A Calculation of the Effect of Production Rate Upon Ultimate Recovery by Solution Gas Drive
- Charles C. Miller (The Atlantic Refining Co.) | E.R. Brownscombe (The Atlantic Refining Co.) | W.F. Kieschnick Jr. (The Atlantic Refining Co.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- September 1949
- Document Type
- Journal Paper
- 235 - 247
- 1949. Original copyright American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Copyright has expired.
- 4.1.4 Gas Processing, 4.6 Natural Gas, 4.5 Offshore Facilities and Subsea Systems, 4.1.2 Separation and Treating, 5.1.1 Exploration, Development, Structural Geology, 1.2.3 Rock properties, 5.2.1 Phase Behavior and PVT Measurements, 4.1.5 Processing Equipment, 5.4.2 Gas Injection Methods, 5.2 Reservoir Fluid Dynamics, 4.1.9 Tanks and storage systems, 4.3.4 Scale
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The possibility has been mentioned that large pressure gradients in asolution gas driven field caused by high production rates might lead to areduction in the ultimate recovery obtainable compared to that which would beobtained by a very slow rate of production. In the present study the reservoirconditions accompanying a high rate of production and the correspondingultimate recovery were compared with those obtained if the reservoir wereproduced at some marginal rate throughout its entire life. The method ofcalculation involved the application of fluid flow - material balance analysisto a series of successive steady state conditions in the reservoir. In the casestudied very little difference in recovery was obtained at the abandonmentpressure. An analysis of the basic factors involved indicates that the sameresults would hold for considerable variation in properties of reservoirfluids, permeability of the formation or well spacing. Even if the reservoirhas a water drive it appears that no harm will be done by open flow productionif the rate is cut back before any appreciable free gas is produced. However,any condition which leads to disproportionate withdrawal rates and which causeslarge pressure differences over large areas might result in substantial loss inultimate recovery.
When the pressure declines in a reservoir, gas is evolved from solutioncausing a shrinkage in the reservoir oil so that a stock tank barrel of oilwith its residual dissolved gas occupies a smaller volume than originally. Fora given reservoir oil saturation, therefore, stock tank oil content will behigher at the lower pressure. At the same time the evolved gas which remains inthe reservoir reduces the reservoir oil saturation, and this would be expectedperhaps to cause a reduction in stock tank oil content. However, around thewell the shrinkage occurs so rapidly that stock tank oil may actuallyaccumulate in this region in spite of the simultaneous reduction in reservoiroil saturation. If this accumulation should continue, spreading into a largerzone, the loss might be appreciable and because larger pressure gradientsaccompany higher rates the accumulation might possibly be large if wells areproduced at too high a rate. It is the purpose of this paper to determine theeffect of rate of flow on ultimate recovery by solution gas drive.
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