The Supergiant Kashagan Field: Making a Sweet Development Out of Sour Crude

Malik, Z.A.; Charfeddine, Mohsen; Moore, Scott; Francia, Luigi; Denby, P.

doi:10.2523/iptc-10636-ms

Cited by 3 publications

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Injection of Acid Gas Mixtures in Sour Oil Reservoirs: Analysis of Near-Wellbore Processes with Coupled Modelling of Well and Reservoir Flow

2010

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The reinjection of sour or acid gas mixtures is often required for the exploitation of hydrocarbon reservoirs containing remarkable amounts of acid gases (H 2 S and CO 2 ) to reduce the environmental impact of field exploitation and provide pressure support for enhanced oil recovery (EOR) purposes. Sour and acid gas injection in geological structures can be modelled with TMGAS, a new Equation of State (EOS) module for the TOUGH2 reservoir simulator. TMGAS can simulate the two-phase behaviour of NaCl-dominated brines in equilibrium with a non-aqueous (NA) phase, made up of inorganic gases such as CO 2 and H 2 S and hydrocarbons (pure as well as pseudo-components), up to the high pressures (∼100 MPa) and temperatures (∼200 • C) found in deep sedimentary basins. This study is focused on the near-wellbore processes driven by the injection of an acid gas mixture in a hypothetical high-pressure, under-saturated sour oil reservoir at a well-sector scale and at conditions for which the injected gas is fully miscible with the oil. Relevant-coupled processes are simulated, including the displacement of oil originally in place, the evaporation of connate brine, the salt concentration and consequent halite precipitation, as well as non-isothermal effects generated by the injection of the acid gas mixture at temperatures lower than initial reservoir temperature. Non-isothermal effects are studied by modelling in a coupled way wellbore and reservoir flow with a modified version of the TOUGH2 reservoir simulator. The described approach is limited to single-phase wellbore flow conditions occurring when injecting sour, acid or greenhouse gas mixtures in high-pressure geological structures.

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Injection of Acid Gas Mixtures in Sour Oil Reservoirs: Analysis of Near-Wellbore Processes with Coupled Modelling of Well and Reservoir Flow

2010

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Offshore oil and gas records circa 2020

Kaiser

2020

Ships and Offshore Structures

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Streamline-Based Miscible Gas Flood Performance Evaluation and Pattern Balancing: A Case Study from the Giant Kashagan Field

Ashenov

Francia

Haynes

2020

Day 2 Thu, October 22, 2020

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Miscible gas injection in the Kashagan platform started in 2017 and has been ongoing for three years. Gas injection in the platform carries both EOR and a facilities de-bottlenecking component. Initial flood assessment studies done using classical FD simulation have not provided the full picture of the reservoir dynamics to understand the performance of miscible gas injection. Areal reservoir depletion, pressure support and gas breakthrough events were challenging to quantify and characterize in terms of standalone full field FD simulation. Reservoir management strategy for operating the gas injection area was to maximize production from nearby producers and inject the full compressor potential. However, due to the fact that wells have different potentials driven by reservoir heterogeneity, areal distribution of cumulative reservoir fluid withdrawals and injection ended up being significantly different, which lead to flood pattern imbalances. The operator has implemented a modeling workflow that combines post-processing of history matched numerical simulation model with streamline tracing and integration of time-lapse well allocation factors (WAFs) to quantify and analyze flood performance. This paper presents how to use streamline modeling to estimate well-pair dynamic control volumes and a numerical integration workflow of the dynamic WAFs to evaluate pattern performance to guide flood balancing strategy. Streamline-based modeling workflow provides additional value by 3D visualization of the dynamic flood patterns and quantification of the individual pattern metrics. Numeric integration of injector-producer allocation factors (WAFs) and control volumes (CVs) allowed the construction of well pair conformance plots. Ranking of the patterns and I-P pairs filtered the outlier patterns with over injected and produced volumes and helped to focus on specific areas in need for pattern balancing. A list of producers with the highest pore volumes of gas injected were identified as at-risk wells for gas breakthrough and GOR elevation, which was confirmed by well test results. The first three wells with a rise in GOR and breakthrough sequence perfectly matched with the prediction of pattern performance. Those were identified as at-risk producers based on streamline modeling outputs. Verification of the analysis by field surveillance data gave confidence in reliability of the streamline-based flood evaluation approach. The outcomes of this study helped to understand miscible gas front movement and depletion dynamics in the gas injection area. This case study demonstrates how complementing finite-difference modeling with streamline analysis is necessary for achieving a complete assessment of the miscible gas flood performance.

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The Supergiant Kashagan Field: Making a Sweet Development Out of Sour Crude

Abstract: TX 75083-3836, U.S.A., fax 01-972-952-9435.

Cited by 3 publications

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Injection of Acid Gas Mixtures in Sour Oil Reservoirs: Analysis of Near-Wellbore Processes with Coupled Modelling of Well and Reservoir Flow

Injection of Acid Gas Mixtures in Sour Oil Reservoirs: Analysis of Near-Wellbore Processes with Coupled Modelling of Well and Reservoir Flow

Offshore oil and gas records circa 2020

Streamline-Based Miscible Gas Flood Performance Evaluation and Pattern Balancing: A Case Study from the Giant Kashagan Field

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