bluuebunny/crossref_metadata_2025 huggingface dataset:
Challenges in Implementing an EOR Project in the Pre-Salt Province in Deep Offshore Brasil
Authors: de Sant´Anna Pizarro Jorge Oscar , Branco Celso Cesar
Published: April 2012

Carbonate reservoirs contain expressive part of the world oil reserves. The exploitation of these resources, however, presents several challenges mainly associated with their complex pore geometry, large scale variation in permeability and sometimes unfavorable wettability. These challenges can become more significant when we move to a deep offshore environment. As off-shore projects need to be planned well in advance, due to the lack of room in the platforms for future expansion, the pioneer application of EOR methods needs to be considered from the conceptual stage of the development.

This paper addresses the approach used to design the development basis for Lula field, formerly known as Tupi area, in the Pre-Salt Cluster (SBPSC) in Santos Basin, offshore Brazil. It focuses on the strategy of phased development, dynamic data acquisition and actions to add flexibility to the production system and how to manage uncertainties. A comprehensive analysis of the existing uncertainties, such as the reservoir characterization, early water and gas breakthrough, bypassed oil saturation, flow assurance in deep water flowlines and CaCO3 scale possibility in production wells, favored a phased development concept aiming to mitigate risks. The approach used to cope with these uncertainties in a Pilot Project as well as in the future development scenarios is presented. Most of the discussion is focused on how to consider feasible Enhanced Oil Recovery techniques through Pilot testing and future implementation in large scale in the field. It comprises the investigation of different recovery processes and first field results, including miscible processes using hydrocarbon gas and CO2. To optimize the oil displacement, a water alternating gas (WAG) injection process is also being designed.

After one and a half year of extended well test production and the implementation of the first Pilot project in January, 2011, results confirm the decision of providing additional flexibility to the project. Dynamic appraisal proved essential to assess reservoir connectivity, evaluate stimulation methods, support reservoir characterization studies and define aspects related to flow in subsea lines. The first results of the injection of the CO2 stream, separated from the associated gas in the Pilot project, indicate that the chosen strategy has potential to be a successful one. The continuing production and pressure data monitoring of the WAG implementation in the Pilot, from 2012 on, will provide a more definitive conclusion about the feasibility. Good responses will translate in the EOR expansion to field scale.
Drilling Automation: Presenting a Framework for Automated Operations
Authors: Breyholtz Øyvind , Nikolaou Michael
Published: April 2012

This paper will present and discuss drilling automation on the basis of a "mode of automation" approach. Different modes of automation will be presented and explained. In particular, the paper will focus on how closed-loop control can enable higher modes of automation, which is essential to improve the operational and economic performance of drilling operations. Introducing a higher mode of automation may lead to optimal performance, but it also introduces new safety issues that need to be addressed in order to ensure safe conditions in the well. For each increased mode of automation, the work distribution between the automation system and the driller changes and a clear understanding of the human/ machine interaction at each mode of automation is needed.
The Skin Effect and Its Influence on the Productive Capacity of a Well
Authors: Van Everdingen A.F.
Published: April 2012

The pressure drop in a well per unit rate of flow is controlled by the resistance of the formation, the viscosity of the fluid, and the additional resistance concentrated around the well bore resulting from the drilling and completion technique employed and, perhaps, from the production practices used. The pressure drop caused by this additional resistance is defined in this paper as the skin effect, denoted by the symbol S. This skin effect considerably detracts from a well's capacity to produce. Methods are given to determine quantitativelythe value of S,the final build-up pressure, andthe product of average permeability times the thickness of the producing formation.

Introduction

Equations which relate the pressure in a well producing from a homogeneous formation with pressures existing at various distances around the well are generally used within the industry. The relation is quite simple when the fluid flowing is assumed to be incompressible. It becomes somewhat more complicated when the flowing fluid is considered compressible so that the duration of the flow can be considered. In each case the major portion of the pressure drop occurs close to the well bore. However analyses of pressure build-up curves indicate that the pressure drop in the vicinity of the well bore is greater than that computed from these equations using the known, physical characteristics of the formation and the fluids. In order to explain these excessive drops it is necessary to assume that permeability of the formation at and near the well bore is substantially reduced as a result of drilling, completion and, perhaps, production practice. This possibility has been recognized in the literature.

A method to compute the pressure drop due to a reduction of the permeability of the formation near the well bore, which is designated as the skin effect, S, is given in the following paragraphs. To start, equations normally used to describe flow in the vicinity of a well are given without considering this effect. These equations then are modified to include the effect of a skin on the pressure behavior. Finally a method is given to estimate the effect of the skin on the pressure and production behavior of a well.
Spraberry Permeability From Build-Up Curve Analyses
Authors: Dyes A.B. , Johnston O.C.
Published: April 2012

The application of a method for analyzing pressure build-up curves to determine the effective permeability in the Spraberry is presented. Sixteen Upper Spraberry wells of the Driver area are analyzed and show variations in the in-place effective permeability of 2 to 183 md. Since these values are much larger than the.5 md, or less, reported for the matrix rock, a large part of the vertical fractures noted in Spraberry cores must be considered native to the formation.

