The Design of the First Miscible Sour Gasflood Project in Oman

Al-Hadhrami, Abdullah; Davis, Darrell; Deinum, Geurt; Soek, Harry

doi:10.2523/11396-ms

Cited by 5 publications

(3 citation statements)

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“…Injection of various gases involving CO 2 and acid gas into the oil reservoir has been investigated by some authors. There is the miscible HC gas reinjection project with large volumes of sour gas (3-4% H 2 S and 10-15% CO 2 ) at Harweel field in Oman (Al-Hadhrami et al, 2007). The pilot project is a first contact miscible gas injection with 12% H 2 S content which has recently been running in the Tengiz oilfield in Kazakhstan (Wang et al, 2014;Urazgaliyeva et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

An evaluation on mechanisms of miscibility development in acid gas injection for volatile oil reservoirs

Luo

Fan

et al. 2019

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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Produced gas containing the acid gas reinjection is one of the effective enhanced oil recovery methods, not only saving costs of disposing acid gases and zero discharge of greenhouse gases but also supporting reservoir pressure. The subsurface fluid from the Carboniferous carbonate reservoir in the southern margin of the Pre-Caspian basin in Central Asia has low density, low viscosity, high concentrations of H2S (15%) and CO2 (4%), high solution gas/oil ratio. The reservoir is lack of fresh water because of being far away onshore. Pilot test has already been implemented for the acid gas reinjection. Firstly, in our work a scheme of crude oil composition grouping with 15 compositions was presented on the basis of bottomhole sampling from DSTs of four wells. After matching PVT physical experiments including viscosity, density and gas/oil ratio and pressure–temperature (P–T) phase diagram by tuning critical properties of highly uncertain heavy components, the compositional model with phase behavior was built under meeting accuracy of phase fitting, which was used to evaluate mechanism of miscibility development in the acid gas injection process. Then using a cell-to-cell simulation method, vaporizing and/or condensing gas drive mechanisms were investigated for mixtures consisting of various proportions of CH4, CO2 and H2S in the gas injection process. Moreover, effects of gas compositions on miscible mechanisms have also been determined. With the aid of pressure-composition diagrams and pseudoternary diagrams generated from the Equation of State (EoS), pressures of First Contact Miscibility (FCM) and Multiple Contact Miscibility (MCM) for various gases mixing with the reservoir oil sample under reservoir temperature were calculated. Simulation results show that pressures of FCM are higher than those of MCM, and CO2 and H2S are able to reduce the miscible pressure. At the same time, H2S is stronger. As the CH4 content increases, both pressures of FCM and MCM are higher. But incremental values of MCM decrease. In addition, calculated envelopes of pseudoternary diagrams for mixtures of CH4, CO2 and H2S gases of varying composition with acid gas injection have features of bell shape, hourglass shape and triangle shape, which can be used to identify vaporizing and/or condensing gas drives. Finally, comparison of the real produced gas and the one deprived of its C3+ was performed to determine types of miscibility and calculate pressures of FCM and MCM. This study provides a theoretical guideline for selection of injection gas to improve miscibility and oil recovery.

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Section: Introductionmentioning

confidence: 99%

An evaluation on mechanisms of miscibility development in acid gas injection for volatile oil reservoirs

Luo

Fan

et al. 2019

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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“…16,17 The field has a harsh reservoir environment with a formation brine salinity of 275,000 ppm TDS (total dissolved solids) and a reservoir temperature of 377 K with low in situ water saturation. 18,19 It has been shown that both foam and WAG flooding are not applicable in this field as means of mobility control. 16 Hence, with Field A, it is believed that AG mixture thickening may be the only viable approach to counteract unfavorable mobility conditions and improve sweep efficiency.…”

