bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase Behavior in the Methane-propane-n-pentane System
Authors: Dourson R.H. , Sage B.H. , Lacey W.N.
Published: June 2014

The compositions of coexisting phases in the methane-propane-n-pentanesystem were determined at 160? and 220?F. throughout the two-phase region, atpressures above 500 lb. per sq. in. The experimental results permitted thecalculation of gas-liquid equilibrium constants as well as the establishment ofthe critical behavior of this ternary system.

Introduction

Although many binary paraffin hydrocarbon systems have been investigated, the experimental work relating to the phase behavior of ternary paraffinhydrocarbon mixtures at elevated pressures is relatively scarce, being limitedto a study of the methane-propane-n-pentane system at 100?F. However, Guter andco-workers have studied the phase behavior of the methane-ethane-ethylenesystem at relatively low temperatures. Information concerning the phasebehavior of ternary systems is of value in predicting the behavior of thecomponents in multi component systems, since the influence of pressure, temperature, and concentration may be individually ascertained. In the light ofthe importance of such information, the study of this ternary system wasextended to higher temperatures in order to increase the field of temperaturein which the data could be applied.

Since all states encountered in this investigation are above the criticaltemperature of methane, the details of its phase behavior are not of directsignificance. The properties of propane in the heterogeneous region were takenfrom a correlations based upon recently published data. The correspondinginformation for n-pentane was taken from experimentally measured vaporpressures and volumetric data. The methane-propane system has been studiedthroughout the two-phase region at temperatures above 70?F., while the phasebehavior of the propane-n-pentane system has been established for temperaturesabove 16o?F. The volumetric and phase behavior of the methane-n-pentane systemhas been studied in detail. The experimental measurements serve to establishwith adequate accuracy the phase behavior of the components and of theconstituent binary systems for this ternary system. It is believed that, withthe exception of the measurements for the methane-propane system, theuncertainties in the earlier data relating to the pure substances and thebinary mixtures are probably less than those associated with the valuesreported here.

T.P. 1490
Effect of Catalytic Cracking on the Postwar Supply of Motor Gasolines and Distillate and Residual Fuels
Authors: Moore W.G. , Elder T.G.
Published: June 2014

In order to supply the immense quantities of 100-octane aviation gasolinerequired by the military program and to furnish stocks for the manufacture ofsynthetic rubber, the oil industry installed catalytic cracking on a largescale during the war, because none of the existing processes were adapted tothe manufacture of these products in the quantities required, from a limitedamount of crude.

While it had been recognized for some time that this process wouldeventually be widely used in the oil industry, under ordinary conditions theinstallation would have been spread over a number of years through thereplacement of old equipment and as enlargements were required.

However, under the urgency of the war demand, its adoption was imperativeand the industry was forced to make a major change in its equipment before ithad had a chance to become familiar with the effect of the process whenoperating for the usual peacetime products. Because of the peculiar features ofcatalytic cracking, there was considerable speculation among refiners and usersof petroleum products regarding the results it would have on the postwar supplyof motor gasoline, household heating oil and diesel and residual fuel. Thestudy reported in the following paper was made to determine the direction ofthe changes and to evaluate their possible extent.

Status of Catalytic Cracking

Prior to our entering the war, only one of the three catalytic crackingprocesses with which the industry is now familiar was in commercial operation, and the installations of this one were confined very largely to the twocompanies that were instrumental in its development. In fact, if it had notbeen for the war, it seems likely that the adoption of catalytic cracking forthe manufacture of motor fuel would have been gradual, because very markedeconomies are needed to justify scrapping any process of which the design isfairly modern and the equipment in good condition.

However, when it became evident that large quantities of aviation gasolineof 100 octane and above would be required, the economics with respect tomanufacture of motor fuel were disregarded and catalytic units were installedon a large scale, because, by a happy coincidence, they provided, in quantity, both a base gasoline for blending with high-octane components and gasessuitable for charging stocks to alkylation and other processes for theproduction of these components. These gases also provided material for theproduction of synthetic rubber, giving further impetus to the building of thistype of equipment.

