bluuebunny/crossref_metadata_2025 huggingface dataset:
Attainment of Connate Water in Long Cores by Dynamic Displacement
Authors: Slobod Robert L.
Published: April 2012

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.

Introduction

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.

T.N. 55
Lime Content of Drilling Mud-Calculation Method
Authors: Nelson M.D. , Watkins T.E.
Published: April 2012

A method of determining the lime content of drilling muds proposed by Battleand Chaney has been examined both in the Field Research Laboratories ofMagnolia Petroleum Co. and in field drilling operations. This proposedanalytical method is condensed as follows: Titrate one ml of mud and one ml ofmud filtrate, each with 0.02 N H2SO4 to the end point with phenolphthalein. Thevolume of acid in ml required for the mud titration is recorded as Pm and thatof the mud filtrate titration as Pf.

The analytical procedure outlined by Battle and Chaney was found to be quitesatisfactory when reasonable precautions are used in mud sampling technique.Calculation of lime concentration by the method proposed in the abovepublication, however, has given values that varied as much as 100 per cent fromthe known lime content, for muds of either high or low solidsconcentration.

By use of a formula, based on chemical equivalents of acid required fortitration, both laboratory and field data have been satisfactorily correlatedwith the known amounts of lime present in the muds. In this formula acorrection, FL, or volume fraction of liquid in the mud, is made for the solidcontent of the mud. Pm and Pf have the same significance as in the Battle andChaney equation. Table I shows typical data employing both formulas incalculating the lime content of various lime muds.

This suggested procedure ignores lime which is in solution in the mud. Thesolubility of lime in water, normally about 0.5 lb per bbl, is greatlydecreased by the addition of caustic soda, and, in a lime mud, it is probablethat the concentration of dissolved lime is of the order of 0.1 lb per bbl.Such an amount of lime can be ignored, since it is within the range of accuracyof the method.

T.N. 58
Pressure Distribution in Unsaturated Oil Reservoirs
Authors: Brownscombe E.R. , Collins Francis
Published: April 2012

The pressure distribution in a reservoir producing an incompressible fluidby radial flow in a horizontal structure is a simple logarithmic function useddaily by reservoir engineers. The assumption of an incompressible liquid isequivalent to assuming that pressure is maintained constant at the well radiusand at some external ?radius of drainage,? or, in other words, that the entireflow into the well passes across the external radius. In most cases a well issurrounded by other wells draining adjoining areas so that the ?radius ofdrainage? is not a line of constant pressure with flow equal to the flow intothe well but rather a contour of zero pressure gradient across which no flowoccurs, production being due to the expansion of the liquid within thearea.

The radial flow steady state pressure distribution for this case does not seemto be extensively used despite the fact that the mathematical analysis has beengiven in detail and the results are simple and generally applicable. The objectof this discussion is to develop this result from a physical rather than amathematical viewpoint, thereby aiding intuition in judging circumstances towhich it may be applicable.

If the production rate at a well in an unsaturated reservoir is maintainedconstant while no flow occurs across the outer radius a steady state will soonbe reached in which the flow rate or pressure gradient is constant with time atall points in the reservoir. To preserve such a condition it is necessary thatthe pressure decline at the same rate at all points in the reservoir, that is, the curves of pressure versus radial distance at successive times are allparallel. Then each unit volume of oil is expanding at the same rate andcontributing an equal share to the production.

T.N. 61
High-Pressure Mercury Pump
Authors: Spencer J.R.
Published: April 2012

When supplies of high pressure mercury or other liquids are required inanalytical work, it is convenient to have the source of supply at a relativelyconstant pressure and available in sufficient volume to satisfy therequirements of the apparatus in use. It is also desirable that the pressuringdevice be as simple and as inexpensive as possible and convenient to operate.This pump combined with a small storage reservoir containing gas under pressurehas the attributes ofpositive control of the maximum output pressurethrough the use of a regulator in the low pressure air supply;anincreasing capacity as the rate of withdrawal of mercury from the pressuredsystem is increased; andsimplicity, requiring only the use of a lathe, drill press, and welding unit in its construction.

Description

Essential parts of the pump are shown in Fig. 1. In appearance the unit issimilar to the usual steam pump in common use in industrial applicationsalthough considerably smaller in size. The main differences lie in the arearatio of the air and mercury pistons and in the design of the air valvemechanism. Approximate diameters of these pistons are 4.25 in. to 0.375 in.respectively, giving an area ratio of about 130 to 1. The air piston (2) isattached to the end of shaft (4), with the mercury piston being merely areduced extension of the shaft. Mercury intake and discharge to the pump arecontrolled by high pressure check valves that screw into the ports indicated at (6). Air supply is controlled by the valve assembly mounted on top of the maincylinder (1).

