bluuebunny/crossref_metadata_2025 huggingface dataset:
An Empirical Method of Interpretation of Earth-resistivity Measurements
Authors: Moore R. Woodward
Published: June 2014

A graphical method of analyzing the data obtained from shallowearth-resistivity depth tests is presented. The method is based upon empiricalresults and has no theoretical basis. The usual apparent resistivity-electrodespacing curve is used together with a cumulative resistivity-electrode spacingcurve plotted on the same sheet. The greatly reduced scale required forplotting the cumulative values of resistivity together with the effect of thesummation of the individual resistivity values serves to minimize the effect ofpurely local surface anomalies and inadvertent errors of measurement. The pointof intersection of tangents or straight lines drawn to intersect at zones ofmaximum curvature in the cumulative curve indicates the depth to the underlyingmaterial. Numerous figures are presented in which data from published reportsand from recent field studies are analyzed and the results compared with actualdepths established by borings or with depth values obtained by the use oftheoretical methods of analysis. Smoothly rounded curves of apparentresistivity such as are often obtained in the field, and which have been aserious drawback to attempts to analyze the data empirically heretofore, appearto be susceptible to rather accurate analysis by the method described.

The method is best suited to analyses involving shallow two-layerformations. It has been applied successfully, however, in analyzing the dataobtained from tests made over shallow three-layer formations. As with mostempirical methods, its chief advantage is its simplicity and ease ofapplication.

Introduction

There have been published many papers that discuss the interpretation ofdata obtained from earth-resistivity tests when using the four-terminal methodof electrode spacing developed by Wenner. The majority of these have dealt withtheoretical analyses for two-layer and three-layer formations. Some sets of"master curves" have been presented for use in analyzing field data todetermine the depth to the first and possibly the second horizon below theearth's surface. Although practically all of these theoretical methods ofanalysis have appeared to have particular merit and some have been usedsuccessfully in practice, they have been found to be of little value where thelocal conditions surrounding the test failed to conform to those assumed in thetheory.

In certain fields, particularly in civil engineering, relatively shallowexplorations are often involved and geophysical methods of test must competewith the direct methods of exploration ordinarily used. Only when it can bedemonstrated that geophysical methods of test can materially reduce the timeand cost of a given exploration project will the civil engineer abandon directmethods in favor of the interpretations of geophysical exploration data.

T.P. 1743
Case Histories and Quantitative Calculations in Gravimetric Prospecting
Authors: Barton Donald C.
Published: June 2014

Of the four papers that comprise this TECHNICAL PUBLICATION, three are casehistories of individual geophysical prospects, subsequently tested bydrilling.

The bibliography of Dr. Barton's published scientific papers includesinvestigations in physiography and surface geological mapping, as well as hisgeophysical papers, and from this list it is to be observed that he earlyrecognized the place of different types of geophysical prospecting methods inthe search for geological structures of economic importance. Moreover, hisviewpoint was not merely that the structures should be found, but that thegeophysical data should be examined quantitatively to determine the geometry ofthe structures. In other words, that although these data are insufficient todeduce a unique form for the structure that caused the effects measured in thedata, the engineering computations should be carried out to give as much of adefinite configuration to the structure as the data permitted, in order thatthe testing of the structures could be conducted in the most economical mannerand with the idea that the experience so gained could be later incorporated inthe study of structures subsequently found.

Dr. Barton continually emphasized the quantitative use of geophysicalobservations, whereas at the time that he began his specialization ingeophysics it was considered sufficient to use observations only qualitatively.He, more than anyone else, was responsible for the first volume on geophysicalprospecting issued by the Institute in 1929, and his three articles in thatvolume stressed the quantitative use of geophysical prospecting.

The fourth article in this present TECHNICAL PUBLICATION is a furthercontribution to this branch of geophysical interpretation, and is a supplementto the paper in the 1929 volume, "Calculations in the Interpretation ofObservations with the Eotvos Torsion Balance."

T.P. 1760
Gravity Drainage in Oil Fields
Authors: Lewis James O.
Published: June 2014

Gravity drainage is the self-propulsion of oil downward in the reservoir rock.Under favorable natural and operational conditions, it has been found to effectrecoveries comparable to water displacement. With modern technical knowledge, the operator can often make a choice between dissolved gas drive, water driveand gravity drainage as the principal recovery agent in a reservoir. It isdesirable that the operator be able to determine which of the three agents willbe most effective under each set of conditions. So far, gravity drainage hasreceived less consideration than the other two. In this paper an endeavor ismade to set forth some of the principles of gravity drainage, to point out thetypes of reservoirs favorable for it, and to show how it may be applied inthem. Field examples are described and discussed.

