Identifying Fractures and Relative Ages Using Fluid Inclusion Stratigraphy: Preliminary Results

Abstract

Preliminary results are presented on using Fluid Inclusion Stratigraphy (FIS) to identify fractures in geothermal wells. If a technique can be developed to recognize the stage of a fracture, whether it is currently open and transmitting fluids; if it recently has closed; or if it is an ancient fracture this technique would assist in targeting areas for further fracture stimulation in developing an Enhanced Geothermal System. Of the four wells sampled, three have had analysis completed to a point of presenting preliminary results. Results from study of two wells at Karaha Telga Bodas, Indonesia indicate that certain chemical species produce sharp distinct peaks at vein locations and migration into wallrock is by mobile chemicals. The well at Steamboat Springs in Nevada indicates that currently open fractures can be identified by peaks for most chemical species plotted on a FIS log. Also indicated is that total gas and water are high near open, producing fractures and total gas is low and water is high in non-producing, perhaps older fractures.