bluuebunny/crossref_metadata_2025 huggingface dataset:
SP Log Interpretation in Shaly Sands
Authors: Smits L.J.M.
Published: June 2014

A theoretical equation is developed describing membrane potentials of shaly sands as a function of the cation-exchange capacity per unit pore volume of the rock and saturating water salinity. This equation is based on the same simple physical model as that employed earlier describing the electrical conductivity of shaly sands. Experiments conducted with NaCl solutions showed that the equation is obeyed, except in the case of saturated salt solutions where minor deviations were observed. A possible explanation is given for this discrepancy.

As the clay content and the porosity of shales may vary appreciably, shale membrane potentials also vary. It was found that membrane potentials of shales can be calculated accurately with the aid of the same theory. Consequently, changes in membrane potentials can be accounted for by simple measurement of cation-exchange capacities per unit pore volume of both shales and shaly sands. Charts are given to facilitate interpretation of the electrochemical part of the SP in terms of cation-exchange capacities and the salinities of mud filtrate and formation water.

Introduction

A spontaneous potential (SP) log is a record of the way in which the electrical potential of a sonde varies as it passes down a borehole. Such variations frequently reflect rock texture, e.g., permeable beds intercalated in an impermeable series often are indicated by a sharp change in potential. Nowadays it is recognized that SP logs may be interpreted in terms of formation-water salinity and formation shaliness.
The Interpretation of Interference Tests in Naturally Fractured Reservoirs with Uniform Fracture Distribution
Authors: Kazemi H. , Seth M.S. , Thomas G.W.
Published: June 2014

The double-porosity model of Warren and Root for examining pressure drawdown and buildup phenomena in naturally fractured reservoirs has been extended to interpret interference test results. Both analytical and numerical solutions are presented. The practicality of some of the assumptions in the Warren-Root model was also investigated.

The standard procedure for interpreting interference tests in naturally fractured reservoirs heretofore employed an equivalent homogeneous reservoir model. A comparison of our results with the equivalent homogeneous model indicates the latter is inadequate for early time responses. For late time responses, however, the simpler equivalent homogeneous model yields favorable results. Finally, the effects of well spacing and the magnitude of the interporosity flow parameter are briefly cited.

Introduction

Interference tests can be used to provide reservoir information not obtainable from conventional pressure drawdown and buildup tests. The technique involves measuring the response in one or more wells arising from a pressure perturbation introduced into another well. It has been successfully applied to single-layer, homogeneous, unfractured, isotropic and anisotropic formations to arrive at values of well storage capacity and a measure of directional permeability.
Generalization of Wellbore Effects in Pressure Transient Analysis
Authors: Fair W. B.
Published: June 2014

Wellbore effects have been recognized as being important in the analysis of pressure transient tests for many years. Other works have evaluated the effects of wellbore storage and phase redistribution on pressure transient response and analysis methods which account for these effects are well known. It is also known, however, that other wellbore phenomena may affect pressure transient response, but little has been presented which evaluates or generalizes wellbore phenomena in common pressure transient tests.

This paper presents an analysis of generalized wellbore phenomena, including both mass related and momentum affects, shows how these are incorporated into general solutions of the diffusivity equation, and provides general guidelines for recognizing these effects in pressure transient data. In addition, it is shown that the phase redistribution formulation for pressure transient analysis is actually a special case of wellbore mass related phenomena which has much wider applicability than previously realized. Besides general methods for accounting for wellbore phenomena, analytical pressure solutions are also presented for several situations, including heating or cooling of wellbore fluids, phase changes in the wellbore and inertial effects due to rapid acceleration or deceleration of wellbore fluids.
Quantitative Interpretation of Thermal Neutron Decay Time Logs: Part I. Fundamentals and Techniques
Authors: Clavier C. , Hoyle W. , Meunier D.
Published: June 2014

Introduction

The thermal decay time (TDT) log is based on a measurement of the rate of decay (absorption) of thermal neutrons in a formation. The principle of such logs has been described in detail elsewhere. In Ref. 4 the special features (capture gamma ray detection, Sliding Gate detection system) of the thermal neutron decay time log are described.

Chlorine is by far the strongest neutron absorber of the common earth elements, and the thermal neutron decay time, T, is determined primarily by the sodium chloride present in the formation water. Like the resistivity log, therefore, the thermal neutron decay time measurement is sensitive to the salinity and amount of formation water present in the pore volume. Unlike the resistivity log, this log can be run in cased hole.