The effectiveness of the well fracture treatment in connecting the well bore to the native fracture system is analyzed by comparison of the effective permeability as determined from the PI test to that obtained from a pressure build-up curve. These results show that the fracture treatment is sufficiently effective in connecting the well bore to the native fracture system to yield a flow capacity within about ?50 per cent of that dictated by the native fracture system. About two-thirds of the wells show some degree of local blockage.

Introduction

Fractured reservoirs have been known in the past: However, during the past two years the Spraberry formation has directed the attention of the petroleum industry to a study of the performance of a fractured reservoir. The large variation in the number of fractures noted in Spraberry cores, the large variation in the producing ability of offset wells, the dramatic effect of well treatment on well productivity, the unknown quantity of oil stored in the fractures and matrix rock, and the unknown oil to be recovered were part of the initial Spraberry puzzle.

In this type reservoir where the well treatment is an important factor in determining the productivity, it is particularly desirable to determine the in-place flow capacity of the drainage area at distances far removed from the well bore. This value, when compared to the flow capacity obtained from a PI measurement, will show the effectiveness of the well treatment (completion, fracture treatment, acidization, etc.) in establishing a flow capacity in the vicinity of the well bore equal to that in the more remote region. The object of this paper is to show the application of a method of pressure build-up analysis for this purpose in studying the Upper Spraberry formation in the Driver area.
The Core Recorder
Authors: Millison Clark
Published: April 2012

The core recorder, a mechanical instrument for determining the exact depthat which core is recovered, drilled up or lost, is described. Examples ofcharts from the recorder are explained and interpreted. The uses of the corerecorder are discussed.

Introduction

In the experience of geologists and engineers during coring operations ondrilling wells, many will recall the times when a full core was not recoveredand particularly when the requirement was urgent that they know exactly whatpart of the core was lost. To make this determination, the core recorder wasdesigned. Its uses are many, and only the most obvious will be presented here.Although this discussion will be limited to drilling wells for petroleum, thecore recorder can be used in any type of coring operation.

The principle of the core recorder is the proportional reduction of themotion of core entering or dropping out of the core barrel to a stylus movingin such a manner as to record the reduced motion on a chart. The time elementis registered on the same chart by the revolution of a clock which turns thechart drum. Thus the exact amount of core entering or dropping out of the corebarrel is charted and the time of such entry or exit from the core barrel isprecisely correlated to the depth at which the core is recovered or lost. Lackof movement of the stylus which is revealed by the continued revolution of thechart drum indicates that no core is entering the barrel.

The principles are accomplished by an instrument placed inside of the corebarrel. A cylinder which contains the clock and mechanical apparatus has adiameter smaller than that of the core barrel. Near the top of the cylinder isan eighteen hour clock which turns the drum that contains the chart. Near thebottom of the instrument is a serrated wheel which by friction against theinside of the core barrel is turned as core enters or drops out of thebarrel.

T.P. 2542
A Study of Oil and Gas Conservation in the Pickton Field
Authors: Welsh J.R. , Simpson R.E. , Smith J.W. , Yust C.S.
Published: April 2012

This paper presents the results of a complete reservoir study designed todetermine a sound economic program for the conservation of oil and gas in thePickton field, Hopkins County, Texas. The Pickton field produces from the BaconLime with all indications of the study being that production is predominatelyby dissolved-gas drive. Calculations of the total ultimate recovery to beexpected under primary operations indicated only 16.7 per cent of the oiloriginally in place would be recovered. This unusually low recovery is due tothe type of drive operating and the extremely high dissolved gas-oil ratio andshrinkage.

Results are presented for six plans of returning gas to the reservoir, evaluated to determinecomparative recoveries and economics ofreturning gas at a constant rate by supplementing Pickton gas with extraneousgas during the early portion of the operation, andconventional gas-returnoperations without using extraneous gas, andthe optimum size of compressorplant for each type of pressure maintenance.

The over-all economic program considers, for either type pressuremaintenance operation, a gasoline plant to process the unusually richcasinghead gas. Since pressure maintenance will disturb equities, pooling ofroyalties is in the case of Pickton a prerequisite to conservation of oil bythis type of operation, both from an economic and legal standpoint. In theevent pooling of royalties cannot be achieved, the study considers a gasolineplant to operate under a modified primary production operation which will makethe conservation of gas possible.

