Producing natural gas from Tight Gas Sand (TGS) reservoirs will be of increasing importance to the global energy industry in the coming decades. One of the basic decisions concerning the development of TGS reservoirs is to determine the size of the production casing and tubing. Because of low permeability, virtually all of the wells completed in TGS reservoirs must be stimulated to achieve the desired production goals. Therefore, the casing and tubing size must be designed to satisfy the stimulation requirements. Because many TGS wells are completed in reservoirs that have many distinct layers that can contribute to production if adequately treated, it is important to select the optimal diversion techniques in completing these multilayered reservoirs. The casing and tubing size must be designed to allow the selected diversion technique to be used successfully. In addition, during the production period, it is important to continuously remove the liquids from the wellbore. Therefore, the casing and tubing size must also be designed to satisfy the production requirement. In summary, the casing and tubing size must be designed to satisfy the completion, stimulation and production requirements. In this paper, we will provide a methodology we have developed to select the appropriate casing and tubing size for the development of TGS reservoirs.
This work has been part of our effort to build software that we call TGS Advisor. TGS Advisor can be used to provide advice/best practices to engineers developing TGS reservoirs. The user enters the known reservoir data and the program provides advice on how to drill, complete and stimulate the reservoir. We have combined knowledge from the petroleum literature and interviews with experts with detailed calculations to build the TGS Advisor. We evaluated the results of the TGS Advisor with published case histories in the petroleum literature. Currently, the methodology of choosing casing and tubing size for TGS reservoirs has been programmed and incorporated into the TGS Advisor system. Finally, an example of using TGS Advisor to select the appropriate casing and tubing size in TGS reservoir is presented.