[First Hit]

Datapages, Inc.Print this page

Abstract: Development of Cost-Previous HiteffectiveNext Hit Geothermal Probes for Use in Offshore Exploration and Environmental Work

Department of Geosciences, University of Houston, Houston, TX; KEN GRIFFITHS and ARCHIE ROBERTS
Institute for Geophysics, University of Texas at Austin, Austin, TX

We have developed a cost-Previous HiteffectiveTop technique to obtain geothermal profiles of the bottom sediments in relatively shallow (< 500 m) seas and lakes. Information on the geothermal regime is important in offshore hydrocarbon exploration, particularly in maturation analyses and detection of oil/gas seeps. Geothermal measurements in estuaries and lakes are also important in understanding their heat budgets. However, the techniques previously available for underwater geothermal measurements are costly and time consuming. The equipment is heavy, and its deployment requires a large ship equipped with a heavy-duty winch and good station-keeping capability for which operational costs are high. This requirement also precludes making measurements in small inland lakes. We have developed a new geothermal probe that significantly reduces these technical, logistical, and economical difficulties. The new probe utilizes a thin (1-inch diam.), long (> 20-ft.) steel tube which contains a number of thermistors. It free-falls through the water column and, with its momentum, penetrates into the sediments. It can be easily transported and deployed from a very small (i.e., inexpensive) ship. In the current design, the probe transmits the temperature data to the surface through a thin electrical cable. We tested the probe successfully in Lake Travis, Texas in early June and mid-August of 1997. It was deployed in the deepest (~55 m) part of the lake and recorded temperature profiles down to 3 m subbottom. These data are currently analyzed for the regional geothermal heat flow and the annual heat budget.

AAPG Search and Discovery Article #90932©1998 GCAGS/GCS-SEPM Meeting, Corpus Christi, Texas