bluuebunny/crossref_metadata_2025 huggingface dataset:
Unsteady Flow of Gas through Porous Media
Authors: Hetherington Charles R. , MacRoberts D.T. , Huntington R.L.
Published: June 2014

Since the equation of continuity governing transient flow of gases throughporous media cannot be integrated mathematically into a simple usableexpression free from series terms, empirical and approximate equations havebeen advanced relating cumulative production and future production rates fromgas reservoirs with time. In order to check the accuracy of these empiricalequations and to obtain an insight into the initial conditions pertinent to thesolution of the fundamental equation of continuity, experimental work has beenconducted on a vertical 2-in. tube, 91.6 ft. high, packed with unconsolidatedWilcox sand. The results presented in graphical form show the accuracy of theapproximate relations.

Data from unsteady-flow runs on the 2-in. experimental tube are presentedgraphically, and are applied to obtain an equation for this specific case, andare offered as an aid in future investigations of this basic equation.

The close agreement between equations calculated for steady-state flow andthe experiments indicates that the decline of actual gas reservoirs may betreated by an application of these equations without serious error.

Introduction

The steady-state flow of gas through a porous material-that is, flow whereinthe boundary conditions do not vary with time-is subject to analyticalsolution. Muskat has shown that the general differential equation is simply the La Place equation in P2. Direct solutionsmay be at once obtained.

The unsteady state, on the other hand, is not analytically reducible. Sincenearly all phenomena of practical interest in gas production involve flow inthe unsteady rather than in the steady state, it has been necessary to deriveapproximate solutions to the general equation. The validity of suchapproximations has not hitherto been adequately tested.

In the experiments to be described a simple, closed, linear system issubstituted for the real complex gas field. The general results, however, areindependent of the geometry of the system. The problem studied is the rate ofproduction, and the accompanying variations in pressure, when one end of alinear porous system is opened to the atmosphere and permitted to produce toexhaustion. An approximate solution to the general differential equation, basedupon the assumption of an "infinite series of steady states," is thenapplied to the results to determine the validity of this method of dealing withactual reservoirs.

T.P. 1398
Some Factors in the Economics of Recycling
Authors: Kaye Emby
Published: June 2014

It is the purpose of this paper to outline briefly some of theconsiderations that enter into the economics of so-called recycling, thegeneric designation of the relatively recently developed process by which acondensate is separated from gas-distillate gas at high pressure and theresidual gas returned to the reservoir. This subject necessarily embraces notonly a discussion of factors that should be considered in projecting arecycling operation, such as estimating reserves, investment and operatingcosts, but also a comparison of condensate with other types of petroleum. Theplace of condensate in its relation to the total supply of crude oil is pointedout as well as certain logical methods of product disposal. The cost ofdrilling wells and lease maintenance is not pertinent to this discussionbecause income and revenue are in this paper confined to that retained by theplant or plant operator for supplying processing facilities for the gas.

Before the development of recycling a great many gas-distillate gas fieldsin Louisiana and Texas provided no income to their owners. When gas was soldfrom these reservoirs it was accompanied by irretrievable losses of condensatein the formation. The understanding of the function of retrograde condensationresulted in the introduction of a new commercial petroleum recovery process forthese hitherto unexploited fields and now permits the conditioning of this typeof wet gas field for the sale of dry gas therefrom without waste.

Some Economic Factors

The study of a gas-distillate field for possible exploitation necessarilyinvolves the critical appraisal of a number of elements, chief of which will bediscussed here:estimate of distillate in placeestimate of distillatethat can be brought to the surfaceavailable marketcosts.

The considerations affecting the estimating of distillate reserves in placeare in the main subject to the same errors as are involved in determining drygas reserves. Determinable data including acreage, sand thickness, reservoirpressure, reservoir temperature, porosity and connate water provide the basisfor calculating the volume of gas in place. Ample allowance must be made forconnate water, which may occupy from 20 to 35 per cent of the pore space of thesand. The factor of supercompressibility is to a considerable extent nullifiedby the reservoir temperature.

T.P. 1304
An Electrical Device for Analyzing Oil-reservoir Behavior
Authors: Bruce W.A.
Published: June 2014

This paper covers the theory and present state of development of anapparatus for the nonmathematical analysis of complex problems of reservoir andwell behavior.

At the present stage of development of this apparatus, it is capable ofsolving the waterdrive problem of any reservoir performance for which amathematical solution has been presented in the literature, either on the basisof steady or unsteady-state flow analysis.

The theory is presented for the extension of the scope of this analyzeralong the lines of the present development. The resulting apparatus should beable to solve reservoir-performance problems previously thought too difficultfor practical solution by mathematical means.

As an illustration of its operation and present scope, the analysis of areservoir problem and synthesis of expected performance is presented.

