A Geostatistical Analysis of Temperatures in Deep Regional Aquifers, Northeast British Columbia
Ben Kerr and Warren Walsh
Oil and Gas Division, B.C. Ministry of Energy, Mines and Petroleum Resources, Victoria, BC, Canada
Variation in the geothermal gradient as measured vertically within stacked aquifer zones of a basin indicates changes in hydrostatic flow and recharge between aquifer zones. This study identified four regional aquifers from Devonian to Cretaceous in age in northeastern British Columbia. Using a database of temperatures collected from the open hole logging of oil and gas wells, over 100,000 observed geothermal gradient values were calculated and positioned three-dimensionally within the basin. Based on the stratigraphy from these same wells the geothermal gradient values were then partitioned into aquifer groups.
As expected, absolute reservoir temperature for each of the aquifer zones studied increased with burial depth. However, variations identified as “hot” or “cold” (above or below expected geothermal gradient) were observed within each of the aquifer zones. A local measure of spatial autocorrelation was used to analyse these “hot” and “cold” spots. The statistical test was performed at a number of scales identifying localized variations as well as broader trends within the aquifer zones. Descriptive statistics of each aquifer zone are also presented which provide additional information for consideration in interpretation. These variations in the geothermal gradient have implications for hydrocarbon migration/aquifer flow, and in regionally identifying aquifer temperatures conducive to geothermal energy development.
AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas