Properly designed, conducted and analyzed transient tests can be used to determine reservoir behavior and well conditions and estimate reservoir properties needed for field management. Testing the Yacheng 13-1 wells provides a case history for achieving these objectives under conditions of high temperature. The Yacheng wells encountered natural gas at a temperature of 350°F (177°C) and a pressure of about 5600 psi. This paper discusses the testing process and the experience of ARCO China in testing the Yacheng 13-1 development wells. This experience shows the key items needed to assure a successful test in a difficult environment.

The key items are determining the test objectives, designing a test that would achieve these objectives, estimating the pressure and temperature of the well during the test, selecting the proper tools and equipment to obtain the needed measurements, carefully coordinating the tasks between operating and service companies personnel, monitoring the test data in real-time to change the test procedure if needed, analyzing the data to estimate the well/reservoir system properties and finally, using the results to update the testing procedures for subsequent wells.

The tests performed included modified isochronal, drawdown and buildup tests. Tests had to be designed such that PVT-quality samples could be obtained to help design the production and transportation facilities. Carefully designing and conducting the tests, aided by the ability to perform real-time analysis to alter the testing procedure, enabled the operator to obtain the needed information about the well/reservoir system. The paper shows how the information is intended to be used in managing the field.

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