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Unformatted text preview: the thermal simulator and generate a unique solution. This
information can be obtained from the Joule-Thomson inflow temperature and cross flow information contained in the shut-in
DTS temperature data. 4 SPE 115816 Example 1: Gas Well Analysis Compared to a PLT Log
The first well that was logged using the slickline DTS in early 2007 also had a production log to directly compare the DTS to
a conventional spinner analysis.
DTS Data. Fig 9 shows a 3D picture of the temperature data over the reservoir intervals acquired during the flowing (18
hours) and shut-in (12 hour) period and the upper reservoir interval at 3260 meters develops a stable decrease in temperature
due to the inflow cooled gas by the Joule-Thomson effect. Smaller cooling events are present in two lower reservoir intervals
at 3650 m and 3675 m.
When the well is shut-in at 9:00 pm on the 28th, the temperature profile starts to return towards the geothermal baseline.
During shut-in selected depths above the reservoir were plotted in Horner time and to generate a geothermal gradient as
plotted in Fig 10. Selected temperature curves during the flowing period, immediately after shut-in, and 12 hours after shut-in
are shown in Fig 11. The geothermal gradient can be seen passing through a “pivot” point where both flowing and shut-in
temperatures coincide and about 1 to 2 Deg C of cooling below the geothermal is evident at the lower reservoir zones with 4
Deg C at the upper zone.
The Joule-Thomson cooling for each zone relates the decrease in temperature below the geothermal of the inflowing gas
to the decrease in pressure due to production drawdown though the Joule-Thomson coefficient as shown by equation 1
Δt = Δp.J …………………………(1) Simulation Analysis. The analysis requires two important parameters for each producing reservoir zone; the value of the
Joule-Thomson inflowing temperature of the gas from the reservoir and the flow rate of that gas. In this example, the upper
flowing zone clearly has a cooler Joule-Thomson inflowing temperature than the lower zones reflecting higher drawdown
and thus higher reservoir pressure. Model reservoir pressures and “pseudo” permeabilities were adjusted to create the correct
drawdown and flow rates from each zone, resulting in a match of the models output temperature curve to the measured DTS
The calculated gas inflow distribution compares favourably to the production log spinner curve as shown in Fig 12. The
production log data was not available until after the DTS analysis had been performed and verified the accuracy of the DTS
analysis technique. The dominant upper reservoir zone is modeled with a higher pressure to generate sufficient JouleThomson cooling, as shown in Fig 13. Example 2: Analysis of a Multi-zoned Gas Well with Cross Flow on Shut-in
DTS Data. In this case, the flowing DTS data was acquired on the 26th and the well was shut-in on the 27th, with no data
acquisition overnight; the 3D plot of the flowing and shut-in periods are shown on Fig 14. Large...
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- Spring '08