Static Formation Temperatures — How to Achieve Them

Bottom-hole temperatures (BHTs) are useful in determining in situ or static formation temperatures. Static formation temperatures yield valuable information regarding fluid movement, hydrocarbon maturation, and help correlate formations as well as correct other logging tool measurements sensitive to temperature. However, because of the drilling process and the circulation of fluids, the BHTs gathered from open-hole well logs are not at equilibrium and are generally cooler than static formation temperatures, thus requiring an uncertain correction. The use of pressure logs is a common practice in the oil and gas industry and provides a great deal of information about the overall condition of the reservoir including fluid migration, in addition to reservoir pressure and temperature. Older pressure-temperature technology was quite primitive and limited. Today, new digital technology pressure-temperature tools capture the static formation temperature, since they are run months to years after drilling, thus measuring the formation’s current in situ state. Traversing logs such as pressure-temperature exist as part of the typical package run, which opens a whole new set of data that is currently being measured. Since production logs are mainly used by engineers, the geological community is quite unaware of their existence and usefulness. This study compares BHT data from open well logs with quasi-static pressure-temperature logs and equilibrium temperature data, highlighting the advantage of utilizing high-quality, digital pressure-temperature logs to determine true formation temperatures.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California