bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability of Simply Shaped Icebergs
Authors: Allaire P.E.
Published: March 2010

With the advent of petroleum drilling in the Arctic and Eastern Canadian offshore regions, iceberg towing is now being explored as a method of avoiding collisions with offshore platforms. Because of the danger of the berg rolling, more information on stability is required before the method can be completely depended upon.

This study analyses the stability of sixteen simply shaped icebergs chosen to approximately correspond to above-water classifications given by the Ice Patrol. The results indicate that the stability depends largely on the above-water characteristics of the berg and is relatively independent of the below-water shape. For the shapes chosen, the minimum stable ratio of waterline width to above-water height is approximately 6:1 for blocky or tabular shapes, 4:1 for drydock shapes, 3.8:1 for dome shapes and L8:1 for pinnacled shapes.

Based solely on the above-water characteristics, which are easily measured, these figures may provide a quick estimate of stability which could be essential in the field. First, the type of berg is determined from the Ice Patrol classifications. Second, the ratio of waterline width (smallest waterline dimension) to approximate height is calculated. Finally, if this ratio is near the minimum stable ratio for this particular class, the iceberg is probably close to instability. With sufficient field experience, a towing crew may be able to determine when special precautions are necessary.

Introduction

PETROLEUM DRILLING in the Eastern Canadian offshore has created a great deal of interest in the towing of icebergs to prevent collisions with stationary offshore platforms or vessels. In studies of this method, a number of medium- and small-size bergs have been successfully towed (Bruneau and Dempster, 1972; Duval, et al, 1970; Hydrospace, 1970), indicating that the method is feasible.

The stability of icebergs under tow is an important consideration. Observations of North Atlantic icebergs (Murray, 1969; Smith, 1931) show that they roll quite frequently. If one should roll over, the towing equipment would likely be lost or thrown off. Then there is the danger of a collision with the offshore structure if too much time is lost in getting it under tow again, A large rolling berg might even endanger the towing ship. Before the towing method can be completely depended upon more information on stability is required.

TABLE 1- ABOVE-WATER ICEBERG SHAPE Classifications* BLOCKY – Steep precipitous sides with horizontal or flat top. Very solid berg. Length: height ratio 2.5:1 DR YDOCK – Eroded so that a large U-shaped slot is formed, with twin columns or pinnacles. Slot extends into the water line or close to it. DOME – Large smooth rounded top. Solid type of berg. PINNACLED – Large central spire or pyramid of One or more spires dominating shape. Less massive than dome-shaped berg of similar dimensions. Tabular – Horizontal or flat-tooped berg with length: height ratio of 5:1. GROWLER- A mass of glacial ice that has calved from a berg or is the remains of a berg.
Calculation of Friction Factors For Use In Flowing Gas Wells
Authors: Dranchuk P.M. , Abou-Kassem J.H.
Published: March 2010

A study of test data for a number of Alberta gas wells has revealed that flow during such tests is seldom in the "fully developed" turbulence region. Because computer programs used to calculate pressure profiles usually assume "fully developed" turbulent flow, they tend to underestimate the friction factor, and as a. result the pressure drop due to friction, in such wells. In order to avoid such bias, a subroutine, which generates the Moody friction factor chart, is present and recommended for use in computer calculation.

THE CALCULATION of bottom-hole pressures or pressure profiles in flowing gas wells may be effected by various methods.(1–3) Despite the differences between these methods, they have one thing in common they all require the estimation or calculation of a friction factor.

(Equation in full paper.)

Although these approximate methods are handy and appropriate to desk calculation, the modern practice of calculating pressure profiles by means of high-speed computers has made such approximations unnecessary and in some instances inappropriate. For example, one may set up a simple subroutine for calculating friction factors, using the expressions employed by Moody, as is indicated in Figure 1. Such a program will permit the use of absolute roughness values other than 0＿0006 in., and will do away with approximation error.

Because the Colebrook equation approaches the von Karman expression asymptotically, the point at which one changes from the former to the latter depends on the percentage error one is willing to accept at that point. Thus, if one is willing to accept a 1% error at the change-over point one should select the point Re=1600 d/E. On the other hand, one may use Re=3200 d/E for a 0.5% maximum error, as suggested by Moody, or Re = 16,000 d/E when the maximum permissible difference is 0.1 %＿ If, however, one is willing to incur the added cost of iteration in the region where f is essentially insensitive to further changes in Re, he may use the Colebrook equation for all values of Re greater than 4000. This is, in fact, the method that was employed by Aziz, Govier and Fogarasi(8).