Introduction

The Pickton field, located in Hopkins County, Texas, was discovered inNovember, 1944, by the completion of Humble's C. D. Nichols 1, in the Baconlime of the Lower Glen Rose formation, through perforations from 7,888 to 7,896feet. The well initially produced 50.2 API gravity oil with a gasoil ratio of1,350 cubic feet per barrel. Subsurface samples of the reservoir fluid obtainedsoon after completion of the discovery well showed that the Pickton crude isunique in that it has an extremely high dissolved gas-oil ratio and is subjectto very severe shrinkage.

T.P. 2564
Estimation of Reserves and Water Drive From Pressure and Production History
Authors: Brownscombe E.R. , Collins Francis
Published: April 2012

A study has been made of the material balance-fluid flow method ofestimating reserves and degree of water drive from pressure and productionhistory data. By considering the effect of random pressure errors it is shownthat in a particular example a standard deviation of three and one-half poundsin each of ten pressure surveys permits the determination of the reserves witha standard deviation of 8 per cent and the water drive with a standarddeviation of 15 per cent, assuming that certain basic geologic data arecorrect. It is believed that this method of estimating reserves and water driveis useful and reliable in a number of cases. The method is particularlyvaluable when reservoir pressure data are accurate within a very few pounds, but may also be applied with less accurate pressure data if a relatively largereservoir pressure decline occurs early in the life of the field, as forexample in an undersaturated oil field.

Introduction

A knowledge of the magnitude of reserves and degree of water drive presentin any newly discovered petroleum reservoir is necessary to early applicationof proper production practices. A number of investigators have contributed tomethods of relating reserves, degree of water drive, and production andpressure history. Three types of problems of increasing complexity may bementioned. If a reservoir is known to have no water drive, and if the ratio ofthe volume of the reservoir occupied by gas to the volume of the reservoiroccupied by oil (which ratio permits fixing the overall compressibility of thereservoir) is known, then only one further extensive reservoir property remainsto be determined, namely the magnitude of the reserves. A straightforwardapplication of material balance considerations will permit this determination.The problem becomes very much more difficult if we wish to determine not onlythe magnitude of the reserves but also the magnitude of water drive, if any, which is present. In principle, a combination of material balance and fluidflow considerations will permit this evaluation. Finally, if neither themagnitude of reserves, the degree of water drive, nor the ratio of oil to gaspresent in the reservoir is known and it is desired to determine all three ofthese variables, the problem could in principle be solved by a fluidflow-material balance analysis which determines the overall compressibility ofthe reservoir at various points in its history. The change in compressibilitywith pressure would provide a means of determining the ratio of gas to liquidpresent, since the compressibilities of gas and liquid vary differently withpressure variation. However, in practice this problem is probably so difficultas to defy solution in terms of basic data precision apt to be available.

T.P. 2589
Theoretical Generalizations Leading to the Evaluation of Relative Permeability
Authors: Rose Walter
Published: April 2012

Theoretical expressions are presented to describe wetting and non-wettingphase relative permeability relations. These expressions have then beencompared with existing published data, the conformance noted being sufficientlygood to satisfy the requirements of some engineering use. As a consequence, itmay be supposed that relative permeability characteristics of porous media nowcan be inferred from basic core analysis data, in a manner more convenient(although less direct) than presently available methods of experimentalevaluation.

Introduction

This paper presents a new approach to the problem of relative permeabilityevaluation. A classification of published discussions of relative permeabilityconcepts which have appeared in the petroleum literature will show thatpreviously emphasis has been placed on methods of experimental measurement, onthe interpretation of the data so obtained with respect to the variableproperties of the system, and on theoretical and practical considerations whichrelate relative permeability to gross fluid behavior in petroleum reservoirs.Essentially, no detailed examination has appeared which treats the fundamentalfactors controlling the quantitative features of the relative permeabilityrelation, although certain references can be cited where a qualitativeawareness of their existence and nature is indicated. This condition isexplainable in terms of the recognized complexity of the problem, and in orderto provide some basis for theoretical development, the general emphasis hasbeen placed in the past on experimental procedures of evaluation, the validityof which, in principle, could be confirmed by the analysis of well andreservoir performance. However, because of the experimental difficulties whichhave been encountered (notably, difficulties due to the so-called "endeffects"), and because of the general unreliability of field performancetests required to study the applicability of the data, relative permeabilityphenomena continue to be incompletely understood and described.

In this paper is examined the possibility of predicting relative permeabilitiesentirely from fundamental considerations. In addition, attention is called tocertain important factors, previously unemphasized in the published literature, which now can serve as a basis for the eventual experimental confirmation ofthis and similar theoretical approaches, as well as the experimental solutionof the problem in general. Therefore, the analysis presented herein has thedual purpose both of orienting future experimental activity and also ofproviding an immediate solution for the relative permeability problem, sufficiently adequate for some engineering use. It will be seen that theconclusions reached are supported by theoretical and intuitive considerations, and they are not contradicted insofar as gross features are concerned byexisting concepts and interpretations of published experimental data, except asspecifically noted.

