bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of Capillarity in Oil Production
Authors: Hassker G.L. , Brunner E. , Deahl T.J. 
Published: June 2014

Abstract
The capillary effects in reservoir rock are discussed in terms of the pressuresthey cause in sandstones and dolomites. Data for the two phase case (oil-gas orwater-gas) and for the three-phase case (oil, water and gas in rock) are usedto demonstrate that in one sense the wetting preference of a rock depends onits saturation. The nature of capillary hysteresis is described for partiallystable conditions, and the concept is enlarged. Reproducibly measurablepressures include the "capillary pressure," which is the pressuredifference between any two phases that are each interconnected; the "threshold pressure," necessary to force a nonwetting phase throughpartially saturated rock; the "displacement pressure," which is thatspecial case of the threshold pressure in which both phases fully saturateseparate portions of the rock. Displacement pressure is equal to the minimumvalue of the "capillary pressure."
The theory of flow including capillary forces is developed at the producingsurface of a well to reveal the presence there of a pressure discontinuity inthe gas (or other nonwetting) phase that can be controlled to the end that moreoil may, be produced from an oil field. Experiments with packed sand-flow tubeshaving artificial producing surfaces support the theory.

Introduction
The basic surface quantities acting in an oil field are two: namely, surfacetensions and contact angles. These are the quantities, variously expressed, andparticularized as spreading forces, adhesion tensions" heats of wetting, etc., which are measured in the laboratory by techniques mostly confined toflat or circularly cylindrical surfaces. Such measurements have not had theextensive engineering application they seem to deserve because in mostpractical cases they are unavoidably compounded with the complex andunapproached subject of the internal shape of the interstices of rock.
In this paper it is intended that the pressure differences developed in rock bycapillarity be examined, defined, and given some engineering use in terms ofsome new measurements that have been made. Such pressure differences-namely, the capillary pressure, the displacement pressure and the thresholdpressure--seem to provide a proper contact between the basic molecularquantities and the oil field.
While certain modifications of usage will be undertaken, the present effortrests upon the background of work by the U. S. Geological Survey, by Versluys, and especially by W. O. Smith, which has been reviewed recently in papers by Leverett.
The most important concept of pressure difference is the capillary pressure, afunction of saturation that expresses the pressure difference between theinterconnected phases in a rock. It is often measured when water and air arethe fluids present, but it can be measured with other fluids. A number ofcurves of capillary pressure have recently been measured by a method which itis intended shall be published in a later paper.
T.P. 1623
Role of Connate Water in Secondary Recovery of Oil
Authors: Dickey Parke A. , Bossler Robert B. 
Published: June 2014

Abstract
The presence of connate water in oil sands is of far greater practicalsignificance in secondary oil-recovery operations than it is in primaryoperations. The percentage saturations of oil, water, and gas in a depletedfield determine whether it will be economically possible to recover oil bysecondary methods, and whether water-flooding or gas-driving, or either, willbe successful.
It is suggested that economic recovery of oil by secondary water-flooding canoccur only when a rich bank of oil is formed by the encroaching water. If thesand has a greater effective permeability to water than it has to oil beforeflooding, a bank will not be formed, and water-flooding will not be successful, although gas-driving may be. Published results of laboratory work indicate thatthe effective permeability of a sand to oil and water depends primarily on thesaturation of the sand by these phases. They also indicate that a smalldifference in relative saturation produces a large difference in effectivepermeability to the phase in question. There thus exists a critical range ofsaturations, wherein a small change in oil and water content of the sands willmake water flooding possible or impossible.
In gas-drive operations the water saturation is less critical but no lessimportant. The presence of connate water in a sand increases the proportion ofthe residual oil that may be recovered by gas drive. Sands containing oilsaturations too low and water saturations too high to make water-floodingpossible can often be subjected to gas drive with economic recovery ofoil.
The results of laboratory work on test samples that do not contain water cannotbe applied to normal field operations. More tests on cores containing water aswell as oil are desirable, and the improvement of coring technique isnecessary. However, sufficient data are already available to enable an operatorto use core data intelligently in estimating the chances of a secondaryoil-recovery program.

