bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of New Polymers with Better Performance under Conditions of High Temperature and High Salinity
Authors: Wu Yongfu , Mahmoudkhani Amir , Watson Philip , Fenderson Thomas , Nair Mohan
Published: April 2012

It is estimated that about 7,000 billion barrels of oil will remain in reservoirs after production by conventional methods. This value is the target for Enhanced Oil Recovery (EOR) techniques. The purpose of the water-soluble polymers in EOR application is to enhance the rheological properties of the displacing fluids. These polymers have been successfully implemented in China’s oilfields. Given the harsh conditions present in most oil reservoirs, new problems and challenges arise with the use of such polymers. Currently partially hydrolyzed polyacrylamides (HP AMs) are the major class of polymers used for chemical EOR application. However, due to the high flexibility of HP AM chain in aqueous solutions, particularly at high temperature (HT) and at high salinity (HS), the molecular chains begin to fold irreversibly resulting in a significant loss in viscosity. In this paper, we are reporting a bench-scale development of new PAM-based polymers with improved performance in HSHT conditions. The new polymers were evaluated conditions for their viscosity performance at various temperatures and salinities. The polymers were dissolved at different concentrations in brines with TDS (Total Dissolved Solids) of 34,655 ppm and 180,000 ppm. Viscosity measured at room temperature is in the range of 30 to 120 cP at the shear rate of 6 RPM. After aging at 90 °C and 120 °C for six months under ultralow oxygen level (< 5 ppb), viscosity remains relatively stable for some polymers while show a decline for others. Compared with the conventional HPAM polymers, these new polymers have much better stability at HTHS conditions.
Residual-Oil Recovery Through Injection of Biosurfactant, Chemical Surfactant, and Mixtures of Both Under Reservoir Temperatures: Induced-Wettability and Interfacial-Tension Effects
Authors: Al-Sulaimani H.. , Al-Wahaibi Y.. , Al-Bahry S.. , Elshafie A.. , Al-Bemani A.. , Joshi S.. , Ayatollahi S..
Published: April 2012

In this study, a biosurfactant produced by a Bacillus subtilis strain isolated from oil-contaminated soil from an Omani oil field was tested for its potential in enhancing oil recovery by a series of coreflooding experiments. It was found that the performance of the biosurfactant was increased by mixing with chemical surfactants, by which the maximum production went up to 50% of residual oil at a mixing ratio of (50:50). The second objective of this study was to investigate the effects of the biosurfactant on wettability alteration and to estimate its tendency to loss caused by adsorption. The influence of biosurfactant on wettability was studied by contact-angle measurements, atomic force microscopy (AFM) technique on few-layer graphene (FLG) surfaces, and Amott wettability tests on Berea sandstone cores. Contact-angle measurements showed that the wettability of the biosurfactant solution changes to more oil-wet as the angle decreased from 70.6 to 25.32° when treated with 0.25% (w/v) biosurfactant solution. Amott testing showed a change in wettability index from strongly water-wet in the untreated core toward less water-wet in biosurfactant-treated cores. These results confirmed the ability of the biosurfactant to alter the wetting conditions against different surfaces, thereby serving as a mechanism for enhancing oil recovery. The maximum loss of biosurfactant caused by adsorption was 1.2 mg/g of rock, which is comparable with reported chemical-surfactant values.
Engineering Study of the Cook Ranch Field, Shackelford County, Texas
Authors: Wilson Wallace W.
Published: April 2012

The Cook Ranch Field produces from a very permeable lens of Cook Sand of lower Permian or upper Pennsylvanian age, occurring at an average depth of 1,300'Ft. The field was discovered in 1926, and has been operated with low pressure gas injection since July, 1927, one of the first such projects in Texas. Cumulative recovery to Dec. 31, 1950, was 14,701,131 bbl of crude oil, an average of 1,013 bbl per acre-ft of oil section, and 72.5 per cent of the oil originally in place. Analysis of the reservoir performance indicates that gravity drainage has been an important factor in the producing mechanism. The high permeability and uniformity of the reservoir were extremely favorable for this type of operation.