The subroutine shown in Figure 1 was tested against the Cullender – Binckley and Cullender-Smith methods at 12 points, as shown in Tables 1 and 2. This comparison showed that:friction factor remains reasonably constant over the length of the well, thereby verifying the common assumption that such is the case;flow in gas wells, of the type found in Alberta, is not usually in the fully developed turbulent region;the Cullender-Binckley method provides a reasonable estimate of friction factor in the transition region, whereas the Cullender-Smith method consistently underestimates the friction factor when turbulence is not fully developed.

In addition, the comparison showed that the cost of application of the subroutine exceeds that of the Cullender-Smith method by less than 2 cents per hundred factors calculated.

This subroutine was also compared to that proposed by Aziz-Govier-Fogarasi.
Further On the Calculation of Friction Factors For Use In Flowing Gas Wells
Authors: Fogarasi Maria
Published: March 2010

A comparison of two computer subroutines to calculate friction factors from the Moody(2) chart has been made. The comparison shows that, contrary to the claim of Dranchuk and Abou-Kassem(1), their method and that of Aziz et al.(5) give identical results in the partially-rough-wall and the fully-rough-wall turbulence regions. The transition from the former to the latter is predicted to occur at slightly different Reynolds numbers in the two methods because of the choice by Dranchuk and Abou-Kassem of an arbitrary transition criterion. Both routines are suitable for computer calculation of friction factors, but the Aziz et al. method is more efficient, requiring fewer iterations.

IN A RECENT TECHNICAL NOTE, Dranchuk and Abou Kassem(l) recommend the use of the Moody chart(2) instead of approximate relationships to determine friction factors in pressure-drop calculations for flowing gas wells. Without doubt, fundamental equations with a properly chosen friction factor based on the correct reynolds number and the best estimate of the relative roughness will yield more accurate pressure-drop predictions than equations incorporating approximations for the friction factor(3).

(Equation in full paper)

Dranchuk and Abou-Kassem compare Darcy-Weisbach friction factors calculated by their own and the Aziz et al. method and arrive at the following conclusions:

The Aziz-Govier-Fogarasi method:generates Fanning friction factors;yields values which are higher than Colebrook at low values of Re and lower than Colebrook at high values of Re;yields values which are higher than Moody at low values of Re and lower than Moody at high values of Re when flow is in the transition zone) but higher than Moody at low values of Re and lower than Moody for high values of Re when flow is fully turbulent;cannot generate values for smooth pipe."

These conclusions seem unwarranted. Table 1 shows a comparison of Darcy-Weisbach friction factors calculated by the two methods for a wide range of relative roughnesses and Reynolds numbers. The comparison shows that:the friction factors are exactly the same in the PRW and FRW regions, as they should be, because both routines use the same equations;a slight difference (half a per cent or less) at the transition from PRW to FRW turbulence due to the difference in the transition criterion chosen by Dranchuk and Abou-Kassem and the assymptotic approach used in the Aziz et al. routine;the Aziz et al. routine is more efficient, requiring fewer iterations.

(Table in full paper)

Keeping in mind that Moody indicated that his chart would predict friction factors with no better than 10 per cent accuracy, the small differences are insignificant. The friction factors, for practical purposes, are the same.

Finally, the Aziz et al. method was not intended for the calculation of friction factors in smooth pipes. It was designed only to deal with the practical problem of estimating pressure drops in actual gas wells, which may always be expected
Calculation of Z Factors For Natural Gases Using Equations of State
Authors: Dranchuk P.M. , Abou-Kassem H.
Published: March 2010

The generalized Starling equation of state has been fitted to the Standing and Katz Z-factor correlation and a computer program is presented for the ge11eration of Z factors by means of this equation. A comparison is made of the performance of the Hall and Yarborough, Dranchuk et al. and above-mentioned methods, and the results are discussed.