T.P. 2563
Experiments on the Capillary Properties of Porous Solids
Authors: Calhoun John C. , Lewis Maurice , Newman R.C.
Published: April 2012

A report is made of experimental work performed on the capillary retentionof water within porous solid systems, the displacement being accomplished withair and various organic liquids. A portion of the experiments were designed tomeasure the lowering of vapor pressure of water within a porous solid withsubsequent conversion of such vapor pressure data to capillary pressure values.The form of the capillary pressure curve at high capillary pressures has beenelucidated from this data. Certain theoretical approaches are presented toindicate the correlation between work done by previous investigators. Thepresent work is correlated also with theory. Surface area values are calculatedfor the various core systems studied.

Introduction

Leverettt in 1941 presented a paper which gave the essential concepts ofcapillary behavior in porous solids. His presentation included both theoreticaland experimental aspects of the problem. He defined the term "capillarypressure" and applied it to an ideal porous system. His work included thedefinition of a dimensionless quantity which was a function of fluid saturationand which could be correlated with porosity and permeability for clean, unconsolidated sands. His experimental work was performed by the drainage ofwater from packed columns of unconsolidated sands. Subsequently, other authorshave presented experimental techniques which permit the determination ofcapillary pressure data on small core samples. Data have been presented onporous systems other than unconsolidated sand and with the use of liquids otherthan water. Notable among these are the works of Hassler, Brunner and Deahl, Bruce and Welge, Amyx and Yuster, and Purcell. Others have indicated theapplicability of such data to field problems without regard to the theoreticalaspects of the capillary pressure saturation function. Within the recentpublished literature there have also been reported studies of the correlations between capillary pressure data and otherfundamental properties of porous solids. It was the intent of the presentreported work to investigate the behavior noted by water and various otherliquids within porous systems in an attempt to amplify existing correlationsbetween capillary properties, surface properties, and other fundamentalcharacteristics of porous systems. The experimental work described here wasperformed as two different investigations but due to its nature it is reportedas separate phases of the same general topic.

T.P. 2640
Factors Involved in Removal of Sulphate From Drilling Muds by Barium Carbonate
Authors: Bergman W.E. , Fisher H.B. , Carpenter P.G.
Published: April 2012

The conditions under which barium carbonate can be used to remove sulfatesfrom drilling muds are limited. The amount of sulfate remaining in solution inthe system after treatment with barium carbonate is shown to be a function ofthe concentration of the carbonate and barium ions and the concentration ofother electrolytes. Barium hydroxide may advantageously replace bariumcarbonate when the contamination is not entirely due to anhydrite (calcium inthe system is then stoichiometrically less than sulfate) or when the carbonateconcentration is high. The effect of substances such as quebracho, phosphates, and chromates, which form complexes or precipitates with barium, isdiscussed.

Introduction

As the complexity of the operations in drilling for oil has increased, moreattention has of necessity been directed to the problems pertaining to themaintenance of good drilling mud properties. As a result, chemical treatment ofmuds has become an important factor in recent years. Some of these treatmentshave been designed to eliminate the deleterious effects of contaminants inaqueous mud systems by precipitation or other means. The most common ofsubstances encountered during drilling include sodium chloride, cement, andcalcium sulfate while various other contaminants, usually in small amounts, maybe introduced from the water, clays, and other materials used in preparation ofthe mud. In certain cases, for example where continued salt-water flow isencountered or massive anhydrite is drilled, special muds may be used so thatthe physical properties of the mud will remain satisfactory for drilling. Inother cases, it is desirable to remove the contaminants so that solubleelectrolytes in the system are maintained at low values.

For sulfate contamination, the common practice in the field is to add bariumcarbonate to precipitate the sulfate as barium sulfate. Ordinarily such aprocedure gives satisfactory results. There have been important instances, however, where addition of barium carbonate was not effective in removal ofsoluble sulfates from drilling muds, and it is to these cases that the presentpaper is directed.

T.P. 2639
Some Examples of Fluid Flow Mechanism in Limestone Reservoirs
Authors: Keller W.O. , Morse R.A.
Published: April 2012

The properties of limestone reservoir rocks such as the distribution anddegree of continuity of the pore systems, and the relative volumes andpermeabilities of the systems making up the complex cause large variationsbetween performance of individual limestone reservoirs and their susceptibilityto secondary recovery methods. The effects of these factors on the mechanism offluid flow cannot be adequately evaluated with presently developed concepts, laboratory data, and geological information. The observance and interpretationof the performance of individual limestone reservoirs provides, at present, themost adequate approach for evaluating the integrated effects upon performanceof the many, now immeasurable variations in the properties of limestonereservoirs.