Introduction

The Cook Ranch Field is the largest of a number of relatively small, shallow producing areas near Albany, in Shackelford County, Texas. This field is one of the first to be operated by gas injection in Texas, and probably is the most successful low pressure gas injection project ever attempted. The field is owned entirely by Roeser and Pendleton, Inc., and Continental Oil Co., aud has been operated by Roeser and Pendleton, Inc., since it was discovered. This study has been made possible through the cooperation of Roeser and Pendleton, Inc., in making available a remarkably complete set of records covering all phases of their operations. The purpose of this paper is to present a summary of the history of the operations through Dec. 31, 1950, and to analyze some of the factors which appear to be responsible for the success of the project. Information concerning the physical plant and the early gas injection history has been presented in an earlier paper.
A Method of Predicting Availability of Natural Gas Based on Average Reservoir Performance
Authors: Davis Ralph E. , Meltzer Lee Hillard
Published: April 2012

Introduction

During the past few years emphasis has been placed upon methods of estimating the future expectancy of gas production from natural gas fields. Before technical methods were applied, the production expectancy over future years was based upon the knowledge of gas well behavior, learned through long experience and embedded in the "know-how" of men long in the gas producing business. It is doubtful that a technical study of future expectancy of a gas field or a group of fields was ever prepared for the preliminary planning of a natural gas pipe line system built prior to about five years ago.

The decline in well production capacity was naturally recognized by all familiar with the business since its earliest beginnings more than 75 years ago. In 1953, the Bureau of Mines published Monograph Number 7, "Back-Pressure Data on Natural Gas Wells and Their Application to Production Practices," which gave to the industry the first technical analysis of the decline in production of individual gas wells. This method affords a means of estimating the future production in relation to decline in reservoir pressure.

The demand for technical determination of expectancy of future gas productivity from fields or a group of fields led technical men to the application of the knowledge of well behavior to the problems. The decline in a well's ability to produce as pressures declined could be estimated by the use of the curve known as the "back-pressure potential curve" as developed by the Bureau of Mines. A field containing few, or even numerous, wells could be analyzed on the basis of the sum of potentials of all wells.

In most studies of this nature, the problem is to estimate the rate of production that can be expected, not only from present wells but also, from wells that will in the future have to be drilled into the reservoir being studied. The "back-pressure potential" method requires that the following data be known or estimated:Proved gas reserves.Current shut-in pressures and rate at which shut-in pressures change with production.Back pressure potential data on wells in the source of supply.Ultimate number of wells which will supply gas, and their potential.Limitations on productivity such as line pressures against which the wells will produce, friction drop in the producing string, and so forth.
Volumetric Efficiency of Sucker Rod Pumps When Pumping Gas-Oil Mixtures
Authors: Connally C.A. , Sandberg C.R. , Stein N.
Published: April 2012

This paper describes the results of volumetric efficiency tests on oil, well pumps handling gas oil mixtures. The work was performed in a large scale, above ground unit wherein test conditions could be accurately controlled and measured.

The main variables studied were gas/oil ratio (including gas from solution and free gas mixed with oil), pump compression ratio, pump stroke length, pump speed, and clearance volume between the valves at their closest approach. Results are presented for two different pumps and for oils of two viscosities.

Relatively small amounts of gas entering the pump resulted in large decreases in volumetric efficiency. Under conditions where the pump was operating at reduced efficiency because of the presence of gas, it was found that variation in the clearance volume between. the standing and traveling valves had a considerable effect on pump efficiency level. This effect of the valve clearance volume was found to be significantly altered by the viscosity of the oil used in the tests. The effects on pump efficiency of the other variables studied were found to be relatively small over the range of conditions utilized.

Introduction

The production of oil by pumping is often hampered by low volumetric efficiency. A direct increase in lifting costs results from low volumetric efficiency. An indirect increase in lifting costs, probably greater than the direct increase, results from additional wear and tear on pumping equipment and from the down-time necessary for the repairs which can be traced to low-efficiency operation. Both increases in lifting costs tend to reduce economically recoverable oil.

A number of different factors can contribute to low pump efficiency. A known basic cause of low efficiency is the presence of free gas in the pumped fluid. Pump volumetric efficiency is calculated only on the basis of liquid pumped and because any free gas pumped is discounted, this volume of free gas would represent a loss of pump efficiency. However, gas also causes a reduction in pump efficiency because it is a highly compressible fluid.
Use of Permeability Distribution in Water Flood Calculations
Authors: Stiles Wm. E.
Published: April 2012

A method is presented for predicting the performance of water floodingoperations in depleted, or nearly depleted, petroleum reservoirs. The methodmakes use of permeability variations and the vertical distribution ofproductive capacity. From these two parameters can be calculated the producedwater cut versus the oil recovery. Derivations of the mathematical analogy isshown and sample calculations and curves of prediction are presented. Comparison is made of the predicted and actual performance of a typical 5-spotin an Illinois water flood.

Introduction

The use of water as a flooding medium in both depleted and "flush"oil reservoirs is gaining greater recognition and acceptance. Many of theshallower fields, depleted by primary production, have been and are beingsubjected to water injection in order to obtain some part of the large volumeof oil remaining after primary production. Some of the earlier water floodinstallation proved highly discouraging and the value of water flooding wasoften questioned. Many of these earlier floods were haphazardly selected anddeveloped as little was known of the physical characteristics and contents ofthe producing formations. The prior evaluation of the flood performance wasimpossible.