Also, the thermal decay time log is relatively unaffected by drilling and completion conditions for the usual borehole and casing sizes encountered over pay zones. Consequently, when formation water salinity permits, this log can detect the presence of hydrocarbons in formations that have been cased, as well as changes in water saturation during the production life of the well. The log is thus useful for evaluating oil wells, for diagnosing production problems, and for following reservoir performance. With a version of the tool that is 1 11/16 in. in diameter, it is possible to enter a producing well through the tubing under pressure without having to kill the well.
Quantitative Interpretation of Thermal Neutron Decay Time Logs: Part II. Interpretation Example, Interpretation Accuracy, and Time-Lapse Technique
Authors: Clavier C. , Hoyle W. , Meunier D.
Published: June 2014

Introduction

In the second of this two-part treatment of the subject, three main topics will be discussed.The interpretation techniques developed in Part I will be illustrated with an example in a Middle East well. The thermal decay time log was made with a 1 11/16-in. tool lowered through tubing. Neutron and gamma ray logs furnish the necessary porosity and shaliness data. The final results are presented as a computer-produced log.A study is made of the errors that may be tolerated in each of the following items appearing in the equation for water saturation: Slog, Sma, Sh, Sw, Ssh, øe, and Vsh. "Tolerance factors" for each enable the analyst to evaluate the accuracy of actual log interpretation.The time-lapse technique is discussed. In this method two thermal decay time logs are compared, the first one being a reference log run early in the production life of the well. This comparison provides a more accurate evaluation of changes in saturation. The degree of accuracy can be evaluated by means of tolerance factors provided as a result of the error study.

Interpretation Example

Gamma ray, neutron, decay time (run through tubing), and induction-log conductivity curves over an interval of a typical Middle East well are shown on Fig. 1.
Effect of Treatment Parameters on the Geometry of a Hydraulic Fracture
Authors: Daneshy Abbas Ali , Williams James R. , Tinsley John M.
Published: June 2014

The parameters influencing the geometry of a hydraulic fracture are divided into three categories:those upon which there is no control, such as Young's modulus and Poisson's ratio of the formation, far-field stress and the reservoir pressure,those which are easily controlled such as treatment-fluid viscosity and time andthose which are partially changeable, like fluid leak-off and injection rate.

In this paper a study is made of the effects of each individual parameter on the geometry of a hydraulic fracture. Based on the findings reported here, it is concluded that at the present time the treatment-fluid viscosity appears to be the most promising factor for influencing the geometry. Increasing the viscosity has two effects. Directly, it increases the width of the generated fracture, thus yielding better conditions for the transportation of the propping agents. Indirectly, it reduces the volume of fluid lost as leak-off.

Another important conclusion of the paper is that the computed fracture geometries are, to a large degree, influenced by the assumed value of the fracture height. A "reasonable" geometry can be obtained only if one assumes a "reasonable" value for the fracture height.
The Analysis of Single-Well Pulse Tests in a Finite-Acting Slab Reservoir
Authors: Falade Gabriel K. , Brigham William E.
Published: June 2014

Introduction

Most of the published literature on pulse testing has concentrated on the analysis of pulse tests in infinite domains. Few known comprehensive analyses have been made on tests in finite-acting domains. This is despite the known fact that pulse test results based on the simple infinite model are subject to serious errors if boundary effects are present.

This paper is an illustration of the practical application of the theoretical model presented by Falade and Brigham on "The Dynamics of Vertical Pulse Testing in a Slab Reservoir" with special considerations for the boundary effects.

Review of Model

The transient pressure response due to equal and alternating periods of shut-in and injection (or production) into a test well during vertical pulse testing in a slab reservoir can be described as follows.
Fuel Oil in the Southwest With a Bibliography of Fuel Oil Generally
Authors: Phillips William B.
Published: June 2014

This paper was prepared at the request of Capt. A. F. Lucas, Chair man ofthe Institute's Committee on Petroleum and Gas, as a preliminary discussion ofthe fuel oils which are used in the Southwest, giving their composition, uses, prices, etc. Should it afterward be found desirable, these observations may beextended over a larger area. In this connection, I suggest that samples of allkinds of fuel oils, including various tars, from all over the country, becollected and sent to some testing laboratory for examination. We would be gladto extend the facilities of the laboratory of the Bureau of Economic Geologyand Technology, at the University of Texas, for this purpose, and to do thework free of all expenses. After such examinations are made and the resultsclassified and studied, it would be possible to suggest specifications underwhich fuel oils should be purchased, and to arrive at some conclusionsrespecting the uniformity of such specifications, with due allowance forclimatic and other more or less local conditions. While such specifications donot now depart from a common standard anything like as much as specificationsfor illuminating oils do, yet there are discrepancies which should not exist.Some of these discrepancies are of lessening importance, due to the pronouncedtendency to distill every crude oil that can be distilled with profit, and tosend residues into the market for fuel oil. Residues from the refineries are ofa more uniform chemical composition and physical nature than many of the crudeoils that go direct into the fuel market.

The lower flash-point oils are disappearing from the fuel trade and in place ofthem we are getting oils that do not flash below 220? F., nor burn under 320?F. In the Southwest, it has not been long since we had fuel oils that flashedas low as 110? F, and the average flash point over a considerable period was151? F. Now we are using oil that flashes at about 30? lower than the formerburning point, which was 258? F. In other words, the flash point has risen, onthe average, 100?; and the burning point about 75?.

