Establishing geothermal gradient using a new static temperature analysis method

This work presents a new methodology for determining the static formation temperature (Tei) by using transient well-test data. We show how a semianalytic method, involving the rectangular hyperbola technique for obtaining Tei, was used for establishing a region's geothermal gradient. Insights into heat-transfer processes were applied to develop methods of data collection and analysis. Several options were enacted to gather valid transient temperature data. For instance, sensor placement above the test interval ensured that the produced fluid had the opportunity to cool during shut-in periods, thereby creating useful perturbations. Tests accompanied by large pressure drawdowns caused Joule-Thompson heating, leading to subsequent cooling during well shut-in, even when the sensor was at the midpoint of a producing interval. Transient temperature data were gathered during pressure buildup tests in various boreholes ranging from 2,200 to 14,500 ft, encompassing different geologic horizons in Kuwait. Data collected from traditional open- and cased-hole logging were used and compared with the new approach. Statistical analyses clearly showed the superiority of the proposed procedure. Results of the new approach established Kuwait's geothermal gradient (gG) at 0.012F per ft with a mean surface temperature (MST) of 87.23F.

Establishing geothermal gradient using a new static temperature analysis method Academic Article