Electric submersible pump as an effective artificial lift method to control bottom-hole pressure in a producing gas hydrate well, JOGMEC/NRCan/Aurora Mallik 2007-2008 Gas Hydrate Production Research Well Program

Abstract

Gas hydrate is a potentially vast, high-energy hydrocarbon resource. It is known to occur in deep water marine sediments along continental margins, and in cold Arctic regions beneath thick permafrost. The challenge in producing methane gas from gas hydrate lies in controlling the gas hydrate dissociation process through depressurization and/or thermal stimulation (addition of heat). The first sustained production of gas hydrate was achieved at the Mallik site in Canada's Mackenzie Delta over a period of 6.8 days during March 2008, as part of the 2007-2008 JOGMEC/NRCan/Aurora Mallik Gas Hydrate Production Research Well Program. In this test, gas hydrate dissociation was initiated by simple depressurization of the gas hydrate reser-voir, using mechanical manipulation of fluid levels within the producing well to maintain bottom-hole pressure and temperature conditions outside the methane hydrate stability field. This paper addresses the design criteria and equipment selection for the artificial lift component of the 2007-2008 gas hydrate production test. The equipment was specially configured to operate in the very low ambient wellbore temperatures and potentially abrasive conditions. An electric submersible pump (ESP), pressure and temperature sensors, down-hole induction heater, and a variable speed drive were used to maintain the stable pump-intake pressure and temperature required to sustain the dissociation process. The ESP down-hole equipment operated as expected and was capable of significant turn-down to produce at relatively low flow rates of 10 to 15 m3/d under a variety of intake pressures. The variable speed drive enabled the maintenance of stable intake pressures throughout the production test.