Introduction
In recent years laboratory work has led to a much better understanding of theprinciples of oil-reservoir performance. The general principles of theexpulsion of oil from sandstone by gas or water were developed by geologists ofthe Second
Geological "Survey of Pennsylvania in the 1870 SI but only recently has themechanism of gas or water drive been intensively investigated. Most publishedarticles have applied the facts established in the laboratory to the primaryproduction of oil from flush fields. This paper is not based on any newobservations, but is an attempt to apply some of the conclusions obtained inthe laboratory and described in the literature to the recovery of oil fromdepleted pools by secondary methods.
One of the most important factors that determine whether or not a secondaryrecovery operation is economically successful is the ratio of injected fluid tooil recovered. This ratio may be expressed as the over-all or cumulativegas-oil ratio if gas is the driving medium, or water-oil ratio if water is thedriving medium.
T.P. 1608
A Statistical Approach to the Interstitial Heterogeneity of Sand Reservoirs
Authors: Law Jan 
Published: June 2014

Problems of oil recovery are attacked from the approaches dictated by thetwo strikingly dissimilar complexes that comprise an oil reservoir-the fluidcomplex and the interstitial complex. Knowledge of the fluid complex, due tolabors in the fields of fluid mechanics and physical chemistry, has faroutdistanced knowledge of the interstitial characteristics of the sand complex.This paper is concerned with the latter and applies the technique of statisticsto petrographic facts-namely, porosity and permeability-dealing with what mightbe called petrometry.
Statisticians have long worked within the problem of reconstruction of auniverse of variables by means of samples that comprise a small percentage ofthe universe from which the samples were drawn. Core analysis data comply withthe requisite of random sampling as stipulated by theoretical statistics. Abasic concept of statistics employs the following substitution:The results of sampling are arranged as a frequency distribution.The observed frequency distribution is compared with a mathematicallyprecise distribution.If a sufficiently good agreement is found between the two, the precisedistribution is substituted in all subsequent operations involvingcharacteristics of the sampled material.
This mathematically precise distribution is also known as the normal curve, curve of error, the probability, the Gaussian, and the bell-shaped curve and isdescribable with but two figures. Further, these two figures, the arithmeticaverage and the standard deviation, are subject to mathematicalmanipulation.
This paper demonstrates that, in some cases in the Dominguez field of SouthernCalifornia, if sufficient core-analysis samples are taken over not too great athickness of sediments, the resultant permeability and porosity assemblagesgive satisfactory agreement with normal curves.
It is shown that the indications are strong that oil wells wherein asatisfactory agreement is found are predictable as to productivity. Since thepredictions are made by employing the laws of chance that are operative withinsedimentation, it follows that the mechanism by which the predictions were madeis a basic concept of reservoir mechanics. Therefore, tentative examples aregiven of the application of normal curves to the solution of problems ofprimary and secondary recovery.

Nature of Permeability Frequency Distributions
Core-analysis data are made available as a tabulated depth vs. permeabilityprofile. The nature of the distribution of permeability values within a givenstratigraphic interval may be approximated from an array constructed withsamples plotted in the order of their appearance with depth (accession number)against their permeability value in millidarcys.
T.P. 1732
Flow into Slotted Liners and an Application of the Theory to Core Analysis
Authors: Dodson C.R. , Cardwell W.T. 
Published: June 2014

This paper presents the results of a theoretical and experimental study ofthe effect of preperforated liners on well productivity. The analysis concernsthe rectangular type of slot, either machine or torch cut, which is common inCalifornia.
Muskat treated this problem recently in a mathematical analysis of the flow ofoil or gas from natural reservoirs into both gunperforated and slotted liners.This paper presents additional and simplified analytical considerations andconclusions for the slotted liner, the solutions being applicable in thelaboratory as well as in the field.
An application of the analytical methods to permeability measurements onmounted core samples is given, to show the effects of sealing wax or otherobstructions on the end faces of the cores.

Results
Fig. 1 compares the results of some theoretical calculations with the resultsof electrical analogy experiments performed in the Standard Oil Company ofCalifornia's Production Technology Laboratory at La Habra, California.
Fig. 1 indicates that the flux into short, "three-dimensional slots" of the relative dimensions encountered in practice is approximately equal tothat into full-length, "two-dimensional slots" having the same openfraction of pipe. (The same numbers of slot rows, and the same radius ratio arealso implied.) It can be seen from physical considerations that the closenessof this approximation must improve as the ratio of the external radius to theinternal radius increases.
T.P. 1724
Calculation of Static Pressure Gradients in Gas Wells
Authors: Rzasa M.J. , Katz D.L. 
Published: June 2014

Abstract
The derivations of three methods of computing the static pressure gradientsin natural gas wells have been presented to show the assumptions made. Chartswere developed from which the pressure gradients may be read when the well-headpressure, the well fluid gravity, depth, and the average well temperature aregiven. A chart for estimating the well fluid gravity from the condensatecontent and separator gas gravity is included. The effect of the increasedaverage well temperature after flow on the calculation of the static pressuregradient is discussed.

