predicted normalized MER results compared favorably well with the MER test data, with an absolute average error of 7.62%. For the case examples, de-normalization of the predicted MER results increases the absolute average error. Among the predicted P10, P50 and P90 MER results, the predicted P10 results are the nearest to the MER test results. Improvement in the predicted probabilistic results depends on the mean value of the predicted normalized MER considered. The combination of the MER model and the improved erosional velocity-based correlation can be a useful tool for MER test results verification and determination, and in overall for optimization of oil wells.