Comparative Economic and Technical Evaluation of AG FLNG with One vs. Two Trains of Liquefaction Cycles

Nguyen, Xuan Chi; Regt, Ceed de; Mihaeye, Komla; Kim, Mungyu; Kim, Munsung; Yoo, Dong-Hoon; Lee, Charles; Lee, Daniel; Kumar, Balesh; Kim, Jung-Hoon

doi:10.4043/27731-ms

Day 3 Wed, May 03, 2017 2017

DOI: 10.4043/27731-ms

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Comparative Economic and Technical Evaluation of AG FLNG with One vs. Two Trains of Liquefaction Cycles

Xuan Chi Nguyen

Ceed de Regt

Komla Mihaeye

et al.

Abstract: This study presents a methodology based on the Life Cycle Cost (LCC) to define the optimum yearly Liquefied Natural Gas (LNG) production of a Floating LNG (FLNG) based on the proven gas reserve of an Associated Gas (AG) Field. This methodology developed specifically for these specific FLNG Concepts can be extrapolated to other type of FLNGs such as full-fledged FLNGs. For this purpose, several FLNG concepts of Associated Gas (AG) FLNGs are compared. A previous study presented to t… Show more

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A Decision Method at the Concept Select Stage for Choosing Onshore LNG or Floating LNG Production Facilities for Large Offshore Gas Discoveries

Meulengracht,

Djukvik

2023

Day 2 Wed, October 11, 2023

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Objectives/Scope Several offshore areas with large gas discoveries (> 2 Tcf of reserves) that are distant from markets now have 2 different LNG development options. The first is the classical onshore LNG production facility and the second is the offshore floating LNG (FLNG) production facility, a comparatively new development solution. This paper examines both options from technical and economic perspectives and proposes a method for selecting the best development solution at the Concept Select stage. Methods, Procedures, Process Appropriate gas production profiles and costs including DRILLEX, CAPEX and OPEX were determined for 2 remote prospective gas basins areas - Australia's North West Shelf and the Rovuma basin offshore Mozambique. Both areas have comparable physical settings in terms of reserves, reservoir depth, water depth and distance to shore but they are different from a gas industry maturity perspective. Australia's North West Shelf has both onshore LNG facilities and the Prelude FLNG in operation and is a mature oil and gas area with significant local construction and operational experience. Mozambique's Rovuma basin now features the Coral South FLNG in production, and several onshore LNG production facilities are being planned. However the latter area is in the early phase of building upstream construction and operational expertise. The technical analysis was based on a comparison of key physical settings and project parameters such as production profiles, costs and schedules. This was performed for both FLNGs and onshore LNG production facilities in the 2 mentioned areas. The economic analysis was based on detailed after-tax cash flows of all technical options and provided the key economic metrics for both types of solutions in both areas. Where appropriate a portfolio analysis was performed to include the effect of being in tax positions with multiple units (FLNGs) in operation. Results, Observations, Conclusions The technical and economic analyses were combined to create decision tables for both mature and less mature areas. These tables can be used as a tool at the Concept Select stage to determine under which conditions that an FLNG (or several) is a preferable development solution to onshore LNG, and vice versa. The method was applied to relevant examples. Novel/Additive Information The floating LNG production facility is a relatively new development solution for remote offshore gas discoveries compared with the classical onshore LNG supplied with offshore gas. The novelty of the developed decision tables is that they provide a simplified approach for making high level decisions on whether to choose onshore LNG or floating LNG production facilities at the Concept Select stage.

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A Decision Method at the Concept Select Stage for Choosing Onshore LNG or Floating LNG Production Facilities for Large Offshore Gas Discoveries

Meulengracht,

Djukvik

2023

Day 2 Wed, October 11, 2023

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Advanced Dual Refrigerant Expansion Cycle for Liquefaction