COMPRESSIBILITY FACTORS have been calculated by means of computer for almost twenty-five years(1). During this period, the techniques available for effecting such calculations have been gradually improved and refined. In the recent past, experimental data have been fitted with various equations of state and these fitted equations have been used to generate Z factors(2,3,4,5). These equations represent a significant step forward in that they may be used as algebraic expressions for Z in dealing with its functions.

As most of these fittings have been made using the Standing and Katz correlation or data in the same region, their application would appear to be restricted to that region. However, there are occasions when Z is required outside this region. Consequently, the object of this study was to examine the extent to which these equations could be extrapolated and to try modified fittings which would extend the region of application.

Preliminary examination showed that the Redlich Kwong equation could not be generally compared with the Standing and Katz correlation, because it is not expressed in reduced form. Furthermore, this equation could not be tested against experimental data where critical properties rather than gas analyses are reported. In view of these problems, this equation was eliminated from further study.

It was observed that the Hankinson et al. fitting of the BWR equation was restricted to the region 1.1 ≤ Tr ≤3.0 and that the manner of fitting was such that errors in Z in the fitted region were considerably higher than those produced by either the Hall and Yarborough or Dranchuk et al. methods. On the basis of this observation, the Hankinson et al. fitting was eliminated from further examination.

A comparison of the Hall and Yarborough fitting of the Starling-Carnahan equation of state and the Dranchuk et al. fitting of the BWR with each other and with experimental data showed that both are reasonably accurate when extrapolated to Pr values in excess of 20. However, neither equation is valid at Tr = 1.0 in the vicinity of the critical, and both show marked error increases when extrapolated into the region of Tr < 1.0.

The Starling equation of state may be written as

(Equation in full paper)

and may be generalized and rearranged to express the Z factor as

(Equation in full paper)

This equation has been shown to be valid in the extended regions for pure components and has been recommended for mixtures(7). In view of this and the equation"s similarity to the BWR equation used in the Dranchuk et at fitting, it was decided to fit Equation (2) to the 1500 data points used in the Dranchuk et al. fitting.
Analysis of ''Slug Test'' Or DST Flow Period Data
Authors: Ramey Henry J. , Agarwal Ram G. , Martin Ian
Published: March 2010

In recent years, there has been a great interest in the "slug test" which involves the instantaneous removal of a specific quantity of fluid from a wellbore and measurement of the resulting pressure-time response.

Although a skin effect term was introduced by Jaeger, most recent studies have not considered a skin effect in analyzing slug test data. A new approach to conventional well-test analysis by Earlougher and Kersch was used to prepare type curves for the slug tech which include the skin effect. This study includes: results presented in both tabular and graphical form to aid application, a new material on the radius investigated and the time of duration of slug test, and the presentation of field example illustrating the application and important limitations of the method, as well as limitations of conventional DST analyses. The main application of the slug test method is in the analysis of pressure data for cases wherein the fluid influx into the drill pipe tends to kill the flow (sometimes even before the tester valve is closed). On the other hand, many field test have been observed wherein the phenomena of critical (acoustic velocity) flow destroys the application of the method. The slug test, as currently developed, does not consider critical flow.
Verification of the Gladfelter-Tracy-Wilsey Concept For Wellbore Storage-Dominated Transient Pressures During Production
Authors: Ramey Henry J.
Published: March 2010

Introduction

The fact that real wells have finite volumes leads to inertia in the sandface response of a well to a production rate change at the surface. The duration of wellbore storage (sometimes called "afterflow" for buildup or "annulus unloading" for production tests) rate changes is not often more than a few days. It may be as short as a few minutes. Perhaps for this reason, and also because it usually impossible to determine the sandface production rate with much accuracy, the Gladfelter-Tracy-Wilsey(2) afterflow correction for pressure buildup tests received minimal application. Actually, the Gladfelter et al. idea has a broad and important application in handling production rate change effects in general – rather than the specific production rate changes during pressure buildup. In 1965(1), the Gladfelter et al. pressure buildup afterflow correction was extended to production testing for the special case of an exponential production rate (starting from a zero producing rate and increasing toward the constant rate, q). Because of publication of both production pressure drops and sandface production rates(3, 4) for the classic wellbore storage boundary conditions(5, 3), it is possible to test the Gladfelter et al. idea for the wellbore storage case as well. Winestock and Colpitts(6) Carter(7), Aron and Scotts(9, 10), and others have also noticed that the reciprocal productivity index, (Δp/q), is often a linear function of the logarithm of producing time. This is a simple alternative to superposition to match production rate changes.
The Toxicity of Some Formation Fluids And Methods of Rehabilitation Subsequent to Their Spillage
Authors: Shaw D.R.
Published: March 2010

