Gas Current Perspective on Well Testing in Storage Fields

Abstract

Introduction Gas well testing is not new, but the practical approach which forces innovation and departure from the laboratory technique may present a challenge. This is especially true in testing wells penetrating gas storage reservoirs developed in aquifers. It is hoped that this paper will present some of the aspects of well testing for storage fields which will also pinpoint the direction for future laboratory research. The analysis of the data is not covered in the scope of this discussion, but rather the objectives of the tests and the procedures used to conduct the tests are explored. Since all gas well testing is performed for certain specific needs and objectives, it is not difficult to understand the reason for the approaches presented in this paper. Whether it be company justification or regulatory requirements, all storage well testing is geared to the ultimate proof of the storage reservoir. Well condition is indicated, but basically each test run on a storage well or group of wells will prove the injectability or the deliverability of each storage zone tested. The authors' experience in gas well testing has been primarily with storage developed in aquifers. That is reservoirs which have not previously contained gas or oil. The views presented will therefore indicate actual problems associated with this type of reservoir. The similarity in many respects to conditions encountered in depleted oil and/or gas reservoirs converted to gas storage reservoirs will be of interest to those concerned with such storage facilities. The unusual aspects of gas well testing in "aquiferstorage" will point out the areas where additional research has been done or needs to be done for the progress of this phase of reservoir technology. Gas Well Testing - Storage Fields Gas well testing is normally concerned with the deliverability of a gas well. Gas well testing in storage fields is primarily concerned with both injectability and deliverability of a well or of many wells. As will be explained in this discussion, injection and withdrawal characteristics of an entire field may be more important or at least equally important as individual well performance. Most storage fields are developed to fulfill a specific basic requirement of a gas company. This basic need is the ultimate efficient service to the customer. By the nature of their purpose, transmission and distribution companies are the major developers of storage projects. This may be small capacity, low volume rate service or large capacity, high volume rate service depending on the need.