Condensate Spill Fate and Transport (PNG)
In the Southern Highlands of Papua New Guinea, a natural gas (condensate) pipeline links the Hides Gas Condensate Plant and the Central Processing Facility. It was anticipated the pipeline would traverse four major rivers and six lesser watercourses and numerous minor watercourse crossings. The length of the pipeline is approximately 109 km and includes steep terrain, regions of high rainfall and flooding, and sensitive cultural areas and ecological habitats.
As part of the mitigation planning, and in the event of a release of condensate to surface waters along the pipeline, an understand of the impacts and transport through the local environment was required. Water Technology was engaged to undertake condensate fate and transport modelling for the Papua New Guinea Liquefied Natural Gas (PNG LNG) pipeline project at Lake Kutubu, and the waterways along the pipeline route. The modelling assessed dilution and volatile losses, the spill effect and surface water drainage pathway flow duration, with the results were used to provide information for the development of site specific spill response plans.
The modelling considered condensate loss to the atmosphere, residence within the water column and the formation, and maximum size, of the condensate plume at the water surface. To do this, the condensate was modelled separately in the near-field and far-field. The reason for modelling these zones separately was to enable an understanding of the dynamics of a spill plume both close to the spill location and as it is transported further downstream. The focus of the near-field modelling was on the geometry and dilution characteristics of the initial spill mixing zone, while the emphasis of the far-field modelling was to track the spill plume as it is transported away from the spill site by the flow.
The modelling involved detailed assessment of near-field plume mixing using the package CORMIX, coupled with extensive 1D models (MIKE 11) of the river network in the Southern Highlands. The lake was modelled in 2D (MIKE 21) in order to describe the lake hydrodynamics and mixing in more detail. Based on the outcomes of the modelling a toxicology assessment was undertaken to describe the potential ecological effects and potential impacts of any condensate spill.
Key Services Provided
- Hydrological Assessment
- Near-field and far- field spill and transport modelling
- 1-D and 2-D Hydrodynamic modelling