Gas Lift Production Benchmarking Using IPR Risked Inflow Modeling: Case Study

Abstract Ensuring effective production benchmarking studies and field management requires a through and continuing understanding of the reservoir performance. Deviations from anticipated performance must be recognized and, if necessary, corrected before they impact the expected life cycle performance and value of the project. This study was performed to establish (Inflow Performance Relationship) IPR risked modeling for a variety of completion options and to assess the likely well performance under gas lift production benchmarking of a field. The IPR risked inflow modeling used the Monte Carlo simulation method to define the range of potential outcomes associated with uncertainties in key reservoir and completion input data. Skin data for the completion options being considered, i.e., Open Hole Gravel Pack (OHGP), Cased Hole Frac-Pack (CHFP) and Cased Hole Gravel Pack/Internal Gravel Pack (CHGP/IGP) were then used to establish the probabilistic distribution, which could then be used in combination with reservoir uncertainty data to perform the risk-based inflow modeling. The results of the risk-based IPR modeling showed that the completion options for the CHFP proved to be the best overall performer. The CHGP/IGP completion proved to be the least effective, primarily because of the high skin associated with this type of completion. The OHGP completion compared closely to the CHFP, but the greater probability of higher skin resulted in poorer performance compared to the CHFP. Tornado analysis was carried out to highlight the parameter leading to the greatest uncertainty in well performance. This analysis proved that permeability, in most cases, had greater negative impact on well performance than skin when there was a higher permeability layer in the reservoir. It should be noted that this can reverse; skin can be the most significant negative factor for lower permeability ranges. In all cases, skin had the greatest positive impact on well performance due to negative values of skin for all completion types. To validate the model, well test data was used to validate the probabilistic skin model results for CHFP completion. The gas lift modeling was carried out based on IPR Risked inflow modeling to reduce the gas lift design uncertainties for vertical and deviated wells. Gas lift was extremely beneficial in the lower productivity index (PI) or higher water cut (WC) wells. Impact of gas injection depth on oil production was assessed for each reservoir layer at various stages of the field life.