DEAD-END PORE VOLUME AS DISTRIBUTED SOURCES AND SINKS

1961 ◽  
Vol 65 (8) ◽  
pp. 1440-1441 ◽  
Author(s):  
Walter Rose ◽  
H. C. Tung ◽  
Claude Newman
Keyword(s):  
Pore Volume ◽  
Sources And Sinks ◽  
Dead End

Predicting Dead-End Pore-Volume in a Reservoir from Single Tracer Experiment

2017 ◽  
Author(s):  
Jyoti Phirani ◽  
Shantanu Roy ◽  
Harish J. Pant
Keyword(s):  
Pore Volume ◽  
Tracer Experiment ◽  
Dead End

Dead-End Pore Volume and Diffusion Measurements

1967 ◽  
Vol 31 (5) ◽  
pp. 711-712
Author(s):  
R. D. Jackson ◽  
A. Klute
Keyword(s):  
Pore Volume ◽  
Dead End ◽  
And Diffusion

Dead-End Pore Volume and Dispersion in Porous Media

1964 ◽  
Vol 4 (01) ◽  
pp. 73-84 ◽  
Author(s):  
K.H. Coats ◽  
B.D. Smith
Keyword(s):  
Porous Media ◽  
Diffusion Model ◽  
Concentration Profile ◽  
Pore Volume ◽  
Concentration Profiles ◽  
Simple Diffusion ◽  
Effluent Concentration ◽  
Dead End ◽  
Capacitance Model ◽  
Simple Diffusion Model

Abstract Experiments in which calcium chloride displaced sodium chloride from four cores showed the extent of asymmetry in the resulting effluent concentration profiles. These results provided a check on how validly the mixing process is modeled by a differential (i.e., not finite-stage) capacitance mathematical model. The effluent concentration profile from two consolidated cores exhibited considerable asymmetry, while two unconsolidated cores yielded nearly symmetrical profiles. All runs resulted in breakthrough of the 30 per cent concentration significantly before one pore volume was injected. In addition, velocity appreciably affected the effluent concentration profile from a Torpedo sandstone core. The differential capacitance model matched the data significantly better than a simple diffusion model. The capacitance model allows determination of the amount of dead-end pore space in a porous matrix and the effect of velocity on the rate of diffusion into this space. An experimental program yielding insight into the physical validity of the capacitance effect is described. Introduction Axial dispersion - the mixing accompanying the flow of miscible fluids through porous media- has been the subject of many relatively recent studies and a comprehensive review of the topic has been given by Perkins and Johnston. This dispersion is of practical interest in studies of the miscible displacement process, fixed-bed chemical reactors, and the adsorption of solutes from a flowing stream onto the surface of a porous medium. In the latter case, the effect of dispersion must be considered when adsorption parameters are determined from the nature of concentration profiles.In general, early studies of dispersion assumed applicability of a simple diffusion equation and were concerned with correlation of the experimentally determined "effective" diffusion coefficient with system properties over a large range of the latter. Recent investigators have been concerned with the deviations between the asymmetrical effluent concentration profiles observed and the symmetrical ones predicted by the diffusion model.In the present study, effluent concentration profiles were obtained from consolidated and unconsolidated cores. These profiles were compared with those predicted by a differential (i.e., not finite-stage) capacitance model. Solutions to the simple diffusion model, for three sets of boundary conditions, were compared with one another and with the experimental profiles. SUMMARY OF PREVIOUS WORK The reader is referred to Perkins and Johnston for an extensive review of studies of dispersion in porous media. Many investigators have employed the simple diffusion model characterized by Eq. 1 below: (1) The dispersion coefficient D for unconsolidated systems is correlated by ....................(2) for 2 less than less than 50, where v is interstitial velocity and dp is particle diameter. Since heterogeneity of the sand pack affects the mixing, this equation is also expressed as (3) where a is proportional to the degree of heterogeneity and is about 3.5 for random packs of unconsolidated sand. Eq. 3 holds for. For a homogeneous (regular) type of packing, a should be 1 or less. Aris and Amundson and Carberry and Bretton consider a to be the number of particle lengths per mixing cell in the finite-stage model. Data from consolidated cores indicate a dp to be about 0.36 cm for outcrop rocks, Torpedo sandstone having a reported value of 0.17 cm. SPEJ P. 73^