T.N. 62
Some Controlling Factors Regarding Variable Weighting of Cement Slurries
Authors: Mallinger M.A.
Published: April 2012

A series of laboratory tests was conducted to determine the limits ofpracticability in regulating the weights of various cement slurries. It wasfound that slurry weights of 12 to 19 lb per gallon could be obtained by addingbentonite to decrease the weight and barytes ore to increase the weight. It wasalso found that barytes ore was not usable in all cements.

Lightweight Cement Slurries Introduction

During the drilling and completion of oil wells the magnitude of the hydraulicpressures exerted on certain formations is critical. In many cases considerablecare must be exercised to prevent drilling mud weights from becoming too high, and in those wells where loss of circulation is a problem, the use of normalweight cement slurries will generally result in lost returns during casingcementing operations. While mud weights can easily be controlled, it isnecessary to exercise care in the selection of weight reducing additives forcement slurries in order that slurry weights may be reduced sufficiently toprevent the loss of a large portion of the cement to the thief formationswithout seriously affecting the setting properties of the cement.

Experimental Results

An extensive search revealed that a large number of materials that might havebeen otherwise practicable as a weight reducing additive were not acceptablefor use with oil wet cements because the imposition of pressure on the slurriescaused the additive being tested to be compressed or to absorb water from theslurries, resulting in negligible decrease in the slurry weight.

This search for lightweight additives disclosed that bentonite, a material verycommonly used for reducing the weight of drilling muds and cement, produced thebest results without undue harmful effects on the properties of oil wellcements.

T.N. 64
An Investigation of the Electrokinetic Component of the Self Potential Curve
Authors: Wyllie M.R.J.
Published: April 2012

Eight laboratory-prepared aqueous base drilling muds representing common mudtypes, and 15 aqueous base drilling muds sampled in the field, have been usedin an experimental investigation of the relationship between the streamingpotential developed across a mud filter cake and the differential pressurecausing filtrate flow.

It has been established that the relationship is of the form, Es = kPy, where Es is the streaming potential, P the differential pressure and k and yare constants for any particular mud system at constant temperature. Beyond acertain minimum thickness this relationship is independent of filter cakethickness. Experiment has shown that both k and y are temperature dependentparameters and that in certain mud systems there is a critical value of P abovewhich the simple relationship Es = kPy ceases to hold. The constant k tends tobe a function of the mud resistivity at 77'F, but the exponent y has not beenfound to be related to any commonly measured mud property.

Certain field experiments are described which serve to demonstrate that thetotal SP (self potential) developed opposite a formation may be quantitativelyaccounted for as the algebraic sum of an electrochemical potential and anelectrokinetic potential. A chart to permit the simple use of mean solutionactivities in the interpretation of electrochemical SP data is given and itsuse described.

Various field methods for computing the electrokinetic SP component of thetotal SP are considered and rejected as being unduly complicated andinaccurate. It is shown that the employment of low resistivity drilling muds isessential if optimum accuracy is desired in the use of the S.P. curve for thepurpose of computing connate water salinities by the electrochemical SP method.The use of such low resistivity drilling muds is accordingly recommended.

T.P. 2940
Special Considerations in Predicting Reservoir Performance of Highly Volatile Type Oil Reservoirs
Authors: Cook Alton B. , Spencer G.B. , Bobrowski F.P.
Published: April 2012

Introduction

In estimating production gas/oil ratios and oil recoveries from reservoirscontaining highly volatile oils it is highly important to include condensatethat may be recovered from the gas produced from the reservoir. The volume ofthe hydrocarbon liquid condensed from the production of the solution gas thathas been liberated in some reservoirs may equal or even exceed the volume ofrecoverable stock-tank oil as estimated by present methods. The usual procedurein estimating future reservoir performance includes use of relativepermeability data of the reservoir rock to gas and oil and includesmaterial-balance calculations utilizing data on the volume of the reservoirfluids, oil and gas production and reservoir pressure decline, and data on thephysical properties of the initial reservoir fluids. The inaccuracy in theprocedure results from the false assumption that all of the free or liberatedgas that enters the well bore of reservoirs containing highly volatile oilsremains in the gaseous phase as it is produced.

This paper presents a method for estimating future reservoir performance andoil recoveries based on special laboratory analyses of reservoir-oil samplesand recognition of the additional volume of hydrocarbon liquid that will berecovered at various stages of depletion from a solution-gas-drive reservoir.The method also includes calculations of the volume and composition of thehydrocarbon liquids that can be recovered by processing the produced gas in anatural-gasoline plant. The development of the method resulted from a study oflaboratory analyses of reservoir samples and of field data obtained from tworeservoirs containing oil of the highly volatile type.

Relatively high pressures and temperatures prevail in oil reservoirsdiscovered at the greater depths of present-day drilling. The contained fluidsmay have high saturation pressures and large volumes of gas in solution. Theoils and gases under these conditions may be almost identical in compositionsand densities. Also, engineers have noted that, for a number of oil reservoirsand especially the deeper reservoirs, the API gravity of the stock-tank oilincreases as the production gas/oil ratios increase. They attributed thisincrease in API gravity of the stock-tank oil to the formation of condensate asthe liberated gas in the reservoir is being produced.

