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Probes record temperature during hot oiling

April 8, 1996

Figure 1: Temps. During Hot Oiling [37774 bytes] Small probes placed in a sucker-rod string can record downhole temperatures to help evaluate the effectiveness of hot oiling for removing paraffin from producing wells. Hot oiling is one of three main alternatives for cleaning paraffin from wells. The other common methods are chemical treatments and tubing scrapers. Sandia National Laboratories, Albuquerque, N.M., developed the probe which is now manufactured by Flexbar Inc., Odessa, Tex.

Figure 1: Temps. During Hot Oiling [37774 bytes]

Small probes placed in a sucker-rod string can record downhole temperatures to help evaluate the effectiveness of hot oiling for removing paraffin from producing wells.

Hot oiling is one of three main alternatives for cleaning paraffin from wells. The other common methods are chemical treatments and tubing scrapers.

Sandia National Laboratories, Albuquerque, N.M., developed the probe which is now manufactured by Flexbar Inc., Odessa, Tex.

Each probe is a battery-operated micro processor/sensor module with a memory that is sealed in a slightly elongated sucker-rod coupling, (about 5-in. long). The probe is sealed into the coupling with a standard pipe plug.

To record temperatures at various depths, an operator can install several couplings with sensors in different sections of the sucker-rod string. Typically, four or five probes might be run, according to Sandia.

After hot oiling, rods need to be pulled to recover the sensors and recorded data. The temperature data are downloaded from each sensor to a spreadsheet with the software provided.

In its first field trial, the temperature probe confirmed the temperature measurements of Sandia's downhole dynamometer.

In another downhole field test, Mobil Exploration & Producing U.S. Inc. used the probes during hot oiling a well. The figure compares the temperatures recorded by one probe compared to Sandia's "hot oiling spreadsheet" calculations.

Sandia indicates the difference in the curve is due to the spreadsheet not being capable of accounting for complex casing configurations. In this case, the Mobil well had a tie-back liner that created a convection cell.

Access to Sandia's "hot oiling spreadsheet" and additional information on the temperature probe can be obtained from Sandia's Internet site, http://www.sandia.gov/apt/.

The temperature probe was developed under the Natural Gas & Oil Technology Partnership, a cooperative effort of the U.S. Department of Energy, its national laboratories, and the American petroleum industry.