A Tertiary COFCAW Pilot Test In the Sloss Field, Nebraska

Parrish, David J.; Pollock, C.B.; Ness, Nathan; Craig, F.F.

doi:10.2118/3839-pa

Cited by 15 publications

(5 citation statements)

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“…A number of successful high-pressure air injection projects in light oil reservoirs have been documented in the literature (8)(9)(10) . Most of these projects have been operating for many years, attesting to their technical and economic success.…”

Section: Introductionmentioning

confidence: 99%

Is High-Pressure Air Injection (HPAI) Simply a Flue-Gas Flood?

Montes

Gutiérrez²,

Moore

et al. 2010

Journal of Canadian Petroleum Technology

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High-pressure air injection (HPAI) is an enhanced oil recovery (EOR) process in which compressed air is injected into a deep, light-oil reservoir, with the expectation that the oxygen in the injected air will react with a fraction of the reservoir oil at an elevated temperature to produce carbon dioxide. Over the years, HPAI has been considered a simple flue-gas flood, giving little credit to the thermal drive as a production mechanism. The truth is that, although early production during a HPAI process is mainly due to re-pressurization and gasflood effects, once a pore volume of air has been injected the combustion front becomes the main driving mechanism. This paper presents laboratory and field evidence of the presence of a thermal front during HPAI operations, and of its beneficial impact on oil production. Production and injection data from the Buffalo Field, which comprises the oldest HPAI projects currently in operation, were gathered and analyzed for this purpose. These HPAI projects definitely do not behave as simple immiscible gasfloods. This study shows that a HPAI project has the potential to yield higher recoveries than a simple immiscible gasflood. Furthermore, it gives recommendations about how to operate the process to take advantage of its full capabilities. Introduction High-Pressure Air Injection (HPAI) is an emerging technology for the enhanced oil recovery (EOR) of light oils that has proven to be a valuable process, especially in deep, thin, low-permeability reservoirs(1-7). A number of successful high-pressure air injection projects in light oil reservoirs have been documented in the literature(8-10). Most of these projects have been operating for many years, attesting to their technical and economic success. The improvement in recovery of light oil by HPAI involves a combination of complex processes, each contributing to the overall recovery. These processes include flue gas sweeping, field re-pressurization, oil swelling, viscosity reduction, stripping of the lighter components of the oil, and thermal effects. Early production during the HPAI process is related to re-pressurization and gasflood effects; hence, the influence of the thermal zone is secondary during the early life of an injector. The oil displaced directly by the thermal front will depend on the effectiveness of the generated flue gas on oil displacement from outside the thermal region.

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Section: Introductionmentioning

confidence: 99%

Is High-Pressure Air Injection (HPAI) Simply a Flue-Gas Flood?

Montes

Gutiérrez²,

Moore

et al. 2010

Journal of Canadian Petroleum Technology

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show abstract

“…The first extended field test of HPAI began in 1963 on the Sloss field in Nebraska (Parrish et al 1974a(Parrish et al , 1974b, where Amoco's Combination of Forward Combustion and Waterflooding (COFCAW) process was applied as a tertiary-recovery process to a deep (6,200 ft), thin (11 ft), light-oil (38.8°API), watered-out reservoir. This COFCAW pilot recovered 83,992 bbl of oil, which is equivalent to 43% of the oil left in the five-spot pattern after waterflood.…”