T.P. 3017
Interfacial Tensions at Reservoir Pressures and Temperatures; Apparatus and the Water-Methane System
Authors: Hough E.W. , Rzasa M.J. , Wood B.B.
Published: April 2012

An apparatus for the determination of fluid-fluid interfacial tension by thependant drop method has been constructed. The apparatus is refined beyond thosepreviously described in that the samples are introduced into an evacuatedwindowed cell without contacting air or mercury.

Interfacial tension data are reported for the water-methane system between 74and 280'F and 15 and 15,000 psi.

The variation of wettability of the stainless-steel dropper tip withpressure and temperature was observed incidentally to the measurements.

Introduction

The most refined previous apparatus for the determination of fluid-fluidinterfacial tension at reservoir conditions was built by Hauser and Michaels.These authors used the pendant drop method, previously investigated by Andreas, Hauser, and Tucker. Recently, Fordham has made the pendant drop method anabsolute one by numerical integration of the differential equation of dropshape. It is necessary to know the difference in density of the two fluids andthe acceleration due to gravity in order to evaluate the interfacial tensionfrom measurements of drop dimensions. Contact angle is not involved in themeasurements by this method.

Some precise tests of the method have been made at atmospheric pressure and77?F by Douglas, who found agreement with established values to within about0.1 per cent for water and air, cyclohexane and air, benzene and air, andbenzene and water. No values of interfacial tension from the recent pendantdrop apparatus have been published by Hauser and Michaels. However, values forthe water-benzene and water-decane systems are given in Michaels thesis forpressures from 15 to 10,000 psi and temperatures from 73 to 268?F. Somedeterminations on gas-oil and gas-water systems in the range of 15 to 4,000 psiand 78 to 178 of have been made by Hocott, by the drop-volume method. Thecapillary rise method has been used to investigate the interfacial tension ingas-oil systems at 88 of to several thousand psi by Swartz. Otherdeterminations in gas-oil systems at pressures under 1,000 psia have been madeby Jones, and Beecher and Parkhurst. The scarcity of data for pressures above5,000 psi is apparent.

T.P 3019
Variable Characteristics of the Oil in the Tensleep Sandstone Reservoir, Elk Basin Field, Wyoming and Montana
Authors: Espach Ralph H. , Fry Joseph
Published: April 2012

In the spring of 1943, when it was evident that the Tensleep sandstone inthe Elk Basin Field, Wyoming and Montana, held a large reserve of petroleum, Bureau of Mines engineers obtained samples of oil from the bottom of nine wellsand analyzed them for such physical characteristics as the volumes of gas insolution, saturation pressures or bubble points, shrinkage in volume caused bythe release of gas from solution, expansion of the oil with decrease inpressure, and other related properties. The composition of the gas in solutionin the oil was studied. The pressures and temperatures existing in thereservoir and the productivity characteristics of the oil wells weredetermined.

The data obtained indicate that the oil in the Tensleep Reservoir of the ElkBasin Field has unusually varying physical characteristics, such as asaturation pressure of 1,250 psia and 490 cu ft of gas in solution in a barrelof oil at the crest of the structure and a saturation pressure of 530 psia and134 cu ft of gas in solution in a barrel of oil low on the flanks. The hydrogensulfide content of the gas in solution in the oil varies from 18 per cent foroil on the crest to 5 per cent for oil low on the flanks of the structure. Ofeven greater significance is the fact that these and other variablecharacteristics of the reservoir oil are related to the position of the oil inthe structure. Many geologists and petroleum engineers have considered that allthe oil in a petroleum reservoir has rather uniform physical characteristicsand that equilibrium conditions prevailed in all underground accumulations ofoil and gas; that such is not always so is borne out by the results of thestudy by the writers.

T.P. 3018
Vaporization Characteristics of Carbon Dioxide in a Natural Gas-Crude Oil System
Authors: Poettman Fred H.
Published: April 2012

The vaporization characteristics of carbon dioxide in a League City naturalgas - Billings crude oil system were studied at three temperatures, 38?, 120?, and 202' F and for pressures ranging from 600 to 8,500 psi. Variation of carbondioxide concentration up to 12 mole per cent in the composite showed no effecton the equilibrium vaporization ratios (K values) of the hydrocarbonconstituents or on the K value of carbon dioxide itself. It was shown thatcarbon dioxide is more soluble in crudes than in distillates which is contraryto the behavior of methane.

A working chart of carbon dioxide K values is presented.

Introduction

The study of the equilibrium vaporization ratios of mixtures of paraffinhydrocarbons has been rather thorough. In the past few years considerableattention has been paid to the vaporization characteristics of the so-callednoncondensable gases such as nitrogen, carbon dioxide, and hydrogen sulfide inmixtures of hydrocarbons, since they usually occur to some extent in most crudeoils and natural gases. Knowledge of this behavior is useful to both theproduction and refining phases of the petroleum industry.

