Abstract
A steam pilot in the Yates Field is underway to assess the economic viability of improving gravity drainage in the gas cap of the fractured San Andres reservoir. A thorough monitoring program has been implemented which employs the latest in seismic and logging technology. As steam is injected, downhole geophones monitor passive seismic events caused by thermal expansion of the rock to estimate the areal and vertical extent of the heated zone. At the same time, time-lapse carbon-oxygen logs are being used to monitor changes in oil saturation behind the thermal front. Careful design and planning are required to dedicate several wells in the pilot area solely to the application of these technologies. Results from the geophones and repeat logs will be combined to estimate the volume of oil mobilized as a result of steam injection. This volume will be compared to oil production increases and with results from fluid sampling and temperature monitoring in the pilot area to assess the economic viability of the steam pilot.