Introduction

Since early in the history of the oil industry, it has been recognized thatgravity is one of the three important natural forces for expelling oil from thereservoir rock. As knowledge of the technology of oil recovery progressed, ideas changed with respect to the relative importance of the three forces andwith respect to the manners in which they functioned. For a time, disproportionate emphasis was placed on the importance and function of gas andthe need for conserving gas pressures. More recently, disproportionate emphasishas been placed on encroaching edge water. Only lately has there been evidencethat the function and importance of gravity was to receive dueconsideration.

Study of this 'neglected phase of oil recovery is needed to round out ourknowledge of reservoir behaviors and to gain a balanced viewpoint of theinterplay of forces that may operate in varying importance in reservoirs. Thepurpose of this paper is to discuss mainly in a qualitative way, the functionsof gravity, to present some concrete instances where it has been important andto raise some questions that should be investigated further.

Oil-Recovery Agents

The important natural agents for effecting oil recovery that may be originallyavailable in a reservoir are gas, both dissolved in the oil and free in gascaps, encroaching edge water and gravity. Each of these agents can act in adual capacity-physically to overcome the surface energies that hold the oilwithin the pores and mechanically to overcome viscous resistance and to propelthe oil through the porous reservoir 'rock to the wells.

Advancing edge water displaces the oil from the pores and lifts it up dip tostructurally lower wells. Gravity drains the oil from the pores and flows itdown dip to the wells. Gas displaces oil from the pores, entrains it in the gasstream and flows it to the wells, but gas in solution also affects the physicalproperties of the oil and thus can influence oil recovery by the other agents, whether or not the mechanical energy in the gas is utilized.

T.P. 1664
Vapor-liquid Equilibria of Natural Gas-Crude Oil Systems
Authors: Standing M.B. , Katz D.L.
Published: June 2014

Equilibrium data are reported on the composition and densities of coexistingvapor and liquid phases as a function of pressure and temperature for fourhydrocarbon systems prepared from crude oil and natural gas. The data wereobserved over a range of pressures from 1000 to 8220 lb. per sq. in. and attemperatures ranging from 35? to 250?F.

The compositions of the hydrocarbon systems were such that the criticaltemperatures of the mixtures were lower than the range of the investigation.Under these conditions, it is shown that the composition of the systems has amarked effect upon both the absolute value of the equilibrium constants and thechange of the constants with pressure for the several components comprising thesystem. From weight-balance considerations, it has been possible to constructthe partial phase diagram of a mixture of a 49.9? A.P.I. crude oil and naturalgas having a gas-oil ratio of 3660 cu. ft. per barrel. Descriptions of theapparatus used, the analytical procedure, the material used, and theequilibrium measurements are included.

A knowledge of the physical behavior of naturally occurring hydrocarbonmixtures is fundamental to the treatment of many problems in the production, transportation and refining of petroleum. The recent discoveries of poolshaving formation pressures up to 7500 lb. per sq. in. and higher, and the development of full-scaleequipment to operate at pressures of 5000 lb. per sq. in. or more have greatlyincreased the need for knowledge of the composition, temperature, pressure anddensity relationships of coexisting vapor and liquid hydrocarbon phases.

The following paper presents the results of investigations upon 22 mixtures ofnatural gas and crude oil of known composition that had been brought toequilibrium under controlled conditions of temperature and pressure. Data arepresented upon the densities and compositions of the coexisting vapor andliquid phases for four different systems containing hydrocarbon material havingboiling points from minus 258?F. to well over 1000?F. The data were observedover a pressure range from 1000 lb. per sq. in. to 8220 lb. per sq. in. and atemperature range from 35? to 250?F.

The accepted method of computing the physical relationship between twocoexisting phases of a hydrocarbon mixture is by use of the "equilibriumconstant" K as proposed by Souders, Selheimer, and Brown.

T.P. 1651
Selective Adsorption of Hydrocarbon and Water Vapor on Alumina at Atmospheric Pressure
Authors: Ku Chen Chun , Huntington R.L. , Reid L.S.
Published: June 2014

The simultaneous adsorption of water and hydrocarbon vapor from natural gas bythree grades of alumina has been studied at atmospheric pressure andtemperature. Results of this investigation reveal that the presence of watervapor in the gas inhibits the adsorption of hydrocarbon vapor, although thepresence of the latter does not have a pronounced effect upon the adsorption ofwater vapor. Adsorption of water-hydrocarbon mixtures from gas is divided intothree phases. In the first, both water and hydrocarbon vapor are adsorbed; inthe second, adsorption of water vapor proceeds while desorption of hydrocarbontakes place; in-the third phase, the adsorbent approaches complete saturationwith respect to both water and hydrocarbon vapors. Both theory and experimentaldata can be applied to design and operation of commercial dehydration plants, and an illustration is presented.

Introduction

Dehydration of natural gas becomes increasingly important as the operatingpressures employed in gas processing and transmission are increased above 500lb. per sq. in. Gas produced from high-pressure wells is saturated with watervapor when it leaves the reservoir and it continues into the processing plantor transmission system in a saturated condition because of the substantialdecrease in temperature due to expansion at the wellhead. Usually this gas isaccompanied by liquid water and hydrocarbons that have condensed with thechange in temperature and pressure.