Introduction

In this method of analyzing problems of petroleum-reservoir and wellbehavior, the porous continuum of the reservoir is assumed to be divided intosmall blocks, or units. Each block is assumed to be small enough so that for amaterial balance on the fluids in the block an average pressure for the blockcan be used. In analyzing reservoir behavior from this point of view bymathematical means, a set of simultaneous difference equations would beobtained (two for each block), which must be solved or combined into a partialdifferential equation. In the method to be described here, instead of solvingthese sets of equations analytically, electrical units are constructed, whichwill behave in respect to the flow of electricity exactly as the reservoirunits behave under various conditions of fluid flow. The electrical units arethen wired together in the same way that the reservoir units are connectednaturally by virtue of their geometrical locations and shapes.

T.P. 1550
The Use of Electrode Spacing in Well Logging
Authors: Zinszer Richard H.
Published: June 2014

Application of electric logs has been used in correlation of subsurfacestructure to determine the size and shape of the oil reservoir.

Such a knowledge is hardly complete until saturation and productivity aredetermined for the various horizons. It is difficult to use electric logssuccessfully for this purpose because of the many factors that influence thecurves. In this work an effort was made to establish an empirical correlationbetween formation resistivity for a series of electric-log curves and watersaturation and oil productivity of sand. Electric logs were obtained byrecording with 10 different electrode spacings through the same interval of awell. In the analysis of these curves all factors except two, a dependent andindependent variable, were held constant. The interval studied had been coredand a large number of samples were analyzed in the core laboratory in order tocompare the values of permeability and saturation with the measured values offormation resistivity.

Results of this analysis indicate:the depth to which mud filtrateenters a sand bodya correlation between permeability and sand resistivityfor shallow penetration depthsthat the water saturation for an oilsand can be determined from the measured sand resistivity after making suitablecorrections for sand thickness.

The procedure in the last method depends on acorrection for thickness factor and a theoretical curve. The accuracy of thetheoretical curve is now being tested in the laboratory.

Introduction

In an effort to place the analysis of electric logs on a quantitative basis, there is need for a better understanding of the many factors that influence anelectric-log curve. These factors may be large differences in sand thickness, permeability of the sand, salinity of the interstitial water, mud resistivity, formation temperature, and other sources. A number of examples were presentedby Archie, which treat the effect of sand thickness on measuredresistivity.

T.P. 1590
The Effect of Casing Perforations on Well Productivity
Authors: Muskat Morris
Published: June 2014

Analytical calculations have been carried out on theeffect of casing perforations on the productivity of wells, and formulas havebeen derived for general types of perforation patterns. The numericalcalculations, however, show that the resultant well productivity is essentiallyindependent of the perforation pattern, but is determined mainly by the totalperforation density. thus, for example, for a density of three perforations perfoot of casing the well productivity will be cut to one third of that of theuncased well for a perforation radius of 1/8 in., and to approximately one halfof a perforation radius of 1/4in., regardless of the detailed manner in whichthe perforations are distributed over the casing surface. the analytical theoryis also extended to included wells completed with slotted liners. it is showthat the reduction in productivity due to such liners will be relativity smallas compared with that due to perforated casings.

Introduction

The increasingly important role being played byproductivity factors of wells in determining well potentials and in the generalevaluation of producing formations lends interest to the analysis of all thevarious factors that may influence the productivity of a well. In recent papersthe results have been given of theoretical studies made to determine the effecton the productivity factors of a well of the gas-oil ration of the productionand the connate water within the sand. These have served to show that both ofthese factors may, under suitable conditions materially reduce the effectiveproductivity factors below those that would be anticipated on the assumptionthat the wells produce homogeneous fluids.

In this paper will be presented the results of theanalysis of an entirely different factor influencing the productivity of awell.This refers to that resulting from the increased use of the methodof completing wells by setting casings opposite all of the productive strataand then gun-performing the particular zones of immediate interest. Thepractical success of this method of completion would appear to be an answer tothe question as to whether it seriously reduces the well productivity ormaterially cuts down the ultimate oil recovery that may be derived from theproducing section.
The Geophysical History of Darrow Dome, Ascension Parish, Louisiana
Authors: Eby J. Brian , Harkins T.I.
Published: June 2014

This paper outlines the geophysical investigation of the area covering theDarrow salt dome, Louisiana. Surveys with the refraction seismograph andtorsion balance failed to disclose the dome, but reflection dip shooting wassuccessful and was confirmed by later drilling.

Introduction

The Darrow salt dome and oil field lies in western Ascension Parish, Louisiana, on the outside of a sharp bend and on the east bank of theMississippi River. The dome occurs about 30 miles south of Baton Rouge and 80miles northwest of New Orleans. Its geology, shape and structure have been ablydescribed in detail by Carroll E. Cook and, except for the general features, will not be repeated here. The purpose of this paper is to record some of theinteresting and pertinent geophysical data contributing to the discovery of thedome and eventually the oil field.