This paper reports the equilibrium vaporization ratios (K's) of carbondioxide in a mixture of League City natural gas and Billings crude oil, andcompares them to those obtained in a natural gas-distillate system. Theequilibrium vaporization ratios for the hydrocarbon components in this systemhad previously been studied by Roland. In addition to the determination of theK values for carbon dioxide, the K values for methane and ethane were alsodetermined in order to observe what effect, if any, the presence of carbondioxide had on these K values. The concentration of carbon dioxide was alsovaried in order to observe the effect of this variable on the carbon dioxide Kvalues.

Experimental Procedure

The apparatus used in this study consisted of a stainless steel equilibriumcell of about 2 liters capacity. The cell was mounted on trunions permittingrocking in a thermostatically controlled oil bath. Two high pressure valvesfitted with steel tubing were mounted on the top of the cell, one was used forsampling the equilibrium gas phase and the other for sampling the equilibriumliquid phase by means of an induction tube within the cell. Stainless steeltubing from the bottom of the cell led to a mercury reservoir and manifoldwhich was connected to a free-piston type pressure gauge manufactured by theAmerican Instrument Co. and to a volumetric pump. The temperature of the oilbath was measured by means of a calibrated mercury-in-glass thermometer.

T.P. 3058
Mineralogical Studies of California Oil-Bearing Formations I - Identification of Clays
Authors: Nahin P.G. , Merrill W.C. , Grenall A. , Crog R.S.
Published: April 2012

A progress report of an experimental investigation into the role of clay inreservoir performance is presented. The paper gives some of the reasons forconsidering clay as a significant component and outlines the objectives of abroad field of study which it is intended to pursue. Descriptions of theanalytical methods used are given; these include X-ray diffraction, electronmiscroscopy, thin section petrography, infrared spectroscopy, and cationexchange analysis. A suite of the more important clay minerals has beenassembled and characterized by these methods for use as standards in coreanalysis. From the data obtained it appears that although no one method ofanalysis is diagnostic for all of the clay minerals the infrared techniqueshows considerable promise in this direction. For the present, one or moresupplementary methods should be used to confirm the clay mineralidentifications.

The methods of analysis are applied to field cores taken from representativeand widely differing strata especially as regards their susceptibility todamage by fresh water. Wells completed in the Stevens and Gatchell Zones in SanJoaquin Valley are particularly clear-cut examples of this behavior withStevens Zone wells being more adversely affected by fresh water. Cores fromthese zones have been studied and are discussed. It appears that differences inthis behavior can be ascribed to differences in the nature of the containedclays. The value of the infrared spectra of the clay fractions in establishingthe identity of the predominant clay minerals is given particular emphasis.

Introduction

It is a challenge to the technical resources of the petroleum industry thatwhen the economic limit of production is reached, from 40 to 70 per cent of theoil in California reservoirs remains unproduced even by use of the bestpresently known methods of recovery. The magnitude of this abandoned volume ofoil can be appreciated when it is considered that to 1950 in excess of 8billion bb1 has been produced from California reservoirs with estimatedeconomically recoverable reserves in known fields and pools totaling nearly 4billion bbl. If for every barrel of oil produced there is at least anotherbarrel still in place, it is evident that the revenue obtained from therecovery of only a few per cent of this volume would repay the cost of therequired research manyfold.

T.P. 3059
A Modified Low-Strength Cement
Authors: Morgan B.E. , Dumbauld G.K.
Published: April 2012

The need for a low-strength cementing composition for use in well cementingis reviewed and results are presented of laboratory and experimental fieldtests of a modified cement having a controlled ultimate tensile strength ofapproximately 200 psi. The modified cementing composition may be prepared fromeither high early strength or normal portland cements by the addition ofbentonite clay and a suitable agent for dispersing and controlling the set ofthe slurry. Substitution of the modified cement for conventional slow-setcements may give better completion results in many wells because the modifiedcementing composition has lower set strength, lower slurry density, and greaterslurry stability than conventional cement slurries. The lower ultimate strengthallows greater penetration with less shattering of the set cement whenperforating casing and cement. The lower slurry density allows the placement oflonger columns of cement slurry, and the greater slurry stability reduces thepossibility of having an uncemented section caused by the settling of cementparticles before the cement sets.

Introduction

High strength has always been one of the accepted criteria of a good cement.During the early use of portland cement in well cementing, emphasis was placedupon securing cements with higher strengths. In 1931, Barkis reported that,?Normal oil well cements have been improved to develop greater strengths anduniformity of product, which has aided in producing successful jobs incementing the deeper strings.?

