bluuebunny/crossref_metadata_2025 huggingface dataset:
Fundamental Operating Pressures in Oil-gas Reservoirs
Authors: Stephenson Eugene A.
Published: June 2014

In November, 1932, Dr. Lacey, of the California Institute of Technology, presented before the American Petroleum Institute some of the results of hisresearch under Project 371? The investigations described dealt particularlywith changes in the physical properties of petroleum that result from thesolution of natural gas therein.

The solubility of Santa Fe Springs dry gas, containing 87 per cent methane, 8per cent ethane and 5 per cent propane, had been determined in various crudesat 100? F., and 2000 lb. pressure per square inch as shown in.Table 1 and Fig.1 herewith. Originally the computations were made in terms of cubic feet perbarrel, but for a more uniform basis of comparison the results are also shownas cubic feet of gas per cubic foot of oil.
Variations in Reservoir Pressure in the East Texas Field
Authors: Schilthuis Ralph J. , Hurst William
Published: June 2014

The nature of the forces that are important in producing the oil in the EastTexas field and the manner in which these forces are affected by the rate ofproduction have always been problems of outstanding interest. These questionsare of great interest to the industry as a whole on account of the economicimportance of the East Texas field and to the engineers in particular onaccount of the unique character and behavior of the field. Subsurface pressuredata throughout the field have been collected systematically, so that a quitecomplete history of the reservoir pressures has been kept as the field has beendeveloped and produced.

Subsurface samples of the oil and gas have been taken and these have beenexamined to obtain data on the physical properties of the reservoir fluidsunder the actual conditions of temperature and pressure. All of these data havebeen valuable because they have afforded the basis for a careful study of the means by which the oilis produced. It is the purpose of this discussion first to point out several ofthe important facts revealed by the data mentioned and then to describe studiesthat have been made concerning the interpretation of these facts.

Reservoir Pressure Data and Properties of Oil

The reservoir pressure data on the East Texas field have shown conclusivelythat the pressures are readily affected by changes in the rate at which thefield is produced. This can well be seen in Fig. 1, where the average reservoirpressures obtained from time to time are plotted with the daily productionrates and the cumulative production of the field. It is noted that the averagereservoir pressure has declined irregularly, depending upon the rate ofproduction, from the estimated original value of 1625 lb. per sq. in. to thevalue of 1228 lb. per sq. in. observed for Aug. 11, 1934. The decline inpressure has been more rapid at the higher rates of production than at thelower rates. In contrast, the average reservoir pressure has increased, onseveral occasions, upon reduction of the withdrawal rate from a high value to alower value.
Active Oil and Reservoir Energy
Authors: Schilthuis Ralph J.
Published: June 2014

In 1929, Coleman, Wilde, and Moore undertook an investigation of thetheoretical decline in reservoir pressure as related to the production of oiland gas. The most important part of this work was presented in an equationdefining the relationship between the reservoir pressure, the quantities of oiland gas produced the oil and gas content of the reservoir, and the propertiesof the reservoir fluids. With this equation, it appeared that, with sufficientdata, it would be possible to calculate the oil content of the reservoir andpredict quantitatively the effect of gas-oil ratio on the decline of reservoirpressure. Needless to say, such an expression would be highly important inevaluating fields and in arriving at a choice of production methods to beused.

Unfortunately, at the time these investigators published their work, there werenot sufficient data available to permit application of the equation. Thetechnique of measuring reservoir pressures had not been developed, gasmeasurements were uncommon, oil and water production records were in most casesinadequate, and little was known of the properties of the complex hydrocarbonmixtures making up the oil and gas in the reservoirs. For these reasons, littleadditional work of a similar nature could be done. However, during the pastfour years many data have been systematically accumulated on reservoirpressures and the properties of oil and gas, and it is now possible to usethese data in furthering the studies on the behavior of oil and gasreservoirs.

It is the purpose here: first, to present the derivation of a modified form ofthe equation given by Coleman, Wilde and Moore, which will permit thecalculation of what later will be defined as the "active oil" contentof a reservoir; second, to derive formulas for calculating the reservoir-energychanges that occur during the course of production, and finally, to discuss thelimitations and application of the equations developed.
Experiments on the Vertical Flow of Gas-liquid Mixtures in Glass Pipes
Authors: Gosline J.E.
Published: June 2014

In any theory of a hydrodynamic nature dealing with the vertical flow ofgas-liquid mixtures in pipes, the two factors that present the greatestdifficulty are the relative motion between the phases and the energy lossresulting from turbulence work. The former has generally been referred to inthe literature as "slippage" and the latter as "friction." Athird factor of importance is the nature of admixture between liquid and gasfor both the relative motion between the phases as well as the turbulence workare functions of the type of mixture.

Although much work of a general nature has been performed on the vertical flowproblem, there have been very few attempts made to study experimentally thefactors involved in the phenomenon individually. Of these, perhaps the mostnotable is the work of Moore and Wilde on slippage.

