Importance Of Bottom-Hole Flow Monitoring During Transient Pressure Testing Available to Purchase

The analysis of transient pressure data collected during conventional well testing may lead to erroneous results. This is in many cases due to the absence of the downhole flow performance picture during the test. This paper presents evidence from actual field tests performed in the Middle East that the simultaneous measurements of pressure, rate, density and temperature performed downhole by the Production Logging Tool (PLT), are not only needed to reduce testing time by incorporating the measured afterflow into the analysis, but also needed to do the proper interpretation of test data. The paper presents several interesting test examples, that would have been misinterpreted completely if the downhole flow monitoring was not performed during these tests. The theory for using these simultaneous PLT measurements is reviewed briefly in connection with this part of the paper. The paper also shows a new use of the simultaneous PLT measurement of pressure, rate and temperature to derive deliverability and turbulence parameters of gas wells, without performing one of the conventional deliverability multi-rate testing methods. This new approach uses the PLT measured afterflow following the closing of the well at surface as a variable rate schedule, from which deliverability and turbulence parameters could be calculated. Results obtained from this approach are compared to those obtained from conventional isochronal gas well testing on several Middle East gas wells. The clear advantage of the method is reducing gas well testing time, however, it is applicable only for dry gas reservoirs. The production logging and testing data given in the paper should be very useful to extend the afterflow analysis to gas wells. Although the examples given in this paper are from the Middle East, it is believed that the new ideas presented are also applicable elsewhere.