Interaction Between Surface Facilities and Wells at an Operating Geothermal Flash Plant

Abstract

Geothermal wells are usually flow tested individually, using surface facilities whose main requirements are to provide accurate measurement of flow and enthalpy while safely disposing of the produced fluids. Such facilities provide a poor model of the complex gathering system to which a typical well may ultimately be connected. Without carful analysis, such test results can lead to unrealistic expectations of well output under operating conditions. All production wells on a gathering system are affected by changes to any component of that system, whether it be a new well connected to the system or a piping modification Such changes alter the operating pressures throughout the system, including wellhead pressures at all the wells. All well outputs will therefore be affected, regardless of their location. As a result, connecting a new 10 MW well to the system may only add 5 MW or less to the plant output. This paper presents a method to account for such surface interference effects, and determine the true net effect of such changes as adding a new well or modifying the piping system.