The salt dome is circular in outline and comes to within about 4625 ft. ofthe surface. At this depth the diameter of the salt plug is approximately 4800ft. The dome has only a thin cap rock of less than 75 ft.

Some oil has been found and is being produced in Miocene sands above the caprock, but most of the field's production comes from a narrow ring of wells aroundthe east and south flanks of the dome. Producing horizons on the flank arefound at 5670 to 5840 ft. in the Miocene and 6890 to 6985 ft., 7028 to 7060 ft.and 8260 to 8270 ft. in the Oligocene. The deepest well that has been drilledis the Humble Oil and Refining Company's Community B-5, on the south flank ofthe structure, which reached a depth of 10,013 feet.

The size and shape of the field and the area of production are indicated onFig. I. The line showing the area of production encloses all wells nowproducing and all abandoned producers, both on the top and flank of the dome.This line of production is shown on all subsequent geophysical maps as a directmeans of comparing the early geophysics to later drilling development.

T.P. 1495
Waters from the Frio Formation, Texas Gulf Coast
Authors: Jessen F.W. , Rolshausen F.W.
Published: June 2014

It is the purpose of this paper to present data on brines occurring in the Frioformation of the Texas Gulf Coast, and to show how their composition varies,with depth below the surfacewith depth below the top of theformationalong the approximate strike.

The brines vary in chloride content from 3,180 to 73,000 p.p.m., though theaverage salinity of the salt waters is shown to vary with total depth; theconcentration being 35,000 to 40,000 p.p.m. at 3500 to 5500 ft., slightly lessthan 50,000 p.p.m. chloride at 5500 to 6500 ft. and average 38,000 to 40,000below 6500 feet.

From the analyses available, it appears that the highest concentration of saltsoccurs in the upper 300 ft. of the formation, while lower salinity is foundwith increasing depth below this point.

The salt waters from wells in Starr County show less concentration of dissolvedsalts than in any other group of wells farther north along the strike.

In all, 116 analyses from 63 fields and 14 wildcats, from depths ranging from1300 to 11,400 ft. below the surface and from 2 to 3240 ft. below the top ofthe Frio, are recorded.

Introduction

Brines have been studied for many years in' an attempt to solve some of thegeologic and production problems associated with the production of oil and gas.One practical application of study of water analyses is the correlation ofwaters occurring above, in, or below the producing sand in the same field orthroughout the same formation.

The Frio formation, the series of sands and shales occurring below theMarginulina zone and above the Vicksburg, is.one of the major oil andgas-producing formations in the Texas Gulf Coast. Fossils are rare or absent inthe upper Frio throughout most of the area. When available, cuttings and cores, and electric logs were used to determine the top of the Frio. A change inlithology was used to determine this point in most of the wells, and fossilswere used in some of the deep wells.

It is realized that a change in lithology is not perfect for correlationpurposes over long distances and some of the trends may be influenced by theinability to differentiate between the nonfossiliferous Marginulina zone andthe Frio. It underlies virtually all the area shown on the accompanying map(Fig. I). Although it is not productive in the up dip facies, it has beenexplored to a limited degree below 12,000 ft. Furthermore, toward the coastline future drilling to deeper depths should encounter this formation.

Although thousands of wells have penetrated or drilled entirely through theformation, very few water samples have been secured from the many sandsoccurring in this formation and analyzed.

Previous Investigation

No previous published study has been made of the chemical composition andconcentration of waters from the Frio formation.

T.P. 1729
A Method of Drilling in Deep Water
Authors: Gross Henry Emmett
Published: June 2014

The waning supplies of domestic petroleum make it desirable to develop oilfields in new provinces, among the most attractive of which appear to besubmarine deposits; notably, in the Great Lakes. The author's portable openfoundations and means of oil-field development are presented. His designs for30 to 100 ft. of water, and for 100 to 600 ft., which offer possibilities ofcompletely exploiting the continental shelves, are set forth. It is emphasizedthat foundations must be of sufficiently low cost to be attractive. A methodfor overcoming ice hazards is outlined.

Introduction

New sources of petroleum and natural gas are beneath large bodies of watersuch as the Great Lakes, except Lake Superior, and ultimately the continentalshelves.

It is now particularly desirable to exploit the Great Lakes because:there is an acute shortage of petroleum and natural gas in the surroundingarea;the Lakes are far inland and safe from enemy raidersthey offerthe shallowest possible sources remaining in this countrythe water isnot as rough as in the open seas.

The one discouraging condition, floating ice in the winter, should offer noproblem.