Some writers on the subject have assumed that over a wide range of operatingconditions the controlling type of mixture is one in which gas bubbles ofuniform size are distributed throughout the liquid, and that the data obtainedfrom experiments on the motion of single bubbles through various liquids may beused in evaluating the slippage. Versluys has further assumed anothercontrolling type of mixture in which the liquid occurs as a dispersed phasewithin the gas and applies data on the fall of drops of water in air tocalculating the relative velocity.

It was for the purpose of studying the applicability of data on single bubblemotion to the slippage factor and to further observe the nature of mixturesthat a research program was conducted at the University of California during1932 and 1933.
Structure of Clay Gels
Authors: Lewis W.K. , Thompson W.I.
Published: June 2014

The authors presented an article last year on colloidal properties of claysuspensions in which they attempted to sustain the position that the behaviorof clay suspensions is due primarily to the mechanical interference of theplaty particles, the nature and extent of the interference being profoundlyinfluenced by the character of the surfaces of the particles, which in turn isdetermined primarily by the nature and amount of adsorbed foreign materialsheld on the surface of the particles by forces which are predominantly chemicalin type. The following discussion is a continuation of that article to extendthese same interpretative points of view to the behavior of clay gels. Insightinto the mechanism of gelation is certainly of outstanding importance in thehandling of drilling muds.

In the former article it was suggested that the thin, flat plates thatconstitute the ultimate clay particles may build up aggregates by theoverlapping of the ultimate plates face to face much longer and perhaps alsomuch wider than the ultimate plates themselves, but not appreciably thicker.Exhaustive microscopic examinations of characteristic clays show no tendencyfor the larger particles, clearly visible under the microscope, to orientthemselves in this way. It is true that the gelation of the clays is dueprimarily to the smallest particles, unresolvable other than by theultramicroscope, so that the possibility of the development by them of anoverlapping structure is not excluded. Furthermore, as one approaches the limitof resolving power of the microscope, the difficulty of observing accuratelythe shapes and relative positions of particles increases excessively. However, in the absence of any observable tendency toward overlapping orientation of thelarge, visible particles, one hesitates to ascribe such a tendency to thesmaller particles beyond the range of visibility. Should it develop that onemust exclude the assumption of overlapping orientation, the explanationsoffered in the previous article are changed in only one respect; namely, onewould now have to assume that the ultimate particles themselves have length, and probably also width, very large in comparison with their thickness.
An Investigation of Experimental Methods of Determining Sucker-rod Loads
Authors: Kemler Emory
Published: June 2014

The problem of determining the most desirable operating conditions of anoil-well pumping unit, the selection of the proper material and size of suckerrods, and the design of the pumping unit, requires that the sucker-rod loads beknown with a reasonable degree of accuracy. In production practice, it is alsodesirable to know the effects of operating speeds and strokes on a plungermotion, as well as on the rod loads.

For a particular well, data on rod loads can be obtained by measuring the loadin sucker rods with a dynamometer. This method is not satisfactory because itdoes not permit the various factors to be investigated independently. It isalso impossible to measure the plunger motion simultaneously with rod motionunder operating conditions. The mathematical solution is impractical because ofthe simplifications that have to be made to get a solution and the tremendousamount of numerical work that is necessary after such a simplified solution hasbeen attained. This paper shows how analogies and models can be applied to thesolution of these problems.

The loads set up in a sucker-rod string during the ordinary pumping cycle aremade up of the weight of the rods, force required to accelerate the rods, weight of the oil and force required to accelerate the oil on the upstroke, rodfriction, stuffing-box friction, plunger friction, friction of the oil in thetubing and rods, and friction loss through the valves. The problem ofdetermining the sucker-rod load is further complicated by the fact that thelong oil column and the sucker-rod column act as springs, which affect thetransmission of the polished-rod motion. A further complication is the factthat the motion cannot be transmitted at a speed greater than that of thevelocity of sound in the material, and this means that there will be a time lagin the transmission in the motion, as well as a modification of its magnitudeand a phase displacement.
Laboratory Investigations on Acid Treatment of Oil Sands
Authors: Plummer F.B. , Newcome R.B.
Published: June 2014

The practice of introducing acid into oil wells to increase production ofoil and gas has been in use since 1894, when it was first used in thePennsylvania oil fields. It is only since 1928 that it has been used to anyextent in the Mid-Continent. The process has proved successful in increasingproduction, at least temporarily, in depleted oil fields where the producingformation is highly calcareous and where water drive is not too pronounced. Inthe Zwolle field in Louisiana, where the producing horizon is a chalk, increases of 100 per cent have been recorded In north-central Texas, where theoil is produced from the Marble Falls limestone, equally pronounced increaseshave resulted. The production also in some fields yielding oil from quartz sandcemented with calcite has been benefited. The evidence of actual increase intotal recovery of oil, however, has been questioned by some engineers. It hasbeen pointed out that the results of the treatment of a well in a new district, where the process has never been tried out, can never be predicted withcertainty, since other factors besides percentage of calcareous content of theoil sand playa large part in determining the success of the method.

