The Potential for Energy Recovery and Electricity Generation in High-Pressure Production Wells and Gathering Systems Using Turboexpanders

Abstract

The potential for energy recovery and electricity generation in production wells and gathering systems with high pressures currently not used in two geothermal fields is discussed. Losses of available high-pressure include the pressure drop at the wellhead production orifice plates which reduce the wellhead pressure to that of the current steam separation and transportation, and pressure drops occurring in the flow regulation valves of some steam transportation pipelines. Two cases were analyzed, one for the Cerro Prieto Geothermal Field (CPGF) and one for the Los Humeros Geothermal Field (LHGF), which involve the use of a 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 of energy recovery equivalent to 20.7 MWe and 10.6 MWe, respectively. A third case involves replacement of two regulation valves located near the inlet of the Cerro Prieto 4 area (CP4) power plants by turboexpanders to take advantage of the large steam flow rate and pressure drop occurring at these valves. The analysis for this case shows 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.