Reservoir Simulation Framework to Evaluate the Potential Benefit of Radial Jet Drilling Technology Accounting for the Risk of Irreversible Radial Collapse

Abstract

This study presents a reservoir simulation framework to investigate the oil production uplift performance of Radial Jet Drilling (RJD) technology for a naturally fractured diatomite reservoir undergoing waterflooding. The findings from the study can help better design a field trial and plan Surveillance, Analysis and Optimization (SA&O) activities. The framework allows for the flexible definition of various parameters that control the topology of the RJD well (including number penetrated layers, number of radials per layer, and radial segment length) as well as the pressure drop along the radial segment (including the segment roughness and hydrodynamic diameter). The framework relies on advanced wellbore modeling capabilities that compute the pressure drops inside the well; this allows for the consideration of radial segment collapse whenever the radial segment pressure is below a radial collapse pressure. The simulated behavior relied on a dual porosity dual permeability (DPDK) reservoir model that had been history-matched for primary depletion and waterflooding over a cumulative 72-year period. The RJD well oil production performance is evaluated over a 16-year period controlled with a bottomhole pressure constraint. The model is calibrated to representative type curves in the absence of radials (perforations only case) and in the presence of radials for a specified topology. Once the model has been calibrated, 162 simulation cases are considered to evaluate the sensitivity of the oil production uplift to various model parameters and operational conditions. Radial segment length, radial collapse pressure and number of penetrated layers showed the greatest impact on oil production uplift. Increasing radial segment length and number of penetrated layers and decreasing the radial collapse pressure led to an increase in oil production uplift. We introduced a cumulative radial segment length metric that accounts for the impact of number of penetrated layers, number of radials per layer, and radial segment length. For a fixed cumulative radial segment length, configurations with a higher number of penetrated layers and a lower number of radials per layer led to a higher oil production uplift. The simulation tool and framework developed can be used to assess the potential benefit of the RJD technology, including risks arising from radial segment collapse. For all radial collapse pressure scenarios, a gentle drawdown strategy proved to be the most consistent in terms of oil production uplift performance. Production performance monitoring (e.g., via dedicated test separators) can help identify major radial collapse events as evidenced by discontinuous trends in the oil production rate, gas/oil ratio, and/or water cut.