Without dehydration, gas temperatures must be held at relatively high levels toprevent solidification of gas hydrates. According to Hammerschmidt's data onthe relationship of pressure to the freezing point of natural-gas hydrates, theminimum safe operating temperatures range from 55? to 90?F for pressuresranging from 500 to 3000 lb. per sq. in., respectively. Often it is difficultto maintain gas temperatures above the hydrate-freezing temperature because ofclimatic conditions, unless flow-line heaters are installed. Also, inprocessing gas for its gasoline content at high pressures, it is desirable toemploy operating temperatures lower than the hydrate-freezing point. Indistributing high-pressure gas, the large pressure drop from line pressure totown-gate pressure often produces sufficient cooling to freeze the regulatorsand disrupt consumer service. Therefore, it is highly essential to dehydratehigh-pressure natural gas if smooth and economical operation is to bemaintained at all times.

Few published data are available on the simultaneous adsorption of water andhydrocarbon vapors.

T.P. 1628
Petroleum Engineering Education and the Quantitative Approach
Authors: Power Harry H.
Published: June 2014

The specific purposes of formal engineering education include training inthe basic sciences, the engineering-problem method, the rudimentary developmentof technical skills, an appreciation of values and costs, and an understandingof the art of engineering as distinguished from its science. Two majordivisions of an educational program in engineering are recognized:thescientific technological, andthe humanistic-social.

Hence, the entirecurriculum for the four-year program in specialized petroleum engineeringschools must be designed to give the student an initial impetus in thedirections indicated. In accordance with suggestions from the EngineeringCouncil for Professional Development, more attention is being given to thefundamental approach in the undergraduate curriculum.

This paper presents a cross-sectional viewpoint of the various educators in thepetroleum engineering schools concerning course contents in the specializedcurricula. An outline is suggested for the content of the specialized courseswherein the engineering problem method or quantitative approach is emphasized.Although the particular viewpoints of the author have been stressed, yet dueacknowledgment is made to a considerable number of petroleum engineeringeducators and engineers in industry interested in educational work, for theircontribution of course outlines or helpful suggestions with respect to programsthat will be of maximum value to students, institutions, and the industry theyserve.

Although ‘standardization’ of course material is not suggested, the advantageto be gained by cooperative determination of purpose and scope are apparent, particularly from the standpoint of the proper accreditment of petroleumengineering schools by petroleum engineering educators who have laid a basisfrom which to measure educational values. Petroleum engineering has ?come ofage? and deserves the same careful attention with respect to curricula that hasbeen accorded other engineering branches.

T.P. 1815
Average Permeabilities of Heterogeneous Oil Sands
Authors: Cardwell W.T. , Parsons R.L.
Published: June 2014

This paper discusses the practical problem of estimating a single equivalentpermeability for an oil reservoir, or a portion thereof, whose actualpermeability varies in an irregular manner. Limiting averages for general typesof permeability. variation are developed, and illustrated by examples involvingimportant, specific types of variation.

Introduction

The theory of the flow of fluids through porous media is becoming increasinglyimportant in predictions of oil-reservoir behavior. In practical applications, however, reservoirs are seldom found.to which simple theory strictly applies.Actual reservoirs have complicated shapes and non-uniform permeabilities andporosities.

This paper discusses the problem of estimating a single equivalent permeabilityfor an oil reservoir, or a segment of an oil reservoir, whose actualpermeability varies in an irregular manner. The equivalent permeability of areservoir segment is defined as the permeability of a homogeneous segment ofthe same dimensions that would pass the same flux under the same pressure drop.It is the permeability value that can be used in simple theoretical formulas tocalculate the reservoir behavior.

To the authors' knowledge, previous theoretical calculations on systems ofnon-uniform permeability have been carried out only by Muskat and he has notdealt with irregular variations, except in writing down the generaldifferential equation for the pressure in variably permeable systems. a

In practical work, many calculations necessarily have been made to estimateequivalent permeabilities from the permeability profiles obtained by coreanalyses. Regarding such calculations, Johnston and Sherborne say:

Simple arithmetic and weighted averages have been tried on many wells and ithas been found that, where frequent sampling has occurred, the arithmeticaverage is as satisfactory as a weighted average. It is possible that theapplication of statistical methods to the analysis of permeability data asrecently presented by Laws may prove fruitful.

Law has made a valuable contribution in showing how statistical analyses mayaid in picturing the characteristics of a reservoir from those of a necessarilylimited number of core samples. It is believed however that the particularproblem of the estimation of equivalent permeabilities can be most directlyapproached from a fluid dynamical viewpoint as given in the present paper. Anexample is presented of the use of the conclusions herein in conjunction withLaw's method.