T.P. 1731
Possibility of Converting the Large-diameter War Emergency Pipe Lines to Natural Gas Service after the War
Authors: Swensrud Sidney A.
Published: June 2014

The 24-in. crude-oil line and the 20-in. petroleum-products line, built as awar emergency by the United States Government and running from points in Texasto the New York-New Jersey-Philadelphia area, were constructed only because ofthe inability during the war to continue normal ocean tanker movements from theGulf Coast to the East Coast. The postwar disposition of these lines may beconsidered as one of the important problems of the postwar readjustments in theoil industry, if not the most important one. In the first place there appear tobe many complications in keeping the lines in crude-oil or petroleum-productsservice. This conclusion was reached also in a study by T. E. Swigart, President of Shell Pipeline Corporation.

Since the lines are too large for anyone company to utilize, and since itappears likely that a surplus rather than a deficiency of tankers will existafter the war, most companies probably will feel that they can achieve lowercosts and more satisfactory results from the resumption of tanker movements tothe East Coast rather than by endeavoring to take over or utilize the capacityin the large pipe lines under some tariff-rate structure.

As for using the lines for making deliveries to the middle west or centraleastern areas, it would appear that when the war is over and normaltransportation arrangements can be resumed, there will be no need of any extracapacity for such deliveries. Therefore, the War Emergency lines could beutilized for this purpose only if privately owned pipe lines and othertransportation facilities were to be displaced.

Against this rather unprepossessing prospect for use in petroleum or productservice is the fact that at or near the source of the lines lie the greatestdeveloped gas reserves in the world, for much of which there is at present nosatisfactory market outlet; and at the other end of the lines lies one of thegreatest concentrations of population in the world, which is not now served bynatural gas. Those who have been fortunate enough to use natural gas can havelittle doubt of its desirability as a domestic fuel. An analysis of the marketpotentialities and comparison with other areas where natural gas is beingdistributed, and where it has displaced manufactured gas, makes it seem clearbeyond question that the full capacity of both of the large-diameter linescould be fully utilized in this service, and this without creating any unduedrain upon the gas reserves of the nation.

C.N. 135
The Role of Capillarity in Oil Production
Authors: Hassker G.L. , Brunner E. , Deahl T.J.
Published: June 2014

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

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

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

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

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

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

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
Some Recent Developments in Mud-analysis Logging
Authors: Pixler B. Otto
Published: June 2014

Method

As the drilling of a well progresses, the drilling bit dislodges anddisintegrates a cylindrical section of the formation. If oil or gas iscontained in the pore spaces of the cylinder, some of the contents of theseporous spaces will be entrained in the drilling fluid. In wall logging by mudanalysis, the mud is continuously examined for oil and gas on its return to thesurface, and the results are correlated back to the actual depth of the hole atthe time the mud was clearing the eyes of the bit.

The test for gas is made by diverting a portion of the circulating mud from theflow line to a separator or gas trap, where the mud is thoroughly mixed withair and a portion of the gas entrained in the mud is removed. A stream of airis drawn countercurrent to the flow of mud in the gas trap, thus materiallyassisting the separation of the gas from the mud. The air-gas mixture is thendrawn into a "hot-wire" gas-detector instrument where the percentage ofthe combustible gas is determined.

The presence of oil in the formation drilled is detected by a physicalexamination of the drilling mud under ultraviolet light. A sample of the mud istreated to reduce the surface tension and gel strength, after which it isplaced in a viewing box.

Mud-analysis logging provides identification of the fluid content of formationsdrilled by the rotary method and permits the accurate correlation of oil andgas shows with the depth. Mud-analysis logging eliminates much coring and hasan especially important application in drilling programs when coring isparticularly hazardous or the electric log is difficult to interpret correctly.An appreciation of the factors that influence the results of the mud analysis, such as rate of penetration, mud properties, coring, and characteristics ofreservoir rock as related to the "flushing effect," permits a betterunderstanding of the mud-analysis log.