During the past decade the development of the required reservoir engineeringtools -core analysis, reservoir fluid analysis, electric logs, fluid flowformulae, etc.- has allowed the engineer to construct and apply the methodswhich are presently being used to evaluate the economic and mechanicalsusceptibility of a reservoir to flooding.

This discussion will present a method for taking into account the effectof permeability variations in predicting the performance of water floods indepleted reservoirs.

Permeability and Capacity Distribution

It is generally agreed by most investigators that in a single phase systemfluid will flow in a porous and permeable medium in proportion to thepermeability of the medium.

Producing formations are usually highly irregular in permeability, bothvertically and horizontally. However, zones of higher or lower permeability areoften found to exhibit lateral continuity. Thus, while structurally comparablestringers in adjacent wells may differ several fold in permeability values, they usually bear resemblance as being part of a general continuous higher orlower permeability section.

T.P. 2513
Effects of Transient Conditions in Gas Reservoirs
Authors: MacRoberts D.T.
Published: April 2012

A simple disturbance in a gas reservoir travels with a finite velocity whichis nearly independent of the amplitude of the disturbance. As a result verycomplex transients may be set up which seriously affect observation at a well.The time of transient is much longer than commonly supposed.

Introduction

A change in pressure at a gas well is not propagated through the reservoirinstantaneously but with a definite finite velocity. Knowledge of the period ofthis transient is of value because:Observations of pressure and flow-rate during the transient may affectinterpretation of back-pressure tests.Interference effects between wells may be used to determine continuity offormation.Additional information concerning the physical characteristics may possiblybe deduced from the behavior of a well during the transient.

Mathematical Development

It will be assumed that the well is initially closed in and that thepressure is constant throughout the reservoir. As the initial disturbancepasses outward from the well it is further assumed that a logarithmic pressuredistribution is established between the most distant point reached and thewell.

Conclusions

The great length of time which may be involved in transients may becalculated from the appropriate constants. Thus the Monroe gas field containsareas having transient time of the order of years. This produced the anomaly ofa field effectively depleted in one portion but with virgin pressure in anothereven though both were connected.

Some attempts have been made to establish or disprove continuity offormation by the observance of interference effects between wells. Althoughthis is theoretically possible and such interference effects have been observedthe observational difficulties are formidable and the probable existence ofcomplex transients further decreases the likelihood of an extensive applicationof this method.

The same conclusions, even more forcibly, apply to attempts to measurereservoir constants by transient observation.

T.P. 2547
Outline of Weather and Wave Forecasting Techniques
Authors: Glenn Alfred H. , Graham Joe E.
Published: April 2012

Introduction

Oil operators engaged in drilling on the Continental Shelf of Louisiana andTexas are in agreement that adverse weather and wave action are two of thegreatest hazards to the safety and efficiency of their work. It was anticipatedwhen the offshore operations commenced that such would be the case, andexperience to date has verified this assumption. Because atmospheric conditionsand wave action involve tremendous amounts of energy it is highly unlikely thatit will be possible to control any but the most localized weather and wavephenomena within the foreseeable future. Thus, as long as the offshoreoperations involve the movement of small craft and barges over exposed waters, and the transfer of personnel and heavy equipment from these craft to eitherfixed structures or larger craft at close quarters, the weather and waveproblem will remain.

Taking into consideration the persistence of the wave and weather problemand the improbability of achieving a direct solution, the Humble Oil & Refining Company, in planning its offshore campaign investigated thepossibility of forecasting wave and weather conditions in order to providewarnings of dangerous conditions and increase efficiency in day-to-day planningof work. It was recognized that predictions of wave and weather conditionsbased on meteorology and oceanography, both geophysical sciences, are not 100per cent accurate and application of forecasts in the offshore work wasdependent on whether they provided information which was sufficiently greaterin accuracy than the layman's guess to be worth the expenditure involved.

During World War II, meteorology and oceanography were used with success inreducing danger resulting from environmental conditions and increasingefficiency of operations exposed to the elements. This success was partiallythe result of improvement in the scientific techniques involved and theprocurement and distribution of observational data, and partially due to thelarge scope of the military operations which meant that a reduction of lossesof a relatively small percentage of the total cost amounted to a large figureexpressed in terms of dollars. Since the offshore drilling involves anextremely large financial investment, it was considered that the experience ofthe Armed Services in successfully employing meteorology and oceanography mightbe duplicated in the oil industry. In addition, the oil industry's successfulexperience in utilizing seismology, geology, and terrestrial magnetism; allgeophysical sciences, indicated that meteorology and oceanography, also of thefamily of geophysical sciences and sharing their scientific assets andliabilities, might be profitably put to use.