Kim

et al. 2018

Day 1 Mon, April 30, 2018

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This paper presents a LNG Liquefaction cycle configuration using two stages of methane expansion and a single stage of nitrogen expansion (Dual Refrigerant) to improve the efficiency of the conventional methane and nitrogen refrigerant expansion cycle. The chosen configuration further optimizes the composite cooling and heating curve of the liquefaction cycle, resulting in a higher thermodynamic efficiency. The production efficiency of the liquefaction cycle can be improved by reducing the interval between the cooling curve of the natural gas and the warming curve of the refrigerant: the closer both curves are, the better the efficiency of the cycle. This optimization is achieved by adjusting the refrigerant operating temperatures and pressures. The advanced dual refrigerant expansion cycle includes three levels of expansion, each having different temperature and pressure levels. In the methane expansion loop there are two stages, which are classified warm and cold. The warm loop is applied in the pre-cooling zone and the cold loop is responsible for the main liquefaction. The nitrogen loop is a single stage and is used for sub-cooling. This configuration allows the methane and nitrogen warming curve to closely match the cooling curve of the natural gas cooling curve by changing the methane and nitrogen warming curve from two straight lines into multiple intersecting straight lines of different gradient. That is to say, the additional new methane expander generates an added inflection point within the cold composite curve. As a result, thermodynamic inefficiencies are minimized and the power requirements are reduced when compared to Methane & Nitrogen Expansion Cycle. In comparison with other previous expansion cycles, the cycle efficiency has increased approximately from 13.13 to 12.08 kW/ton/day (8% efficiency increase) assuming similar feed gas (methane: 80%, MW: 21.38). The composition of this feed gas is representative for associated gas or pipe line gas which is preliminary treated to remove bulk water and hydrocarbon condensate. A case study is presented for an open sea associated gas FLNG concept, comparing three kinds of liquefaction processes (Double Nitrogen Expansion Cycle, Methane & Nitrogen Expansion Cycle and Developed Dual Refrigerant Expansion Cycle). A Life Cycle Cost (LCC) analysis based on Net Positive Value (NPV) also shows an improvement in terms of project NPV, against a minor increment of the CAPEX of these cycles.

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Optimization of Advanced Dual Refrigerant Expansion Cycle for Liquefaction

Kim

Ryu

Lee

et al. 2019

Day 1 Tue, October 29, 2019

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This paper shows the sequential search algorithm that makes it possible to find the optimum operating conditions of Advanced Dual Refrigerant Expansion Cycle that is used for LNG liquefaction process. The operating conditions are key parameters in determining the overall liquefaction efficiency of system, so it is the core process to find out these optimized key parameters in LNG industries. The steps of this method are as follows. 1) Defining input variables based on understanding of liquefaction cycle and thermodynamics. 2) Setting simulation to apply the sequential search algorithm. 3) Searching sequentially several local optimum points between the upper and lower limits of several input variables considering minimum/average efficiencies and the number of points satisfied with minimum approach 4) Repeat step 3) with narrower ranges and step sizes of each input variable based on previous results. 5) Get the global (final) optimum point considering final results and realistic operation. The operating conditions of Advanced Dual Refrigerant Expansion Cycle are eventually optimized with the best overall liquefaction efficiency of system by using the sequential search method. It is directly related to economical effect in terms of the high production rate against supply power, small size of equipment and the associated pipe lines, simple system layout and so on. During searching, several local optimum points of the operating conditions can be recorded in order to compare the liquefaction efficiencies at each of points by using this method. It serves as the objective evidence to understand trends of the efficiencies calculated from variable inputs. In addition, this method can provide a variety of selecting the main equipment such as compressor, expander, heat exchanger and so on because it is possible to identify several local optimum points have similar efficiencies. This new sequential search method can be applied for the optimization of existing other gas expansion liquefaction cycles and the mixed refrigerant (MR) LNG liquefaction cycles by making adjustments to input variables e.g. MR compositions can be available input variables as well in case of MR cycles.

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Comparative Economic and Technical Evaluation of AG FLNG with One vs. Two Trains of Liquefaction Cycles

Cited by 3 publications

References 0 publications

A Decision Method at the Concept Select Stage for Choosing Onshore LNG or Floating LNG Production Facilities for Large Offshore Gas Discoveries

A Decision Method at the Concept Select Stage for Choosing Onshore LNG or Floating LNG Production Facilities for Large Offshore Gas Discoveries

Advanced Dual Refrigerant Expansion Cycle for Liquefaction

Optimization of Advanced Dual Refrigerant Expansion Cycle for Liquefaction

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