Numerous articles have been published on acid treatment and on the effects ofacid on limestone, yet very little has been written concerning experimentalwork on the actual effect of acid on capillary pores and larger oil-coatedvoids of oil sands. This is due partly to difficulties in duplicating fieldconditions in a laboratory and partly to the fact that the process has beencarried out largely by contracting companies that have been unwilling topublish details of their results for fear of loss of business to competitors.The authors, using equipment developed to measure the radial permeability ofoil-sand cores, have developed a method of investigating the results of acidtreatment which has enabled them to test numerous cores and to study in somedetail the action of acid on the different types of rocks, particularlyfine-grained rocks.
Plug-back Cementing Methods
Authors: Parsons C.P.
Published: June 2014

During the past year considerable interest has been shown in cementingoperations for shutting off bottom water, whip stocking, etc. A number ofplug-back methods have been used, with various adaptations for specialconditions, but those described in this paper are representative of the methodsnow in use.

Conditioning the Well

Various preliminary operations for improving the results from plugbackoperations have been evolved. In one method, a nitroglycerin shot is dischargedat the upper portion of the formation to be plugged off, the purpose being tomake a wide place in the hole in order to give the cement a more secure anchoragainst thrust pressure of the water against the bottom of the cement plugafter the well is again put on production. Another is intended to attain asimilar result by under-reaming a wide place in the hole by means of a rotarywall scraper. In one well in which this device was used there was a water sandat the bottom of the well immediately below the cap rock above which the oilsand occurred. Before the plugging back operation, the water sand wasunderreamed in an attempt to get a square shoulder on the underside of the caprock, in order to prevent the water from breaking in over the top of the cementplug after the well should be put on production, and also to get a more secureanchor for the cement plug against the thrust pressure of the water againstit.

As an aid in calculating the amount of cement required to fill a given amountof hole to be plugged back, a device has been developed for measuring andrecording the irregularities and cavities in open holes, called an "open-hole recording caliper." It consists of a steel shell, 5 in. indiameter, which encloses a recording mechanism that receives impressions fromfour movable arms that make sliding contact with the wall of the hole. The armsoperate a ratchet, which raises and lowers a recording stylus against a chart.Each arm registers its own radius. The device is run into a well on a steelmeasuring line.
Influence of Production Practices on Gravity of Produced Oil
Authors: Boyd Robert R.
Published: June 2014

The gravity discussed here is that of the clean oil produced. Gravities offluids containing water, free or in the form of emulsion, sand, drilling mud ormineral salts of a no bituminous nature do not represent the gravity of crudeoil as considered in this paper.

During recent years it has become a frequent occurrence for operators to becalled upon to explain to landowners the reasons for variations in gravity onshipments of oil from wells in which they are interested as royalty owners. Inregard to single well leases it has been noted that marked changes in gravityfrequently have occurred for no apparent reason. Data collected on the subjectand correlated with production methods reveal interesting facts. It is thepurpose of this paper to present some of the highlights on the subject.

These gravity changes in the natural crude oil are with a few exceptions theresult of the liberation under varying conditions of the volatile hydrocarbonsfrom the natural oil-gas solution contained within the pool. The subject of theliberation of gases from natural oil-gas solution has been investigated by BenE. Lindsly, of the U. S. Bureau of Mines, and the observations recorded hereare in the main consistent with his conclusions.

Investigators have recognized two methods of liberation of gas from solutionflash and differential. In the latter method the vapors are removed from theliquid as rapidly as formed and have no opportunity to come to a condition ofequilibrium with the oil. In flash liberation an equilibrium condition betweenthe oil and the gas exists at the pressure of separation. Mr. Lindsly has foundthat the method of liberating the gas from the oil has a pronounced effect onthe final gravity and that differential liberation results in a higher A.P.I.gravity due to the higher ratio of gasoline producing hydrocarbons left in theoil.

Under actual production practices with high velocities in flow strings, it isour contention that conditions of perfect equilibrium between gas and the oilrarely exist, and that gas separation is made under varying conditions, sometimes approaching that of equilibrium and at other times departing fromit.
Bibliography on the Acid Treatment of Oil Wells
Authors: Fitzgerald P.E. , Gindlesperger J.C.
Published: June 2014