As long as most wells were completed by the open-hole method, the use ofcements having high strengths seemed desirable, and there was no objectionraised against high-strength cementing compositions. For a number of years, however, the industry has been completing a large number of wells by settingand cementing casing through productive horizons and then obtaining productionby gun-perforating the section of casing opposite the desired interval.Although this method has been generally successful, difficulties have beenexperienced in some cases in completing or recompleting wells because ofapparent lack of adequate penetration by the bullets through the casing andsurrounding sheath of cement and into producing formation. In addition to thepenetration trouble, there have been indications that fracturing and shatteringof the set cement by perforating might be a contributing factor in causing thefailure of some jobs to exclude water or gas from oil producing zones.

T.P. 3062
A Gravel Pack Completion for Exclusion of Gas and Water
Authors: West Thomas S.
Published: April 2012

A gravel pack completion is described which, in addition to sand screening, permits the exclusion of water and gas from the oil production.

A gravel pack composed of alternate layers of different particle sizes isemployed which has horizontal but not overall vertical permeability to drillingmud. A packer is run on the tubing and set in the screen member, around whichthe gravel layers are placed. The hydrostatic pressure of a mud column preventsthe entry of fluid above (or below) the level of the packer. The producinglevel may be changed by raising or lowering the tubing.

Vertical coning is controlled by replacing the mud column with oil andcontinually injecting oil into the sand section above (or below) thepacker.

Three well histories with this completion are described in detail.Statistics on the first 100 completions of this general type are given.

Introduction

Gravel pack type completions have heretofore been almost exclusively for thepurpose of preventing sand production. This paper describes and presents welldata on a gravel pack procedure which is primarily a selective completionmethod. Although complete sand screening is achieved, the exclusion of gas andwater is the primary objective. The application of this procedure is thereforenot limited to unconsolidated sands. Application to hard sand or limestonereservoirs is equally feasible.

Gravel Pack Procedure

Figs. 1 and 2 illustrate the gravel pack procedure employed. The gravel isplaced by means of the frangible disc type dump bailer shown by Fig. 1. Thisbailer has its lower end closed by a plate glass or steel rimmed cement disc.This disc breaks when the bailer passes over the liner allowing the gravel tobe deposited around the liner. The liner employed is usually 2 3/8 in. to 2 7/8in. OD and 1.995 in. or 2.07 in. ID (ID of 2-in. tubing or 2-in. line pipe).Two types of slotted sections have been employed. One type employs horizontalhacksaw cut or milled slots of about 1/32 in. width opposite the producingsection. The other type employs the same type of horizontal slot, but slots areplaced in groups of six at intervals of about 8 in.

T.P. 3060
The Quantitative Application of Radioactivity Logs
Authors: Bush Robert E. , Mardock E.S.
Published: April 2012

The object of this paper is to report recent developments in thequantitative interpretation of radioactivity logs. The use of reference linesis described in the application of the new zero radioactivity reference linefor the determination of neutron derived porosities is discussed. Illustratedexamples are shown of logs from the reef limestone of the North Snyder Fieldand from the Lansing-Kansas City limestone of central Kansas.

A method of using an interrelation factor calculated from the neutron andgamma ray curves, called the neutron productivity number, for the estimation ofproductivity from sandstone formations is discussed. When used in a relativemanner the neutron productivity number has aided in predicting whether a givenzone will produce gas or liquid or whether it is too shaly to produce. Examplesof logs from wells in the Freites District, Venezuela, and in East Texas areshown to illustrate the application of the neutron productivity number.

Introduction

The petroleum industry was introduced to some of the preliminary results ofinvestigations into the quantitative interpretation of radioactivity logs inOctober, 1949: It was stated at that time that the methods presented wereentirely relative because they involved the use of reference points obtainedfrom the radioactivity log, i.e., shale reference lines, dense zone referencelines, or a combination of both shale and dense zone reference lines. Theserelative methods offered many advantages to the industry in interpretingradioactivity logs in terms of porosity with particular application tolimestone and dolomite reservoirs. However, these relative methods did notoffer the wide range of applicability desired because the establishment ofreliable reference points from shale in some areas were difficult. It wasrecognized that a more reliable means of establishing reference lines wasvitally needed. Such a method is now available through the introduction of aninstrumental zero device. It is the purpose of this paper to discuss theapplication of this new zero reference to the quantitative interpretation ofradioactivity logs.

Previously all applications of quantitative interpretations of radioactivitylogs have been made in limestone reservoirs with little or no emphasis placedon sandstone reservoirs. A brief resume of investigations into the quantitativeinterpretation of radioactivity logs in sandstone reservoirs is presented here.This discussion deals primarily with the interrelation of the gamma ray andneutron curves and the response of the latter to the density of the fluidsfilling the pore space in relatively homogeneous sandstones of uniformporosity. The authors believe that the methods presented herein are onlyapplicable locally to specific fields and reservoirs, and that they probably donot offer a wide range of applicability.