AIME 048–47
Cementing Oil and Gas Wells
Authors: Knapp I.N.
Published: June 2014

Foreword

I herewith present some notes on the use of Portland cement to cement in thecasing, and for plugging, to exclude water from oil and gas, wells, and the methods employed. I have used my best efforts to make each step of theoperation of cementing wells perfectly clear. The information is the result of actual experience and observation. The illustrations are from original drawingsmade especially for this paper.

Portland Cement

It is not necessary to discuss here the manufacture of cement. Anyestablished brand of the slower setting Portland cements may be purchased withthe confidence that it will harden, if properly used, and exclude water fromand plug wells efficiently.

Setting.- By the setting of cement is meant its initial change from a soft orplastic mortar to a friable solid. After the cement has become thoroughly set it is still very weak and can be readily pulverized in thefingers. Setting is thought to be effected by the crystallizing out of the silicate and the aluminate of lime, which are soluble in water in theiranhydrous form. After dissolving in the water they pass to the hydrated state, in which they are insoluble, and hence are precipitated in acrystal line form.

Ordinarily neat Portland cement mortar remains perfectly plastic for from 1 to 1 1/2 hr. after mixing with water at about 70 degrees F. A highertemperature accelerates and a lower retards setting.

Hardening.-This is due to a continual crystallization of salts fromsolution, and to further chemical and physical changes which develop slowly, but which continue for long periods of time.

Testing.-It is no more necessary for an operator to go into the scientifictesting of cement to be used in a well than to so test the pipe used. He must depend for the quality of each on the tests and reliabilityof the manufacturer. Cement or pipe may be damaged in shipment so as to be unfit for use and such damaged material can easily be avoided by proper inspection.

A practical test of cement can be made in advance of its use for thispurpose by filling a common galvanized-iron bucket one-third full of water and stirring in neat cement until the mixture is as stiff as it can bemade and still be fluid enough to pour or pump. Then fill several tin cans (oldfruit cans will do) with the mixture and at once immerse these samples inwater. Take out one sample in 24 hr. and examine for set and hardness, anotherin 48 hr., and so on daily for a week. Thus a fair idea of how a given cementwill act in use may be formed.

AIME 048–51
Oil in Southern Tamaulipas, Mexico
Authors: Ordonez Ezequiel
Published: June 2014

The great activity with which the oil resources of the northern Cantons ofthe State of Veracruz have been developed has largely resulted from the greatsuccess obtained by the important explorations carried out since 1902 in theEbano district in the North, and several years later near Tuxpam, in the South.It must not be thought that these successes were quickly obtained, since thepreliminary studies by good experts, the acquisition of what were thought to bethe most promising coast lands, the extensive clearing thereof, and finally thenumber of unsuccessful drillings at great depth, signified an original outlayof some tens of millions of dollars before finding commercial oil.

The discovery of oil in industrial quantities at Cerro de la Pez, Ebanodistrict, and the famous Dos Bocas gusher some years later, which was burned, once and for all made famous the Veracruz coast, where today is concentratedthe Mexican output of mineral oil. In 1917, this production was nearly61,000,000 bbl. It is well known that this output represents only a fraction ofwhat the wells in actual production can furnish, because with adequate means oftransportation and storage, the present extraction could be somewhat over300,000,000 bbl. a year.

These enormous potential oil resources of the Veracruz coast proceed from arelatively small number of wells, scattered over a few oil fields, separatedfrom each other by large unexplored areas, wherein may be found other favorablefields which, in time, will undoubtedly become just as great centers of oilproduction.

Experts who know our Gulf Coast believe that lands with commercial oilresources lie not only between the Panuco and Tuxpan Rivers, but thatindications are that the oil zone of Mexico, with more or less interruption, takes in the coast zone from Northern Tamaulipas to the foot of the SierraMadre of Chiapas, and the banks of the Usumacinta River. This generalization isnot merely the outcome of optimism, but is the result of the persistency withwhich one finds, throughout this Gulf Coast, the most usual characteristicsupon which we depend for recognizing oil-bearing lands.

AIME 061–48
Cement Plugging for Exclusion of Bottom Water in the Augusta Field, Kansas
Authors: Shidel H.R.
Published: June 2014

This paper summarizes the results obtained from the preliminary cementing of wells in an effort to cut off the bottom water. The object of this work was two-fold:To prevent the oil sand from becoming flooded.To plug off bottom water, thereby preserving the individual well and reclaiming production.

Valuable suggestions and help have been given by the following named: Messrs. Kyle and La Velle, of the U. S. Bureau of Mines; Magnolia Petroleum Co.; Freed Oil and Gas Co. The cementing work was carried out under the personal supervision of L. J. Snyder.

In an unpublished paper on the "Water Problem in the Augusta Field," S. K. Clark reaches the following conclusions:That the great amount of water present is bottom water, occurring in the Varner sand, the main producing or the 2500-ft. horizon.That the only striking connection between structure and water is in the area of the marked fault on the Ralston, E. C. Varner, and F. Varner leases in sections 8, 9, 16 and 17.That the oil occurs in porous streaks, generally separated by fine-grained, well cemented sand, which is barren. Possibly two or three such pay streaks may be found. That under a pay, fine-grained sand occurs, which is presumably barren at the time of drilling, but soon reveals water.