The Acidizer (Trade Publication of Dowell Inc.):No. 1.Aspects of Acidizing.No. 2.Inhibited Acid.No. 3.The Value of Acidizing.No. 4.The Chemistry of Acidizing.No. 5.Jelly Seal in Acidizing.No. 6.Loosening Stuck Drill Pipe.No. 7.The Geology of Acidizing. I. C. Albright: Acid Is Being Used for Cleaning Intake Wells inWater-flooded Areas. Oil Weekly (Sept. 23, 1935) 24. D. H. Bancroft: Acid Tests Increase Production of Zwolle Wells, MillerCounty, Arkansas. Oil and Gas Jnl. (Dec. 22, 1932) 42. A. H. Bell: Possible Areas for Acid Treatment in Illinois. Pub. ofIllinoisIndiana Petro Assn. and Illinois Geol. Survey (1934) 49. N. A. Best: Treating Limestone Formations Consists of More than PouringHydrochloric Acid in the Well. Oil and Gas Jnl. (April 5, 1934) 54. L. G. E. Bignell: Sealing Off Salt Water from Oil-bearing Formations. Oiland Gas Jnl. (Jan. 30, 1936) 59. L. G. E. Bignell: Acidizing Upper Limestone Formation Facilitated by the Useof Jelly Seal. Oil and Gas Jnl. (March 5, 1936) 30. L. G. E. Bignell: Bailing, Shooting, Tubing and Acidizing Have All BeenTried in Deep Test at Binger, Oklahoma. Oil and Gas Jnl. (May 10, 1934)38. L. G. E. Bignell: Dowell Incorporated Increasing Its Field Service for AcidTreatment of Wells. Oil and Gas Jnl. (June 7, 1934) 62. L. C. Chamberlain, Jr. and P. E. Fitzgerald: Oil Well Acidizing inMichigan. Mich. Acad. ScL Papers (March 1937). M. E. Chapman: Some of the Theoretical and Practical Aspects of the AcidTreatment of Limestone Wells. Oil and Gas Jnl. (Oct. 12, 1933) 10. C. E. Clason and J. G. Staudt: Limestone Reservoir Rocks of Kansas ReactFavorably to Acid Treatment. Oil and Gas Jnl. (April 25, 1935) 53. W. F. Cloud: Cleaning and Reconditioning Oil Wells-Reconditioning by Use ofAcid (Petroleum Production 1937), 389. University of.Oklahoma Press,1937. 1\. A. Covell: Developments in Eastern Production Practice. Acid Treatmentof Mi('higan Wells. Amer. Petro Inst. Prod. Bull. 213 (1934) 77; Oil' and GasJul. (May 31,1934) 89; Oil Weekly (May 28,1934) 17. B. A. Cunningham: Acid Treatment of Lime Formations. Amer. Petr.Inst. Paper 901 (1933) 9D, 1–7. 0.1. DeSchon: Pondera Production up 22,000 Barrels. Montana Oil & Min.Jnl. (Jan. 26, 1935)
Recent Developments Related to Petroleum Engineering
Authors: Jensen Joseph
Published: June 2014

Recent developments related to petroleum engineering discussed in this paperare:Drilling wells in with oil or the use of chemical compounds or "mudsolvents" for removing rotary mud from wells in order to increase or makepossible oil production.Comparison of results of electrical logging methods in locating water, asshown in a recent test on a well in the Los Angeles Basin.A new method for logging formations through casing, known as the Stratagraph.

Drilling Wells In With Oil or the use of Chemical Compounds or MudSolvents

During the time that the California fields showed high gas pressures, thepressure of the gas within the formation was sufficiently great to break downthe mud wall or cake formed while the well was drilling. That this did notalways occur was demonstrated by the fact that in some of the older fields newwells sometimes had substantially higher initial productions than other wellsnear by. The explanation seemed to be that some sands were mudded off in theoriginal drilling. Their pressure was then not great enough to break down themud wall in competition with the higher pressure of the sands, but thesituation reversed itself so that a later well benefited by the pressure inthese originally weaker sands. As time passed, in wells deeper than 5000 ft.the difficulty of bringing wells on production became more pronounced. This ledto a hunt for substitutes, of which a number have been tried. The one that hasproved most successful in our experience at Ventura is known as the Nabssolvent.

At well No.1 of the Associated-Ventura Land &Water Co. when it wasrecompleted in February 1936, about 10 days were spent in trying to bring thewell in in the regular manner, but only about 113 bbl. of water could beswabbed from the well, and even this quantity decreased as time passed.
Flow of Gas-liquid Mixtures through Sands
Authors: Muskat M. , Wyckoff R.D. , Botset H.G. , Meres M.W.
Published: June 2014

The subject of the flow of homogeneous fluids-gases alone or gas-freeliquids-through porous media may be considered at the present time to be fairlywell completed. That is, analytical, graphical, numerical, or experimentalmethods are now available for obtaining detailed descriptions of the behaviorof such homogeneous fluid systems of any reasonable geometry. Thus, satisfactory empirical techniques are now well established for thedetermination of the permeability of porous media for homogeneous fluids, thenumerical magnitude of this permeability uniquely and completely describing aporous medium as a carrier of a homogeneous fluid.