In the Great Lakes, four places appear attractive for prospecting for oil:the western end of Lake Eriethe northwest half of Saginaw Baythe east side of Lake Michigan between Benton Harbor and Ludingtontheshallow south end of Lake Huron.

The title to submerged lands beneath navigable waters of the United Statesis owned by the various states. The boundaries are established. Leasing wouldhave to be from the states, but before mineral could be extracted, approvalmust be obtained from the War Department.

Methods of Development

The shallower parts of such small bodies of water as the western end of LakeErie, Lake St. Clair or Saginaw Bay, could be prospected and drilled by thesubmersible barge of Giliasso, one of which can keep a single string of toolsrunning for about eight months of the year. Some of the deepest wells have beendrilled from submersible barges in the bays and bayous of the Gulf Coast. TheCedar Point field in Galveston Bay was developed by barge drilling. This methodat present is limited to water less than 10 ft. deep, and is not suitable inopen water like that offshore in the Gulf of Mexico or the Pacific Ocean.

T.P. 1722
Natural Potentials in Well Logging
Authors: Mounce W.D. , Rust W.M.
Published: June 2014

The almost universal acceptance of electrical logging by the petroleum industrycalls for a critical examination of the physical bases of the common methods.This is particularly needed for the natural potential log. The conventionalexplanations are based on the phenomena of electro filtration and electroosmosis. However, experimental data show that they fail to give a basis that isquantitatively sound. Moreover, they lead to interpretations of details ofelectrical logs that are erroneous.

It was found experimentally that when a plug of shale is placed in a chain ofdissimilar electrolytes, a current flow results. Experiments on oil-well coresand fluids similar to those existing in wells show that potentials are set upwhich are in reasonable agreement with those encountered in electrical logging.Doubtless other sources of potential are important but this explanation notonly accounts for much of the potential but also clarifies some fairly familiarexamples of misinterpretations.

Introduction

The extraordinary value of electrical well logging as a tool for petroleumengineers and geologists is now so universally recognized that it is notnecessary to point out the ways in which it can be useful. It is sufficient tomention only the saving that has resulted from the elimination of much coringthat would have been necessary under former practices and the considerableadditions to reserves resulting from the discovery of sands missed incoring.

Paradoxically, the very remarkable success that has resulted from theapplication of electrical logging to correlation and completion problems hascost some of its most consistent users dearly. 1 The fact that some operatorshave placed unwarranted faith in erroneous interpretations of electrical logsdoes not reduce the value of the logs. It should, however, make one pause longenough to ask why experienced users should be misled. The answer to thisquestion is not hard to find. In nearly every case, the fault has beenoversimplification. This is illustrated very aptly by the familiarinterpretation and theory of the natural potential log.

Recording and Interpreting Logs

The natural potential log is extremely simple to record precisely enough forall present-day uses. One needs only an electrode, a cable to lower theelectrode through the drilling mud, a recording meter and a surface groundconnection. The electrode can be elaborate but need not be. A simple brass rod2 in. in diameter and 2 or 3 in. long is quite satisfactory. The cable need notbe particularly well insulated, nor need it have a very low resistance.

T.P. 1626
Postwar Uses of the War Emergency Pipe Lines for Petroleum Transportation
Authors: Swigart T.E.
Published: June 2014

The two War Emergency Pipe Lines were built by the United States Governmentto meet the serious transportation shortage caused by the diversion of thetanker fleet from the Gulf to East Coast run. The estimated 140-million dollarcost of these pipe lines approximates that of two battleships; however, becausethe lines have been so widely publicized as national defense measures, andfurther because their utility is so closely linked with the daily convenienceand welfare of the civilian population, their importance in the public mind isprobably magnified beyond that of two ships of the line. Thus, there may bestrong demand by the public, Congress, and the executive branch of theGovernment to maintain these lines in operating condition after the war.

Probably the simplest means of maintaining them in good condition is tocontinue them in operation. In keeping with American principles of privateenterprise, it will be desirable if they can be shown to have a place in theeconomic life of the country and can be operated by industry.

The most obvious use for the lines would be the movement of crude andproducts from Texas to the East Coast; for this business they will have tocompete with tankers. Their location enables them also to handle movements intoDistrict 2, for which business they must compete with existing privately ownedpipe lines and with barges. This paper attempts to analyze economic factorsthat bear on the use of these two big lines in the postwar period and todevelop through estimates the competition they may offer to other forms oftransportation.

The writer has purposely refrained from making recommendations as to theutilization of the War Emergency lines for petroleum transportation because itseems likely that prospective purchasers would be one or more operating oilcompanies, each of which would analyze the utilization of the lines in light ofits own business requirements. It is doubtful whether the lines would beacquired by a non-petroleum financial group for operation as commercialcarriers because interstate common carriers are prohibited from contracting tofurnish services to shippers, a restriction that implies that carriers, inturn, cannot expect to obtain guarantees of traffic from independent shippersin great enough volume to ensure return of their investments.

