Evaluation Of Gas Storage Well Completions With Well Logs

This paper was prepared for the 45th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Houston, Tex., Oct. 4–7, 1970. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Many of the problems connected with the underground storage of natural gas, in both aquifer and depleted reservoirs, can be solved by the proper application of modern wireline logging tools. Well logs are useful in gas storage wells for the location and inventory of gas-bearing zones, determination of levels where gas enters or is produced from the formation, determining well deliverability, and the location of casing leaks as well as points where the pipe is defective due to corrosion. logs run after the well is completed can help to evaluate the effectiveness of a stimulation process or the mechanical integrity of the completion. logs run at intervals, as the storage well is produced, can define changes in gas saturation movement produced, can define changes in gas saturation movement of fluid contacts, and growth of the gas bubble, thus permitting a periodic inventory. Major changes in injection patterns and withdrawal rates are usually symptoms of problems. Suitable logging programs can help define these problems and indicate the remedial action necessary to bring the field back to maximum efficiency. The open-hole logs and the logs run immediately after completion provide valuable background information for the interpretation of logs run later in the life of the well. In existing storage fields, where background information is not available, data must be gathered in order to help define the existing problems. A thorough evaluation of the existing subsurface hardware must also be made. Small-diameter tools and pressure-control systems are available with which most logging operations may be made in either tubing or casing without interrupting the well operation. Field examples from gas storage projects in several different areas are used to illustrate the interpretation techniques.