A Calculation of the Effect of Production Rate Upon Ultimate Recovery by Solution Gas Drive

Miller, Charles C.; Brownscombe, E.R.; Kieschnick, W.F.

doi:10.2118/949235-g

Cited by 6 publications

(5 citation statements)

References 4 publications

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“…Both concluded that producing rate had a negligible effect on ultimate recovery. Ridings et CL* 7 showed that performance of long horizontal laboratory systems coincided closely with performance calculated by numerical modeling techniques, with one exception. Noticeably increasing recovery was observed with increasing production rate in the laborato~system, whereas the numerical model showed no rate effect.…”

Section: Introductionmentioning

confidence: 72%

A Numerical Model Study of Gravitational Effects and Production Rate on Solution Gas Drive Performance of Oil Reservoirs

Morse¹,

Whiting²

1970

Journal of Petroleum Technology

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Ultimate oil recovery by solution gas drive can be greatly affected by variations in production rates --- in general the higher the rate the higher the recovery. However, the quantitative relationship for a given field will be influenced by factors other than rate and vertical permeability: reservoir thickness, gas solubility, shrinkage factor, oil permeability: reservoir thickness, gas solubility, shrinkage factor, oil viscosity, relative permeability, and capillary pressure. Introduction The relationship between ultimate oil recovery and rate of oil production has been the subject of many investigations since 1924 when Cutler published a study of field data. Cutler concluded that higher oil production rates yielded higher ultimate oil production rates yielded higher ultimate oil recoveries. Subsequent studies of performance from a variety of fields showed that factors other than producing rate caused so much variation in total oil producing rate caused so much variation in total oil recovered that no conclusion could be reached concerning the effects attributable to this single factor. Because of the impossibility of imposing different production histories on a given reservoir to observe production histories on a given reservoir to observe the difference in ultimate oil produced, confirmation of any such relationship had to depend on analytical studies and laboratory model tests. Analytical approaches using simplified models, in which effects of capillary pressure and gravity forces were ignored, led to the conclusion that any effect of production rate upon ultimate recovery was negligible. They did show gross differences in horizontal saturation distributions imposed by production rate variations. In 1953 and 1954 the foundation was laid for solution of the unsteady-state fluid flow equations by use of difference approximations and high-speed computers. The development of these techniques led to numerous mathematical model investigations of fluid displacement in one and two dimensions. These works treated a range of fluid systems in one and two dimensions; generally they were confined to incompressible fluids, and included gravity and capillary, effects. When simulating compressible fluid systems, gravity and capillary forces were ignored. Levine et al. and Heuer et al. studied the effects of production rate on ultimate oil recovery by solution gas drive, using these more sophisticated mathematical techniques. Both efforts neglected the effect of gravity, but Levine included capillary forces. Both concluded that producing rate had a negligible effect on ultimate recovery. Ridings et al. showed that performance of long horizontal laboratory systems performance of long horizontal laboratory systems coincided closely with performance calculated by numerical modeling techniques, with one exception. Noticeably increasing recovery was observed with increasing production rate in the laboratory system, whereas the numerical model showed no rate effect. Gravity was not a factor in either system. Since the production rate sensitivity was less on very long production rate sensitivity was less on very long laboratory systems than for the shorter ones, it was concluded that the rate effect observed on the short laboratory system was, for reasons not specified, typical only of short systems. It bas been recognized for some time that, under certain conditions, gravitational forces can be very important in the displacement of oil from natural reservoirs. Muskat treats exhaustively the performance of wells and reservoirs in which gravity is performance of wells and reservoirs in which gravity is the sole driving mechanism. JPT P. 625

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Section: Introductionmentioning

confidence: 72%

A Numerical Model Study of Gravitational Effects and Production Rate on Solution Gas Drive Performance of Oil Reservoirs

Morse¹,

Whiting²

1970

Journal of Petroleum Technology

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“…From relative permeability relations, for a given sw, (10) K./Ko=</> (S1) And This relation must be evaluated (integrated) graphically from r. to r w, and intermediate points to obtain p as a function of r. Since, at abandonment condition, Qo is determined by economic factors and pw by physical factors, value of these, variables must be fixed in evaluating pressure and saturation distribution at abandonment conditions. The total gas-oil ratio, however, is chosen as a function of p •.…”