T.P. 1852
Volumetric and Phase Behavior of Oil and Gas from Paloma Field
Authors: Olds R.H. , Sage B.H. , Lacey W.N.
Published: June 2014

Samples of liquid and gas were obtained from the primary separator of a well inthe Paloma field. The volumetric properties of the samples and of sixsystematically chosen mixtures of the samples were experimentally determined at100?, 190?, and 250?F. at pressures up to 5000 lb. per sq. inch.

From these data the influence of pressure and temperature upon the compositionand specific volume of the bubble-point liquid and of the retrograde dew-pointgas was established. The formation volumes and gas-oil ratios of the mixturesinvestigated were calculated on the basis of the plant-product oil, which isdefined as the isobutane and less volatile portion of each mixture. The resultsare presented in graphical and tabular form.

The volumetric behavior of the mixture corresponding to that produced by thewell at the time of sampling was determined for 235?F., the reported reservoirtemperature, by graphical interpolation of the experimental data with respectto composition and temperature. The results indicate that the well-productionmixture probably existed as a gas at its retrograde dew point under theconditions of temperature and pressure believed to prevail in the producingzone at the time of sampling.

The effect upon the phase behavior occasioned by the omission from thewell-production mixture of certain components of intermediate molecular weightwas investigated. In the first case, all of the isobutane and n-butane, andsubstantially all of the isopentane, were removed from the mixture of trapsamples corresponding to the well production. In the second case, all thepropane, isobutane and n-butane, and substantially all of the isopentane, wereremoved. Both modifications led to considerable increases in the retrogradedew-point pressure at 235?F.; an increase of 558 lb. per sq. in. above that ofthe unmodified well-production mixture in the first case, and an increase of1208 lb. per sq. in. in the second.

It was concluded that-the materials remaining after the removal of certaincomponents of intermediate molecular weight could not be injected back into thereservoir in the same proportion in which they were produced without entailingappreciable loss of liquid material through condensation within theformation.

Introduction

Under the usual conditions of production practice, petroleum arrives at thesurface of the earth in a physical state considerably different from that inwhich it existed in the underground reservoir. The relative rates of productionand the properties of oil and gas measured at surface conditions do notconstitute, in general, even a qualitative description of the fluids existingin the reservoir.

The estimation of reserves and the attainment of optimum efficiency with regardto rate, quantity, and cost of production require accurate data concerning thephysical properties of petroleum throughout large changes in pressure andtemperature.

T.P. 1861
An Engineering Study of the Lafitte Oil Field
Authors: Vance Harold
Published: June 2014

The Lafitte field, the largest oil reserve in South Louisiana is inJefferson Parish, some 25 miles due south of the City of New Orleans.

The discovery well, The Texas Company's No. I., Louisiana Land and ExplorationCo., in the southeast corner of sec. 19, T. 17 S., R. 24 E., was completed onMay IS, 1935. The initial production of this well was 960 bbl. of 34.9 A.P.I.gravity oil per day, through choke, with a tubing pressure of 1600 lb. per sq.in. Producing depth was 9558 to 9572 ft., the total depth being 9572feet.

The development of the field has been at the rate of three to eight newproducing wells per year. Up to Jan. I., 1944, 60 producing wells and three dryholes had been drilled, while two of the original producing wells had beenabandoned.

Although the field is not unitized, The Texas Company was the sole operator inthe field until the Lafitte Oil Co. completed its No. I Jefferson Parish, nearthe center of the west line of the NW /4 sec. 20, T. 17 S., R. 24 E., on July27, 1941. No additional wells have been drilled by the Lafitte OilCompany.

Drilling and Well-Completion Practices

All drilling operations have been conducted with the steam-driven rotaryequipment mounted on submersible barges.

A canal is dug to the well location and the drilling unit is floated intoposition. The seacocks are then opened and the barge settles to the bottom.After the well is completed, seacocks are closed and water is pumped out of thebarge. This procedure permits the barge, with drilling equipment still inplace, to be floated and moved? off the location.

The conventional open-hole and the gun perforation method of completing wellshas been used in this field. Where possible, the initial completion is from thedeepest sand and recompletions are made progressively up the hole, by pluggingback with cement to the upper sand and gun perforating opposite the newsand.

The oil string usually is 7% in., 26 to 34-lb. casing. Three wells have beencompleted using 9%-in. 44-lb.casing set below 10,000'Feet.

Fig. I shows the completion and recompletion practices on one well in thefield. This figure also shows the relative locations of the different producingsands as shown on the electric well log.

Structure

The structure is an elongated dome, cut by two north-south faults, whichdivides the field into three segments. The west segment is the higheststructurally and contains most of the recoverable oil and gas. The centersegment is less important and the east segment is of little value.

Figs. 2,4,6,8 and 10 are depth contour maps on top of the five main producingsands in the field.