Introduction

The development and application of techniques for increasing the efficiencyof oil recovery from natural reservoirs is a problem of primary importance tothe industry. During the past several years, a great deal of effort has beenexpended by the technical personnel of the industry toward the improvement ofpresent known methods of oil recovery, and evaluating the factors which controlthe susceptibility of particular reservoir types to economic application ofsecondary recovery methods. Providing adequate and accurate laboratory data onthe properties of the reservoir rock and its contained fluids, together withgood production statistics, are available, methods have been evolved forestimating with reasonable accuracy the performance of an oil reservoir undereither continued natural depletion or conditions imposed by introducingadditional displacing fluid into the reservoir from an extraneous sourcethrough the injection of gas and/or water.

The susceptibility of limestone reservoirs to secondary recovery by gasinjection is very much dependent upon gas-oil relative permeabilityrelationships for the reservoir in question. In a rock formation in which theporosity is of the intergranular type such as is found in sand stones and somenonfractured dolomites, a representative sample of the pore structure can beobtained in a small core plug. In this type of reservoir, it has been shownthat relative permeability data obtained from laboratory experiments can beproperly applied to evaluate the flow relationships actually observed duringthe depletion of a reservoir. In addition, a good idea of the fraction of thereservoir which will be swept by the injected gas may be obtained from thespacing pattern used and the permeability profile of cored wells. From thesedata, it has been demonstrated that reliable estimates of performance andrecoveries under gas injection operations can be made for reservoirs in whichthe porosity is of the intergranular type.

T.P. 2638
The Performance of the Ten Section Oil Field
Authors: Lietz W. Tempelaar
Published: April 2012

Introduction

The Ten Section oil field is located in the San Joaquin Valley in KernCounty, California, about 12 miles southwest of Bakersfield in Township 30South, Ranges 25 and 26 East. The accumulation is in a low relief anticlinaldome and has a productive area of approximately 2,200 acres. Discovered in 1936as a result of seismic work, it was the first field on the floor of the Valleyto obtain production. It had a small primary gas cap, and since its inceptionhas been produced by depletion with controlled withdrawal from the gas cap tominimize blowthrough.

Structure and Stratigraphy

The Ten Section structure is an elongated anticlinal dome with flank dips ofonly about 7 degrees. A map of the field, now fully developed, and a compositelog are shown in Figs. 1 and 2. Contours shown on the map are on the top of thefirst zone, or Marker XA as indicated on the composite log.

As shown, the field has a productive closure of only some 350'Feet, and thereapparently is no faulting in the reservoir.

The productive measures in Ten Section are of Upper Miocene age and are knownas the Stevens sand. They contain thin, irregular shale or siltstone streakswhich vary considerably in stratigraphic position and thickness and apparentlyare rather discontinuous. As a result, individual sands and shales cannot becorrelated over any appreciable area, which makes it difficult to subdivide thesand body into separate zones which are distinct throughout the field. However, there are two fairly persistent siltstone bodies that at the time ofdevelopment were considered to divide the productive measures into threegeneral zones.

The first, or uppermost zone is productive over the entire field and has anaverage thickness of 180'Feet, of which some 65 per cent is sand. It had aprimary gas cap in the crestal area with an areal extent of 930 acres. Thesecond zone has a productive area somewhat smaller than the first zone, but itdid not have any original gas cap. It has an average thickness of about 360feet, of which 55 per cent is sand. The third zone has a very limited arealextent and a maximum productive thickness of 100'Feet, of which 80 per cent issand. Recently, a deeper oil accumulation, termed the "53" sand, wasdiscovered, but it is not discussed in this analysis. In the first and secondzones the water table was at 7,980'Feet subsea, while in the third zone it wasat 8,080'Feet subsea.

T.P. 2643
Multiple Condensed Phases in the Methane-Decane-Tetralin-Bitumen System
Authors: Billheimer J.S. , Yundt C.G. , Sage B.H. , Lacey W.N.
Published: April 2012

As a part of a general investigation of the separation of bitumen fromhydrocarbon mixtures a study was made of a restricted quaternary systemcomposed of methane, decane, tetralin, and bitumen. The work was limited to apressure of 8000 psi, a temperature of 220'F, and to a fixed relativeproportion of decane, tetralin, and bitumen. The measurements permitted thedetermination of the distribution of these components in each of the fluidphases. It was not possible to distinguish a second liquid phase in the courseof these measurements. Gas-liquid equilibrium "constants" of each ofthe components were found to vary markedly with the composition of the systemwhile temperature and pressure remained fixed.