Recent studies of the relationship of the two gas readings obtained by thegas-detector instrument have proved significant. The difference between thetotal combustible gas reading and the higher molecular weight gas readingindicates the presence of methane. With few exceptions, zones not showing anincrease of methane probably can be condemned. Mud-analysis logging furnishesvaluable information, which generally cannot be obtained by othermethods.

Introduction

Logging by mud analysis of wells drilled with rotary tools is a direct methodof locating oil-and-gas-bearing formations. The use of this method of logginghas increased each year until now more than 20'Field units are being used in 13oil-producing states and in some foreign countries. Several papers have beenpublished in the petroleum trade journals describing in detail the equipmentand the application of mud-analysis logging. This paper will discuss brieflythe method and review its application and some of the late developments.

T.P. 2026
Geothermal Gradients in Mid-Continent and Gulf Coast Oil Fields
Authors: Nichols Earl A.
Published: June 2014

The purpose of this paper is to present a contour map that shows thegeographical variation in geothermal gradients in the Mid-Continent and GulfCoast oil fields.

Introduction

Frequently there arises the need for an estimation of the temperature to beexpected at a predetermined depth in working with a wildcat or in deepening oldproduction into zones that are relatively unknown. The study of geothermalgradients in oil fields has been made previously by many investigators. One ofthe pioneers in this work was C. E. Van Orstrand, who, as well as most of theother investigators, was primarily interested in the relation betweentemperature and depth in a given locality. Between 1921 and 1929, AmericanPetroleum Institute Research Project No. 25 fostered a thorough study of earthtemperatures. R. W. French did some work in California, the results of whichwere published in 1939.3 In most of these studies, an attempt was made tocorrelate temperatures in a rather localized area. This paper will show theresults of an attempt to correlate temperature gradients over rather largeportions of the Mid-Continent and Gulf Coast area.

Method of Obtaining Data

It has been found that for complete thermal equilibrium to be established in awell, the well must stand undisturbed for a period of several hours to severalweeks, depending upon the way the well was produced prior to the shut-inperiod.

The data in this paper were obtained in conjunction with running pressures inwells or in taking samples of reservoir fluid. Glass maximum recordingthermometers were used in all but a few instances. The wells had been shut infrom one hour up to 10 or 12 days. Since the wells were normal producing wells, some of the shut-in times undoubtedly were insufficient for complete thermalequilibrium to have been established and the temperatures measured do notnecessarily represent the true earth temperatures. They do represent thetemperature conditions that will? be encountered in a well that is producingoil. The data, therefore, can be useful in working with or in estimating thetemperatures to be expected in producing reservoirs.

In obtaining a thermal gradient by dividing the difference in temperature ofthe formation and the mean annual surface temperature by the depth of theformation, one is assuming the depth-temperature line to be straight.Depth-temperature curves are almost straight lines. However, on closeexamination of accurate data, a slight curvature usually is observed. Mostwells yield curves with slopes increasing with increasing depth. These curvesare believed to be from wells that are in and are underlain by sedimentarymaterial. Some few curves have slopes that decrease with increasing depth.These curves are believed to be from wells that are underlain rather closely bygranite or some other igneous rock.

T.P. 2114
Some Experiments on the Mobility of Interstitial Waters
Authors: Russell R.G. , Morgan F. , Muskat M.
Published: June 2014