The writer takes partial exception to the last point, because well defined shale, slate, lime, or hard sand breaks have been encountered in a great many cases, separating the pay streaks under which water is often found. This is not an invariable occurrence, as cases have been noted when the oil has been followed immediately by water in the same stratum.

In an effort to overcome the water menace, the following methods of plugging were tried:Plugging with wood, lead, and limit plugs.Plugging with sand pumpings.

AIME 061–53
Petroleum Industry of Trinidad
Authors: Macready George A.
Published: June 2014

Trinidad, British West Indies, is an island near the north coast of SouthAmerica, situated between latitudes 10? and 11? N., and opposite the numerousoutlets of the Orinoco River Delta. It is separated from Venezuela by the Gulfof Paria (salt water) and straits over 5 mi. (8 km.) wide. The area of theisland is approximately 1750 sq. mi. (453,250 hectares) and the population isapproximately 400,000. The climate is tropical with an annual rainfall of from45 to 60 in. (114 to 152 cm.).

The oil fields consist of several units, or fields, located in the southernhalf of the island. Approximately 90 per cent. of the total production has beenyielded by fields situated within 7 mi. (11.3 km.) of the famous asphalt lakeand on the southwest peninsula.

The most important producing fields, or units, are the following, which areshown on the accompanying map:

Brighton, or Pitch Lake Field, operated by the Trinidad Lake Petroleum Co., Ltd., is situated beside the famous Pitch Lake; it even encroaches on thelake.

Vessigny Field, operated by the Trinidad Lake Petroleum Co., Ltd., is situated2 mi. (3.2 km.) south of Pitch Lake.

Lot One Field, operated by the Petroleum Development Co., Ltd., the UnitedBritish Oilfields of Trinidad, Ltd., and Stollmeyer, Ltd., is situated 3 mi.south of Pitch Lake upon Lot One of Morne l'Enfer Forest Reserve and adjoiningproperties.

Parry Lands Field, operated by the United British Oilfields of Trinidad, Ltd., and the Petroleum Development Co., Ltd., is situated 3? mi. south of Pitch Lakeon Lot Three of Morne l'Enfer Forest Reserve and adjoining properties.

Point Fortin Field, operated by the United British Oilfields of Trinidad, Ltd., is situated at Point Fortin, 6 mi. southwest of Pitch Lake.

Fyzabad Field, operated by Trinidad Leaseholds, Ltd., is situated several milessouthwest of Fyzabad Village and 6 mi. south-southeast of Pitch Lake.

Barracpore Field, operated by Trinidad Leaseholds, Ltd., is situated severalmiles south of San Fernando and 15 mi. (24.14 km.) east of Pitch Lake.

AIME 065–10
Drilling and Production Technique in the Baku Oil Fields
Authors: Knapp Arthur
Published: June 2014

No oil territory in the world has been so rich in large producing wells, ina comparatively small area, as the Baku field. Particularly is this true of theBibi Eibat field, which formerly produced millions of ?poods? of ?gusher,? oras it is called in Russia, ?fountain? oil. The Bibi Eibat and Balachany fieldshave been exhausted of gas and ruined by water, but, the Surachany andBenegadi fields are still fountain territories and many outlying districts thathave only been prospected produce rich fountains.

The method of controlling fountains, or gushers, is the result of growth, alongwith the Russian system of drilling, where large diameters and riveted casinghave been in vogue. The screw casing is seldom used except to exclude water.Formerly the method of finishing wells and the condition of the casing at thetop of the well would not permit the use of gates, manifolds, and connectionsas is standard elsewhere.

The life of the flowing wells is very short, particularly those 10 in. (25 cm.)or more in diameter, which produce large quantities of sand and often flow forbut a few days and are then a complete loss. More than 1,000,000 poods in 24hr. have been claimed in several instances, but in no case was the flow formore than a few days.

The oil sands of this district are free uncemented sands and vary in thicknessfrom paper thin to a maximum of 10 ft. (3 m.). The sands are interlaid withstrata of soft clay. In spite of this, the practice has been to drill into suchsands and produce from the open hole without screen or liners. Sometimes thecasing is set below the oil sand but in this case holes from 2? to 3 in. indiameter are drilled opposite the oil sand, which would not have the effect ofa screen.

Fig. 1 is an outline of the fountain shield ready for the control of afountain. It is composed of an inner and an outer covering made from roughboards. The framework is made of rough round poles. When a light flow isexpected, only the inner lining is built; and when the fountain comes inunexpectedly, it is often possible to build only the outer cover. The bridge isfor the purpose of renewing the blocks as they become worn by the flow. Thelower block, as here shown, is made of hardwood and is bolted to the crossbeamswith brass bolts. The grain end is toward the flow. The upper block, as shownhere, is made of cast steel and is also bolted to the cross beam with brassbolts.