Introduction
Reservoir pressures have been calculated from well-head pressures for gaswells for many years. As the pressure measurements become more accurate, theneed for a reliable calculation of the static pressure gradient often arises.This paper will develop the several methods for computing the pressure gradientin gas wells and make a comparison between them.
The method of calculating static pressure gradients in common use is Eq. I(ref. I) or its counterpart which includes a factor for the deviation of thegas from the ideal gas law.
An alternate method is to compute the average density of the gas in the welland multiply by the well depth in a manner similar to that used for liquidgradients.

Derivation of Formulas
A static pressure gradient is a special case of the general fluid-flowequation. Consider a pound of fluid flowing in a vertical column from point Ito point 2, Fig. I.
T.P. 1814
Analysis of Decline Curves
Authors: Arps J.J. 
Published: June 2014

Abstract
Since production curtailment for other than engineering reasons is graduallydisappearing, and more and more wells are now producing at capacity and showingdeclining production rates, it was considered timely to present a brief reviewof the development of decline-curve analysis during the past three or fourdecades.
Several of the commoner types of decline curves were discussed in detail andthe mathematical relationships between production rate, time, cumulativeproduction and decline percentage for each case were studied.
The well-known loss-ratio method was found to be an extremely valuable toolfor statistical analysis and extrapolation of various types of curves. Atentative classification of decline curves, based on their loss ratios, wassuggested. Some new graphical methods were introduced to facilitate estimationof the future life and the future production of producing properties wherecurves are plotted on semilogarithmic paper.
To facilitate graphical extrapolation of hyperbolic-type decline curves, aseries of decline charts was proposed, which will make straight-lineextrapolation of both rate-time and rate-cumulative curves possible.

Introduction
During the period of severe production curtailment, which is now behind us, production-decline curves lost most of their usefulness and popularity inprorated areas because the production rates of all wells, except those in thestripper class, were constant or almost constant.
While production-decline curves were thus losing in importance forestimating reserves, an increasing reservoir consciousness and a betterunderstanding of reservoir performance developed among petroleum engineers.This fact, together with intelligent interpretation and use of electric logs, core-analysis data, bottom-hole pressure behavior and physical characteristicsof reservoir fluids, eliminated a considerable part of the guesswork inprevious volumetric methods and put reserve estimates, based on this method, ona sound scientific basis. At the same time, a number of ingenious substituteswere developed for the regular production-decline curve, which made it possibleto obtain an independent check on volumetric estimates in appraisal work, eventhough the production rates were constant.
With the now steadily increasing demand for oil to supply the hugerequirements of this global war, proration for reasons other than prevention ofunderground waste is gradually disappearing. More and more wells are, or willbe, producing at capacity or at their optimum rates, as determined by soundengineering practice.
T.P. 1758
Performance of Distillate Reservoirs in Gas Cycling
Authors: Hurst W. , Van Everdingen A.F. 
Published: June 2014

Abstract
A distillate-bearing sand complex is often made up of sand stringers ofdifferent permeabilities. In order to take into account the influence of thedifferent permeabilities, ?parallel flow? is defined and this concept is usedto compute the recovery efficiency of recovery efficiency of recycling such asand complex. In the first approximation the position of the wells with respectto one another is not considered.
In order to compute the effect on the recovery efficiency of the recoveryefficiency of the position of the wells, the area of a field is considered tobe made up of rectangles; each rectangle containing one input well in thecenter and two producers located symmetrically with respect to the input well.Formulas are given from which to obtain the pressure and streamlines in asteady-state flow. A method is devised to compute rapidly the successivepositions of the dry gas front. If the field is irregular in shape, pressureand streamlines can be obtained by a potentio-metric electrical model study fora homogenous formation, the effects of different permeabilities and of thelocation of the wells can be established. From these studies it is apparentthat the efficiency of recycling can be profoundly influenced by differences inpermeability among the various strata.

Introduction
With the discovery of an increasing number of gas-distillate fields in the GulfCoast, engineers have had occasion to give more thought to the performance ofthese reservoirs, as evidenced by the literature published in recent years. Inthe majority of studies published so far the formations are considered toconsist of uniform, homogeneous sand. In this paper the authors wish to bringout the effect of variations in the permeability of the formations on theover-all recovery efficiency of wet gas in cycling operations. The importanceof the permeability profile is clearly indicated by the fact that in gascycling, highly permeable stringers in an otherwise tight sand can allowcomplete displacement of wet by dry gas in these stingers long before the wetgas in the tight portions of the sand is displaced. This by-passing will bereflected by a reduction in the condensate content of the production soonerthan can be anticipated from a mathematical analysis or an electrical modelstudy on uniform sands.
Electrical model studies or mathematical analyses cannot take intoconsideration the manifold variations of permeability within the reservoir.Experimental as well as analytical difficulties make it necessary to considerthe prototype for either of these studies as a perfectly uniform thickness, butit is essential that the sand be considered homogeneous, so thatthree-dimensional flow can take place.
T.P. 1969
Some Factors Influencing the Plugging Characteristics of an Oil-well Injection Water
Authors: Cerini William F. , Battles Willis R. , Jones P.H. 
Published: June 2014