Introduction

The separation of bitumen from naturally occurring hydrocarbon mixtures hasbeen of importance for a number of years in the production of petroleum, especially in the California area. The deposition of this material from crudeoils was noted in earlier studies of the solubility of natural gas in crudeoil. Studies of the separation of bitumen from crude oils from the Greeley andSanta Fe Springs fields were carried out. The behavior of these systemsappeared complex and studies of two restricted ternary systems involvingmixtures of n-pentane, tetralin, and bitumen, and of decane, tetralin, andbitumen, confirmed this belief. Reviews of the literature pertaining to theseparation of bitumen from naturally occurring and refined hydrocarbons areavailable.

The important effect of methane in the separation of bitumen from naturallyoccurring hydrocarbon mixtures was apparent from the earlier studies, and forthat reason it appeared desirable to investigate a restricted quarternarysystem involving mixtures of methane, decane, tetralin, and bitumen; dataconcerning the behavior of mixtures of decane, tetralin, and bitumen havingalready been obtained. This study was restricted to a pressure of 8000 psi, atemperatue of 220'F, and fixed relative proportions of bitumen, decane, andtetralin. This composite constituent, hereinafter designated as the lessvolatile constituent, was made up of 0.0455 weight fraction bitumen, 0.0909weight fraction decane, and 0.8636 weight fraction tetralin.

The experimental method involved bringing together mixtures of methane and theless volatile constituent in varying proportions in a constant volume containerat the pressure and temperature indicated above. The composition of each of thephases was determined and from this the extent of the separation of bitumen wasestablished.

T.P. 2718
Lakeview Pool, Midway-Sunset Field
Authors: Sims W.P. , Frailing W.G.
Published: April 2012

The Lakeview Pool of Kern County, California, was discovered in 1910 withthe drilling of Lakeview No. 1 which blew out and produced an estimated8,250,000 bbl of oil in 544 days of uncontrolled flow. The well has since beenknown as the Lakeview Gusher. Full exploitation of the pool did not take placeuntil about 25 years later. A total of 112 producing wells were completed inthe Lakeview sand through April 30, 1949. As of that date, about 30 per cent ofthe total wells drilled were still producing, with an average pool productionrate of approximately 2000 bbl per day. The cumulative oil production was about41 million bbl of oil, or 55.3 per cent of the tank oil originally inplace.

The pool is bordered on its downstructure side by a body of inactiveedgewater and water production where present has been principally the result ofconing.

Since the depletion of the greater portion of the gas energy by the LakeviewGusher, the pool has operated under gravity drive. Relatively high angle dips, good permeabilities and favorable fluid characteristics have made gravitydrainage particularly effective. Since January, 1942, the oil recovery has beenrelatively constant at about 53,000 bbl per ft drop in fluid level.Correlations between the volume of reservoir space drained and the cumulativeoil produced indicate that an ultimate recovery of 63.3 per cent of the tankoil originally in place is attainable.

Introduction

The Lakeview Pool is an outstanding example of gravity drainage. It is oneof many productive reservoirs of the Midway-Sunset Field, and is located inKern County, approximately five miles southeast of Taft and two miles north ofMaricopa, California. Its position relative to surrounding pools and to theThirty-Five anticline is shown on Fig. 1. The northern portion of the pool liesin sections 32 and 33, Township 32 South, Range 24 East, Mt. Diablo Base andMeridian, while the southern portion lies in sections 25, 26, 35 and 36, Township 12 North, Range 24 West, San Bernardino Base and Meridian. As no twosections bear the same number, they will hereafter be referred to by sectionnumber alone.

The purpose of this paper is to review the performance of the Lakeview Poolin an effort to evaluate the effectiveness of gravity drive as a recoverymechanism.

T.P. 2779
Some Preliminary Investigations of Quantitative Interpretations of Radioactivity Logs
Authors: Bush Robert E. , Mardock E.S.
Published: April 2012

The objective of this paper is to present practical methods of applyingradioactivity logs to problems of interest both to those engaged in evaluatingfundamental reservoir data as well as to those engaged in subsurface structuralwork. The basic theories underlying the operation of radioactivity loggingmethods are briefly discussed along with some of the problems arising in theinterpretation of the log. Relative methods of quantitative interpretation aredescribed, with a discussion of relative reference lines and specific examplesare given showing the application of these relative quantitative interpretationmethods. To show the variation of the methods described, specimen wellspenetrating formations widely divergent in point of geologic age were selectedto demonstrate the application. A relative reference line is determined for theNeutron Curve and by comparison to known petrophysical data such as porositiesfrom diamond cores, a direct quantitative relationship is developed. Theapplication of this relative calibration curve to logs of unknown wells willpermit a reasonably accurate determination of porosity in limestone anddolomite formations. Specific examples are given showing the application ofthese relative methods of interpretation to logs of the Smackover limestone inLouisiana, the Edwards limestone and dolomites of South Texas, and Permiandolomites of West Texas.