T.P. 2546
Method of Establishing a Stabilized Back-Pressure Curve for Gas Wells Producing From Reservoirs of Extremely Low Permeability
Authors: Haymaker E.R. , Binckley C.W. , Burgess F.R.
Published: April 2012

A method of establishing stabilized back-pressure curves for gas wellsproducing from formations of extremely low permeability is presented. Actualwell performance under many different operating conditions is shown by thestabilized back-pressure curve. By use of the method, it is possible to conductback-pressure tests with a critical-flow prover on wells that stabilize slowly, and save approximately 88% of the gas ordinarily vented to obtain satisfactorytest data, with a great reduction in time required for testing.

Introduction

The reasons for establishing dependable back-pressure curves on gas wellshave been pointed out by previous publications. The publication most referredto, of course, is the United States Bureau of Mines Monograph 7, titled"Back-Pressure Data on Natural Gas Wells and Their Application toProduction Practices". The technique generally established therein has beenaccepted and used by many engineers; and, when proper tests are conducted, theresults can be used for the analysis and solution of several practical problemsconcerning field operation and development.

Even where formations of low specific permeability are encountered, thedetermination of a well's actual performance by the back-pressure test methodpermits the engineer to analyze many problems in individual well operation andalso to predict necessary future field development. Such problems as thedetermination of the ability of a well to produce into a pipe line at apredetermined line pressure, the design of gas gathering systems and metersettings, and the determination of the time and the number of wells required tobe drilled to meet future market obligations, can be solved, in part, by theuse of a reliable back-pressure curve. In addition, the computed well deliveryrates determined by data from backpressure tests ordered by state regulatorybodies, when compared with the true back-pressure curve, permit the operator toascertain whether such data represent unstable or relatively stabilizeddelivery rates for given pressure conditions of the well.

The technique of back-pressure testing, as described in this report, wasdeveloped by Phillips Petroleum Company engineers from data obtained during atesting program that started in 1944 and has been continued to date. Threehundred and eleven back-pressure tests were conducted on 299 wells located inthe southern part of the Hugoton Field. The gas-bearing zone is composed ofseveral dolomitic formations of the Permian Age; the important ones are theHerington, Upper Krider, Lower Krider, and Winfield. The average bottom-holetemperature is approximately 91'F., and the initial wellhead shut-in pressuresrange from 400 to 440 psig. The spacing pattern is 640 acres per well with eachwell located near the center of the section. The range of back-pressurepotentials on wells tested was from 500 to 23,000 Mcfd.

T.P. 2545
Production of Oil Under Unitization in Wertz Dome Field, Wyoming
Authors: Swedenborg E.A.
Published: April 2012

The unit agreement for the Wertz Dome field, Wyoming, was approved by theActing Secretary of the United States Department of the Interior on November 4,1937, effective on December 1, 1937. The stated objectives of the agreement areto conserve and put to beneficial use all oil and gas produced; to makepossible a uniform withdrawal of oil and gas in order to maintain equalizedreservoir pressures; to provide for an orderly determination of the structuralfeatures of the productive horizons; and to permit the injection of gas forpressure maintenance. The purpose of this paper is to show by a discussion ofthe problems involved and the engineering practices employed by the unitoperator, how well the objectives of the unit agreement have been accomplishedin the development and production of oil and gas from the field.

History and Development

The Wertz Dome oil and gas field is located 88 miles southwest of Casper and 38miles north and westerly from Rawlins, Wyoming. It is served by a statesecondary oiled road connecting with U. S. Highway No. 220 at Lamont, adistance of 3 miles from the field. It has been a producing field for 27 years, first as an important producer of gas and more recently of oil.

The Producers and Refiners Corp. completed Well No.1, NE?SW? sec. 7, T. 26 N., R. 89 W., the first productive well in the field, in September, 1921, in theMuddy sandstone of Upper Cretaceous age, at a depth of 3435 feet for an initialproduction of 42,000,000 cu. ft. of gas per day. In 1922 pipe lines were laidto Casper, Wyoming, for supplying fuel to the Standard of Indiana refinery, theadjoining town of Mills, and the Producers and Refiners Corp. pump station No.6in Mills; and to Parco (now Sinclair), Wyoming, for supplying that refinerywith fuel. The gasoline content of the gas was extracted in an absorption plantlocated near the town of Mills. No compressors were used as the line pressurewas sufficiently high to flow the gas through the absorbers. As high as30,000,000 cu. ft. of gas per day were treated in the plant extracting 6000gallons of gasoline. In September 1937, the pipe line was discontinued and theplant was dismantled at which time 61,000,000,000 cu. ft. of gas had beenproduced from the seven Muddy, Cloverly, and Sundance gas wells drilled in thefield. Of this volume of gas 800,000,000 cu. ft. were produced from theFrontier formation, 34,200,000,000 cu. ft. from the Muddy sandstone,24,000,000,000 cu. ft. from the Cloverly, locally called Dakota, and2,000,000,000 cu. ft. from the Sun dance formation. The pipe line wasdiscontinued because of the near depletion of the gas reserves in Wertz andnearby fields, and because of the local field requirements demanding theretention of the remaining gas reserves.