Section: Introductionmentioning

confidence: 99%

“…Unlike foam injection and water alternating gas (WAG) flooding, the application of gas thickeners is not dependent on the reservoir rock petrophysical properties and fluid saturations . Field A in southern Oman has suffered from early gas breakthrough due to the high mobility of the AG mixture injected as part of an MGI process. , The field has a harsh reservoir environment with a formation brine salinity of 275,000 ppm TDS (total dissolved solids) and a reservoir temperature of 377 K with low in situ water saturation. , It has been shown that both foam and WAG flooding are not applicable in this field as means of mobility control . Hence, with Field A, it is believed that AG mixture thickening may be the only viable approach to counteract unfavorable mobility conditions and improve sweep efficiency.…”

Section: Introductionmentioning

confidence: 99%

New Approach to Alternating Thickened–Unthickened Gas Flooding for Enhanced Oil Recovery

Hinai

Saeedi

Wood

et al. 2018

Ind. Eng. Chem. Res.

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Direct gas thickening is a conventional mobility control method to improve volumetric sweep efficiency for miscible gas injection (MGI) projects. However, the viability of this approach with technically feasible thickeners has not been verified at the field-scale due to a combination of high costs and/or environmental issues. One approach to make this technique economically more attractive is the implementation of an alternating injection scheme (similar to water-alternating-gas (WAG)) that would require less of the thickened gas compared with a continuous injection scheme. In this study, the effectiveness of this approach where a miscible alternating injection of thickened associated gas (TAG) or thickened CO2 (TCO2) with unthickened AG is explored in both nonfractured and fractured composite carbonate cores. Twelve core-flooding experiments were conducted using different injection schemes (i.e., continuous unthickened, continuous thickened, and alternating thickened–unthickened). These tests demonstrate that overall the experimental results indicate that the alternating injection of TAG or TCO2 with unthickened AG mixture as an enhanced recovery technique may produce results similar to those with continuous thickened gas injection. This reduces the consumption of thickening agents noticeably resulting in reduced operational costs and improved economic viability for this method.

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Lessons Learnt from Nine Years of Immiscible Gas Injection Performance and Sector Modeling Study of Two Pilots in a Heterogeneous Carbonate Reservoir

Konwar¹,

Tariq²,

Khan³

et al. 2011

All Days

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The subject reservoir is a heterogeneous carbonate formation in a giant field located offshore Abu Dhabi. Five gas injection pilots were initiated in late 2001 in the Eastern, Central and Western parts of the field both as secondary and tertiary recovery methods to evaluate the benefit of gas injection for pressure support and for recovery improvement. With less than 10% of HCPV gas injection, the pilots to date have provided valuable insight on production performance and pressure support, gravity override, swelling effect and flow assurance issues (such as asphaltene deposition) in the field. Using a 3D compositional model, a sector modeling study was carried out for comprehensive evaluation of the pilot performance to date and to predict definitive results within reasonable time frame (3-5 years) which will have ramifications on long-term full field development decisions. Additionally, the objectives of simulation efforts were to evaluate different recovery processes (gas/water/WAG) and assess key reservoir uncertainty (volumetric sweep) due to reservoir heterogeneity (high permeability streaks). Initially, the sector model was history matched with nine years of pilot performance while both reservoir heterogeneity and well spacing sensitivities were tested in the model. The history matched sector model was utilized to predict performance under different operating conditions using both gas, water and water alternating gas (WAG) injection methods. This paper describes the pilot performance, field observations and results of a sector model study including history match, sensitivity and predictions under different injection scenarios on two of the pilots. Based on the performance and surveillance data gathered on the two pilots and sector modeling study, it was established that both pilots have met their objectives and can be concluded. Through the integration of field observations and sector modeling work, the study provided valuable insight on optimum recovery processes, well spacing and well completion requirements for long-term field development.

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The Design of the First Miscible Sour Gasflood Project in Oman

Cited by 5 publications

References 0 publications

An evaluation on mechanisms of miscibility development in acid gas injection for volatile oil reservoirs

An evaluation on mechanisms of miscibility development in acid gas injection for volatile oil reservoirs

New Approach to Alternating Thickened–Unthickened Gas Flooding for Enhanced Oil Recovery

Lessons Learnt from Nine Years of Immiscible Gas Injection Performance and Sector Modeling Study of Two Pilots in a Heterogeneous Carbonate Reservoir

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