AIME 065–42
Efficiency in Use of Oil as Fuel
Authors: Best W.N.
Published: June 2014

This paper is not intended as a scientific discussion of the combustion ofoil but is written from the standpoint of an operator who has the experienceand qualifications necessary to guide others in producing the most economicalresults in the use of liquid fuels. Oil, in this paper, usually means petroleumor its products but incidental reference is made to other liquid and gaseousfuels, so that the term may be considered as referring to all liquid andgaseous hydrocarbons in comparison with solid fuels, as coal and wood. However, only a few of the principal factors in the use of oil as a fuel can begiven.

The present, and prospective, high price of coal is causing users of fuel torenew inquiry as to the merits of other forms of fuel for industrial purposes.Crude oil (petroleum) is proving to be one of the world's most valuable mineralresources. The recent discovery that oil underlies a considerable area of theUnited States, Mexico, and other parts of the world to a greater extent thanwas formerly believed and the large production of some of the wells in theseareas shows the probable quantity of fuel oil that may now be available.Through the energy of Lord Cowdrey, who was one of the pioneers of the oilindustry in Mexico, oil has been discovered in England; some prominentgeologists believe that it may be found in quantity in Great Britain.

For years, oil has been known to be of great value in the manufacture ofmetals. It has proved incomparable in forge shops, steel foundries, heat-treating furnaces, and wherever accuracy of temperatures is essential, orwhere a maximum output is desired as well as quality of metal. In some types ofequipment, the output produced with oil as fuel is double that obtained withcoal and at a reduction of 50 per cent. in the cost of the fuel. For example, in drop-forging plants, the metal is always waiting for the man when oil isused as fuel, whereas with coal, the man must wait for the metal to becomesufficiently heated.

It has only been since January, 1919, that the oil supply could be relied onfor boiler service, owing to the war conditions and the inability to get oiltankers for the delivery of the oil from Mexico to Atlantic ports; but now aconstant supply is assured, and many manufacturers are installing it in theirpower plants.

AIME 065–48
A Possible Origin of Oil
Authors: Rae Colin C.
Published: June 2014

The absence of paraffin and other oil hydrocarbons in the soil although theyare concentrated in extensive deposits in some localities, the commondistribution of plant remains through many formations that are not productivefor oil, and many other factors, seem to indicate the existence of anintermediate organic compound between the complex plant compounds and thepetroleum hydrocarbons; and much evidence points to the humus acids orassociated organic compounds, which are probably collected by surface watersand concentrated in certain areas by means of precipitation by electrolytes, which would be contained in sea water or possibly in various inland seas orlakes.

Present-Day Evidence

There are many present-day evidences of the association of petroleum withhumus acids. Binney, in 1912, made observations without explanations on thepeat mosses of Down Holland, England, where he found petroleum being formed bydecomposition in the presence of an infiltration of sea water. The analysis ofa typical peat will show its relationship to the humus acids underconsideration.

J. D. Haseman and others have noted the association of asphalt andhydrocarbons with the swampy, boggy areas, particularly adjacent to thesea.

Many of the rivers carry much humus acid in solution, and some tropicalrivers carry in the aggregate millions of tons of humus each year. The amountof humus is a variable factor, depending on climatic conditions, and on thesalts and alkalies present in the water, also on the density andtemperature.

AIME 068–81
The Electrical Dehydration of Cut Oil
Authors: Mahone F.D.
Published: June 2014

Much crude oil, as produced from the well, carries varying amounts of water, which may be present as free water in globules sufficiently large to settleout, in time, if the fluid is allowed to stand, or as an emulsion formed bymyriads of minute water particles, each surrounded and entrapped by a film ofoil through which it cannot break under the action of gravity alone. Such anemulsified mixture of oil and water is commonly termed "cut oil."

When such an emulsion is subjected, under proper conditions, to theinfluence of a high-potential alternating-current field, the minute waterparticles rupture the enveloping oil films and coalesce into larger waterdroplets this procedure continuing until all the water is freed into drops ofsuch size that they readily settle out. This action has been photographed bythe micro-moving-picture camera; under the microscope, the breaking-up of theemulsion, as described, is seen to be accomplished in a few seconds.

The low power requirements of the process, from records of commercialplants, substantiate the theory that the action is that of a multitude ofelectrical condensers in series, rather than that of a number of conductingpaths. The minute water particles serve as the metallic elements, or plates, ofthe condensers and the separating oil acts as the dielectric. Such surfacecharges as the particles may have are removed, and the intervening oil isbroken, probably electrically by the voltage and mechanically by the attractiveforce between adjacent oppositely electrified particles.

The principle of breaking up an emulsion under the influence of analternating electric field was discovered by F. G. Cottrell and Buckner Speed, through experiments conducted, at the University of California, which resultedin a plant being installed on the property of the Lucile Oil Co. in theCoalinga field, California, early in 1909. This plant was able to reduce 14-percent. emulsion to less than 2-per cent. with commercial success.