Section: Introductionmentioning

confidence: 99%

Recovery Factors in High-Pressure Air Injection Projects Revisited

Gutiérrez¹,

Taylor

Kumar

et al. 2008

SPE Reservoir Evaluation &Amp; Engineering

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High-pressure air injection (HPAI) is an increased-oil-recovery (IOR) process in which compressed air is injected into a deep light-oil reservoir with the expectation that the oxygen in the injected air will react with a fraction of the reservoir oil at an elevated temperature to produce carbon dioxide. The resulting flue-gas mixture provides the main mobilizing force to the oil downstream of the reaction region, sweeping it toward production wells. The combustion zone itself may provide a critical part of the sweep mechanism.In 1994, proposed a method for estimating recovery factors of light-oil air-injection projects on the basis of the performance of two successful HPAI projects. Their suggested method relies on the extrapolation of the field gas/oil ratio (GOR) up to an economic limit. In other words, it treats HPAI as an immiscible gasflood and neglects any potential oil that could be recovered by the combustion front. The truth is that, although early production during an HPAI process is mostly caused by repressurization and gasflood effects, once a pore volume of air has been injected, the combustion front becomes the main driving mechanism. Moreover, one of the unique features of air injection is the self-correcting nature of the combustion zone, which promotes good volumetric sweep of the reservoir. This paper presents laboratory and field evidence of the presence of a thermal front during HPAI operations, and its beneficial impact on oil recovery. An analysis of the three HPAI projects in Buffalo field, which are the oldest HPAI projects currently in operation, shows that only a small fraction of the reservoir has been burned and, if time allows and the projects are managed appropriately, burning of more reservoir volumes could result in much higher oil recoveries than predicted by the gasflood approach. (482-572°F) range, while in heavier oils, bond-scission reactions are more likely to occur above 450°C (842°F). During oxygenaddition reactions, oxygen atoms are chemically bound into the molecular structure of the oil, producing various oxygenated compounds such as hydroperoxides, aldehydes, ketones, and acids. The compounds tend to further react and polymerize with each other, forming heavier, less-desirable fractions. To compound the problem, because oxygen is being removed from the gas phase to the

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“…The Sloss in situ combustion project was conducted by Amoco Production Co. as a pilot test from 1963 to 1965 (Parrish et al 1974a) and as a full field operation from 1967 until 1971 (Parrish et al 1974b). The Sloss field is located near Kimball, Nebraska.…”

Section: Sloss Nebraskamentioning

confidence: 99%

“…Air was injected at an average rate of 40,200 m 3 (ST)/d (1.42 MMscf/d) and water at a rate of 300 m 3 /day (1,880 bpd), giving a water/air ratio of 7.46 kg/m 3 (ST) (1,324 bbl/MMscf). Parrish et al (1974a) were careful to point out that the large amount of injected water did not "put the fire out". In terms of production, the five-spot producers, all of which had originally been watered out, captured 11,800 m 3 (74,221 bbl) of oil over the pilot period, giving an average air/oil ratio of 2,930 m 3 (ST)/m 3 (16,903 scf/bbl).…”

Section: Sloss Nebraskamentioning

confidence: 99%

Potential for In Situ Combustion in Depleted Conventional Oil Reservoirs

Moore

Mehta

Ursenbach

et al. 2012

SPE Improved Oil Recovery Symposium

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In oil producing regions like the US Mid-Continent, there are a large number of mature conventional oil fields that have reached or are approaching their production limit by conventional techniques, however, current strong oil prices and security issues justify additional EOR/IOR efforts. Air injection-based techniques (fireflooding or in situ combustion) have been demonstrated to provide commercially successful recovery from medium and light oils reservoirs. While the history of air injection-based EOR is littered with the perception of failed projects, many of the failures were associated with low oil prices. In other cases, failures were due to compressor problems, or incorrect concepts of how air injection processes operate. Ineffective ignitions, failure to inject enough air, and applications in reservoirs that had no hope of success explain the trouble with many past projects. This paper reviews some of the successful air injection projects in higher gravity oil reservoirs and discusses the elements that are critical for success. These include the ability to ignite and continuously burn a fraction of the oil at reservoir conditions, the suitability of the reservoir for a gas-injection based recovery process, the availability and suitability of preexisting infrastructure, and a reasonable prediction of how much air should be injected and how much oil recovery could be expected. The paper also discusses possible options for taking advantage of the product gas stream.The purpose of this paper is to arm the petroleum engineer with the relevant information and the right set of questions to ask when considering the application of air injection in a given field.

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A Tertiary COFCAW Pilot Test In the Sloss Field, Nebraska

Cited by 15 publications

References 0 publications

Is High-Pressure Air Injection (HPAI) Simply a Flue-Gas Flood?

Is High-Pressure Air Injection (HPAI) Simply a Flue-Gas Flood?

Recovery Factors in High-Pressure Air Injection Projects Revisited

Potential for In Situ Combustion in Depleted Conventional Oil Reservoirs

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