Section: Discussionmentioning

confidence: 99%

Critical Analysis of the Effect of Well Density on Recovery Efficiency

Keller

Callaway²

1950

Journal of Petroleum Technology

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The various theories as to the well spacing-recovery relationship are reviewedin considerable detail and these theories analyzed in terms of theirconsistency with modern reservoir engineering concepts. It is concluded thatthe well spacing problem must be analyzed in terms of recovery efficiency andthat a positive answer to the relation between well density and recoveryefficiency is not available from direct comparisons of the production historiesof wells and fields. The results of an engineering analysis designed to permit approximatecalculation of recovery efficiencies as a function of well spacing in adepletion type reservoir from basic reservoir data is presented. Results ofthis type analysis indicate that the effect of well spacing on recoveryefficiency in depletion type reservoirs can be expected to be very small.Limitations of this approach are pointed out, particularly with respect to itsapplication in lenticular reservoirs. Testing techniques are outlined which should indicate whether or not areservoir is continuous between wells and whether or not satisfactory drainageis being obtained with present spacings. A mass of data of this type indicatescontinuity to exist in most fields. Introduction The purpose of this paper is to review critically the engineering aspects ofthe well spacing problem, both from the standpoint of certain concepts and fromthe standpoint of reservoir mechanics. The well spacing problem is primarily aneconomic problem in which the optimum well density for a particular field isthat density which will yield the greatest oil recovery consistent withjustifiable development costs. The well spacing answer in terms of economicconditions, however, is extremely sensitive to the variation in recoveryefficiency with well density. The variation in recovery efficiency with welldensity is properly an engineering problem. Different opinions as to thecorrect answer to this engineering problem is the basis for most of the widedifference in opinion among various members of the industry as to optimum wellspacing. This paper will be confined to the engineering problem of the relationbetween well density and ultimate oil recovery; economic considerationsnecessary for the evaluation of optimum well density for any particular fieldwill not be discussed. T.P. 2938

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“…Miller et a/. 31 employed fluid flow and material balance analysis to a series of successive steady state conditions in the reservoir. They divided the reservoir into a number of annular rings surrounding a well.…”

Section: Introductionmentioning

confidence: 99%

Material Balance Calculations for Solution-Gas-Drive Reservoirs With Gravity Segregation

Ambastha

Aziz

1987

SPE Annual Technical Conference and Exhibition

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In this work, a reservoir simulator is used to study the phenomena of gas percolation and gravity segregation, and their effects on reservoir performances. The sensitivity study of reservoir performance to block and time-step sizes shows that for typical solution-gas-drive reservoirs, large errors in average reservoir pressure may result from improper control of time-step in the simulator.The comparison of simulation results with the Tarner' s 1 method shows that the latter predicts faster reservoir pressure and oil saturation decline, and thus, undetpredicts the reservoir producing life and recovery.We propose a new material balance method for predicting the performance of thick, homogeneous, depletion-drive reservoirs. This method accounts for the vertical pressure and saturation gradients, and the secondary gas cap. The thickness of the secondary gas cap can be estimated with good accuracy using an idealized saturation profile. An iterative procedure relates average reservoir pressure to well pressure. The pressure and saturation at the well are then used to calculate the producing gas-oil ratio. The idealized saturation profile is also used to develop pseudo-functions to simplify the simulation of solution-gas-drive reservoir with gravity segregation.

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A Calculation of the Effect of Production Rate Upon Ultimate Recovery by Solution Gas Drive

Cited by 6 publications

References 4 publications

A Numerical Model Study of Gravitational Effects and Production Rate on Solution Gas Drive Performance of Oil Reservoirs

A Numerical Model Study of Gravitational Effects and Production Rate on Solution Gas Drive Performance of Oil Reservoirs

Critical Analysis of the Effect of Well Density on Recovery Efficiency

Material Balance Calculations for Solution-Gas-Drive Reservoirs With Gravity Segregation

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