Methane Extraction From Geopressured-Geothermal Brine at Wellhead Conditions

Abstract

Disposal of geopressured geothermal brine effluents by injection this expected to be costly, even into shallow aquifers. If injection into the production reservoir becomes necessary to maintain productivity and to minimize subsidence, the injection pumping costs can become overwhelming. An option aimed at reducing injection pump operating costs is to maintain a higher than normal pressure at the production wellhead to reduce the injection pumping work load. The crucial element, however, is that a significant portion of CH4 remains in the solution an must be recovered in order for the pressure maintenance option to be cost effective. A laboratory and field test capability has been established, and were are presently evaluation several methods for extracting dissolved CH4 at high temperature and pressure. Solvent extraction and use of hydraulic motors or turbines coupled to CH4 recovery systems are the leading candidate methods.