Transok, Inc. operates over 2000 miles of gas gathering and transmission pipelines in the state of Oklahoma. In 1982, the company decided to acquire a transient gas flow model for in-house use. The model was primarily intended to support engineering analysis of proposed system changes and to aid in the resolution of operating problems. A commercially available transient gas flow simulator, TGAS, was selected for use. Using this package, Transok personnel developed models of the company's main gas transmission network in addition to a model of a portion of the company's gathering system. Both models have proved useful in the company's ongoing operation. A recent application involved evaluation of a proposed compressor relocation which was shown to be unnecessary, thereby saving several thousand dollars in relocation costs. Other examples in which the models have been of practical benefit are discussed and the company's plans for future model applications are outlined.
In recent years, the use of transient simulation technology has become prevalent in the gas industry, replacing the use of formulas and the more traditional steady-state simulation technology. Detailed descriptions of the principles of dynamic simulation of pipelines and associated equipment are available in the literature. The technology is field-proven and has been commercially available for many years. Once the decision is made to acquire or develop a transient simulator, a gas company must take several important steps in order to insure eventual success of the project. This paper discusses the process, starting with Transok's decision to acquire a transient model. Several applications in which the simulator has provided tangible benefits are presented, as well as applications which are planned for the future.
The initial operating philosophy of Transok was to transport natural gas to Public Service Company of Oklahoma (PSO) power stations to burn as the primary fuel. Transok was purchased by PSO for this sole purpose in the mid-l950's. A single 24 inch pipeline carried gas from south central Oklahoma to northeast Oklahoma where the power stations were located. The role of a provider of fuel gas for PSO continued as more power stations and pipelines were built. An intrastate network of 800 miles of transmission pipelines up to 24 inches in diameter resulted from fulfilling the responsibility of providing a reliable fuel source for PSO. Also, as the pipeline system circumvented Oklahoma, other customers were discovered. The volumes delivered daily to these customers are presently approaching the rates supplied to PSO. Therefore, the operating philosophy now includes dependable transportation of gas to other customers in addition to PSO.
The Transok pipeline network collects gas from over 1400 wells scattered throughout the state of Oklahoma. The gas flows into the company's main transmission grid via several small diameter gathering pipelines. The transmission lines carry gas to six electric power generating stations and numerous other customers. Overall, the network consists of over 2000 miles of pipeline. A system schematic is shown in Figure 1.