What Happens after the Onset of Liquid Loading? — An Insight from Coupled Well-Reservoir Simulation

Abstract

Liquid loading is an inevitable production issue for mature gas fields. A varied group of phenomena after the onset of liquid loading has been observed in field, including the natural cyclical production of liquid loaded wells. Most previous modeling studies focused on predicting the onset of liquid loading. The production behaviors after the onset of liquid loading is equally important and requires strict modeling techniques to simulate dynamic interactions between wellbores and reservoirs. In this paper, we apply a newly developed fully implicitly coupled well-reservoir simulator to systematically investigate the well behavior after the onset of liquid loading. The model honors the mass and momentum balances in both reservoir and wellbore systems, and thus allows us to analyze both wellbore and reservoir dynamics after the onset of liquid loading. The simulation results indicate that there exist a gas-water coproduction period and a zero liquid production period after the onset of liquid loading. For reservoir permeability as low as 0.1md, the liquid-loaded horizontal well might experience natural cyclical production after the onset of liquid loading, which coincides with field observations. Both uniform stimulation and multi-stage hydraulic fractures help mitigate the production phenomenon. The near-wellbore reservoir pressure build up and wellbore fluid reinjection are also evaluated. This work demonstrates the successful application of the coupled wellbore reservoir model in predicting the rich production phenomena of stimulated horizontal wells after the onset of liquid loading.