T.P. 3075
The Southwest Antioch Gibson Sand Unit
Authors: Ockerhauser T.E.
Published: April 2012

Introduction

The Southwest Antioch Oil Field located in T2&3N - R2&3W, GarvinCounty, Okla., was discovered in February, 1946, by The Globe Oil & Refining Co. and The Vickers Petroleum Co. at their Melinda Gibson No. 1. Oilproduction was encountered at a depth of 6,525 ft in 14 ft of lowerPennsylvanian sandstone.

The producing sand, locally called the "Gibson" or "ThirdDeese," is a sand bar deposit strung along the west flank of the PaulsValley uplift in a northwest-southeast direction. The oil reservoir is definedto the east by the edge of sand deposition along the uplift and to the west bythe gradation of sand into shale. Within the Antioch Unit, the sand dips from150 to 400'Ft per mile southwesterly and has a pay thickness varying from 10 to55 ft and averaging 28 ft.

Several areas of Gibson production have been developed, including the Katiepool on the south, the Elmore Area of the Southwest Antioch Gibson Sand pool, the Southwest Antioch Gibson Sand pool proper, the Southwest Maysville pool andthe New Hope pool on the north. Production extends over a belt 22 miles long byabout two miles wide and is continuous except into the Katie and New Hopepools. It appears that drilling will soon prove these intervening areasproductive. To March 1, 1950, approximately 18,000 acres have been developedwith 450 Gibson wells. It is likely this count will ultimately reach 32,000acres with 800 wells.

Reservoir

The natural production of oil from the Gibson reservoir is primarily due tosolution gas expansion though gravity also plays a part. There is no indicationof water drive or evidence that an initial gas cap existed.

Gibson oil has a stock tank gravity of 43? API and was saturated at theoriginal reservoir pressure of 2,925 psi. It contained 1,340 cu ft of gas perbbl in solution and had a high shrinkage of 70 per cent. Connate water amountsto 15 per cent. Reservoir temperature is 130'F.

Porosity averages 15.5 per cent and permeability ranges from less than onemd to over 1,000. Based on measurement of 400 core plugs from 15 wells, 78 percent of the permeabilities fell within the 10 to 1,000 md bracket and averaged167.

Primary oil recovery is estimated at 140 bbl per acre-ft or 22 million bblfor the present 137-tract unit.

T.P. 3057
The Phase Behavior of a Natural Hydrocarbon System
Authors: Weinaug Charles F. , Bradley Howard B.
Published: April 2012

The phase behavior of a naturally occurring hydrocarbon system whosecritical temperature is near the reservoir temperature has beendescribed.

The same volume per cent liquid was observed for the first time at threedifferent pressures for isotherms immediately below the critical temperature.The shapes of the isothermal equilibrium constant curves necessary to predictthis phenomena are discussed and illustrated.

Introduction

The phase behavior of a number of hydrocarbon systems has been reported;however, very little data are available on natural occurring hydrocarbonsystems whose critical temperature is near the reservoir temperature. Thisappeared to be the case for the fluid studied here; therefore thepressure-volume-temperature data for this system were determined forpresentation.

Method

The PVT data were obtained with equipment similar to that described byWeinaug and Katz, consisting principally of a two-section, double-windowedgauge mounted in a constant temperature air bath. The procedure followed wasessentially that used by Katz and Kurata except that a cathetometer, readingdirect to 0.01 cm, was used to determine the height of each extreme phaselimit.

The system studied was formed by recombining vapor and liquid samples from thefirst stage separator of the well. Portions of these samples were displacedwith mercury into the cell which had previously been filled with mercury. Apredetermined amount of the liquid sample was introduced, while an excess ofvapor was admitted. The resulting mixture was brought to equilibrium at thecondition of the separator during sampling. By adding mercury to maintain thepressure, enough vapor was displaced to give a gas/oil ratio within the cellequal to that produced by the separator at the time of sampling. The remainingmaterial was then considered to be equivalent to the reservoir fluid. Ananalysis of material in the cell, computed from analysis of vapor and liquidsamples and the separator gas/oil ratio, is given in Table I.

T.P. 3097
Primary High Pressure Water Flooding in the Pettit Lime Haynesville Field
Authors: Akins D.W.
Published: April 2012

The case history of a combination gas and water flood instituted early inthe life of a field is described. It was recognized from the beginning thatrecovery would be low, under normal production methods, from the severalseparate, thin beds of porous limestone which had such poor native permeabilitythat the wells would not produce without acidizing. It is thought that thecombination flood gives excellent recovery efficiencies for this type ofreservoir. The chief function of the gas flood now is to maintain bottom holepressure in that part of the reservoir which will not be affected by the waterinjection program until later. Present estimates are that ultimate recoverywill be approximately double the recovery expected under the original solutiongas drive mechanism. Wide (80-acre) spacing has enhanced the economics of theover-all field program by the elimination of more than $5,000,000 worth ofunnecessary wells.

