This paper discusses the challenges in expanding the capacity of the Dampier to Bunbury Natural Gas Pipeline (DBNGP) which has its capacity transportation services defined by probability of supply with specific interruption limits. The DBNGP has two main types of capacity services, namely, Firm and Non Firm. The Firm Capacity Service has a 98% probability of supply and it may not be interrupted for more than 2% of the time. The Non Firm Capacity Service is an additional capacity over and above the Firm Capacity service. This could be made available on a fully interruptible basis. These types of capacity services require a different flow modelling approach - the Firm Capacity Service can only be derived from simulating thousands of steady state runs under different compressor operating configurations (compressor on/off-line cases). It is not only a challenging and time consuming process to model the firm capacity levels for the DBNGP, but its complexity increases when assessing the expansion options for this pipeline. Typically, for each of the expansion options, a massive number of steady state simulations must be carried out before the new capacity level can be ascertained. This can become a daunting process in selecting the most optimum expansion options involving different compressor types, sizes and locations, different loop lengths, diameters, and many other feasible options. This paper describes the development of a pipeline modelling tool specifically designed for DBNGP's probabilistic capacity services. This modelling tool can be used for not only day-to-day steady state and transient simulations, but also for the capacity expansion plan and its optimisation.
The Dampier to Bunbury Natural Gas Pipeline (DBNGP) connects the gas processing plants located near Dampier in the North West of Western Australia to Bunbury in the state's South West. It is about 950 miles (1530 km) long with ten compressor stations situated approximately 90 miles (150km) apart from each other. Currently, all of the Gas Producers are located at the top end of the pipeline supplying gas to the majority of the users at the bottom end of the pipeline. There are only a limited number of interconnections with other pipelines. By world standards, it is a relatively small and simple pipeline. This paper presents: An overview of the DBNGP and its Capacity Services. Overview of an advanced pipeline simulation tool specifically designed for the modelling of the DBNGP's Capacity Service and for its capacity expansion plan.
The following lists the chronology of the pipeline: 1984: Built by the State Government of Western Australia 1998: The privatised pipeline was acquired by Epic Energy (which was owned by El Paso, Dominion and other Australian Funds) 2004: Acquired by Alinta (20%), Alcoa (20%) and DUET (Fund Managers) (60%) 2007: Alinta's 20% share purchased by Babcock & Brown Infrastructure (BBI) Figure 1 shows the route of the pipeline in relation to the major towns and cities of Western Australia. Physical characteristics of the pipeline are included in Table 1.
