Palm Valley Well Test Analysis and Gradient Survey Final Report

Abstract

This report presents the results of a well test analysis and gradient pressure survey analysis performed by Edinburgh Petroleum Services Ltd (EPS) for Magellan Petroleum Australia Ltd (Magellan). The pressure buildup tests on 6 wells of Palm Valley field have been analysed, using EPS' proprietary Pan System software. Magelllan provided the required information as hardcopy reports and/or electronic files. Based on an initial review of these data 32 tests were considered to be analysable. The quality of some of these tests and the gauge resolution are low. A variety of reservoir and boundary models have been tested. From the analysis the most suitable model for the reservoir is identified to be dual porosity (pseudo-steady-state), but for well PV#6 a vertical fracture-infinite conductivity model appeared to be the best model. Due to the high mobility of gas compared with oil and water, for gas reservoirs a constant pressure boundary could not be considered. Therefore if there is any kind of boundary for these wells it must be considered as a no flow boundary. The data of some tests, particularly well PV#7, are very sparse and therefore any conclusions must be treated with caution. Gradient pressure surveys have been performed on all the Palm Valley wells since completion. Hard copies of these tests were provided by Magellan. A total of 133 pressure gradient reports have been reviewed. All this data has been re-analysed in order to monitor static and flowing pressure profiles in all wells. Since some of these wells are deviated (PV#6B, PV#7 and PV#9) all measured gauge depths have been corrected to true vertical depths (TVD) for proper pressure gradient calculations. Measured pressure data at different gauge depths under static and flowing conditions is presented in this report for each test in tabular and graphical forms. Usually a plot of pressure vs gauge depth gives a clear indication of the fluid pressure gradient profile inside the well. Appendices 1 to 6 include the details of all analyses performed for the Palm Valley gas reservoir. Appendices 7 to 15 summarise chronologically all pressure gradient surveys performed on each of the Palm Valley wells. Refer to PR1999-0053 for the 'Review of Palm Valley welltest analysis and pressure gradient surveys' by the Northern Territory Department of Mines and Energy.`