Introduction

The Haynesville Pettit Field was discovered in November, 1941, with thecompletion of T. L. James Co.'s Callie Akin No.1, located in the W ? of the NE? Section 27–23N-8W, Claiborne Parish, La., at an approximate depth of 5,30'Ft. The center of the field is about two miles north and a mile west of thetown of Haynesville, La. A total of 189 producing wells have been drilled on14,500 acres. An additional nine dry holes were drilled. The Louisiana-Arkansasstate line divides the field so that 34 wells are in Arkansas and 155 are inLouisiana.

Governmental sections are divided equally to contain eight production unitsmaking 80-acre spacing where the sections are regular. Along the state line inLouisiana there is an irregular tier of sections, each of which containsapproximately 456 acres. When divided equally into eight production units thespacing is 57 acres per well for these three and a fraction productivesections. All Haynesville Pettit wells are identified by their section numberfollowed by their position in the section as determined by numbering theproduction units counterclockwise beginning in the upper right corner of thesection.

All of the producing wells in the field except two are unitized and operatedby the Haynesville Operators Committee. These two wells are located in theextreme northern part of the field in Arkansas. Efforts to bring them into theUnit are being continued.

The Pettit operators organized the Haynesville Operators Committee and thefield became a unit operation May 1, 1944.

T.P. 3077
Report on the Mamou Field Pressure Maintenance Project
Authors: Crego William O. , Henagan James M.
Published: April 2012

The Mamou Field, located in Evangeline Parish, La., is an elongatedanticlinal structure on the downthrown side of a major east-west fault with oiland gas production from the upper part of the Wilcox formation. Two mainproducing horizons occur at an approximate depth of 11,500'Ft and have beendesignated the Morein sand and the Deshotels sand.

The upper sand (Morein) had an original bottom-hole pressure of 6,788 psig, which is some 1,500 psi above the normal pressure for that depth. Oilproduction with high gas/oil ratios and fluid analyses giving high shrinkagefactors prompted a study of the reservoir in its early stages. The resultsindicated a closed reservoir producing under solution gas drive with lowexpected ultimate oil recovery.

The early study of the Wilcox formation and its contained hydrocarbonsresulted in the presentation of the data to the Department of Conservation ofthe State of Louisiana, with suggestions for field rules and a request forpermission to inject extraneous water into the Morein sand. The water injectionplans eventually led to complete unitization of working and royalty interests, to the construction of a gasoline plant, and to a central tank batteryinstallation for the field. Deshotels sand wells were reworked to the Moreinsand, and the water injection system was installed and ready for continuousoperation in the early part of 1949. The injection of water was started in timeto arrest the bottom-hole pressure decline at or near the bubble-pointpressure. This injection was calculated to increase the ultimate recovery andto conserve natural resources. Pressure maintenance, the extraction of LPGproducts, and the sale of residue gas (early 1950) represent an attempt toproduce an oil field with utmost efficiency.

Introduction

The two principal Wilcox oil horizons in the Mamou Field are the Morein sandand the Deshotels sand, occurring at 11,500'Ft and 11,700'Ft subsea, respectively. Minor oil production has been encountered in Morein stringersands. (Fig. 1.)

This paper deals only with the Morein sand, which is blanket over the MamouField. It is, however, segmented by the northwest-southeast "E" faultas shown in Fig. 2. The west segment is the area involved in the waterinjection pressure maintenance program. To date the east segment has operatedlargely under the influence of a strong water drive.

The paper presentsbrief history of field development,resume ofreservoir conditions which led to the decision to inject extraneous salt waterinto the principal producing horizon, andsummary of reservoir analysisand performance.

T.P. 3192
Interstitial Water Determination by an Evaporation Method
Authors: Messer E.S.
Published: April 2012

A knowledge of the magnitude of the irreducible interstitial water in aporous medium is so important to petroleum engineering that its determinationhas become routine in core analyses.

The method of determination, being a production problem, should encompassthe basic requirements of simplicity in technique and calculations, withreproducible results obtainable in a short interval of time. The results of theevaluation tests outlined in this report indicate that the evaporation methodfor determining the irreducible water is a technique which meets therequirements.

The procedure consists, as the name implies, of permitting the saturant inthe pore spaces to evaporate until only an irreducible volume remains. Thedetermination of this volume can be made either graphically or by amathematical comparison of fluid flows; the time required for eachdetermination being dependent on the fluid used.

When fluids other than those having reservoir characteristics were used, avolume factor had to be calculated which was based on the relative volume ofvarious liquids adsorbed on grain surfaces and retained in pores. This factormade possible the calculation of an irreducible water volume when more volatilefluids such as toluene and benzene were used as the saturants.

Also presented is the theoretical discussion necessary for the calculationof the capillary pressure as determined from the evaporation curve. Acomparison is made between the calculated values and those obtained byexperimental means.

