Gas Production Optimization Using Thermodynamics Hydrate Inhibition Flow Assurance Method

Abstract

Production from gas wells could be very challenging and can lead to spontaneous shutting down of wells for reasons other than known equipment or operational. Some of these wells shut in, not because of surface or sub surface pressure safety settings, but due to Joule Thompson effect. The case study well in this paper is producing but shuts down frequently. The main aim of studying this well is because it is the fuel gas source to the flow station. It is used to run the instruments and the turbine generators, hence production sustainability of the wells in this field depends on the well. This became even more crucial when the well began to shut down frequently, without an immediate known cause. A temperature-sensitive production performance model was developed to mimic the well's performance from the gas reservoir for various surface bean sizes. It was then compared with the thermodynamic model of the well's tubing head and flow line conditions and optimized production rule was made subject to the flow assurance and reservoir management requirements. Chemical hydrate inhibition program was found not to be of immediate necessity after the optimization modeling, hence well was produced by increasing choke size to increase the flow line pressure. This resulted to increase in the flow line temperature and the well was then produced at the non-hydrate formation region of the thermodynamic profile. A stable and uninterrupted production was then achieved with choke increase. Frequent choke erosion as well as the Joule Thompson effect was eliminated by the choke increase. Cost of injection of chemical hydrate inhibitor (methanol) was then saved. Well production of about 800 BOEPD was also restored even with an optimum reservoir performance outside sustaining flow for other wells in the field (4,000 BOPD).