AIME 070–58
Separation and Purification of Liquids by Centrifugation, with Special Reference to Petroleum
Authors: Meston A.F.
Published: June 2014

Centrifugal force has been used for centuries for separating liquids butmachines for doing this are a comparatively recent development. The use ofthese machines is being extended into many industries but this paper isconfined to their use in the oil industry. The centrifugal machine is found atthe well where ?cut oil? is dehydrated for acceptance by pipe lines; and in therefinery and byproduct plant. In fact, wherever finely divided suspendedparticles should be removed from an oil, there is a possible use for acentrifugal machine, if the particles have, or can be made to have, a specificgravity different from that of the oil. Centrifugal machines are also used forcleaning fuel and lubricating oils and dehydrating transformer oils.

Applications and Results

When oil comes from the well mixed with water, it is spoken of as cut oil.Settling often does not remove sufficient water for the oil to be accepted bypipe lines, thus necessitating chemical or other treatment. Centrifuging alone, or following chemical treatment, effectively prepares such oil for pipe lines, as is shown by the following data:

On the Oklahoma lease, the machine was cleaned of solid material once in 12hr. At first, it was thought that chemical treatment was necessary to startseparation and 1 qt. of prepared compound was added to each 100 bbl. of the cutoil before centrifuging.

AIME 070–59
Use of Gas Meters for Determination of Pay Strata in Oil Sands
Authors: Millikan C.V.
Published: June 2014

When a flowing oil well is being drilled in with cable tools, it isdifficult to determine when an additional streak of pay sand is drilled. Byplacing a gas meter on the gas-release line from the oil and gas separator, anyincrease in volume of gas that comes with oil production is recorded. Inaddition to the better knowledge of sand conditions, these data are a valuableaid in determining the size and depth of shots, plugging off water, andestimating ultimate production. The meter also gives a record of operationwhile the well is drilling in; and if allowed to remain on the well aftercompletion will give information that may lead to a more efficient recovery ofthe oil from the sand.

A vertical cross section of any oil sand will show great variation inporosity and oil content. In some sands, the entire thickness contains oil, thevariation being only the degree of porosity or oil content, but more often thepay streaks are distinctly separated by shells or barren streaks. These paystrata vary in number and may be thin or thick. The total thickness of the sandmay be several tens of feet while the part containing oil may be only 1 or 2ft. thick. The amount of production is not proportional to the thickness of thesand but rather the thickness of the pay streaks.

If the total thickness of the sand or the amount that can be drilled issmall, or if the initial production is small, the depth at which each stratumof pay is encountered can be determined sufficiently accurately for all presenteconomic purposes. However, when drilling through sand of considerablethickness, giving large initial production, especially where conditionsnecessitate that the production go through the same gas trap with that from oneor more wells already producing, it is difficult to determine the depth atwhich the pay strata are encountered even accurately enough to guide theplacing of shots, and small pay streaks are apt not to be recognized atall.
The Sanding of Oil Wells
Authors: Suman John R.
Published: June 2014

Excepting the very few oil fields of the world in which the production comesfrom a limestone formation, the greatest problems encountered in oil wells comefrom trouble caused by sand. These troubles are brought about by sandaccumulating in the strainer, liner, tubing, or cutting out various parts ofthe well equipment. The remarks here made are intended to apply to theso-called "soft sand" producing areas such as those of California andthe Gulf Coast of Texas and Louisiana. However, there are certain features ofsanding problems in pumping wells which are almost universal.

In the "soft sand" producing districts such as California or the Gulf of Texas and Louisiana, wells often come in flowing at the rate of severalthousand barrels of oil per day, and after flowing a few hours, "sandup." In many cases it will be found that when the sand is cleaned out ofthe strainer or liner, and the well again starts flowing the production will bebut a small fraction of what it was originally. Many and varied opinions havebeen handed down by oil men to account for this condition.

The most satisfactory explanation of this failure of wells to come back toinitial flow, after once sanding, will be found from a close study of theproducing formations. It will usually be found that the oil-producing zoneconsists of alternating layers of sand and shale. In the Gulf Coast districtthese alternating layers may be only a few feet or a few inches thick. When thewell blows out or starts to flow with an accompaniment of strong gas pressurethe sand is blown into the hole through the screen, strainer, or perforatedpipe. Large quantities of sand quite commonly accompany these flows. Theholding of back pressure on the wells by use of "flow beans," etc., tends to hold back the sand. Also the use of fine-gage screen helps to hold thesand back; but if the pressure is very strong and the gas is present the screenis usually cut out in short order.

The explanation of the failure of the well to "come-back" afterbeing cleaned out, consequent to the initial sanding up, will be found back ofthe liner or screen.
Waters of the Salt Creek Field, Wyo.
Authors: Young H.W. , Estabrook E.L.
Published: June 2014

The analysis of oil field waters in the Salt Creek field as an aid in fielddevelopment and operation was begun by the Midwest Refining Co. in a systematicway during the spring of 1923. Previous to that time some samples had beentaken for analysis but uncertainty as to the sampling methods employed casts acloud on all these early analyses.