T.P. 1869
Significance of Declining Productivity Index
Authors: Millikan C.V. , Beardmore Herbert F.
Published: June 2014

Declining Productivity Index, as considered herein, is a productivity indexthat has a substantially and consistently decreasing value when measured over aperiod of a few hours. If not recognized, it may be interpreted as representingan unsettled or unstable condition in a producing well. It forms the basis of anumber of predictions as to future performance compared with the performance ofwells in which the productivity index does not decline. The most important ofthese are that:the rate of oil production will decline more rapidly,the gas-oil ratio will usually increase abnormally,the amount of waterultimately produced will be negligible, if any,stop-cocking will increase current production and decrease gas-oil ratio.

When such relative well performance is indicated, it follows that certain reservoir performance andoperating practices may be anticipated:disappointing recovery,longernatural flow,no active water drive,better evaluation of acidizing, shooting and reworking,intermittent operation of wells,smallerpumping equipment required.

It is significant that the basis of these importantpredictions is bottom hole pressure tests that can be made immediately aftercompletion of the wells.

Introduction

"Productivity index" is the number of barrels of oil produced per dayper pound per square inch of differential pressure between the reservoir andthe bottom of the well. ?Declining Productivity Index," as consideredherein, is a productivity index that has a substantially and consistentlydecreasing value when measured over a period of a few hours.

Productivity index can be determined only when the rate of production can bestabilized. In most wells the rate of production and bottom-hole pressure ateeasily stabilized to give a constant productivity index for a period of manyhours. A few produce so erratically as to preclude probability of an acceptabletest in the usual sense. A satisfactory productivity index can be determined insome wells only by gauging the production accurately by hours, measuring thebottom-hole pressure continuously, and from these data calculating theproductivity index for successive hours. Such figures frequently will have adecreasing value-that is, a declining productivity index-and when plotted ondouble logarithmic cross-section paper with productivity index as ordinate andtime as abscissa will be a straight line curve. The angle between the curve andthe abscissa is referred to as the rate of decline.

Declining productivity index may appear to be the result of change inpermeability to oil due to decreasing saturation of oil and increasingsaturation of gas in the reservoir.

T.P. 1872
Formaldehyde as an Inhibitor of Corrosion Caused by Hydrogen Sulphide
Authors: Menaul P.L. , Dunn T.H.
Published: June 2014

This paper discusses the results of an investigation made to develop a methodof combatting corrosion of subsurface oil-well equipment caused by brinescontaining hydrogen sulphide. Carbon monoxide, aldehydes, and certain cyanidecompounds were found by laboratory tests to effectively inhibit corrosion ofsteel by sulphide brines. Experiments were made for one year in eight wells inWest Texas fields using formaldehyde as an inhibitor. It was found that theinhibitor treatment successfully prevented the severe corrosion previouslyexperienced in these wells, and effected important net savings in operatingcosts.

Introduction

Corrosion of oil-field equipment has long been a problem in areas producingsour crudes. These areas include the major fields of Arkansas, Western Kansas, West Texas and New Mexico. Corrosion in these fields is caused primarily by thechemical action of hydrogen sulphide in the presence of water and by electriccurrents entering the wells through flow lines. Hydrogen sulphide isnon-corrosive to iron or steel in the absence of water but under the usualconditions prevailing in oil wells where more or less water is present, hydrogen sulphide is very corrosive. This type of corrosion occurs over the pHrange below 9, which includes all natural oil-field brines. If air is presentin addition to hydrogen sulphide and water, corrosion proceeds at an extremelyrapid rate. It was reported several years ago that a string of oil-well tubingwas literally dissolved within 50 days where an air lift was used on a wellproducing considerable water and hydrogen sulphide. Air is generally absent inwells producing sour crude.

After hydrogen sulphide corrosion starts, it proceeds with increasing severityand its correction becomes progressively more difficult. This characteristic ofsulphide corrosion has been attributed to the formation of galvanic couplesbetween the iron and steel equipment on one hand and the products of corrosionon the other.

Severe corrosion of subsurface oil-well equipment leads to a multitude oftroubles. In addition to destruction of costly equipment, producing sands oftenare damaged by flooding with water leaking through corroded casing; badmechanical conditions may develop in a well due to obstructions caused bycorroded equipment lost in the hole, or partly collapsed casing; pumpingoperations are interfered with, and severe emulsification problems may resultfrom the homogenizing action of corroded balls and seats.

A typical case of severe corrosion caused by hydrogen sulphide was reported inHoward County, Texas, where it was necessary to pull tubing once a week torepair leaks after the tubing had been in use for only one year. On one well inthis area a string of tubing was pulled II times in 8 months; II joints oftubing being replaced because of leaks.

T.P. 1970
A Neutron Method for Measuring Saturations in Laboratory Flow Experiments
Authors: Brunner E. , Mardock E.S.
Published: June 2014

A method of measuring oil saturations in cores or sand packs by neutronscattering is described. This method permits local saturations to be measuredin a core enclosed in a steel pressure vessel without interrupting the flow.Calibration data and a saturation distribution measurement obtained with theapparatus are included by way of illustration.