Core experiments with radioactive tracers are reported in which an artificialradioactive material, radiovanadium, was used in aqueous solution in a study ofthe mobility of connate water. Sandstone cores saturated with active water werefirst oil-flooded to simulate virgin sand conditions in which the pores arefilled with oil and connate water. They were then subjected to flooding withinactive water. Measurements were made of the activity of various portions ofthe effluent as well as the activity of the core after the flooding process wascompleted. In additional experiments the distribution of activity along thecore was measured during the flooding process. In still other experimentsdirect flooding tests were made on cores fully saturated with active water. Inall cases it was found that after injecting into the core a volume of inactivewater equal to a pore volume, the effluent contained more than 80 per cent ofthe active content originally in the core. It is felt that these results implya high degree of mobility of the connate water when subjected to flooding, although at least a partial contribution of the effect of tracer transferwithin the core cannot be definitely excluded. The implications of this resultwith respect to water-flooding, core analysis and electric logging arediscussed. A better approach to determining the connate water saturation ofoil-producing rocks, by measuring the fluid content of core samples at thesurface, is by the use of crude oil or oil-base muds as the coring fluid.

Introduction

Although water flooding is of considerable importance in the recovery of oil, comparatively little is known with certainty about the role played by theconnate water during the operations. Two possibilities exist. Either theconnate water is retained in the formation while the flood water sweeps past, or it is pushed along to a greater or lesser degree by the flood. Thus far noexplicit recognition in terms of quantitative studies appears to have beengiven to the displacement of connate waters by the intruding extraneous waters, although such a possibility might be important in determining the efficiency ofthe oil -displacement process in water-flooding operations, especially inargillaceous rocks. On the other hand, it is a common observation that thefirst water produced with the oil as a result of water-flooding is definitelysaline. Similar questions regarding the mobility of the interstitial waterarise in the quantitative description of the advance of edge-water drives.

T.P. 2054
Estimating Interstitial Water by the Capillary Pressure Method
Authors: Thornton O.F. , Marshall D.L.
Published: June 2014

Results of the determination of the interstitial water content of several coresamples from oil reservoirs are presented. Data obtained by the capillarypressure method, which has recently been developed, are compared with watersaturations measured in cores cut with oil-base mud and with values calculatedfrom the electrical resistivity of the formation. The agreement between thecapillary pressure and other methods, combined with the fact that similaragreement has been obtained by others, indicates that the capillary methodproperly applied yields results sufficiently accurate for most engineeringpurposes. In some cases, it may be possible to extend the utility of dataobtained with the capillary pressure method by correlation of interstitialwater saturation with more easily measured physical properties of themedia.

Introduction

Several methods are in use for determining or for estimating the interstitialwater saturation at given points within oil and gas reservoirs. The directmeasurement of the water content of cores obtained with nonaqueous fluid in thehole is believed to be an accurate method under most conditions. The water'saturation may be calculated by use of the resistivity curves of the electriclog, 1 although this method is not applicable under conditions that exist insome reservoirs. Recently, a method has been developed and described whereinthe interstitial water saturation of cores is measured at a capillary pressuresuch that conditions existing in the reservoir are simulated. The purpose ofthis paper is to present data obtained by use of this latter method, and tocompare the results obtained with determinations made by other means.

Method

The theory underlying the capillary pressure method applied to petroleumreservoirs has been discussed adequately in the literature by Garrison, Leverett, and others. Briefly, and simply, capillary pressure is defined as thedifference in pressure between two contacting fluid phases, such as oil andwater. For the simplified sand, water and oil system illustrated in Fig I, thepressure difference can be stated as follows where p. is the capillary pressurein pounds per square inch, Y is the interfacial tension between oil and waterin pounds per inch, 7, and 72 are the radii of curvature of the interfacebetween oil and water in inches.

Capillary pressure varies in a given reservoir with depth because of thegreater density of the water phase as compared with oil or gas.

T.P. 2126
Plastic Used to Consolidate Incompetent Formations
Authors: Cardwell P.H.
Published: June 2014

The effect of various plastics upon the permeability of a sand and themechanism of their ensuring permeability within the consolidated sand body isdiscussed, Data are presented on various properties of the plastic materialsused in sand consolidation and the effect of temperature and usable temperatureranges are considered.

The recovery of petroleum from unconsolidated sands presents serious productionproblems, owing to sloughing of the formation. The solution of some of theseproblems usually has been by mechanical methods. The ideal way of controllingthe sloughing tendencies of these unconsolidated formations, however, is toprevent the movement of the individual sand grains by the use of a bondingmedium.

