How Drag Reducer Agents Can Enhance Gas and Condensate Production?

Abstract This document presents the results of the DRA (Drag Reducer Agent) efficiency analysis produced for 12 flowlines from a Middle East field using Transient multiphase software modelling. 12 flowlines were selected for their potential for DRA application. Validation of the models A model was created for each flowline using the measured data from field. The inlet pressures of the flowlines were used to validate the models. Only the flowline 10 model underwent a modification, with the inner diameter reduced to fit with the measured inlet pressure. With this modification, the variation of inlet pressure between the given data and the model does not exceed 9% and for most of cases is under 2%. Compatibility of flow pattern with DRA application The models allow to identify the flow pattern in each flowline. In all the flowlines but the flowline 1, the oil and gas are stratified until the riser where slug formation can occur, and the water is dispersed in oil. In the flowline 1, the oil and gas phases follow the same pattern, but the water is not dispersed in oil. In both case, these are good conditions for the application of DRA in the oil phase. Simulation of DRA efficiency In the Transient multiphase software, it is possible to decrease the friction gain at the interfaces between the phases and between each phase and the wall. Decreasing the oil-wall friction gain and the oil-gas friction gain allows to simulate the effects of DRA application. The DRA efficiency is measured through the diminution of the pressure drop from 0 to 100% DRA efficiency, with 10% steps. The obtained curves show a steady increase in pressure gain as the DRA efficiency increases. Only with the 1 flowline the curve reaches a peak at 70% DRA efficiency, due to the increase of the water phase friction. Comparison with theoritical curves The curves obtained with Transient multiphase software are then compared to theorical curves calculated using the Darcy-Weisbach equation. The main interest of this curves is to track the consistency of the results provided by Transient multiphase software. For all the flowlines except 1, the two curves follow the same trend, with the theorical curve slightly above the Transient multiphase software curve. For the flowline 1, the theorical curve does not consider the water phase, which lead to a divergence between the two curves. Results of simulation By experience, a field application of DRA corresponds approximately to a 60% DRA efficiency in the simulation. For these flowlines, at a 60% DRA efficiency, the potential pressure gain varies from 1.7 to 8.6 bars, with 9 potential gains higher than 3.7 bars. These gains are equivalent to 20 to 30% of the total pressure gain. The results of simulation are consistent with the first observations on compatibility of DRA application with flow pattern. The application of DRA on these flowlines looks promising. With the pressure gains calculated with Transient multiphase software, corresponding production gains will be calculated for this Middle east field and compared to the costs of DRA application to assess the economic interest of DRA application.