Energy Recovery Using Turboexpanders in Production Wells and Gathering Systems With High Pressures

Abstract

This paper discusses the potential for energy recovery using turboexpanders to take advantage of some high pressures currently not used in the production and gathering system of two geothermal fields. Losses of available high-pressure include the pressure drop occurring at the wellhead production orifice plates which reduce the fluid pressure from its wellhead value to that of current steam separation and transportation, and pressure drops occurring in the flow regulation valves of some steam transportation pipelines. Three cases were analyzed. Two of these, one for the Cerro Prieto Geothermal Field (CPGF) and one for the Los Humeros Geothermal Field (LHGF), involve the use of a very high-pressure steam separator-turboexpander system to take advantage of the pressure drop occurring in the production orifice plate of some wells. The results show a potential to recover 20.7 MWe and 10.6 MWe, respectively. The other case involves replacement of two regulation valves close to the inlet of the Cerro Prieto 4 (CP4) power plants by turboexpanders to take advantage of the large steam flow rate and pressure drop occurring at these valves. The results for this case show a potential for energy recovery of 6.3 MWe. No additional mass or energy needs to be extracted from the reservoir nor would any additional pollution would be involved.