T.P. 2588
Pilot Gas Injection - Its Conduct and Criteria for Evaluation
Authors: Elkins Lincoln F. , Cooke John T.
Published: April 2012

Introduction

Injection of gas to increase oil recovery has been considered for almost allimportant discoveries during the past ten or fifteen years. However, the numberof gas injection projects having sufficient history and data is too limited topermit valid generalities of effectiveness of gas injection. Management andengineers are faced with a difficult problem of selecting those reservoirswhich are susceptible to profitable application of gas injection.

Injection of gas to maintain high pressure favors some factors affectingreservoir performance such as viscosity, surface tension, and formation volumefactor of oil by keeping gas in solution and favors some operating featuressuch as extending flowing life of wells and storing part of the produced gasfor future use or sales. Injection of gas at low pressure involves lowercompression ratio, or at least a single gas-gathering system, largerdisplacement volume in the reservoir per unit of gas handled, and permitseffective utilization of the naturally existing energy and agent for oildisplacement that is gas dissolved in oil. Each program is thus a compromise tomeet optimum economic conditions while striving to attain maximum recovery ofthis important natural resource.

The statement has often been made that pressure maintenance would greatlyincrease oil recovery by permitting abandonment of formation oil inflated withgas in solution rather than abandonment of the same liquid volume of tank oil, if the same terminal oil saturation could be attained. Simple calculationsindicate increases in oil recovery as high as one hundred per cent on thisbasis for high formation volume factor oil encountered in current deepdrilling. Important in this statement is "if the same terminal oilsaturation could be attained."

T.P. 2646
Selective SP Logging
Authors: Doll H.G.
Published: April 2012

An earlier paper on the general subject of the SP log has analyzed thelimitations of that log, in particular when dealing with thin permeable bedsenclosed in thick highly resistive ones. Under such conditions, the SP log doesnot give a good definition of the permeable beds.

Selective SP logging is a new method which gives an accurate determinationof the permeable beds, even in highly resistive formations, except when thesalinity of the mud is extremely high. It also permits a close approximation ofthe static SP to be obtained.

The method consists generally in controlling the potential of auxiliaryelectrodes located in the drill holes in the vicinity of the measuringelectrode. In this manner, the flow of SP current along the drill hole ismodified to counterbalance the effect of highly resistive strata.

Several procedures and arrangements used to record selective SP curves andstatic SP curves are explained.

Field examples illustrating these methods are given and discussed.

Introduction

In an earlier paper, the shape of the SP curves and the amplitude of the SPpeaks were analyzed, considering how the circulation of the SP current isinfluenced by the subsurface media as a function of their geometricalconfiguration and their resistivities. It was shown, in particular, that thepermeable beds situated between highly resistive formations are sometimesindistinctly indicated by the deflections of the SP log.

It is the purpose of this paper to discuss a new method now being developed, namely selective SP logging, whose principal feature is to enable a moreaccurate determination of the depths of the permeable beds present in highlyresistive formations, such as occur in limestone fields.

It will be shown also how an additional curve called the static SP log can hederived from the selective SP log, or recorded directly, to facilitate theinterpretation.

T.P. 2850
Corrosion Mitigation Within Dehydrating Tanks
Authors: Kartinen Ernest O.
Published: April 2012

This report is the accumulation of eight years of experience on only onesmall phase in the business of oil production. It is not intended as a finalreport but rather as a progress report dealing with the internal corrosion ofoil field dehydrating tanks.

The corrosion of dehydrating tanks continues to be a problem in the productionof crude oil. The deterioration by corrosion of these tanks falls into threegeneral classifications:Atmospheric corrosion of exterior areas,corrosion of the underside of deck and the rafters and top area of the upperrow of staves in that part of the tank which is known as the vapor space, andcorrosion of the bottom and shell areas, and the steam coils which arenormally immersed in water and thus exposed to the corrosive action of thewater.

Atmospheric corrosion is primarily a paint problem, and has been omitted inthis discussion.

The corrosion in the vapor space, in this company's experience, which has beenof great concern only in one area, has also been omitted in thisdiscussion.

The third, and most troublesome type of corrosion, and the one with which thisreport deals, is that which occurs in the water-exposed areas of dehydratingtanks, and, to a lesser degree, in some stock tanks.