Introduction

Radioactivity logs have been used extensively by the petroleum industry fora number of years and recognition of their value has grown steadily, not onlyas tools to aid in the solution of specific stratigraphic problems, but also aspotential sources of the basic data necessary for the estimation of net pay andreserves. The value of radioactivity logs for stratigraphic work has beenpointed out in the literature, and now has long been recognized by theindustry, but the quantitative application of the logs has advanced but littlebeyond the stage of a strong conviction that radioactivity logging curves willsome day provide the information on such important quantities as the porosityand the liquid saturation of the formations.

T.P. 2780
Ability of Drilling Mud To Lift Bit Cuttings
Authors: Hall H.N. , Thompson Howard , Nuss Frank
Published: April 2012

Removal of bit cuttings is an important function of drilling muds. In aneffort to obtain better understanding of the factors influencing the removal ofcuttings, an extensive series of laboratory tests were made in which slipvelocities of various sizes and shapes of particles were measured in muds ofdifferent physical properties. Empirical equations were then derived from theseexperimental data. These equations show that slip velocity is dependent oncutting size and shape, mud flow constants, and flow state of the mud.Applicability of these equations for field use is demonstrated by comparingcomputed slip velocities with slip velocities obtained from field tests.

Introduction

Drilling muds have many functions, but perhaps the most important is theremoval of bit cuttings from the well. In a 10,000'Ft well, the weight of rockwhich is drilled and must be carried to the surface is over 150 tons. Inaddition to this, the mud must remove any sloughings from the well bore.Failure of the mud to promptly remove either bit cuttings or sloughs from thewell bore causes re-drilling and excessive wear on bit teeth, slows downdrilling rate thereby increasing well costs, and greatly increasespossibilities for stuck drill pipe when circulation is stopped for any lengthof time.

Drilling muds lift bit cuttings to the surface by means of the upwardvelocity of the drilling mud in the annulus. Because a density differenceexists between the rock being drilled and the drilling mud, there is adifference between mud velocity and the rate of bit cutting travel, called thenet rise velocity.

T.P. 2782
The Presence of Conductive Solids in Reservoir Rocks as a Factor in Electric Log Interpretation
Authors: Patnode H.W. , Wyllie M.R.J.
Published: April 2012

Introduction

In the quantitative interpretation of electric log data it is essential toknow the formation factor, defined as the ratio of the resistivity of theformation 100 per cent saturated with brine to the resistivity of the brine.This concept implies that the formation factor for any given rock is constantirrespective of the resistivity of the brine or solution with which it issaturated. It is apparent that this can be true only when the rock matrix iswholly non-conductive. As reservoir rocks may contain clay or shale having anappreciable conductance one may expect these constituents to influence thedetermination of true formation factor.

The formation factor may be theoretically derived from log data by dividingthe resistivity of the mud filtrate invaded formation by the resistivity of themud filtrate. Such a method of calculation has implicit in it the assumptionthat the fluids in the invaded formation are wholly replaced by mud filtrate, that the solid matrix is non-conducting, and that the formation factor of theinvaded zone is identical with the formation factor of the uninvaded zone.Since the validity of the first two basic assumptions regarding the insulatingcharacter of porous matrices and the displacement of the interstitial fluidsin porous media do not appear to be fully established, the formation factors of anumber of cores and clay slurries have been measured under conditions suitablefor verifying the assumptions and the extent of any errors inherent inthem.

Core Studies

Apparatus and Procedure

Resistivity measurements were made on short cylindrical permeable coreswhich had been previously mounted in lucite. The cores were clamped by means ofinsulated bolts between brass plates about 5 cm square and 1 cm in thickness.The plates were provided with a ring seal to prevent leakage between them andthe core mount, and had a centrally located orifice so that fluids could beflowed through the mounted core. The brass mounting plates were used aselectrodes and any current flow between them necessarily passed only throughthe constituents of the intervening core.

Fluid saturation of the core, and fluid flow through the core, were effectedby a centrifugal pump connected to the outflow end of the core, thus providinga differential pressure across the core of approximately one atmosphere.

T.P. 2797
Determining Friction Factors for Measuring Productivity of Gas Wells
Authors: Smith R.V.
Published: April 2012

The theoretical background for calculating friction factors for flow in gaswells by two methods is presented. The first method, requiring pressures, temperatures and specific volumes of the flowing fluids at various depths inthe well bore, shows how the mechanical-energy-balance equation for verticalflow may be graphically integrated over the actual path of the expansion of thefluid in the well. Thus, assumptions regarding the effective temperature andeffective compressibility of the fluid in the well are avoided. The secondmethod presents an equation derived on a basis of the assumptions that both thetemperature and the compressibility are fixed at constant effective valuesthroughout the flowing column of gas. The second method provides a convenientand practical means of calculating friction factors for gas wells and lendsitself readily to the problem of calculating subsurface pressures in a flowinggas well. The application of both methods to actual test data taken on aflowing gas well is illustrated in the paper.