Introduction

In laboratory flow experiments designed to study the mechanism of oilproduction it is frequently necessary to measure the oil saturation in a coreor sand pack containing oil, gas, and perhaps brine. It is sometimes desirablethat the saturation measurement refer to a relatively small portion of thecore, so as to eliminate end effects; that it be made without interrupting theflow, and that it be applicable to a core enclosed in a steel pressure vesselcapable of withstanding the pressures encountered in petroleum reservoirs. Noneof the usual methods of measuring saturation meets all of these requirements.To measure the gas saturation by observing the apparent compressibility of thegaseous phase would require the interruption of the flow and would give anaverage saturation for the. whole core. An electrical conductivity method isavailable for measuring brine saturations, but it is not applicable to oil. Aradioactive tracer might be used if a suitable substance could be found thatwould dissolve in the oil, emit gamma radiation, and not be adsorbed on thesand, the steel core holder, or in an aqueous phase. The large gamma-raybackground from the mass of radioactive oil in other parts of the apparatusmight, however, be undesirable.

There remain for the saturation measurement methods involving the absorption orscattering of some penetrating radiation produced outside the apparatus. Itmight be possible to use X-rays or gamma rays; but these radiations would be somuch less strongly absorbed and scattered by the oil than by the steel walls ofthe core holder and by the sand that it seems doubtful that much precisioncould be attained. In a beam of neutrons, however, there is a radiation that isvery penetrating and, moreover, its scattering by substances containinghydrogen, such as oil, is qualitatively different from that occasioned by othermaterials. It would seem possible, and has proved to be quite practicable, tomeasure oil saturations accurately under the required conditions by means ofneutron scattering. The first, to our knowledge, to suggest neutron scatteringas a means of measuring oil saturation were F. Brons and J. A. Bottema, of theAmsterdam laboratories of the Bataafache Petroleum Maatschappij, who made a fewpreliminary experiments to test the method while they were engaged in exploringthe possibilities of neutrons for well-logging purposes.

T.P. 1986
The Engineering of Oil-well Abandonments
Authors: Schoeneck William E.
Published: June 2014

This paper presents the problem of oil-well abandonment as a group of studiesinvolving the compilation of physical well data, the use of special curves, maps and interpretative procedures, in order that operations can be analyzedand means for reducing costs can be effected.

Methods for the calculation of the economic limit of production and resultantoil reserves are suggested in order that profitable production may be continuedand premature abandonment prevented.

Introduction

Purpose

Extensive studies have been made and much has been written on the proceduresfor prospecting, drilling, completion, production and repair of oil wells, butthe writer has long felt the need for a study of the procedure that should befollowed when considering the abandonment of a well. The production fromnumerous well bores of a fluid material (a circumstance peculiar to the oilindustry) that is continually decreasing in quantity leads to an increasingratio of operating cost to production. It is for this reason that oil fieldsare not abandoned as a whole and detailed consideration of each well isrequired before it can be determined whether more is being expended than willbe returned on any well or lease in question. It is the purpose of this paper, therefore, to compile, correlate, and present all matters worthy ofconsideration in the problem of oil-well abandonment; to suggest interpretativeprocedures, the possibilities for corrective measures conductive to economicalproduction, thereby extending both profitable reserves and lengths oflife.

Scope and Approach

Compiling data and outlining a study having the complexity of the problem athand and naturally subject to the personal experiences of one who undertakesthe study; however, the chosen approach and grouping of the subject materialmay be helpful in the consideration of abandonment problems. Consideration hasbeen given to wells that make gas and water incident with the production ofoil; but considerationhas not been given to either gas or wells orcondensate-producing wells, for wells of the latter type have sufficientproblems to warrant separate investigation. The major subdivisions of thispaper- physical considerations and economic considerations and economicconsiderations- do not imply that either of these phases can be consideredindependently, but rather that the two are mutually dependent and are thecomponent parts of and engineering study.

T.P. 1946
A New Technique for Determining the Porosity of Drill Cuttings
Authors: Westbrook M.A. , Redmond J.F.
Published: June 2014

A method is presented for obtaining porosities of consolidated formationsfrom the drill returns. The method provides a means of determining the bulkvolume of a large number of particles, such as drill cuttings, by employing acapillary diaphragm for removal of surplus surface liquid from saturatedcuttings having pores of capillary size, which reduces the amount of errorpresent in former attempts to determine the porosity of drill cuttings. Themethod makes it possible to obtain a considerable amount of supplementary dataon consolidated formations.