Considering this constant as known, the treatment of a wide variety of specificproblems involving either the flow of gases or liquids has been carried throughto satisfactory conclusions. Beginning with the simple case of strictly radialtwo-dimensional flow of a liquid or gas into a well under steady-stateconditions, generalizations have been developed to apply for systems where theflow is not strictly radial, due either to a lack of uniformity in thereservoir pressures at points distant from the well or deviations fromcircularity of the external boundary. whereby the fluid is being supplied, andfinally, to the lack of complete penetration of the well into the producingstrata. Satisfactory descriptions are now available for cases where gravity isacting as the driving agent inducing the flow of liquid into the well, eitheralone or as a supplement to the effect of pressure. The effect of acidtreatment on limestone wells has been given a reasonable interpretation on thebasis of the fundamental theory of the flow of homogeneous fluids throughsands, as have the important features of the problem of water-coning.
Oil-well Behavior Based upon Subsurface Pressures and Production Data
Authors: Miller H.C. , Burnett E.S. , Higgins R.V.
Published: June 2014

Information obtained from subsurface pressure and temperature measurementsin oil wells now is recognized as invaluable to geologists, engineers, andoperators of oil properties. Available only during the past few years, dataresulting from subsurface-pressure surveys in oil wells already have foundwidespread application in the estimation of reserves and in the, planning ofcomprehensive oil-field development programs. Subsurface pressure andtemperature data, together with measurements of fluid volumes produced byindividual wells and specific gravities of the fluids, also are included in thefundamental information essential in, studying the movement of oil, gas andwater through reservoir sands to wells. Heretofore, laboratory findings wererelied upon almost entirely for information, pertaining to the mechanics offlow of fluids through porous media, because there was no way to checklaboratory results with actual performance in underground formations untilsubsurface pressure and temperature instruments were developed. Laboratory andfield experiments now lend themselves to closer correlation-a fact that willaccelerate the interpretation of many phenomena that occur when oil and gasflow through reservoir rocks, thousands of feet below the surface of theearth.

This paper summarizes the results obtained thus far in a Bureau of Mines studyof certain data pertaining to subsurface pressures and production of wellsproducing oil and gas (and water). For wells that have been studied, flowingnaturally under volumetric or hydraulic control, a simple relation has beenfound between the mass rate of fluid (oil, gas and water) production., and thecorresponding drop in pressure in the reservoir sand. The equated relationembodies a productivity factor or ?index? expressed in terms of mass rate offluid production per pound drop in pressure through the sands. The equation asdeveloped is an expression of the ability of a well to produce, which permitscomparison on a uniform basis of the productivities of different wells.
The Productivity Index
Authors: Haider M.L.
Published: June 2014

Much has been said and written on the shortcomings of the open-flow andrestricted potentials of oil wells to determine their relative ability toproduce. The oil industry in general is agreed that the open-flow potential inparticular is grossly inequitable, wasteful and expensive, but that potentialis still used in many pools. This is partly because no thoroughly satisfactorysubstitute has been found and partly because operators are reluctant to adoptother methods that have been suggested; or, as Hamlet would say, we wouldrather "bear those ills we have than fly to others we know not of.

In a great many pools the use of tubing potentials has been substituted foropen-flow potentials, but open-flow potentials through casing are still beingused in many pools, particularly in Oklahoma, although the expense of suchpotentials has been pointed out many times. In one of the most recent pools inOklahoma it is the practice to take open-flow potentials through the casingwith the tubing out of the hole. The well is usually tubed after it is drilledin for the purpose of washing it in and cleaning the hole. After preliminarytests are run the tubing is pulled under pressure preparatory to taking thepotential. After the potential is taken the tubing is rerun, under pressure. Inorder to accommodate the large capacity of the wells, it is customary to setthree separators, six vent lines and large oil-storage tanks. It isconservatively estimated that the equipment not needed for producing the wellcurrently but which is installed solely for the purpose of establishing largepotentials costs the operator at least $5000 per well-approximately 35 per centof the cost of equipping a well for production. Such needless expenditureconstitutes an economic waste in addition to the gas that is wasted in takingpotentials.

Meaning of Productivity Index

A method of measuring the relative ability of wells to produce without openflow that shows considerable promise is the Productivity Index.
Cooperative Development Plan for Buena Vista Hills Oil and Gas Field, Kern County, California
Authors: Nickerson C.M.
Published: June 2014

The possibility of deeper production in the Buena Vista Hills was firstconsidered in 1933. At that time, however, the heavy state curtailment programserved to deter any operator from drilling test wells, which, if successful, might upset the proration schedules. Because most of the acreage was held byseveral major operators and the remainder by substantial independents, theadoption of a plan of cooperative development was considered desirable. Such aplan was formulated for the development of any deeper oil and gas horizons thatmay be found to exist. This plan, which was signed by the Secretaries of theNavy and of the Interior on behalf of the United States on July 9, 1936, is noweffective for the development of lands within the area shown on Fig. 1. Unlikemost unit plans, the present cooperative development plan permits each operatorto drill and produce his own wells.

For the purpose of this plan the Buena Vista Hills field is divided into twopools. The present production is classed as the" old pool," while anyfuture production below a certain marker which roughly coincides with thebottom of the Santa Margarita formation is included in the" pool" towhich the provisions particularly apply.

