A WAG injection pilot in the Lower Brent Formation at the Gullfaks Field

Dalen, V.; Instefjord, Rune; Kristensen, R.

doi:10.1144/gsl.sp.1995.084.01.15

Cited by 8 publications

(7 citation statements)

References 6 publications

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“…If u 1 is the vector for which the maximum is achieved, then the subspace which contain the best fit for the set of points includes u 1 , and u 1 can be selected as one basis vector. The second basis vector in this subspace must be orthogonal to u 1 and maximises u 2 T A c T A c u 2 . The subspace must have dimension q ≤ W c where typically q is equal to two or three.…”

Section: Nomenclaturementioning

confidence: 99%

“…In some North Sea oil reservoirs, produced hydrocarbon gas has been re-injected in water injection wells with the purpose to improve oil recovery and reducing gas export [1][2][3][4][5][6][7][8] . The hydrocarbon gas has been either near miscible [4][5][6] or immiscible WAG [1][2][3]7,8 when contacted with the oil in the reservoir.…”

Section: Introductionmentioning

confidence: 99%

“…The hydrocarbon gas has been either near miscible [4][5][6] or immiscible WAG [1][2][3]7,8 when contacted with the oil in the reservoir. The availability of produced hydrocarbon gas has encouraged use of WAG processes in North Sea oil reservoirs.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of the Immiscible WAG Process Using Cycle-Dependent Three-Phase Relative Permeabilities

Larsen

Skauge

1999

Proceedings of SPE Annual Technical Conference and Exhibition

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractOil recovery by immiscible WAG is dependent on the saturation cycles that occur in a core-flood or in the reservoir. For the reservoir case, segregation of gas and water can generate other saturation cycles than in a core-flood. In order to predict WAG behavior in the reservoir from experimental results, numerical models with an effective hysteresis description of the three-phase oil, water and gas relative permeabilities should be considered.There has earlier been developed a methodology that accounts for both three-phase flow effects and hysteresis effects in numerical simulations of the immiscible WAG process. Simulation studies have shown how three-phase flow description may influence the choice of drive mechanisms and also the design of a WAG process. Furthermore, a principal component analysis (PCA) is conducted on the simulation model that is consistent with the experimental data. The results from the PCA showed how the hysteresis parameters in the simulation model may be correlated to the physical system. The PCA analysis describe how the three-phase effects in water and gas relative permeabilities are connected to oil recovery.The results show that the cycle-dependent relative permeabilities increase the potential for WAG. Furthermore, the oil production trends with respect to slug length and wateroil ratio is different for models with cycle-dependent hysteresis and without hysteresis.

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Section: Nomenclaturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Simulation of the Immiscible WAG Process Using Cycle-Dependent Three-Phase Relative Permeabilities

Larsen

Skauge

1999

Proceedings of SPE Annual Technical Conference and Exhibition

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“…al. 5 reported effective displacement and increasing oil recovery with WAG in the attic zone, a zone at the top of reservoir where oil is accumulated, while Sanchez 6 provided a selection of technical considerations for managing and monitoring WAG projects.…”

Section: Introductionmentioning

confidence: 99%

Injectivity and Gravity Segregation in WAG and SWAG Enhanced Oil Recovery

et al. 2009

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Injectivity and Gravity Segregation in WAG and SWAG Enhanced Oil RecoveryA. Faisal AbstractGas-injection enhanced oil recovery can recover nearly all residual oil where the gas sweeps. Sweep efficiency in these processes is often poor, in large part because of gravity override of gas. Stone and Jenkins presented a model for gravity override in homogeneous reservoirs, showing that the distance gas and water travel before segregation depends directly on injection rate. In cases where injection pressure is limiting, injectivity is key to overcoming gravity override.Stone assumed continuous injection of gas and water as a model for WAG (Water Alternating Gas), contending that this is valid as long as slugs mix near the well. This model for co-injection can be extended to relate segregation distance for co-injection processes directly to injection pressure. Injectivity depends on saturations very near the well, however. Therefore, where injection pressure is limiting, this model is pessimistic because injectivity in WAG is greater than in co-injection.We investigate the increase in injectivity possible with WAG compared to co-injection in 1D and 2D, and the implications for gravity override in 2D, using a range of models for gas and water relative permeabilities. We confirm that the greater injectivity of WAG improves vertical sweep compared to Stone's model when injection pressure is limiting. The greatest improvements occur when slugs violate Stone's assumption: that is, when they are too large to mix fully near the well. The increase in injectivity over co-injection is greater for foam than for WAG without foam, because foam has much lower mobility when gas and water flow together.

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“…[1][2][3][4] WAG has, in most cases, been implemented at a later stage of production as an improved recovery process after a long period of water injection. [1][2][3][4] WAG has, in most cases, been implemented at a later stage of production as an improved recovery process after a long period of water injection.…”

Section: Introductionmentioning

confidence: 99%

Gas Segregation During WAG Injection and the Importance of Parameter Scaling in Three-Phase Models

Hustad¹,

Trygve²,

Lerdahl³

et al. 2002

Proceedings of SPE/DOE Improved Oil Recovery Symposium

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractSaturation histories from simulations on a mesoscopicscale heterogeneous model at immiscible and miscible conditions are compared with emphasis on gas segregation. Selected models for three-phase flow, and scaling of the end point saturations, relative permeabilities, and capillary pressures have been applied. The flow parameters of the facies were obtained from pore scale network modeling with input from North Sea sandstones. The simulation cases included water, gas, and water-alternating-gas (WAG) injection.Gas injection at irreducible water saturation demonstrates stronger gas segregation as the pressure exceeds the minimum miscibility pressure (MMP). Gas segregation is not so evident at the mesoscopic scale during WAG injection. High water saturation in the set-planes hampers the vertical gas flow. A bank of high oil saturation forms in front of the advancing gas at miscible conditions. Oil segregates to the set-plane below and the water cycle that follows mobilizes the accumulated oil.

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A WAG injection pilot in the Lower Brent Formation at the Gullfaks Field

Cited by 8 publications

References 6 publications

Simulation of the Immiscible WAG Process Using Cycle-Dependent Three-Phase Relative Permeabilities

Simulation of the Immiscible WAG Process Using Cycle-Dependent Three-Phase Relative Permeabilities

Injectivity and Gravity Segregation in WAG and SWAG Enhanced Oil Recovery

Gas Segregation During WAG Injection and the Importance of Parameter Scaling in Three-Phase Models

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