This paper deals with the effects that formation fluids have on animal and plant life. Crude oil is a mixture-not only of hydrocarbons, but of suspended salts and of sulphur compounds. The toxicity of some of the hydrocarbons and some of the sulphur compounds is discussed, as is the toxicity of salt. Consideration is also given to the complexity of the hydrocarbon components and the influence of refining methods on toxicity. Some mechanisms by which an animal system may attempt to overcome injurious effects are outlined. Finally, methods of aiding recovery are suggested.

Introduction

Formation or connate fluids consist of mixtures of hydrocarbons and salt water, and mal' also contain various amounts of sulphur compounds, such as hydrogen sulphide and rnercaptans. These components may be present in almost all conceivable proportions-some formation fluids contain no water, some are all water, some consist of only light hydrocarbons (i.e. natural gas) and some contain only very heavy hydrocarbons. Also, these fluids may be sour (containing sulphur compounds) or they may contain no sulphur compounds and are referred to as being sweet., This is largely dependent on the formation of origin. Unfortunately, therefore, a spill of formation fluid will often present more than a crude oil spill problem. Each of the major components of the connate fluid can generate its own set of unique problems. The causes of these problems often obscure each other to the extent that what appears to be a simple oil spill may not respond to treatment. Examination and analysis may show, for example, that the oil spill also contained a salt spill. The salt could have been present in the crude oil as free brine, as emulsified salt water or as suspended micro-crystals in the oil. A high concentration of salt in the oil could have a serious effect on he rehabilitation program. Crude oils have been tested hich contained 20,000 lbs of salt per 1000 barrels of oil.

A crude oil spill may therefore consist of three intertwined problems:a hydrocarbon problem;a mercaptan and hydrogen sulphide problem;a salt problem.

The Hydrocarbon Problem

The hydrocarbons in crude oil are present in a variety of forms; some are volatile, some are waxy solids and some are tarry solids, depending on the kind of crude oil that is involved. Crude oils may be categorized as several types:paraffinic - straight-chain saturated hydrocarbons.naphthenic - cyclic compounds, partially saturated.aromatic - having benzene rings in their structure.asphaltic - generally containing some of the above, but having greater chain length, and having other elements.

Each of these types of crude oils has a light (gasoline-like) fraction and several heavy (oily, tarry or waxy) fractions. Each fraction has a different solubility in water, and usually this appears to modify the over-all undesirable effects on various species of animals and plants encountering the crude oil.

These undesirable effects will be referred to throughout this paper generally as toxicity.
Fireflooding Shallow Tar Sands - A Case History
Authors: Terwilliger P.L.
Published: March 2010

A field pilot test of forward combustion utilizing fracturing techniques was conducted in a shallow tar sand deposit in central Kentucky. The tar sand at a depth of 100 ft had an average porosity of 22%, an oil saturation of 64% (6.4% tar by weight) and a permeability after extraction of about 2000 md. The tar had an API gravity of 10.4 º and a viscosity of 150,000 cps at a reservoir temperature of 561JF. The pilot area, was a small inverted fivespot 107 ft on a side. Horizontal fractures were created on the four producing wells by breaking down the formation with air pressure, and these fractures were propped to a calculated radius of 25 ft by injecting water-base gel carrying 4–8 mesh sand. A pneumatic fracture was created in the central injection well, which was held open by the continuedinjection of air. A down-hole burner was used to initiate the combustion zone.

Oil production responded to the movement of the combustion zone ten days after the fireflood was started. The average oil production was 24 barrels per day for the four months required to complete the test. The total oil production of 8100 barrels was 54% of the 5700 barrels originally in place in the pattern area. The injected air produced oil ratio was 42,000 cu. ft/bbl. The produced oil was upgraded to 14.5 API and 2000 cps at 60 ºF, compared to 10.6 º API and 90,000 cps for the original tar at the same temperature. The major problems encountered were the lack of complete oxygen consumption, the unsymmetrical advance of the fireflood and the tendency of the combustion zone to move toward the top of the reservoir.