Naval Petroleum Reserve No.2 lies within the area and constitutes the majorportion of the Federal leases subject to the plan. There are 39,040 acres and27 operators within the area. Twenty-six operators controlling 99.5 per cent ofthe acreage have signed the agreement.

Geology of the Buena Vista Hills

The Buena Vista Hills consist of a low range in the southern portion of the SanJoaquin Valley, and are roughly parallel to the adjacent Temblor range to thesouth. The Elk Hills oil field parallels the Buena Vista Hills a? few miles tothe north.
Gas Caps, Their Determination and Significance
Authors: Gregory P.P.
Published: June 2014

Natural petroleum gas occurring in the oil-bearing reservoirs is found toexist either as free gas associated with the oil and/or in solution in the oil. In some virgin fields practically no free gas is encountered under thereservoir conditions of pressure and temperature, although in other fields aconsiderable section of the "pay" horizon is occupied by free gas. Inother words, a given oil field mayor may not have a gas cap before theexploitation takes place. However, when the reservoir pressure is reduced to apoint below the critical saturation pressure by withdrawals of fluids from theproducing formation, the gas dissolved in the oil inevitably begins to come outof solution and becomes free gas. Under the controlled methods of productionand drilling, a portion of this gas is produced with the oil to the surface anda portion of it remains within the reservoir to accumulate at higher structurallevels toward which it migrates by virtue of its low specific gravity. The rateof growth of a gas cap in a given structure depends primarily upon the rate ofdecline in the reservoir pressure. If the rate of pressure decline is rapid, the gas cap likewise will grow rapidly. On the other hand, shrinkage in thegas-cap area was noted in some fields in which reservoir pressures wereincreasing.

Determination of Gas-Oil Contact and Thickness of Gas Cap

The gas-oil contact can be conveniently located in the process of drilling awell and by electrical logging. However, very little can be found in thepetroleum literature concerning methods of predetermining gas-oil contacts inproducing reservoirs. Therefore, the writer feels justified in describingbriefly a simple, workable, and inexpensive method of determining gas-oilcontacts and outlining the limits of gas-cap areas in a field where suchknowledge may be essential for efficient production and developmentoperations.

The method involves the determination of the following data:Structuraldata, such as the depth or elevation of the top of "pay" horizon;reservoir pressures;tubing and casing pressures at the well head;static oil-pressure gradient;static gas-pressure gradient.

T.P. 917
Excessive Pressures and Pressure Variations with Depth of Petroleum Reservoirs in the Gulf Coast Region of Texas and Louisiana
Authors: Cannon G.E. , Craze R.C.
Published: June 2014

This paper discusses the results of a study of reservoir pressures in theGulf Coast area of Texas and Louisiana, showing the general relation of thereservoir pressure to its subsea depth, as well as excessive reservoirpressures that have been encountered. The latter are particularly important inmud-control work, and the data show why it is necessary to use muds having arelatively high density in many of the deeper wells drilled in this area. Onlya comparatively few of the wells drilled in the Gulf Coast that haveencountered excessive pressures are discussed, but as far as is known thoseomitted fall within the range of pressure observed by the writers.

Measurement of Pressures

The following methods were used to determine the values of the originalpressures:Estimation of original pressure from subsequent pressure behavior of fields.This method is not precise, and was used only in a few of the older fields inwhich better methods of obtaining original pressures were not available. Onlynormal pressures were determined by this method.Measurement of shut-in pressures soon after completion of the firstproducing well. With one exception, all pressures measured by this method werenormal, this well having a pressure slightly higher than normal.Measurements of pressure in connection with drill-stem tests.Estimates from the maximum hydrostatic head of mud that failed to preventflow from the high-pressure formations into the hole. This method is not exact, tending generally to indicate low pressures.

Normal Pressures

All pressure measurements available are plotted in Fig. 1, with originalpressure at the water-oil contact as abscissa and subsea depth as ordinate.
Pressure Drilling Operations at Kettleman Hills, and Effect on Initial Production Rates
Authors: Winterburn Read
Published: June 2014

This discussion covers only one method of pressure drilling-that developedin the Kettleman Hills field. Thus it is probable that many departures from theprocedure herein described would be advisable, and perhaps necessary, in usingthis method of drilling wells in other localities.

Purpose of Pressure Drilling

By the early part of 1936, formation pressures in the heavily produced northend of the Kettleman North Dome field had declined to range from 1000 to 1500lb. per sq. in. This low pressure, combined with the depth of the wells (8000to 9000 ft.) permitted Water to be filtered out of the mud into the producingsands during drilling operations. The loss of water was indicated by loss offluid from the suction tank while drilling, accompanied by an increase in mudweight. It was found that when water was added to the mud stream at such a rateas to keep the fluid level in the suction tank constant, the mud weight wouldnot vary. This indicates that water only was forced into the sands. The rate ofthis loss at various wells ranged from 2 to 5 bbl. per hour. At some placescomplete loss of circulation occurred, and drilling mud to the extent of 200 to1000 bbl. had to be pumped into the sands before returns were regained. It wasbelieved that these conditions had already begun to harmfully affectproduction, and that such effect would become more pronounced as formationpressures continued to decline. Pressure drilling with oil was introducedbecause it eliminated the danger of loading 'the formations with mud andwater.
Some Considerations in the Selection and Installation of Gravel Pack for Oil Wells
Authors: Coberly C.J. , Wagner E.M.
Published: June 2014

Sand produced with the oil in many fields is one of the major causes of wearand down time on pumps, tubing, gas anchors and other equipment. Arresting thisproduction of sand at its source would materially increase the life of suchequipment and reduce production costs.