Effects of Dispersion and Dead-End Pore Volume in Miscible Flooding

1977 ◽  
Vol 17 (03) ◽  
pp. 219-227 ◽  
Author(s):  
L.E. Baker
Keyword(s):  
Pore Volume ◽  
Field Application ◽  
Column Height ◽  
Published Data ◽  
Model Parameters ◽  
Mixing Zone ◽  
Dead End ◽  
Capacitance Model ◽  
Capacitance Effects ◽  
Dispersive Mixing

Abstract The design of the solvent slug size for a miscible flood process can be improved with data on holdup (or capacitance process can be improved with data on holdup (or capacitance effects) and dispersion of the solvent slug in the reservoir. A modified version of the Coats-Smith dispersion-capacitance model and an improved solution method for the model were used to study dispersion and capacitance effects in cores. The velocity dependence of the model parameters is shown. A correlation is developed for estimating effective dispersion coefficients for field application. The method described provides a means for characterizing the properties of dispersive mixing and microheterogeneity of reservoir properties of dispersive mixing and microheterogeneity of reservoir cores and aids in the design of the volume of solvent for miscible floods. Introduction The amount of solvent that must be injected is a critical factor in the success of a miscible flood. Because of the cost of miscible solvents such as carbon dioxide or rich gas, slug processes generally are used. If the solvent slug used is larger processes generally are used. If the solvent slug used is larger than necessary, the solvent cost will be increased without compensatory increases in oil recovery. If too small a slug is used, some of the oil that could have been moved will be left behind. The slug size required is affected by many variables, including reservoir geometry, interwell spacing, gravity effects, mobility ratios, etc. Slug degradation is caused by mixing (by dispersion) of solvent with oil at the leading edge of the solvent bank and with chase fluid (for example, dry gas) at the trailing edge. Trapping of oil and solvent in microscopic heterogeneities (regions of dead-end pore volume or relatively stagnant flow) also contributes to the mixing-zone growth. This trapping, known as capacitance may be caused by rock heterogeneities or by shielding of oil and solvent by water films. This paper is concerned with predicting solvent slug requirements in an idealized linear system where gravity, mobility ratio, and areal sweep effects are unimportant, but where longitudinal dispersion (mixing at the leading and trailing edges of the bank) and capacitance effects are significant. An example might be a miscible displacement in the pinnacle reef formations of Alberta. A prediction of the effects of dispersion and capacitance was needed for the design of a miscible flood of this type. The oil-column height was about 350 ft, and the flood advance rate was to be downward at 0.0384 ft/D. The oil/solvent viscosity ratio of 10 was unfavorable; however, it was expected that the unfavorable mobility effects would be largely compensated for by the stability effects of gravity at the low flow rate. Published data relating to similar reservoirs indicated that "stagnant volume" that could cause trapping and degradation of the solvent slug might be as much as 10 percent of the reservoir volume. Based on these data, preliminary calculations were made using the Coats-Smith dispersion-capacitance model to predict the mixing-zone profiles. The results indicated that this level of stagnant volume might cause the solvent requirement to be increased by 30 to 90 percent over the amount predicted by a simple dispersion model without capacitance effects if the peak solvent concentration in the enriched gas bank did not drop below 99 percent throughout the life of the flood. Coats and Smith indicated that tests in short cores would show extended mixing zones if capacitance effects were present, but that if the magnitude of the transfer group M(D) = M(L)/u was large (as it would be in a field situation, where L may be very large), the influence of capacitance would be minimized. The prediction of a 30- to 90-percent increase in solvent requirements for the case described above prompted a review of methods for measuring capacitance effects and a search for a more convenient method for predicting the severity of capacitance effects in field application. predicting the severity of capacitance effects in field application. An improved method for modeling data from short core tests was developed, and experimental work was performed to investigate the factors influencing the capacitance-model parameters. SPEJ P. 219

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