Attainment of Connate Water in Long Cores by Dynamic Displacement
- Robert L. Slobod (The Atlantic Refining Co.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- March 1950
- Document Type
- Journal Paper
- 17 - 21
- 1950. Original copyright American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Copyright has expired.
- 5.2.1 Phase Behavior and PVT Measurements, 5.4.1 Waterflooding, 4.3.4 Scale, 5.2 Reservoir Fluid Dynamics, 1.6.9 Coring, Fishing
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In much of the work reported in the literature on long cores, true connatewater values probably have not been obtained because of insufficient flow ofoil to attain equilibrium. A satisfactory method for establishing connate waterin long cores has been developed in which oil flow is maintained until noadditional water is displaced.
Long cores have been used by several investigators in an effort to evaluate theefficiency of oil recovery for various producing schemes. The effects of manyvariables such as rate of displacement, pressure drop, volume of displacingmedium, gas-oil ratio, interfacial tension, and others have been investigated,and the merits of gas drive have been compared with water drive. In the olderexperiments no connate water was used, but in the more recent studies thephilosophy of the experiment calls for a core containing oil and connate water(irreducible water) as the starting point of the experiment. The methodgenerally used to establish this condition in long cores involves dynamicdisplacement wherein one or more phases are forced through the core, flow beingmaintained at a constant rate or at a constant pressure until a steady state isreached wherein there is no change of saturation with time. It is one purposeof this paper to point out that in much of the work reported in the literaturetrue connate water values probably have not been obtained. The reason for thisfailure is pointed out, and a method for obtaining more reliable connate watervalues on long cores is presented. It is impossible at this time to completelyevaluate the effect on the conclusions in the earlier papers resulting from thefailure to obtain true connate water in the long cores, but some data arepresented which indicate that serious errors may be present in many cases.
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