It is possible to materially reduce or eliminate sand trouble in some fieldsby the judicious selection of the openings in perforated liners. However, inother fields this is impossible because of fineness of the sand, poorcompaction of the formation, low bottom-hole pressures, or other conditions. Insuch cases, gravel packing seems to offer a practical and relatively simplesolution of the problem.

Gravel packing of wells, especially water wells, is not new. However, theselection and placing of the gravel have heretofore not been given sufficientstudy, and for that reason the results often have been unsatisfactory. Ananalysis of the problem is presented herein, with the hope of showing thatgravel packing can be put on a rational basis and made a practical method ofcorrecting a condition that has been a constant source of trouble to the oilindustry. Three problems are considered:selection of the proper mesh"gravel" to hold the formation in question,proper placing of thegravel,selection of a properly perforated liner to hold the gravel.

Selection of Liner

The third problem named is the most readily solved. It would seem that aperforated liner that will hold back all of the gravel should be selected. Inthis way the pack will remain permanently intact. This will require a slothaving a width equal to or less than the diameter of the smallest grains in thegravel pack. While a slot with a width twice the grain size at the tenpercentile of the gravel pack would hold the gravel in the accepted sense, thesmall quantity produced during the period the slot bridge is being built upmight be enough to cause the pack to settle, allowing the production ofsufficient formation sand to brand the installation a failure.

T.P. 960
The Origin of Petroleum
Authors: Berl E.
Published: June 2014

This may be a most unnecessary paper-from what does crude oil come and howwas it formed? Many people, inside and outside of the petroleum industry, believe that we have actually enough oil, and that we can easily produce veryimportant products from this extremely valuable raw material. The writerbelieves, however, that the answer to this question concerning the parentmaterial and the formation of oil is of broader interest, because it may bethat from the answer to these problems it would be possible to get answers toother important industrial questions. Therefore, a study in this line seems tobe justified, and the writer will submit some of the results which he hascollected during more than ten years with many very capable collaborators, towhom his thanks may be expressed on this occasion.

Older Theories

There is no doubt that plants were the parent material of coals, but opinion isdivided as to the parent material of crude oil and asphalts. One group ofspecialists believed that they were formed from dead fish. The hydrocarbons ofcrude oil were formed by the splitting off of CO2 from fatty acids formed bythe saponification of the fat (glycerides) of fish. Enormous quantities ofcrude oil are present in many places on the earth, very often in severalnonconnected horizons at the same location. This could hardly be explained bythe so-called" catastrophe theory," which states that fish died throughthe entrance of salt water into fresh water, and vice versa. Furthermore, thistheory cannot explain the presence of aromatic hydrocarbons, which can be foundin nearly all oils, especially in the oil of the Netherlands Indies, which hasmore than 50 per cent of aromatics. Geological and chemical observations bothlead to the belief that the temperature of formation of asphalt, crude oils andcoals, perhaps with a few exceptions, did not exceed 2000 C. Chlorophyll andhaemin derivatives, which decompose above 2000 C., have been found in all thesematerials by Treibs and others.

T.P. 920
Effect of Pressure upon Viscosity of Methane and Two Natural Gases
Authors: Sage B.H. , Lacey W.N.
Published: June 2014

In recent years there has been an increase of interest in the flow of gasesat relatively high pressures. Hydrodynamic calculation of the energy losses inthe flow of gases in conduits, as well as through the porous solid materialsconstituting natural petroleum reservoirs, requires a knowledge of theviscosity of the fluid at the pressure and temperature involved. Although thereare numerous publications concerning the absolute viscosity of hydrocarbongases at atmospheric pressure, there appears to be little information availablerelating to the effect of pressure upon the viscosity of these gases.

Vogel determined the viscosity of methane at 320 F. and atmospheric pressure. His measurements at 320 F. were later substantiated by the measurements ofRankine and Smith at 630 and 2120 F. Ishida also reported values for theviscosity of methane at atmospheric pressure. Trautz and Kurz measured theviscosity of propane at atmospheric pressure, from 830 to 5300 F., by the useof a short capillary tube. Rappenecker determined the viscosity of gaseousisopentane at elevated temperatures. Day6 made an accurate investigation of theeffect of pressure upon the viscosity of isopentane and isopentane at pressuresfrom 2 lb. per sq. in. t to the vapor pressure at 770 F. (approximately 9.8 and 13.3 lb. per sq. in., respectively). Earhart reported data upon the viscosityof several natural gases measured by the long capillarytube method.