Introduction

Porosity is a direct measure of the volume of the voids in a formation. It maybe used for estimating the permeability of a formation provided that acorrelation of these two properties has been obtained from the analysis ofcores from the particular formation, and it forms a desirable aid ininterpreting electric logs. 1 These useful applications have emphasized theimportance of developing a method for determining the porosity of theformations penetrated by a well by some means other than coring, for even inexploration wells it is neither economical nor practical to core allformations. Also, in wells where at the outset the coring program appearscomprehensive, it is frequently found that, after certain layers are drilled, more complete information is required for evaluation. Porosity values, ifobtainable, would be of great assistance in such cases.

In soft formations it is usually possible to obtain porosities after drillingwith cores taken by side-wall coring devices. In hard consolidated formations, that coring procedure is not always practicable and other methods fordetermining porosities must be resorted to. A first choice is the examinationof drill cuttings, if an analytical procedure is available that is bothaccurate and reasonably rapid. Such a procedure has been devised and isapplicable to sand and limestone cuttings having pores of capillary size.Although improvements can yet be made, it is believed that the new technique issufficiently well developed to warrant description.

Preparation of Sample

The well samples containing the cuttings representative of the particularintervals are first washed through a No. 6 gauge screen. The cuttings remainingon the screen are large enough to use for the porosity measurements. From thesized sample, the cuttings to be examined are separated from the shale andother extraneous particles. It is recommended that 10 to 15 c.c. of theselected cuttings be used for measurements, although only 4 to 5 c c. were usedto make the comparative tests described later in this article. These cuttingsare extracted and dried by the same methods used for preparing core samples forporosity and other measurements.

T.P. 1943
Phase Relations of Hydrocarbon-water Systems
Authors: McKetta John J. , Katz Donald L.
Published: June 2014

Recent experimental data on the methane-butane-water system have been combinedwith data in literature to present:the water-vapor content of naturalgases,the solubility of water in hydrocarbon liquids, andthesolubility of natural gases in water.

Introduction

Since water is presented in petroleum reservoirs, experimental data regardingthe behavior of water in hydrocarbon- water systems is of increasingengineering importance. A survey of literature shows that data of these typesare fragmentary at temperatures above the hydrate region. Experimental datataken from the authors? recent investigation of the methane-n-butane-watersystem are presented. The compositions and specific volumes of the coexistingphase were determining in the three-phase region and two-phase region andtemperature of 100'F, 160'F, 220'F, and 280'F and pressures in 3000 psia.Correlations of these data with those in the literature are presented toprovide methods for predicting the behavior of naturally occurringhydrocarbon-water systems.

The water contents of various vapors, the water contents of saturatedhydrocarbon liquids, and the solubility of hydrocarbons in water will bediscussed.

Water Content of Natural Gases

The experimental data presented by Dodson and Standing relating to thecomposition of the coexisting vapor and liquid phase in the natural gas-waterand natural gas-brine system constituting the most complete source ofpublishing information concerning the behavior of heterogeneous systemsconsisting of hydrocarbons and water at elevated temperatures and pressures.Several papers report the water content of the hydrocarbon phase in equilibriumwith water. The data of these papers are in substantial agreement as to thewater concentration at given temperatures and pressures.

T.P. 2123
Use of Plastics in Consolidating Loose Sands in Wells
Authors: Smith R.H. , Polk A.C.
Published: June 2014

The physical properties of the materials are listed, together with a shortexplanation of how this material binds the sand grains together withoutmaterially reducing the effective permeability of the sand. The chemical can beused in wells with bottom-hole temperatures ranging from 105?F to more than350'F. A description of the equipment required and the techniques used forapplying these plastics to the wells is included.

Introduction

Recovering oil and gas from unconsolidated sand formations offers one of themost troublesome of all production problems. These sands generally present noparticular trouble while drilling is in progress, but after the well has beencompleted and a pressure differential has been established across the face ofthe producing zone, the formation begins to "slough," resulting in?sanding up" of the well. The term "sanding up" means thatsufficient volumes of sand have moved into the well bore or casing to cause aserious reduction or complete halt of all flow of oil, water or gas. In rarecases a well may produce only a small amount of sand and still continue to flowor pump, the sand being carried to the surface in the fluid stream. However, insuch instances, the result may be a costly repair bill due to the effect of thesand on surface and pumping equipment.

The difficulty of producing petroleum from sands that are loosely cemented haslong been recognized by petroleum engineers but only within the last few yearshas any new approach to the problem been undertaken. This involves the use ofplastics that are capable of bonding the individual sand grains in placewithout materially reducing the effective permeability of a formation.

The successful application of plastics for the consolidation of poorly cementedsands is relatively recent but now it is widely used in many of the moredifficult areas on the Gulf Coast of Texas and Louisiana.

This relatively new use of plastics in the oil fields has been preceded by muchlaboratory and field research on the use of various chemicals for solvingnumerous well-completion and work-over problems. Plastics now are being usedsuccessfully to control gas-oil and water-oil ratios, in zone isolation, therepair of casing leaks, the elimination of caving in cable tool drilling wellsand in the setting of liners and casing. Sand-consolidating plastics, however, are basically different from all others in that they must not form animpervious seal.