T.P. 1757
Selective Acidizing and Permeability Determination by an Electrical Method
Authors: Hefley Danna G. , Fitzgerald P.E.
Published: June 2014

An apparatus has been developed which permits selective acidizing of producingformations and determination of the relative permeability of a formation byfluid injection. This apparatus, known as the "Electric Pilot," is anelectrical fluid-interface locator, the electrical circuit of which iscompleted when the electrodes in the well are in contact with a conductivefluid, but is not completed when immersed in a nonconductive fluid. Results aregiven for a number of typical acidizing applications in which the interfacelocator was used to control the acid. Description of the method used in makinga permeability survey and the data obtained are also included.

Introduction

Early in the development of the acidizing industry it was recognized that oneof the most important problems to be solved in the chemical treatment of anywell was the determination of what part of the exposed section in the wellshould be treated and the selection of the technique that would insuretreatment of the desired section.

One of the first techniques adopted for assisting in proper placement of theacid, which is still widely used, is the method of confining the acid to theproducing section by means of a column of oil, which is known as the Carrmethod of treatment, named for its inventor. In the Carr method it is notpossible to selectively acidize a specific horizon in a multiple pay zone, somany improvements and modifications of the basic Carr technique were devised toaccomplish this result.

In order to overcome the possibility of the acid entering an undesirablesection at the bottom of the well, organic gel plugs were introduced into thebottom of the well, which served to halt the entrance of the treating solutioninto these zones. These chemical gels later liquefied because of bacterialaction and were removed from the well with the produced fluid.

In fields where a gas cap existed, as in the Goldsmith field of Ector County, Texas, it was imperative that a treating technique be evolved that wouldconfine the acid to the oil-producing zone below the gas cap. By so doing theoil-productive capacity of the wells could be improved without greatlyincreasing the gas production and this would lower the gas-oil ratio of thewell. The technique employed 4 to achieve this effect utilized two pumps, onefor pumping the chemicals down the tubing, the other to simultaneously forceoil down the annular space to confine the acid to the oil pay, thus preventingthe chemicals from entering the upper gas-bearing zones.

Experience has indicated that gas wells and certain types of oil wells respondbetter to "stage treating." This technique utilizes the introduction ofa certain volume of acid and then allows the well to "clean tip" beforeintroduction of the next and usually successively larger stages. Where suchmethods are employed steps must be taken to keep a disproportionate share of, the acid from entering the most permeable and previously treated zones.

T.P. 1604
Water Permeability of Reservoir Sands
Authors: Johnston Norris , Beeson Carrol M.
Published: June 2014

For many years the permeability of reservoir sands has been measured by flowingair through a cleaned and dried core sample. This differs from the truereservoir permeability in one important respect: the rock particles in thereservoir are surrounded by interstitial water, not air, and their physicalshape and condition of hydration are greatly dependent thereon. Permeability asdefined must be measured with a single-phase fluid. Since no means exist forremoving the oil and gas from a core sample by simply flowing water through it, the sample must be cleaned and then resaturated with water before testing. Thepresent discussion attempts to show that after the cleaning process aconsiderably different permeability is determined with salt or fresh water thanis obtained with air. The postulate is made that the salt-water permeability isprobably closer to the true reservoir permeability than is the measurement withair. This is discussed in relation to both physically possible and economicallyfeasible measurements. Data on more than 1200 core samples are given to showthe nature of the effects observed, and a plea is made for others to considerwater permeability measurements as a routine necessity, eventually replacingair permeability in regions where the differences are great.

Introduction

Permeability is defined as "a measure of the capacity of a porous medium totransmit? fluids, when there is no interaction between the solids and thefluid."

T.P. 1871
Prediction of Conditions for Hydrate Formation in Natural Gases
Authors: Katz Donald L.
Published: June 2014

Charts for predicting the pressure to which natural gases may be expandedwithout hydrate formation have been prepared for gases of even gravity.Pressure-temperature curves for hydrate formation were established for gaseshaving gravities from 0.6 to 1.0. These curves and the thermal behavior of thegases during free and adiabatic expansion were used to prepare the charts forestimating the permissible expansion of natural gases without hydrateformation.

The problem was solved by L. F. Albright, W. 'T. Boyd; J. J. McKetta, G.Martin, F. Poettman, and A. P. Snyder, who are first year graduate students inthe department of Chemical and Metallurgical Engineering at the University ofMichigan. This paper is essentially a summary of their results.

