Data
Temperature measurements from 158 wells in 12 selected townships were inspected and empirical observations were made to determine which types of measurements are the most reliable. Horner corrected temperature data were compared to DST, production tests, Equilibrium, and cased hole temperature measurements.
Summary graphics of the Powder River Basin dataset can be viewed in published Tableau Public dashboard
Highest temperatures were recorded by equilibrium and cased hole logs (CHL). DST and 3-point Horner-corrected temperatures under predicted temperatures relative to cased hole logs. While 2-point Horner-corrected temperatures were warmer than their uncorrected bottom-hole temperatures (UBHT), they were relatively unreliable and can under- or over-correct relative to cased hole logs. A singular production test was much cooler than other temperatures in the area. Empirical observations in this study’s data set suggest that CHLs can be considered a proxy for equilibrium temperatures and are more readily available than equilibrium temperature data.
Scatter charts of depth vs temperature showed three domains:
- Shallow zone (0-3500 ft) with a very high temperature gradient due to the presence of coals. The trend was well defined with little scatter. Most of the measurements were from cased hole temperature logs and equilibrium measurements.
- Intermediate zone (3500 – 9000 ft) with a well defined temperature gradient trend with little scatter. The temperature gradient is more typical of foreland basin oil-producing basins (1.1 to 1.7 degF/100ft).
- Deep zone (> 9000 ft) where temperature data is highly scattered, yet the temperature gradient is generally on trend with the intermediate zone. A current working hypothesis is that the large degree of scatter is caused by steep pressure ramps.
For more information on this study contact Dave Advocate dave@geonol-ij.com or dmadvoc@gmail.com