Abstract
A test for determining the plugging characteristic of an oil-well injectionwater has been developed. It consists in measuring changes of the filter rateof a water at constant pressure with cumulative throughput when passing thewater through a medium grade sintered glass disk. Application of the testmethod was made to the water used in the Union Oil Company's experimental waterflood of the Chapman zone in the Richfield field, Orange County, California.This water developed increasing plugging tendencies upon aging, even though thefinished water from the plant filter exhibited few such characteristics. Theplugging material was found to consist of calcium carbonate, ferric hydroxide, and organic substances that were presumed to be bacterial.
Various method of stabilizing this water to prevent the formation of pluggingmaterial were attempted. Lowering the pH to approximately 6.4 by injectingcarbon dioxide provided a moderately satisfactory means for stabilization but abetter method of stabilizing this water was found to be first aging and thenfiltering.

Introduction
An experimental water-flood project was started oil the Chapman zone of theRichfield field in March 1944 and has been described in a previous paper. Itconsists of a single injection well drilled between old producing wells. Awater-treating plant using primary alum flocculation, sedimentation andchlorination followed by secondary flocculation, sedimentation and filtrationis employed to process the water before injection. In all of the water-treatingoperations, the system is open to the air, and no attempt is made to preventthe loss of carbon dioxide or absorption of oxygen by the water. The clearwater is stored in a covered concrete basin and pumped through a Transite lineto the suction of a high-pressure pump at the injection well. The high-pressuretubing in the well to the injection zone is cement lined. The untreatedinjection water is a mixture produced with the oil from the Chapman and Kraemerzones and is supplied from the disposal system.
Because the injection well was relatively deep (injection zone about 3400'Ft.)and would be expensive to replace, it was believed imperative to supply anonplugging injection water and to develop laboratory procedures for evaluatingthe treated injection water with respect to its formation plugging properties.This report describes the development and application of the test procedurebased on the assumption that the plugging properties could be determined bymeasuring the progressive decrease in flow rate of the water through a porousmedium. If the quality of the injection water was good enough so that theplugging action on the Porous medium was of small magnitude, it was reasonedthat the tendency to impair flow in the formation would not be serious.
T.P. 2028
An Application of Statistical Methods to Core Analysis Data of Dolomitic Limestone
Authors: Bulnes A.C. 
Published: June 2014

Abstract
This paper applies the methods of statistical analysis to the interpretation ofcore analysis data of dolomitic limestone from the San Andres formation atWasson and the Clearfork formation at Fullerton.
Probability relationships are shown to connect the porosity and thepermeability and the porosity and the fluid saturation. For example, theporosity-permeability relationship expresses the probability that a sample ofporosity, J, will or will not be permeable.
The over-all porosity frequency distribution of the reservoir together with thefrequency curves of permeability (one for each class interval of porosity)provide a precise basis for computing the weighted average productive porosityof the reservoir for any assigned value of the minimum productivepermeability.
The probability that the permeability of a core specimen from Fullerton willexceed a given value appears to be dependent on the percentage porosity of thespecimen, its void structure type (i.e., porosity in the qualitative sense), and the given value of the permeability. If continuous profiles of voidstructure type and 'porosity are available together with the appropriateporosity-probability of permeability: plots, the, net pay thickness may beestimated.
The Invasion Index of a well is defined in terms of the porosity ‘andpermeability data. This -index’ is suggested 'as a basis for comparing- wellsas regards their suitability as fluid-injection wells.

Introduction
Three problems of importance in the exploitation of limestone reservoirs may'be stated as follows:The determination of the productive porosity of the reservoir.The determination of the number of feet of oil-bearing porous rock that willproduce at a commercial rate into the well bore; i.e., the net paythickness.The choice of fluid-injection wells in a secondary recovery program.
The ultimate recovery of the reservoir is proportional to the productiveporosity. The productive capacity of the well is proportional to the net paythickness.
The principal purpose of this paper is to show that the methods of statisticalanalysis when applied to core analysis data of dolomitic limestones offer auseful approach to the solution of these three problems, as well as others ofimportance in reservoir engineering. The use of these methods was suggested bythe work of Jan Law.
T.P. 2025