Prediction of Conditions for Hydrate Formation in Natural Gases

Each natural gas under a given pressure will form solid hydrates at acorresponding temperature provided sufficient water is present. The temperatureof natural gases below about 5000 lb. per sq. in. decreases when the gases areexpanded freely. This decrease in temperature may cause the expanding gas toenter the region of temperature and pressure at which hydrates will form. Thefinal pressure to which a natural gas may be expanded without hydrate formationdepends upon the initial temperature and pressure and the gascomposition.

This paper presents charts that give the final pressures to which gases ofgravity 0.6 to 1.0 at given initial temperatures and pressures may be expandedwithout formation of hydrate.

Hydrate-Forming Temperatures and Pressures as a Function of Gas Gravity

Experimental data of pressure versus temperature, at which solid hydrate willform, provided sufficient water is present, are available for a series ofgases. A method of predicting the pressure-temperature curve for a given gascomposition has been reported. The solution to this problem requires that thesecurves relating pressure to temperature be established for gases of givengravities.

T.P. 1748
Fractional Analysis of Well Effluents to Trace Migration of High-pressure Reservoir Gas
Authors: Valby E.P.
Published: June 2014

A method is presented in which the hydrocarbon weight fractional analyses ofthe well effluents from a true gas-cap-portion well and a true dark-oil-ringwell furnish the basic data for determining the properties of any mixture ofproduction from the two sources. The effect of injected gas on these propertiescan be computed. Comparison of similar properties of a given well effluent tothe properties of mixtures of the basic well effluents will give the relativeamounts of production from the two sources and injected gas.

Presentation of Problem

Oil fields having an area of gas-cap, or light-oil production, over thedark-oil area present a problem of increasing gas oil ratios during theproduction of an oil well. The use of pressure maintenance in a field such asabove, or a cycling project, wherein residue gas from an absorption plant isinjected into the reservoir, adds to the problem, because a part of theincreased gas-oil ratio may be due to the production of injected gas. Theusefulness of a means to determine the amount of injected gas in a welleffluent led to the development of a method in which well effluent analyses ofa true gas-cap-portion well and a true dark-oil-ring well furnish the basicdata needed to determine Whether injected gas of a known composition is presentin a given well effluent.

Development of Method

The method presented herein is based upon the principle that if two fluids, orwell effluents, having different properties are mixed in known proportions byweight, the properties of their mixtures can be computed. Conversely, if thesebasic data are known, the properties of a mixed well effluent can be used tocompute the relative amounts of each type of well effluent in the mixture. Aconvenient way of making these computations is to have the fractional analysesof the base well effluents and mixtures expressed in weight fractions. Themathematical equations expressing the properties of mixtures will be developedfor a two-component system consisting of the well effluents from the dark-oilring and the gas-cap area. The added effect of injected gas, a third component, will also be developed.

The following assumptions have been made in developing the method:The gas-cap and dark-oil fluids exist initially in separate portions of thereservoir.The fluids in each portion exist in a single phase at pressures above thesaturation pressure for the dark-oil fluid.The composition of each fluid is substantially constant throughout itsrespective portion of the reservoir.Changes in reservoir pressure and temperature will not change thecomposition of the fluid entering the well bore.The injected gas displaces original gas-cap fluid 100 per cent.

T.P. 1873
The Electrolytic Model and Its Application to the Study of Recovery Problems
Authors: Botset Holbrook G.
Published: June 2014

It is possible by means of the electrolytic model to simulate water- floodingor gas recycling systems involving input and output wells, and also theencroactment of a natural water drive. The results are obtained pictorially, and by simple measurements and calculations the percentage of recovery isobtained qualitatively as a function of the total input.

Introduction

The increased demand for the petroleum products, together with the decline indiscovery rate and the higher cost of recovery as deeper formations are broughtinto production, has stimulated interest in methods for studying and predictingefficiencies of various production programs. Among methods of recovery thathave become of increased significance recently are gas recycling in condensatefields and secondary recovery by water-flooding. The electrolytic model is auseful device for studying such methods in the laboratory, at least in aqualitative way.

The original experiments with electrolytic models and the development of theirapplication to the study of secondary recovery problems were published in 1933.Subsequently other investigators continued the development and modification ofthe basic method, with resultant improvements and extension of itsapplications.

The method and equipment to be described here are thought to represent stillfurther improvement in the results obtainable, with increased validity in theirapplication to field problems.

Summary of Principles of Operation

The underlying theory of the operation of the model is given in references 1,2, and 3. However a brief statement of principles involved is given herewith.The applicability of the model is based on the fact that ohm's law and d'Arcy? slaw are exactly analogous; whence electrical flow through a permeable medium.If two electrodes are placed in a conducting (ionized) solution and connectedto the positive and negative terminals of a source of direct current, thepositive ions of the solution will move toward the negative terminal. Since thevelocity of an ion in an electrolytic medium is proportional to the electricalgradient, just as the velocity of a fluid particle in a porous medium isproportional to the pressure gradient, the motion of the ions in the potentialfield will be the same as the motion of fluid particles in a porous medium ifthe positive and negative terminals (input and output wells) and boundaryconditions are made equivalent in shape and distribution.