A step in the desired direction was taken by Irons and Stoesser when theytaught the use of liquid plastics to produce a consolidating deposit thatprevents sloughing. More recently, Wrightsman and Buckley proposed amodification of this process. In this use of the liquid plastic, the sandgrains become coated and the ensuing hardening of the plastic by polymerizationor condensation cements together the sand particles. Liquid plastics that havebeen suggested for this purpose are of the following types: phenolformaldehyde, alkyd resins, vinyl type resins, polystyrene and the acrylic esters.

When the flow of fluids through a sand must not be materially reduced, it isessential only to cement together the sand grains with liquid plastic and leavea portion of the interstitial space for fluid flow. To be assured of obtainingfluid flow through the sand interstices after injection of plastic, it has beennecessary in the past to remove the excess plastic from the interstices betweenthe particles before it sets.

Wrightsman and Buckley suggest two methods for the removal of the excessplastic from the interstices of the sand:to flush the excess plastic backinto the formation, away from the well bore, by use of oil or water;toproduce the well before the plastic has set, thereby moving the excess plasticinto the, well bore.

Under certain well conditions it is very difficult toremove the excess plastic from all parts of the formation by either of thesemethods and leave the formation consolidated with no sections completelysealed.

The method described herein of retaining permeability within a sand body is touse a liquid plastic that upon setting ensures permeability within theconsolidated sand body, This cements the sand grains but obviates the need forremoving plastic from the interstices of the sand. One of the ways ofaccomplishing this is to use a liquid plastic that occupies a considerablygreater volume than the solidified resin it yields on further polymerization orcondensation in situ. In order to be satisfactory, the volume of the plasticwhile liquid should be at least one and one half times the volume of the solidformed.

T.P. 2148
Advantages of Brines in Secondary Recovery of Petroleum by Water-flooding
Authors: Hughes Richard V. , Pfister Rudolf J.
Published: June 2014

The necessity for getting more water into sands of low permeability in anysecondaryrecovery water-flood operation in order to recover all the availableoil always has been a major problem. In the early days of waterflooding theaddition of soda ash and caustic soda to fresh input waters was recommended andtried without success in the Bradford field. The most frequent difficulty wassand plugging. The use of natural and artificial brines often has beensuggested for water-flooding, in the belief that laboratory observations ofdecreasing fresh-water throughput rates in measuring water permeabilities ofconsolidated sand cores might be partially explained by swelling ofclays.

A review of available literature bearing on the subject and related laboratoryexperiments are presented herein, offering an explanation for failure in use ofsoda ash, and caustic soda waters and supporting the recent concept that everywater used for input purposes in the secondary recovery of oil should possesssuch physical and chemical characteristics as to keep the clay content of theproducing sands in a permanently flocculated condition. Produced brines meetthis requirement. Their use is recommended as a means of increasing intakerates of tight sands and oil recoveries, as a solution to brine-disposalproblems, and as a means of conserving a natural resource.

Introduction

There is a general belief among those engaged in the secondary recovery of oilby water-flooding that one of the most important requirements for the successof any such project is an adequate supply of good, fresh water. Fresh watershave the advantages of being more easily stabilized than salt waters and ofbeing usable about the lease for all purposes. The use of brines forwaterflooding never has been given much consideration in the Pennsylvania Gradearea. The use of brines in Mid-Continent operations has been considered largelyas a substitute for fresh waters, which were economically unobtainable for manyoperations.

Estimated recoveries for some water" drive fields indicate that less of theoriginal oil in place will be left upon abandonment than with the above-averagepractices used in Pennsylvania Grade water-flood operations. Lower residual oilsaturations than 25 pet of the pore space following the water-flooding of ThirdBradford sand cores in the laboratory are unusual. In comparison, water-flushedsands surrounding any virgin oil pool are found to be practically devoid ofoil.

T.P. 2127