The operating temperature of these waters varies from 80'F to 160'F and thesalt counts run from a few thousand to as high as 25,000 parts per million.Corrosion in these tanks occurs in three forms:pits,ringworm type ofattack along the vertical and horizontal bolt seams, andas a generalattack, spread over a wide area.

Steam Coils

In dehydrating tanks, our experience has been that the steam coils are thefirst to show signs of corrosion, and then the shell and bottom areas. Thisaction is not uniform throughout this company's operations. Some installationshave coil troubles with very little tank trouble, and some show just theopposite. But in the majority of cases the coils are the more seriouslycorroded areas. This may be partly due to the fact that we have tried byperiodic application to keep a protective coating on the interior areas of thetanks, and some protection has been afforded by these coatings.

T.P. 2847
Review of Cycling Operations in the La Gloria Field
Authors: Justice W.H.
Published: April 2012

Purpose

Cycling operations have been successfully conducted in the La Gloria Zone foreight years. The cycling of this zone is now virtually completed. It isproposed that this report shall review the cycling operations of this reservoirso that the industry can more accurately evaluate the cycling process as aproduction method.

Introduction

The La Gloria project is one of the largest cycling operations in the Stateof Texas. The gas rights in the field are unitized in three operating units. Bymutual agreement Magnolia Petroleum is the designated operator of the projectfor the 12 operators owning the gas rights. The La Gloria Corp. is the ownerand operator of the cycling plant. The development and operation of the fieldare under the direction of an Operators Committee comprised of a representativeof each operator. The Operators Committee is assisted by an Engineering andGeological Sub-Committee.

The La Gloria gas field is situated approximately three miles north ofFalfurrias, Tex., and lies principally in the extreme south end of Jim WellsCounty, with its outer limits extending into the north end of Brookes County, Tex. It is a simple elliptically-shaped dome which has a closure of 350'Ft. Thefield encompasses a surface area of 5,500 acres. The gas reserves are found in20 major sand zones lying in the lower Frio formation and Transition Zone ofthe Upper Vicksburg formation. Approximately 40 gas wells have been drilled inexploring and developing the gas reserves of the field.

Discussion

The La Gloria sand occurs in the lower Frio formation at a depth of 6,515 ft atthe crest of the structure. The average sand thickness for this zone is 32 ft.The reservoir initially had a gas column of 125 ft and did not have an oilcolumn. The sand has an average porosity of 22.2 per cent and an averagepermeability of 521 MD. The productive area of this zone is 2,680 acres. Theoriginal bottom hole pressure was 3,470 psia and the formation temperature is203?F. The average percentage connate water in the reservoir space has beenestimated at 20 per cent.

T.P. 2952
Laboratory Measurements of Relative Permeability
Authors: Osoba J.S. , Richardson J.G. , Kerver J.K. , Hafford J.A. , Blair P.M.
Published: April 2012

This paper presents the results of laboratory measurements of relativepermeabilities to oil and gas on small core samples of reservoir rock by fivemethods, and describes the influences of such factors as boundary effect, hysteresis, and rate upon these measurements. The five methods used were the"Penn State," the "single core dynamic," the "gasdrive," the "stationary liquid," and the "Hassler"techniques.

In those methods in which the results are subject to error because of theboundary effect, the error may be minimized by the use of high rates of flow.In order to avoid complexities introduced by hysteresis, it is necessary toapproach each saturation unidirectionally. Observed deviations of relativepermeabilities with rate can be explained as a manifestation of the boundaryeffect, and disappear as the boundary effect vanishes.

The results indicate that all five methods yield essentially the samerelative permeabilities to gas. Of the four methods applicable to thedetermination of relative permeability to oil, three, the Penn State, singlecore dynamic, and gas drive, gave relative permeabilities to oil which were inclose agreement. The Hassler method gave relative permeabilities to oil whichwere consistently lower than the results obtained by the other methods.

Introduction

The relationship between the effective permeability of a reservoir rock toeach of the fluids flowing through it and the corresponding fluid saturation isan important characteristic of the reservoir rock. Knowledge of thischaracteristic is and gas reservoirs and of the ultimate recovery to beexpected extremely important in the prediction of the behavior of oil undervarious operating conditions. These effective permeabilities are usuallyexpressed as the "relative permeability" to a fluid phase, defined asthe ratio of the effective permeability to the permeability of the rock to asingle phase at 100 per cent saturation.

Relative permeability-saturation relations are not the same for all kinds ofreservoir rock, but may vary from formation to formation, and within thedifferent portions of a heterogeneous formation. In studying the performance ofa specific reservoir, it is necessary, then, that the relative permeabilitycharacteristics of the individual portions of the reservoir be measured. Thesemeasurements may be made in the laboratory on small core samples from thereservoir.