In order for the analogy to hold exactly, the sand must be assumed to haveuniform porosity and permeability and the input and output fluids to haveidentical viscosities and densities. In gas recycling in condensate fields andin water-flooding in oil fields, the variations in density and viscosityusually are not great enough to introduce serious discrepancies intoresults.

T.P. 1945
Related Trends in Future Domestic and Foreign Petroleum Operations
Authors: Page Howard W.
Published: June 2014

Petroleum requirements since V-J day have been appreciably higher thanpredicted. Foreign operations now exceed maximum wartime levels by about 14 percent. Domestic operations since V-J day have averaged 92 per cent of thewartime peak. In spite of maximum foreign refinery runs, large exports of allproducts, except residual fuel oil, are necessary to meet foreign demand.

During the next few years it is expected that foreign operations willcontinue at capacity, including new installations, but that, because ofincreases in foreign demand, exports will continue at about their presentlevel. Domestic operations will increase during this period and crudeproduction probably will exceed maximum efficient rates.

Even after 10 years some exports probably will be required, but eventuallythese will be supplanted by increased output of foreign refineries, except forsmall tributary exports. The increase in domestic requirements will exceed thedecline in exports. Unless findings of crude oil exceed present expectations, the increasing demand will be met by increased imports and syntheticmethods-such as the Hydrocarbon Synthesis Process for conversion of natural gasand coal to gasoline and distillates. Catalytic cracking installations willincrease as crude availability decreases. This will help to meet the increasingdemand for gasoline but will intensify the domestic shortage of residual fueloil. Eventually larger imports will be required to satisfy the demand - forthis product.

Introduction

Under the pressure of the wartime period, there was time only occasionallyto look ahead in anticipation of what the postwar era held for the petroleumindustry. Perhaps the general expectation was that a rather pronounced declinein the level of industry petroleum operations would take place shortly afterthe end of the war, with the impact felt mainly on the economy of the UnitedStates. It is of interest now, nine months after V-J day, to take inventory ofthe near-term situation and see what significant forces are at work. With thisas a starting point, it should be possible to engage in something moresatisfactory than pure speculation concerning trends in the immediate futureand 10 to 20 years ahead.

T.P. 2048
Behavior and Control of Natural Water-drive Reservoirs
Authors: Elliott George R.
Published: June 2014

Methods are presented for measuring and comparing "degree" of waterdrive, and for observing the control that rate of withdrawal exerts overdecline of reservoir pressure.

Degree of water drive is studied from pressure-production curves of 10reservoirs; the method used to present these comparatively is to convertcumulative oil production from barrels to percentage of ultimate. Degree ofwater drive is also represented by a "water-encroachment factor," representing barrels of water influx per pound-month per acre-foot of oilreservoir.

Pressure-production curves for the water-drive reservoirs after a period ofdeclining pressure show a diminishing angle of slope, in some cases to thepoint where pressure ceases to decline or where it even increases; the shapesof these curves are in marked contrast to the dissolved-gas type of curve, which shows a general trend toward zero pressure at ultimate oilrecovery.

Yearly rate of oil production in percentage of ultimate oil recovery iscorrelated with pressure decline. The correct rate of production of oil withits associated gas and water sustains pressure in reservoirs having a highwaterencroachment factor. For reservoirs having a low water-encroachmentfactor, it is necessary to inject the produced water and even inject largevolumes of-water from an outside source.

The discussion of the actual reservoirs is preceded by a general review and isfollowed by a substantial bibliography.

Introduction

It is now generally accepted that water drive is capable of yielding 60 to 80per cent of the original oil in place in most reservoirs, as compared with 20to 40 per cent for dissolved-gas drive. There is no need to question theimportance of controlling a reservoir in order to take advantage of such anefficient mechanism.

What is a water-drive reservoir? Oil reservoirs usually combine two or more ofthe four basic mechanisms: dissolved-gas drive, gas-cap drive, water drive, gravity drainage. A water-drive reservoir is one in which water advances totake the place of the oil and gas produced. When the oil withdrawal rate issufficiently low, the water will tend to maintain pressure. The maximumeffectiveness is attained when the water follows the oil withdrawal so closelythat little or no decline in pressure occurs.

Oil in its underground reservoir is associated with water. This water issignificant in the production of the oil according to the source of supply andthe permeability of the surrounding formation. As oil is produced and thepressure is lowered, water can move in to replace the oil. With adequate supplyand sufficient permeability, actual movement takes place on an extensivescale.