Sands

In the Salt Creek field there are at present five sands which are of specialinterest from the standpoint of the character of the waters which they contain, the Shannon, the First Wall Creek, the Second Wall Creek, the Lakota, and theSundance. There is a Third Wall Creek sand but it is so unevenly distributedthat it hardly seems possible that analyses of water from this source will beof any great benefit. Occasionally water is found in shale crevices above theFirst Wall Creek sand, and has also been found in the Dakota sand within 900ft. structurally of the apex of the dome.

The First Wall Creek sand is divided into two distinct layers, or benches, by an impervious layer of shale or limy sand. The lower bench contains muchmore water than the upper bench. No attempt has been made to distinguishbetween the waters of the two benches. By far the greater number of the watersamples that have been analyzed have come from the First sand.

In certain sections of the field the Second Wall Creek sand is divided intoseveral benches by layers of shale or bentonite, but these layers are notcontinuous as is the dividing bed in the First sand. Comparatively few watersamples have been obtained from the Second sand, as the number of edge wellsthat have been drilled into water is small.

The Lakota sand, like the First Wall Creek sand, is divided into two membersby an impervious layer of shale. Edge water is found in both members, but atslightly different levels. Since comparatively few wells have reached thissand, not many water samples have been obtained.
Theories of Normal Production and Methods of Introducing Gas and Air to Increase Normal Recovery
Authors: Brundred L.L.
Published: June 2014

In one respect only does the oil business compare with the mining industry.They both have for definite purpose the production, refining and marketing ofnatural resources found beneath the surface of the ground. The methods ofobtaining this production are so entirely different that the field engineermust, of necessity, be definitely trained to solve the problems confronting theparticular industry he hopes to enter. Of prime importance to both is thesubsurface information available. Here the mining engineer, by sinking hisshaft and cutting his laterals, is able to examine with the naked eye hisproductive formations. Not so with the petroleum engineer. At best, he has onlythe small cores taken at random to furnish information on the measurespenetrated. As we propose to advance certain theories of oil production, let usfirst examine what subsurface information is available.

Producing Formations

Roughly speaking, it may be said that our present oil production is obtainedfrom the following formations, their importance as producing strata occurringin the order named:sand,sandy shale,porous lime,sandy lime,crevices in either sand, lime or shale, andoil-bearing shales.

Classes1 and 2, sand and sandy shale, are so closely allied as to be practically oneclass. They yield by far the bulk of our present daily production. Classes 3and 4, porous lime and sandy lime, are also closely associated, yielding, forthe moment, enormous wells, which soon decline to the pumping class and readilybecome unprofitable to operate. Class 5, crevices, also yield enormousquantities of oil for a few days but decline most rapidly unless fed from someextraneous source. They can hardly be considered as having a lasting economiceffect on the industry. Class 6, oil-bearing shales, are not vital to thisdiscussion. As we are primarily interested in the formations producing most ofthe oil, we shall confine ourselves to a discussion of the sands and sandyshales.
Effect of Dissolved Gas upon the Viscosity and Surface Tension of Crude Oil
Authors: Beecher C.E. , Parkhurst I.P.
Published: June 2014

In the course of the experimental and development work of Henry L. Dohertyin an endeavor to obtain an increased yield of oil from oil-bearing sands, itwas Mr. Doherty's claim and contention that oil in an undisturbed pool wasdifferent in character and behavior than the same oil when raised to thesurface of the earth, and that the gas dissolved in the oil caused a markedreduction in its viscosity and surface tension. Prior to 1924 no information tosupport this contention could be found in the literature or by a discussion ofthe subject with technical men in Government and private laboratories. So faras could be ascertained no experimental work had been carried on to indicatethat Mr. Doherty's claim was either right or wrong. All parties consultedagreed that the viscosity of the oil would be affected by gas dissolved thereinto the extent that natural gasoline was present in the gas, but so far as couldbe determined any additional effect of the natural gas was unknown.

Accordingly, it was necessary to devise equipment and carry on experimentswhich would either prove or disprove Mr. Doherty's contention or claim. Suchapparatus was built under Mr. Doherty's direction and experiments were carriedon to determine definitely the viscosity and the surface tension of the crudeoils which contain dissolved gases under different pressures. The results ofthe experimental work carried on have proved that the claim and contention ofMr. Doherty were correct in every particular, as will be seen from thediscussion of the subject and the data contained in this paper.

Reduction of Viscosity by Dissolved Gas

At a pressure of 500 lb., and a temperature of 70?F., it was found that anatural gas such as is associated with the oil would reduce the viscosity about50 per cent when a given crude oil was saturated with the gas. Increasing thepressure another 500 lb. could not be expected to reduce the viscosity theremaining 50 per cent. However, some reduction in viscosity would take place asindicated by the curves showing the relation between pressure and relativeviscosity.
Corrosion in Oil and Gas Wells - Its Causes and Prevention
Authors: Mills R. Van A.
Published: June 2014

Introduction

The subject of corrosion is forcing itself to the attention of all branchesof the engineering profession because of the enormous wastes that are involved.Petroleum engineers are obliged to deal with it all the way from the bottom ofthe well to the last still in the refinery and even to the internal combustionengine itself. The subject of corrosion in the petroleum industry is, ofcourse, too broad to cover in a brief paper, but certain phases of its causesand prevention in the producing fields can be outlined to advantage. This paperdeals with underground corrosion in the wells themselves.