Introduction

During 1959 and 1960, Gulf Research & Development Co, conducted a fireflood field pilot test in a shallow tar sand deposit lying about halfway between the towns of Brownsville and Leitchfield, Kentucky. The property had been leased from the Kentucky Rock Asphalt Co., hence the name KYROCK. The fireflooding or forward combustion method has been adequately described elsewhere.(1, 2, 3, 4) and the modification tested at the Kyrock site was the utilization of both pneumatically and mechanically propped fractures. Earlier reverse combustion experiments in the tar sand deposit had indicated that horizontal fractures could be extended at constant depth over considerable distances and that a forward combustion reaction zone could be maintained using these fractures for a major part of the fluid flow.

Although the results of these tests were encouraging, neither further development of the method nor publication of the results was warranted at that time because tar sand production could not compete economically with the adequate supplies of conventional crude. In the last few years, that situation has changed and now supplies of hydrocarbons from any and all sources are needed to augment the declining rate of domestic production.
Thermal Recovery In The Venezuelan Heavy Oil Belt
Authors: Ballard J.R. , lanfranchi E.E. , Vanags P.A.
Published: March 2010

This paper describes a successful cyclic stea1n injection program in the Jobo Field, located on the northeastern edge of the Venezuelan Heavy Oil Belt. The program was commenced in 1974 by Amoco International Oil Company. It is being continued, following reversion, by Amoven, S.A., a subsidiary of Petroleos de Venezuela. The Jobo reservoirs are highly unconsolidated sandstones at a depth of approximately 3,800 feet. The crude gravities range from 9 to 13.5 °API. Wells were completed on 64-acre spacing utilizing techniques designed to withstand thermal processes.

A portable steam generator rated at 30 MMBtu per hour is used and the steamed wells have received between 4,000 and 8,000 metric tons each. This corresponds to between 150 and 200 MMBtu per foot of pay. The wells are placed on production after soak periods varying from one week to one month. In the eleven wells which have been steamed at this writing, peak oil producing rates ranging from two to five times the pre-steam rates have been realized almost immediately on commencement of production.

The techniques described herein have permitted injection of high-quality steam at appreciable depths while avoiding m.ost of the common problems normally expected, such as bottom-hole equipment failures, casing cement and liner failures, and surface equipment malfunctions.

Introduction

STEAM STIMULATION is a well-established technique developed in the early sixties. It has found extensive application in Venezuela, mostly in shallow heavy oil reservoirs ranging in depth from 300 to 3,000 feet and containing oil of moderate gravity ranging from 14 ° to 20 °API. Success has been notable in several areas, mostly along the Juseping trend in eastern Venezuela and the Bolivar Coast on the eastern shore of Lake Maracaibo.

The technique has not been very successful where the reservoir and crude oil properties vary appreciably from the ranges given above. This is the case in the northern portion of the Orinoco Heavy Oil Belt; the reservoir depth is between 3,600 and 4,000 feet, the oil viscosity averages 1,800 SFS and the oil gravity ranges between 8.5 and 13 °API.

This paper describes a successful steam stimulation project in the Jobo Field, located on the extreme northeastern edge of the Orinoco Heavy Oil Belt. The project is notable as a demonstration of the successful application of steam stimulation under conditions of extreme depth, viscosity and gravity.

Field Description

Figure 1 is a map of Venezuela, showing the location of the Jobo Field with respect to the vast Orinoco Heavy Oil Belt. The heavy oil belt contains some 700 billion barrels of oil in place, but has seen only scattered development on the extreme northern fringe. Jobo underlies a 5,500-acre concession originally granted to Amoco Venezuela Oil Company and now under the administration of Amoven, S.A., a wholly owned subsidiary of Petroleos de Venezuela, S.A.

The productive Oficina Sandstone at Jobo is separated into two distinct reservoirs, designated Group I and II.
Oil Sands Research At the Alberta Research Council
Authors: Wiggins E.J.
Published: March 2010

I was very pleased to receive the invitation from the Program Committee to speak on the subject of Oil Sands Research at the Alberta Research Council, since we like to feel that we pioneered in this field in Canada. Our involvement dates back to the work of the late Dr. Karl Clark on the development of the hot water separation process in the early 1920's, and the operation of a small pilot plant at Fort McMurray in 1929.

