Example of processing & interpretation of standard (centered) PLT data + temperature
The well was logged to determine the cause of a substantial loss in production and eventually the source of the water production. The surface flow rates while logging were approximately 5000 BOPD, 2000 BWPD, and 4 MMCFD net gas. The well was deviated.
The spinner data showed highly negative velocities below X900', which indicates downflow of fluids. The temperature however shows a significant Joule-Thompson (or frictional ) heating effect. Such a temperature increase is due to skin damage, which produces frictional heating if liquids enter the well. The density shows a decrease in density at the same depth as the heating effect.
This means that oil enters the well below x900’. The negative velocities are resulting from water recirculation or fallback. This is a phenomenon which is often observed in deviated wells such as this well.
This well would have been a perfect candidate for a PLT with array tools, so that the water recirculation layers could be distinguished from the layer with oil flowing up. Unfortunately only a standard PLT toolstring was used., so that the spinner was only detecting the water flowing down, but not the oil flowing up.
Using a standard analysis approach based on spinner data, this well cannot be analyzed.
Using the temperature we estimated a production of about 300 BOPD below X900'.Combining spinner and temperature data allowed to estimate the remaining production above X900'. The apparent velocity error was increased in the zone where temperature and spinner disagree.
Although this production is small, we demonstrated that the small production was due to a very high skin damage. Based on this information the operator performed a workover on the zone below X900' and increased the production by more than 30%.
Result of the analysis done by the vendor with traditional techniques:
The results of the traditional analysis showed that the oil, gas and water were produced above X900 feet and calculated a significant down-flow from X900' on, which appeared to leak out at the plug.
If the results obtained with the traditional analysis had been followed, a plug was placed at the depth of X900'.
With the results obtained by our analysis as of today 1 million BBL of Oil were saved.