Field Practices

The approach to the sanding-up problem usually has been the mechanicalobstruction of the movement of the sand grains.

T.P. 2147
Apparatus for Determination of Volumetric Behavior of Fluids
Authors: Sage B.H. , Lacey W.N.
Published: June 2014

Apparatus and a method for determining the volumetric behavior of hydrocarbonsat pressures up to 10,000 psi and at temperatures between 0? and 460'F aredescribed. The equipment is suitable for measuring the total volume of thesystem and the volume of a liquid phase as functions of state within theseranges of temperature and pressure.

Introduction

During the past two decades there has been a marked increase in the ranges oftemperature and pressure encountered in underground hydrocarbon reservoirs ofcommercial interest. In addition, greater interest in the intensivecharacteristics of the fluids found in these reservoirs has developed.

Apparatus

Several types of apparatus have been developed in the authors' laboratory forvolumetric measurements of hydrocarbon systems. The earliest equipmentdescribed was characterized by constant volume, and the weight of materialpresent was varied systematically in order to attain the different pressuresdesired in the study. Later another apparatus was built in which the effectivevolume of the cylindrical cell, which confined a hydrocarbon sample of constantweight was varied by injection or withdrawal of mercury. The effective totalvolume of the equilibrium cell was measured by ascertaining the position of themercury surface but no measurement could be made which gave knowledge of thevolumes of individual phases existing within the hydrocarbon system.

A third apparatus was designed for use at higher pressures and temperaturesthan the earlier equipment would tolerate. This apparatus was of the variablevolume type but was built in the general form of a U-tube, the mercury levelbeing measured at the surface which was not exposed to the hydrocarbon system.This arrangement avoided the need of subjecting measuring equipment to theextremes of temperature at which studies were made, but it gave no provisionfor measurement of the volumes of individual phases. Although this lastapparatus was satisfactory as to accuracy and convenience for many purposes, need was felt for measurements of the volume of the liquid phase of thehydrocarbon system.

For this reason a fourth equilibrium apparatus was designed and constructed andit is the purpose of the present paper to describe it. The equilibrium cell hasa working range of temperature from 0? to 460'F at pressures up to 10,000 psi.Provision for measurement of both total volume and liquid-phase volume makes itparticularly suitable for the equilibrium study of heterogeneous systemsconsisting either of simple mixtures or of complex field samples ofhydrocarbons.

T.P. 2269
Some Aspects of High Pressures in the D-7 Zone of the Ventura Avenue Field
Authors: Watts E.V.
Published: June 2014

The D-7 zone of the Ventura Avenue field is of special interest because theinitial reservoir pressure at 9200'Ft nearly equaled the pressure exerted bythe overburden. While the phenomenon has been observed elsewhere in the world, there is no record of a previous case in California. Such high pressures havebeen attributed to sealing of the reservoir, followed either by emergence ofthe beds or by compaction of the sediments in various ways. Oil in the D-7 zoneis undersaturated. At pressures above the bubble point, oil is recovered by theslight expansibility of the reservoir framework and its liquid contents. Morethan 40 pct as much oil probably will be recovered by this mechanism as will berecovered by internal gas drive after pressures pass below the bubble point.Operations are handicapped by sand and pipe troubles.

Introduction

The Ventura Avenue field has been under development since 1915. It has longbeen considered a "high-pressure" field, but interest was heightened bythe extreme conditions encountered in the recent development of the so-calledD-7 zone. The original reservoir pressure in this pool is estimated to havebeen 8300 psi at a depth of 9000'Ft below sea level, or 9200 ? ft below thesurface.

A fluid pressure approaching that exerted by the overlying sediments has beenencountered in other parts of the world, but never before in California to thedegree observed in the D-7 pool.

With few exceptions, the original pressure in California fields is aboutequivalent to the static head of water below the water table in theoutcrop.

Structure

The Ventura anticline is a prominent feature of the Ventura basin, beingtraceable on the surface about 17 miles. The Ventura Avenue field is at theapex.of the anticline. It is about one mile wide and five miles long, themajor axis lying in an east-west direction. The productive limits cover an areaof about 2300 acres.

The entire anticline has been severely folded and faulted. The productiveportions in particular are broken up by three major thrust faults having ageneral east-west strike. The resultant four fault blocks are termed the A, B, C, and D blocks, respectively. Certain electric-log intervals are assignednumbers. Fig 1 is a diagrammatic north-south section of the field near thecrest, looking west, and shows three of the four fault blocks. To the west, theupper fault divides into two branches, which define the B block.

Wells penetrating a fault may duplicate over 1000'Ft of formation. However, thegreater fault movement is the strike shift, which is believed to exceed 2500'Ftboth between the A and C blocks and between the C and D blocks.

The location of water is irregular and unpredictable. A few intermediate watersexist, while some strata have more than 2000'Ft of productive closure.

T.P. 2204