Providing input to the preparation of Front End Engineering Design packages
HPCL Shapoorji Energy Limited (HSEL) – a joint venture between state-owned Hindustan Petroleum Corporation Limited and SP Ports Private Limited – intends to construct an onshore liquefied natural gas (LNG) import and regasification terminal in Chhara, a village in Gujarat, India. HSEL has appointed Engineers India Limited (EIL) as consultant to prepare Front End Engineering Design (FEED) packages, which are used as the basis for bidding the Execution Phase Contracts (Engineering Procurement Construction) and as the design basis. To support EIL in their preparation of FEED, HSEL engaged DHI to carry out a marine modelling study for the proposed terminal.
Chhara port is being developed as an all-weather port with water depth available to -20m chart datum. The wave tranquillity within the port will be achieved by an offshore breakwater on the natural shoal bank approximately 2.5 km away from the shore line. DHI conducted a marine modelling study to help establish if the construction of the terminal was viable. Our scope of work spanned different areas, including:
Using MIKE 21 to model port conditions
We used MIKE Powered by DHI’s two-dimensional (2D) coastal modelling software MIKE 21 to model the current conditions at the port. We studied wave transformation under fair weather and cyclone conditions, currents, sediment transport and morphological evolution.
MIKE 21 allowed us to provide sufficient coverage of the overall port surroundings and maintain the required level of detail at key locations, while achieving reasonable model simulation times. For the wave transformation modelling, we applied our third-generation spectral wind-wave model – MIKE 21 SW. We then analysed the modelled long-term wave conditions. This provided the design wave as well as the normal wave conditions governing port operations. A nearshore wave model was applied to describe the wave conditions inside the port area.
The hydrodynamics modelling was done using MIKE 21 Hydrodynamics (HD). MIKE 21 HD was used to model free-surface flows, based on a finite volume solution to the non-linear shallow water equations. The model simulated water level variations and flows in response to a variety of forcing functions, including tides, winds and waves. The HD model encompassed the Gulf of Khambhat area. It included a detailed representation of the HD flow field and water levels from the general port area and adopted a flexible mesh discretisation of the model domain.
The set-up included a detailed high-resolution description of the proposed LNG terminal berths. The calibrated model was used to simulate the HD flow fields used in the moored vessel analyses.
Storm surge modelling
The processes of selecting design water level and waves are site specific. Storm surge and cyclonic waves are hind casted from cyclonic track records. The cyclone track of the November 1982 cyclone – which resulted in 341 casualties and heavy flooding –made an appearance very close to the proposed terminal. We carried out storm surge simulations using MIKE 21 HD to assess the surge levels at the LNG terminal for eight such extreme events passing near the site. The 2D wind fields are generated with the cyclone wind generation tool in MIKE 21.
The main aim of the mooring study was to review the proposed mooring layout for the berth for three types of LNG carrier vessels, all of different sizes. The results were used to compare against safe operating conditions and minimum breaking load (MBL) guidelines. The outcomes of the mooring analysis were checked against the criteria published by the Oil Companies International Marine Forum (OCIMF, 2008) using the industry-standard mooring software OPTIMOOR.
Provided accurate wave conditions
Established understanding of hydrodynamics and moored vessel interactions
Determined probable future impact on the coastlines
Dushyant ChaturvediProject ManagerHPCL Shapoorji Energy Ltd
HPCL Shapoorji Energy Ltd
MIKE 21 Hydrodynamics (HD)MIKE 21 Spectral Waves (SW)
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