Since there are seven other papers at the Symposium by members of the Alberta Research Council staff dealing with specific aspects of oil sands research, I do not feel that it is appropriate for me to discuss any parts of our program in detail. Instead, I will first give a general picture of the Alberta Research Council's role and activities, and then describe our current involvement in the oil sands field.

The Alberta Research Council is one of eight provincial research councils and foundations in Canada, and all of these have a number of features in common: they are applied research organizations dedicated primarily to the development of their regions; they receive varying amounts of base support from their respective provincial governments, but also carry out research on a contract basis for private industry 'and government departments and agencies; and most of them were originally offshoots of a provincial university. They have no organizational ties with the National Research Council, although they work jointly with it in such fields as the operation of the Technical Information Service in the provinces. Likewise, they have no formal ties with each other although they cooperate in areas of mutual interest and have a national association to represent them in matters such as Federal research incentive and contracting policies. To the best of my knowledge, this system of independent regional research organizations is more highly developed in Canada than in any other country of comparable population. Presumably it is one more reflection of the geographic extent of Canada and of the economic and cultural diversity of its regions.

The Alberta Research Council is typical of these provincial research organizations in that its programs are directed primarily to the economic and social development of Alberta, with only limited activities in other parts of the world. It was originally established by joint action of the University of Alberta and the provincial Government, and for much of its early history was physically a part of the university. For the past 25 years it has had its own staff and facilities, although it still occupies a small amount of space in university buildings and operates several programs jointly with the university. The Alberta Research Council has the status of a provincial crown corporation and operates under the direction of a Board? made up of representatives of the Alberta Cabinet, the private sector, and the universities.
Thawing of Permafrost Beneath a Buried Pipe
Authors: Lunardini V.J.
Published: March 2010

The rate of thaw beneath the center of a hot pipe buried in permafrost was calculated by the quasi-steady approximate method. The solution assumes a purely conductive heat transfer model. The heat loss at the surface was included for the case of a pipe buried at a finite depth. Functions are presented which allow the thaw Tate below the pipe and the heat transfer from the pipe to be calculated for any pipe radius, burial depth, temperature of the pipe surface, as well as initial temperature and thermal properties of the surrounding permafrost. The method allows a quick estimate to be made of the effect of burial depth, temperature and soil thermal properties on the phase change beneath a pipe. The same details can also be applied to the case of freezing around a buried pipe.

Introduction

THE PROBLEM OF THAWING beneath a hot pipe buried in permafrost, or in permafrost regions, has been of considerable interest. Unfortunately, the nonlinear nature of the problem precludes exact solutions when the geometry of the system is curvilinear. However, the exact solution for the semi-infinite region, known as the Neumann problem(1) is available and the details of this solution demonstrate the validity of the quasi-steady, or Stefan(2), approximate method. This idea relies on the fact that the rate of movement of the phase change interface is slow enough that the heat transfer for each region is essentially steady-state at any instant of time. This method was extended by Khakimov(3) to the case of a cylinder embedded in an infinite medium, where the concept was used of a finite volume around the cylinder in which the temperature is disturbed. Gupta'" extended the method to the analogous case of the sphere. There are numerous numerical solutions of the problem, such as those of Lachenbruch(5), but these methods are lengthy when applied to two-dimensional problems and are not convenient for quick estimates.

Theory

Consider the case of thawing of a medium initially frozen at temperature To. A hot cylinder with a surface temperature Ta is inserted into the medium at zero time. The thermal effect will extend, at any time, to a finite distance (a), i.e., the initial temperature of the medium will be unchanged at a location sufficiently far from the hot cylinder. This distance is denoted by the radius (a) and it can be assumed that the ratio α = a/R is a constant, using α = 4.5, as did Khakimov. Using the quasi-steady assumption and letting 0 = T ? To, the temperature for each region (see Fig. 1) will be the solution of the one dimensional conduction equation:

(Equation Available In Full Paper)

The energy required to thaw region 1 and increase the temperature of regions 1 and 2 is the sum of the latent plus the sensible heats and can be written as:
The Electrical Conductivity Of Medium Heavy Crude Oil
Authors: Kendall E.J.M.
Published: March 2010

In this paper, the electrical conductivity of crude oil (S.G.= 0.9) is examined over the temperature range of 50 °C to +75 °C. It is shown that the conductivity of the oil increases exponentially with increasing temperature. Two possible conduction processes based on semiconductor theory and electrokinetic theory are discussed. Conductivities of the order of 2.5 ×10−8υm−1 were observed and the energy gap or activation energy was about 1.0 eV.