Introduction

In all geological formations there exists, in the pore spaces of the rockstructure, water that is held in a state of equilibrium between capillary andhydrostatic forces. "Interstitial water" is the term given to thiswater and is defined as that water coexisting in the pore space with the oilprior to exploitation. The term "connate water" has often been usedsynonymously with this term; however, this can be true only by a specificdefinition since, geologically, it means the water in place at the time therock structure was formed.

The quantity of the interstitial water is a variable factor in anyformation, since it depends on the hydrostatic forces present in anymultiple-phase system. These forces may become unbalanced by the introductionof an extraneous force such as the raising or lowering of the "watertable" or the migration of oil into a water-filled formation. Anyunbalanced force results in a change in the interstitial water.

There exists, however, an irreducible interstitial water, for a particularsand, that is the fraction of the pore space occupied by water when thecapillary pressure at the particular point in question is at an equilibriumwith the hydrostatic head of the oil sand in the reservoir. For this discussionthe term "irreducible water saturation" will be used in place of"irreducible interstitial water saturation" for the sake of brevity;however, they are understood to be identical.

T.P. 3076
The Laterolog: A New Resistivity Logging Method With Electrodes Using An Automatic Focusing System
Authors: Doll H.G.
Published: April 2012

A new electrical logging method called Laterolog is described which providesfor better recording of formation resistivity. In this method a current, preferably of constant intensity, is forced into the formation perpendicularlyto the wall of the hole as a sheet of predetermined thickness by means of aspecial electrode arrangement and of an automatic control system.

The essential advantages of the Laterolog over the regular resistivity logsare explained. With the Laterolog, the mud column has much less influence thanwith conventional methods. The Laterolog is, therefore, particularly useful inwells drilled with highly conductive mud. Moreover, when the electrode systemis located opposite a bed of moderate or small thickness, the disturbing effectof the adjacent formations becomes practically eliminated, provided the bed isthicker than the sheet of current, which itself is usually a few inches to afew feet thick. The sequences of beds are, therefore, much more sharplydifferentiated, and, in many cases, it is possible to read directly from thelogs values close to the true resistivities of the formations without furthercorrections.

Field examples are shown to illustrate the results of the method in varioustypes of formations.

Introduction

As soon as it was introduced into the petroleum industry, electrical loggingproved to be a powerful instrument for the delineation of the strata traversedby bore holes and for correlation of such strata. Research and engineeringefforts were mostly devoted at this early time to the design of the techniqueswhich could provide the best data for these purposes.

Later, attention was directed toward the quantitative analysis of electricallogs, in order to obtain information on reservoir characteristics, and inparticular on oil and water saturation. Efforts have been made, accordingly, with a view to improving the already existing methods, or to finding newmethods which could satisfy these new requirements.

Quantitative analysis implies a determination as accurate as possible of thetrue resistivity of the formations. In fact, however, the "apparentresistivity" recorded in front of a given bed by a conventional electricallogging method is frequently quite different from the true resistivity of thisbed. This is due to the combined influence of the mud column, of the adjacentformations both above and below the bed, and of the invaded zone, in which theoriginal fluid has been more or less replaced by mud filtrate.

T.P. 3198
Fluid Distributions Characterizing Gas-Liquid Flow
Authors: Rose Walter
Published: April 2012

It is the purpose of this note to call attention to the circumstancecomplicating the attainment of uniform gas-liquid distributions in multi-phaseflow systems, and especially in those of the so-called Hassler type. Althoughthe complication arises directly as a consequence of gas compressibility andthe dependence of fluid distributions on interfacial curvature phenomena, little reference to the problem has yet appeared in the literature. In fact, itis only the paper of Geffen et al. which gives any experimental evidence that aproblem exists. On the other hand, previous authors have made the tacit, albeitfallaceous assumption that uniform gas-liquid distributions automatically areestablished in linear flow systems by the expedient of maintaining the pressuregradients equal in the flowing gas and liquid phases. Such a device, it can beshown, will succeed only if the immiscible fluids are both equally compressibleor both essentially non-compressible. Another necessary condition requiredbefore uniform fluid-fluid distributions can be achieved is that the porousmatrix is isotropic.

Uniform fluid saturation distribution conditions obtain in isotropic mediaonly when the curvature of each interface of contact between wetting andnon-wetting fluids is everywhere the same throughout the interspaces. This is anecessary condition which follows from the consideration that variation ininterfacial curvature gives rise to finite capillary pressure gradients andtherefore to variation in the saturation distribution. That this is not asufficient condition follows from the consideration that hysteric possibilitiesallow for different saturations even though the capillary pressure gradient iszero. In any event, it will be recalled that it is the intent in the Hasslerscheme of relative permeability determination to obtain initially (by thecapillary pressure drainage or imbibition process) uniform conditions of fluiddistribution in the core sample, and then to maintain this uniformity duringmixture flow so that the resultant fluid mobilities which are calculated willrefer to steady-state transfer under fixed conditions of uniformsaturation.

T.N. 66