Comparison of LET Correlation and Proposed Modification in Finding Relative Permeability by Model History Matching

Abstract Choosing the correct relative permeability curve to represent flow in laboratory-scale experiments is important when subsequently predicting behavior in simulations at the same scale or in field-scale applications. Several mathematical correlations have been proposed to represent relative permeability so far. According to studies, the LET model is often more effective in capturing the relative permeability of various phases and provides a useful tool for history matching in simulating reservoirs and laboratory studies. However, the LET model contains a large number of unknowns which need to be found to achieve the best match between real measurements and model outputs. This means that a substantial number of model attempts are required as part of any inversion process to find an optimum solution, which will make the process more time-consuming. We have adapted the LET model to reduce the number of empirical parameters that must be determined with the aim of reducing computation time but retaining accuracy. This paper presents modeling processes for three core flood experiments and illustrates the history matching operations using two relative permeability correlations (LET and LT models) and compares them in terms of error percentage, execution time and number of attempts to reach the optimal solution. The results show that modeling using the LET correlation has an advantage in most cases over the modified version (LT) in terms of the error percentage to reach the match, but with a slight improvement in these percentages, while the time and number of modeling attempts required were often better when using the proposed LT correlation in the model-history matching processes. These advantages seem insufficient at the laboratory scale but may have a fundamental impact on studies at the full field scale. The proposed correlation was tested for a narrow range of wettability (mostly mixed-wet) which calls for additional future research on broader wettability ranges as well as investigating multiple or two other phases including the gas phase instead of the water-oil phases in the present paper.