A large part of the corrosion troubles that are now harassing operators inold fields could have been prevented, at only nominal cost, if protectionagainst the corrosion of well equipment had been properly established when thewells were first drilled and equipped. To wait until corrosion troubles developin an oil or gas field is like waiting until an army develops a typhoidepidemic before applying inoculation against the disease.

In presenting this paper, there are three purposes in mind. The first is tooutline briefly the causes for corrosion in oil and gas wells. The second is topoint out reliable methods of detecting corrosive conditions in the wells atthe time they are being drilled and equipped. And the third is to emphasize theadvantages of establishing adequate protection of well equipment againstcorrosion at the time the wells are first drilled and equipped, that is, beforethe corrosion in the wells begins.

The effort has been made to outline as briefly as possible a part of theresults of a three-year investigation of the corrosion of oil and gas fieldequipment by the U.S. Bureau of Mines. The subject has been more broadlycovered in Bulletin 233.
Mechanical Installations for Air-gas Lift in the Gulf Coast Area
Authors: Brundred L.L.
Published: June 2014

The major portion of the production of the Gulf Coast area, represented bySouth Texas and South Louisiana, comes from the flanks of well-defined saltdomes. This oil, containing an excellent lubricating stock, ranges from 17? to28? Be. gravity. Some lighter oil is encountered but the life of such fieldsis, in general, an open question. In fact, there are few light-gravity fieldswhich have proved of much value.

In all of the fields water encroachment, or, more properly, water producedwith the oil, is a vital factor. After the first head of high-pressure gas isremoved, ever-increasing percentages of water appear, and naturally the life ofthe wells is materially affected thereby.

The sands are, as a rule, extremely fine, very soft, and must be carefullyexcluded from the hole by the use of fine screen to prevent sanding up. Allsands are tipped at such extreme angles as to make coring essential for thelocation of water strata, oil-bearing sands and important shale beds. Even withmodern coring, the correlation of logs is a difficult problem.

Due to the fact that the bulk of the oil is refined for its lubricatingproperties, little attention has been paid to losses by evaporation in thefield. This is largely influenced by the fact that the major companies have seta price schedule, showing but two grades, "A" and "B." Theaverage oil company, therefore, does not attempt to use the gas-lift but reliesprimarily on the air-lift and then only on wells considered to be particularlyadapted to its use, namely those capable of producing large quantities of fluidand yet not having sufficient "kick" to flow.

Furthermore, as the gas contained in the reservoirs is mostly methane, suchgas being very quickly vaporized and produced in large quantity in the earlylife of the fields, there is little gas left after the first flush flowingperiod of the wells. In fact, it is very generally conceded that gas is aprecarious fuel to depend on in any of the coastal fields. This situationlargely accounts for the fact that air, as the lifting medium, is almostuniversally used.
Mechanical Equipment of Air-gas Lifts in Oklahoma and Kansas Exclusive of Seminole
Authors: Bond Reid W.
Published: June 2014

The gas-lift is a comparatively recent development in the Oklahoma andKansas fields. It was used to some extent in the old Dilworth field severalyears ago, but the first extensive installations were made in the Tonkawa andGarber fields in Oklahoma early in the year 1926.

Compressor Equipment

During the early development of the system, the equipment used generallyconsisted of small tandem compressors of about 250 cu. ft. per min.displacement, driven by automotive-type gas engines, using a short belt drive.These compressors were first installed at the individual wells largely as anexperiment.

After the experimental installations had proved the method a success, it wasconsidered economically advisable to centralize the compressor equipment instrategically located stations. However, as the information in regard to"gas-lift flowing life" was anything but definite, and the mostoptimistic estimates in regard to it did not exceed six months, portability ofequipment was still the first consideration in the minds of many operators, whocontinued to install small semi-portable compressors in their centralizedstations.

As electric power became available in the fields, the electric motor camerapidly into use as the prime mover for the small compressors. The operatingcost of this motor is greater than that of the automotive-type gas engine forthe same power output, but the greater continuity of service tends to balancethe extra cost.

Aside from the semi-portable units, a number of strictly portablecompressors were used. These consisted of automotive-type gas engines directconnected to vertical compressors. The unit was assembled on one base and couldbe mounted on wheels or skids as desired. The chief objection to these, in thewriter's opinion, was their small capacity - approximately 150 cu. ft. per min.- which made it necessary to use two, three, and sometimes more units per well, thus making the installation rather costly. However, they have been foundvaluable for test purposes and emergencies, where installation time is animportant factor.