The viscosity of air, at atmospheric pressure and 73.40 F., was measured byHarrington 9 by the rotating-cylinder method. Kellstrom 15 has recently made anelaborate investigation of the viscosity of air at atmospheric pressure.
Pressure Distribution in Oil and Gas Reservoirs by Membrane, Analogy
Authors: Miles Aaron J. , Stephenson Eugene A.
Published: June 2014

The pressure distribution in a producing oil or gas reservoir has beenobtained mathematically in a limited number of special cases where the boundaryof the reservoirs are simple geometric figures with the wells convenientlylocated within them. Using some of the previous work as a basis, it can beproved that a number of additional problems of pressure distribution can besolved by use of soap film. This method is particularly applicable to areservoir drained by a number of wells, or to a reservoir of irregular shape, or to both. Since this method obtains the pressure distribution, it alsoestablishes the drainage boundaries of the wells.

This paper derives the analogy between the equation representing the pressuredistribution in a reservoir and the equation of the deflected membrane. It alsodescribes the apparatus and the method of operation. The experimental method isemployed to solve a problem whose mathematical solution is known and theresults compared. These are found to be in good agreement.

The method is applicable to any homogeneous liquid, compressible orincompressible, or to a gas, flowing in a reservoir, of uniform thickness, permeability and porosity. The flow state may be either the steady state or thetransient state wherein the density or pressure of the fluid in the reservoirdeclines at a constant rate.

Pressure-Distribution Problem

Fluids encountered in the oil reservoir are compressible and expand and movetoward the drilled hole where the pressure is lowest. The loss of fluid fromthe reservoir lowers the pressure in the more distant parts of the reservoir, permitting the fluids in these parts to expand and move toward the well.

T.P. 919
Behavior of Contents of High-pressure Reservoirs
Authors: Stephenson Eugene A.
Published: June 2014

In most instances the fluids produced from underground reservoirs have beendescribed as they appear at the surface, and usually it has not been necessaryto distinguish between surface and reservoir phases. More recently it hasbecome imperative to recognize the fact that changes in phase may occur betweenthe reservoir and the receiving unit.

The simple terminology of "wet" and" dry" gases and" crudepetroleum oil "served our needs fairly well in the shallow, low-temperatureand low-pressure fields. It has been left to the legislatures, regulatorycommissions, and courts to decide whether a field is or was a gas field, an oilfield, or both. This they have done by direct definition and also byimplication. For example, in Texas:

The term "gas well" is any well which produces natural gas notassociated or blended with crude petroleum oil at the time of production, orwhich produces more than one hundred thousand (100,000) cubic feet of naturalgas to each barrel of crude petroleum oil from the same producing horizon, orwhich produces natural gas from a formation or producing horizon productive ofgas only encountered in a well bore through which crude petroleum oil is alsoproduced through the inside of another string of casing.

The term "oil well" is any well which produces one (1) barrel or moreof crude petroleum oil to each one hundred thousand (100,000) cubic feet ofnatural gas.

In the state of Louisiana, the same general result is achieved largely by thefollowing paragraph:

Wells producing both oil and gas shall not waste or blow into the air an amountof gas of more value at three cents per thousand cubic feet, than the marketvalue of the oil recovered. The Commissioner of Conservation shall allow areasonable time to determine the status of any well.

T.P. 916
Sulphate-resistant Cement
Authors: Rordam Svend , Willson Cedric
Published: June 2014

The development of a cement that will resist the destructive action of seawater and other corrosive waters is a problem that has occupied cement chemistsfor the past one hundred years. It has been found that of the various saltsthat commonly occur in corrosive waters, sodium sulphate, magnesium sulphateand magnesium chloride are most destructive to cement. Many investigations havebeen carried out in the United States, in Canada, and in Europe to solve theproblem of what constitutes a sulphate-resistant cement, and during the past 10years some of the findings give definite information in this respect.

Composition of Cement

Portland cement is composed of four major compounds:Tricalcium silicateDicalcium silicateTricalcium aluminateTetracalcium aluminoferrite

The two calcium silicates are the main contributors of strength. Thetricalcium aluminate contributes some to the early strength of the cement buthas the least resistance of the four compounds toward the attack of sulphatewaters. The tetracalcium aluminoferrite does not contribute very much to thestrength, but is far more resistant to sulphate waters than the tricalciumaluminate.

When hardened cement is exposed to water containing sodium or magnesiumsulphates, these salts will react with the hydrated tricalcium aluminate in thecement and form compounds that will cause a swelling, disruption and crumblingof the hardened cement.

It has now-been established that a cement having from 0 to 3 per centtricalcium aluminate may be considered practically immune to the attacks ofsulphate solutions, but when the tricalcium aluminate content exceeds 4 to 5per cent failures can be expected.

T.P. 1029