Introduction

As friction factors for the producing strings of flowing gas wells cannot bemeasured directly and must be calculated from flow-test data, study of themethods of arriving at friction factors is a necessary adjunct to understandingthe characteristics of flow in gas wells. There are two methods of calculatingfriction factors for gas wells; they differ from one another mainly in thetreatment of the path of expansion of the fluid in the well. In the flowingwell, the energy consumed in lifting the fluid from the bottom to the top ofthe well, overcoming the friction between the moving fluid and the pipe walls, and increasing the velocity of the fluid as it flows up the producing string issupplied by expansion of the flowing fluid. The available energy is determined, by the expansion of the fluid that follows a path determined by conditions oftemperature, compressibility and phase changes of the fluid during theexpansion. A means of evaluating the available energy in a flowing gas well anddetermining the proportion of the available energy used in lifting the gas, overcoming friction, and increasing the velocity of flow is developed in thisreport. Knowing how much energy is consumed in overcoming friction makes itpossible to calculate friction factors for given flow rates in given sizes ofpipes in wells.

T.P. 2777
An Electronic Analog Computer for Solving the Flash Vaporization Equilibrium Equation
Authors: Bubb F.W. , Nisle R.G. , Carpenter P.G.
Published: April 2012

It is the purpose of this paper to describe an electrical computer which hasbeen constructed to solve the equations for vapor-liquid equilibrium inmulti-component systems. The instrument consists of seven component-computingunits each with proper indicating means and power supplies. Each unit is aresistance network with a voltage matching servomechanism, and each provides anoutput voltage proportional to the mol-fractions for vapor and liquid phases.These voltages are summed and matched with a reference voltage to provide thesolutions. Any reasonable number of such units may be put together to make acomputer. The theory and operation of the computer is discussed. A number ofapplications and examples of computer results are given. The computer yieldsthe over-all vapor or liquid fraction to a probable error of 0.002. Aninterpolation method is described which reduces the probable error to0.0002.

Introduction

The process known as Flash Vaporization may be described as follows: A mixtureof known composition of relatively volatile components is allowed to come tothermodynamic equilibrium at some given temperature and pressure by any pathwhatsoever. In general, a vapor and a liquid phase will be present atequilibrium. The problem is to determine the fractions of the mixture in thevapor and liquid phases, and to determine the mol fractions of the variouscomponents in each phase. The relations that exist between these variousquantities at equilibrium are well known and will be given later. Theseequations are difficult to solve, yielding only to trial-and-errormethods.

The virtues of the analog computer are its speed and the automatic character ofits calculations. The device is operated by turning a crank which varies thevalue of v, the total vapor fraction. This actuates a number of servomechanismswhich perform automatically all computations.

This computer facilitates the solution of such problems as (to mention a few):Analysis of separator operation, studies of changes in composition of reservoirfluids with pressure decline, and analysis of natural gasoline plant operation.Examples of some of these problems are given in detail later.

T.P. 2853
The Force Exerted by Surface Waves on Piles
Authors: Morison J.R. , Johnson J.W. , Schaaf S.A.
Published: April 2012

The force exerted by unbroken surface waves on a cylindrical object, such asa pile, which extends from the bottom upward above the wave crest, is made upof two components, namely:A drag force proportional to the square of the velocity which may berepresented by a drag coefficient having substantially the same value as forsteady flow, andA virtual mass force proportional to the horizontal component of theaccelerative force exerted on the mass of water displaced by the pile.

These relationships follow directly from wave theory and have been confirmedby measurements in the Fluid Mechanics Laboratory of the University ofCalifornia, Berkeley.

The maximum force exerted by breakers or incipient breakers is impulsive innature, reaching a value much greater than that produced by unbroken waves butenduring for only a short time interval. This impulsive force represents theultimate development of the accelerative force and is produced by the steepwave front and large horizontal acceleration at the front of a breaker. Thisimpulsive force greatly exceeds the drag force computed from the particlevelocities of the breaker.

The reader is cautioned that these preliminary results are applicable only tosingle piles without bracing and are likely to be modified somewhat wheremultiple piles are driven, one within the influence of the other or wheremultiple piles are connected by submerged bracing. This paper is essentially apreliminary report submitted at this time because of the current importance ofwave forces in the design of offshore structures. An extended series ofadditional experiments is planned for the near future.

Theoretical Relationships

For the sake of simplicity of treatment, the theory will be developed fromthe equations for waves of small amplitude.

T.P.2846