Various techniques have been proposed for the measurement in the laboratoryof relative permeability-saturation relations. In varying degree, difficultiesattend the use of all of the methods which have been proposed. It is thepurpose of this paper to discuss the factors which influence the measurement ofrelative permeability, the difficulties encountered in several methods, and topresent comparative results obtained by the use of various techniques.

T.P. 3020
An Analysis and the Control of Lost Circulation
Authors: Howard George C. , Scott P.P.
Published: April 2012

During the drilling of wells, fractures which are created or widened bydrilling fluid pressure are suspected of being a frequent cause of lostcirculation. A study of the variables which are believed by the authors to berelated to fracturing led to the premise that the presence of an effective lostcirculation material in a drilling mud stream would serve to plug smallfractures at the moment they are encountered or created and thereby eliminate apossible cause of lost circulation by preventing fluid pressure from wideningand extending the fractures.

A large number of lost circulation materials were classified and tested insimulated fractures and in shallow wells. Granular type materials with agradation of particle sizes were found to be the most effective for plugging.Within the limits of pump ability, the concentration in mud of each lostcirculation material tested was found to be a controlling factor in determiningthe maximum size fracture which could be sealed. A new type centrifugal sorterwas given preliminary tests and found to be capable of concentrating cuttingsfor rejection and reclaiming lost circulation materials.

Introduction

The control and prevention of lost circulation of drilling fluids is aproblem frequently encountered during the drilling of oil and gas wells.

Lost circulation or lost returns may be defined as the loss to formationvoids of the drilling fluids or cement slurries used in the process of rotarydrilling and well completion. The loss may vary from a gradual lowering of mudlevel in the pits to a complete loss of returns. Not to be confused with lostcirculation is the continuous reduction in mud volume caused by the loss of thefluid phase of muds as filtrate and the solid phase as filter cake during thecontinuous filtration process which occurs on permeable formation surfaces.

T.P. 3096
Transient Flow in Gas Transmission Lines
Authors: Olds R.H. , Sage B.H.
Published: April 2012

Introduction

The transient flow of gases in long pipe lines is a problem of industrialinterest. The present discussion deals with the application of the conservationof momentum and material to the transient flow of gas in conduits which arelong with respect to their diameter. Solutions of the resulting equationsinclude consideration of variations in friction and specific volume of thefluid as functions of time and position along the conduit. The changes in statealong the pipe line are established as a function of time. The methods proposedmay be extended to other situations.

The flow of compressible fluids under steady conditions has been consideredin detail. Primary emphasis was placed on the development of simple means oftaking into account the non-uniform flow realized in long conduits under suchconditions. Binder discussed the essential differences between the flow ofcompressible and noncompressible fluids. Bonilla proposed direct methods ofsolution for equations describing isothermal flow in long pipes. Similarconsiderations limited to steady flow have been discussed by Ruth. Palsgrovesuggested a graphical means of solving specific problems relating to the flowof gases in conduits of uniform section. Some of the basic concepts of the flowof a compressible viscous fluid in straight tubes have been described by Kuo.Problems of this type require knowledge of the equation of state of the fluid.In many cases it has been convenient to assume that the fluid follows therelationship ascribed to a perfect gas.

The treatment of unsteady flow of compressible fluids is less complete. Thisstate of affairs results from the fact that the differential equations relatingpressure and flow rate with time and position for unsteady flow are nonlinearin character. Muskat and Wyckoff presented an excellent treatment of thesituation in laminar flow where inertia forces were not of controllingimportance. Somewhat earlier Hurst discussed the unsteady flow of fluids inpetroleum reservoirs. Hetherington, MacRoberts, and Huntington establishedexperimentally the pressure distribution and accumulative flow rate of naturalgas through an unconsolidated sand. Recently Joffe considered the specificproblem of the flow of natural gas in relatively long pipe lines for unsteadyconditions with emphasis upon the economic feasibility of the storage of gas insuch a reservoir. These discussions were based upon approximations of thepartial differential equations applying to the conditions of flow. The resultswere descriptive of the physical situation and indicated the effectiveness oflarge pipe lines as cyclic storage facilities for natural gas.

T.P. 3081
Relaxation Methods Applied to Oil Field Research
Authors: Dykstra H. , Parsons R.L.
Published: April 2012

A numerical method for solving partial differential equations in steadystate fluid flow is described. This method, known as the "relaxationmethod," has two advantages over analytical methods:practically anyproblem can be solved, anda solution can be obtained quickly.

Adisadvantage is that the solution is not general. The method is applied to coreanalysis and relative permeability measurement to calculate constrictioneffects and to calculate the true pressure drop measured by a center tap in a Hassler type relative permeability apparatus. Further applications aresuggested.