The first movement of water takes place by expansion of the water and itsassociated fluids. While this expansion is of little importance in some fields, in others it is sufficient to supply all of the energy required for theproduction of oil.

T.P. 1880
Some Practical Aspects of Radioactivity Well Logging
Authors: Jackson Warren J. , Campbell John L.P.
Published: June 2014

Automatic recording of the radioactivity of the earth's formations provides alog of relative intensities that, if properly interpreted, can be applied tooil-field engineering. Production, engineering, and geological departmentsregard the radioactivity log as a forward step in the securing of moreconclusive information for successful well completions. Explanations of thetechnique, together with some of the problems to which radioactivity logginghave been applied, are presented in this paper.

Introduction

Those responsible for the completion of new oil and gas wells, or with planningworkover operations on old wells, have followed closely the development ofradioactivity well logging because they are interested in reducing the numberof unknowns that usually are present in such work. Many operators have made useof the log, or are acquainted with at least one of the applications, but it isunlikely that anyone operator is familiar with all of the many applicationsthat are possible.

The purpose of this paper is to present a representative example of each of themany applications, wherever the information has been released by an operator, and to illustrate by hypothetical examples other applications, releases forwhich have not been given. In this way, it is hoped that a better understandingof the scope of this new engineering tool may be obtained.

Although the literature contains many references that describe in detail thetheory, development, and application of radioactivity well logging, a briefdiscussion of the technique may be helpful to those who are investigating thesubject for the first time.

All rocks contain radioactive material in varying concentrations. In general, shales contain relatively more radioactive material than sandstones orlimestones. These radioactive materials disintegrate with time into othermaterials of lower atomic weight, and in that process of disintegration therocks are emitting many rays, the most penetrating of which is the gamma ray.The intensity of emission of the gamma ray is proportional to the quantities ofradioactive materials present. A higher rate of emission would be observed, therefore opposite a shale than opposite a sandstone or limestone.

Since measurable intensities of gamma rays are capable of penetrating as manyas five concentric strings of casing, and as the gamma-ray intensity isrelative to the formations, the measurements of variations in gamma-rayintensities offer a means of identifying cased-off formations in their properstratigraphic sequence.

The Gamma-Ray Curve

The measurement of gamma-ray intensities is accomplished by means of anionization chamber that consists of a heavy cylinder, about 3 ft. long, thatcontains two insulated electrodes and is filled with an inert gas under highpressure.

T.P. 1923
A Method for Determining Fluid Movement in Wells
Authors: Pease Sherman L.
Published: June 2014

An inexpensive and relatively rapid method that can be used by field crews isdescribed. Fluid movement is determined by releasing a tracer (dye) in the wellat a predetermined level and, after an interval of time, sampling the wellfluid at another level. The testing equipment consists of a combined crusherand sampler until that is run into the well on a wire line. The rate ofmovement can be calculated from time-volume relationships.

Description of Method

It is often desirable to determine whether there is occurring any transfer offluid from point to point in a shut-in well, and, if so, to measure of the rateof movement.

When it is desired to examine a large number of wells for possible ‘thief’ sands, the time and expense will be considerable unless the method used isinexpensive and rapid. After experimentation with several possible solutions tothe problem, the production Department of the Shell Oil Co., Inc., developedthe apparatus described herein, which has proved satisfactory. Routineoperations with it can be carried out by field production crews with a minimumof technical supervision and with negligible investment in equipment.

The method is based upon releasing a suitable tracer in the well fluid at aknown level and recovering a sample of well fluid at another level after ameasured interval of time. Repetition of this process with different timeintervals between release and sampling gives the necessary data.

For purposes of illustration, the setup for measuring migration of fluid in anupward direction is described in the following paragraphs.

The arrangement of equipment is shown diagrammatically on Fig. 1. The elementsof the combination unit are the tailpiece, the crushing device, the spacer andthe sampling device. The lengths of the tailpiece and spacer and the samplingdevices in the desired positions in relation to the sands being tested. Thecrushing device breaks the glass bottle containing the tracer when thetailpiece strikes the bottom of the well and the tension on the sand line isslackened. Because of the open construction of the crushing device, the traceris quickly and completely disseminated in the well fluid. The sampling deviceis a suction bailer, which obtains a sample of the fluid surrounding theperforated nipple just before the unit is picked up off bottom, the sample isretained in the barrel by the ball value for examination at the surface.

Normally, on the first run into a well, the sample is obtained near thereleasing point of the tracer, and thereafter samples are taken near the baseof the upper sand if migration is indicated by the dilution or absence of thetracer in the initial sample. The length of the time interval between thereleasing of the tracer and the sampling of the well fluid is varied forsuccessive runs, attempting first to establish the rate within limits and thento define it more accurately by additional runs if necessary.

T.P. 1911