Reducing permeability in a zone will reduce the flow

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Unformatted text preview: lating an inflow rate and Joule-Thomson inflow temperatures which are functions of the drawdown and flows from all the other zones in the well. Reducing permeability in a zone will reduce the flow from that zone, but, given that we are constrained by the total flow rate delivered, the drawdown and flow rates from the other reservoir zones will have to increase in the model. A unique match to the measured data is only achieved by honoring the shut-in reservoir pressures, and achieving JouleThomson inflow temperatures that are supported by the short time shut-in zone temperatures. If all the zones have the same reservoir pressure then the solution will be similar to that of Johnson. However, if the reservoir zone pressures are different, i.e. a depleting reservoir, the approach outlined in this paper will result in a unique solution to the problem. Conclusions A novel approach to monitoring gas wells with velocity string completions using DTS fiber conveyed on a slickline has proved a successful and cost effective alternative to conventional production logging. We demonstrate that previous interpretation methods do not necessarily provide a unique flow distribution in depleted multi-zone gas reservoirs and we have developed a new technique that will resolve this problem. The results compare well to the flow profiles obtained from conventional production logging tools which can only be run when the production tubing acting as a velocity string is pulled to allow access for the logs. The analysis results not only deliver producing well production profiles, but may also indicate potential differences in individual reservoir zone pressures, which is important information for effective reservoir management. Acknowledgements The authors wish to thank EnCana Ltd for permission to publish the examples in this paper and the management of EnCana Ltd and Schlumberger for permission to publish this paper. Nomenclature Δt = Joule-Thomson temperature cooling Δp = Reservoir to wellbore pressure drawdown J = Joule-Thomson coefficient V = Flow rate K = Constant Tg = Geothermal temperature Tw = Well temperature δTw/δh = Slope of the tangent to the temperature curve 6 SPE 115816 References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. Ramey, H. J.; “Wellbore Heat Transmission”. Paper SPE 96 presented 36th Annual Fall meeting SPE, Dallas, Texas. Oct 8-11, 1961. Kunz, K. S. and Tixier, M. P.: “Temperature Surveys in Gas Producing Wells”. Paper presented at the AIME Annual Meeting, Chicago, February 13-17, 1955. Schonblom, J. E.; “Quantitative Interpretation of temperature Logs in Flowing Gas Wells”. Paper presented at the Second Annual Meeting of the Society of Professional Log Analysts, Dallas, Texas. May 18-19, 1961. Steffensen, R. J. & Smith, R. C. “The importance of the Joule-Thomson heating (or cooling) in temperature log interpretation”. Paper 4836 presented at the 48th Annual Fall Meeting of the Society of Petroleum Engineers of the AIME in Las Vegas, Nevada. September 30-October 3,...
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