Introduction

Many problems in fluid flow cannot be solved analytically because of thenature of the boundary conditions. For many problems, however, an exact answeris not necessary because boundary conditions are not exactly defined or theparameters describing the porous medium are not accurately known. Therelaxation method can be used to obtain an approximate answer easily andquickly for the flow of incompressible fluids in porous media. The method canalso be used for other types of problems, such as determining the stress in ashaft under load, or the temperature distribution during steady state heatflow. In this discussion only calculations concerned with the flow of fluids inporous media will be considered. The method was introduced by R. V. Southwellin 1935.

Theory

The treatment given here follows that given by Emmons. Consider a porousmedium to be replaced entirely by a net of tubes of equal length and uniformcross-sectional area as shown in part in Fig. 1. Assume that the net of tubesbehaves exactly like the porous medium which it replaces; that is, the net canbe made fine enough to reproduce exactly the porous medium.

T.P. 3145
Laboratory Determination of Relative Permeability
Authors: Richardson J.G. , Kerver J.K. , Hafford J.A. , Osoba J.S.
Published: April 2012

A detailed study of a number of methods of relative permeability measurementhas been made in a search for the technique most suited to routine analysis ofcores taken from reservoir rock. It has been found from tests run on the samesamples of core material by a number of techniques that the Penn State, Hassler, Hafford, and dispersed feed techniques all yield results which arefelt to be reliable. Conditions under which the faster single core dynamictechnique may be used are described. Further work on the calculation ofrelative permeabilities to oil from data obtained by the gas drive method isneeded before this latter rapid method can be utilized.

Correlations between theoretical studies and experimental results have beenobtained in studies of the boundary effect, pressure distribution in two-phaseflow, and gas expansion effects. Previous conclusions that the effects of theoutflow boundary could be made negligibly small have been substantiated.Results of experimentally determined oil and gas pressure distributions along acore sample during flow are presented. Further studies of the effects of rateof flow in the measurement of relative permeability-saturation relations haveshown that results are independent of the rate of flow as long as the flow rateis below the point where inertial effects commence. An analysis of the effectsof a severalfold expansion of gas along the flow path indicates that whilesaturation gradients are induced in the test sample, the errors caused by thisphenomenon in relative permeability measurements are small.

Introduction

Many pages of literature have been devoted to pointing out the need forrelative permeability-saturation relations in reservoir engineering. One of themost attractive ways of obtaining this information is by the analysis ofsamples of core material taken from the formation in question, and againliterature has described many methods for obtaining these data. It is thepurpose of this paper to present the work that has been done in the study ofsome of these published methods together with some other methods that have beenrecently developed in this laboratory. Also, a study of some of the factorsthat influence the laboratory determination of relative permeability-saturationrelations is presented.

T.P. 3375
Sample Grading Method of Estimating Gas Reserves
Authors: Katz D.L. , Turner C.E. , Grimm R.D. , Elenbaas J.R. , Vary J.A.
Published: April 2012

A technique is presented by which well samples and core plugs of dolomiteformations are classified by microscopic examination into seven differentporosity grades. Quantitative values of porosity and permeability aredetermined for each grade by a statistical correlation of the core plug testdata with the porosity grading system. These quantitative values are applieddirectly to the grades exhibited in the well samples for the purpose ofestimating the reservoir void space for wells that were not cored.

The procedure is described for estimating the gas reserves per unit area forthe South Hugoton gas field, but a reserve estimate for the field is notgiven.

Introduction

The miscroscopic examination of well samples and the graphic recording oftheir lithologic qualities and other distinguishing characteristics of variousgeologic formations drilled is both a science and an art of long standing andwide application. Usually the primary objective of a geologist who "sits onthe well" and examines the samples are: to identify the formation beingdrilled, determine the total depth, casing point, and completion interval. Inmost cases the porosity is described, if done at all, in general terms, suchas: trace, scattered, fine, poor, fair, medium, good, excellent, or in someother relative terms. In fields where various geologists have examined samplesand recorded observations on many wells considerable variations in lithologicterms and porosity descriptions occur unless there is primary effort toestablish uniformity of logging observations and standards of recordingobservable porosity.

When an estimate of the pore volume of a reservoir is made a geologicconcept of the processes that control the magnitudes of porosity andpermeability is developed by microscopic examination of well samples. Thecharacteristics and appearances are then mentally related to rather generalquantitative units of porosity based on physical core data from the samereservoir or on such data or experience in other reservoirs that have similarqualities. The reliability of such estimates depends largely on the variationsof the lithology of the formations, the geometric properties of its voidsystem, the extent of comparisons of sample appearances with porosity data, aswell as the uniform recording of all relevant characteristics. This statementis particularly significant for dolomitized limestone formations of substantialthicknesses and heterogeneity such as the Permian Dolomites of the Hugoton gasfield.

T.P. 3374