Introduction

With the wide use of electrical logging and the future possibility of the use of electrical heating methods for the extraction and processing of crude oil, detailed knowledge of the variation and nature of its electrical conductivity is required. To date, work seems to have been done on an ad hoc basis and very little has been published (1,2). The present work was performed On a variety of heavy crude oils (S.G. = 0.9) as extracted, because it is in this state that the oil is first encountered. No attempt has been made to explain the variations encountered for oils from different sources, as each sample followed a similar pattern. Later work will correlate changes in carrier concentration and mobility with chemical composition and the source of the oil.

Experimental Method

The apparatus consisted of two polished circular stainless steel plates, each 100 cm2 in area, spaced 1 cm apart in a perspex holder. The sample oil was poured on top of the lower plate and the upper plate was pressed into position in the holder, pushing some oil into the reservoir provided. The sample was kept in a nitrogen atmosphere to prevent excessive oxidation. The apparatus was installed in a temperature-controlled oven-refrigerator in which the temperature could be varied from −100 °C to + 400 °C, and a thermocouple was installed on the lower plate.

The oven was set at a particular temperature and a series of current measurements were made on the sample for a variety of voltages. Some problems were encountered with initial changes in the results. These appeared to be due to the fact that the oil took an appreciable time to make intimate contact with the electrodes. This settling down period was considerably shorter at higher temperatures. A period of two or three hours was allowed for equilibrium to set in after each temperature change.

The temperature range used was from −50 °C to +75 °C, because below −50 °C the resistance of the oil becomes too high to measure with the present apparatus with any reasonable degree of accuracy. At about +100 °C the various oil specimens became volatile, with a tendency to boil, and the results were not consistent. The apparatus was carefully and scrupulously cleaned and dried between each specimen change.

Experimental Results and Analysis

Initial results at 25 °C showed no change in resistivity with changing voltage or with changing the polarity of the electrodes after various periods of time. This means that the conduction process through the oil is not sensitive to the electrical field applied, at least not from 0 Vm−1 to 10 kVm−1.
Yield Stress Measurement Of Gelling Oils
Authors: Batycky J.P. , Ritter R.A.
Published: March 2010

An instrument has been developed which permits the reliable measurement at yield stress in gelling crude oils. The improvement of the present apparatus over the standard tubular instruments appears to be related to a lack of formation of fissures in the gel on cooling and also to the fact that a direct measurement o yield stress is obtained. Implications for pipeline start-up are described which suggest that the shear stress must be exceeded locally in all parts of the line. The temperature dependence of yield stress is illustrated for both a refined oil preparation and a crude oil. For the particular curing temperatures employed, the yield stress does not appear to be sensitive to duration of annealing, duration of cooling or the rate of application of stress.

Introduction

Many crude oils throughout the world display properties which can be rheologically described as being thixotropic(1,6,8,10,17,20). Such oils are equivalently characterized as being "high-pour-point" oils. Using a standardized test, the pour point is that experimentally measured temperature at which an oil shows a tendency to gel or to not pour while it is being cooled. The word "high" refers to situations in which this temperature is higher than the ambient conditions which can be encountered as the oil is moved to the refinery. Consequently, its interpretation differs from one geographical region to another. The undesirable gelling behaviour of a thixotropic oil can manifest itself as the oil is being cooled while at rest below a certain temperature, or when the cooled oil is permitted to remain static for a prolonged period.

Often, sufficiently low temperatures can be expected to occur during handling. The implications for storage or pipeline transportation of this type of oil are beyond those normally considered in the design of facilities (1,4,6,7,10,15-19). Difficulties in starting due to the gelling of a thixotropic oil can arise in a pipeline once flow has terminated either as the result of a breakdown or a refitting of the line. With the temperature of the oil at a suitably low level and if the oil has had sufficient time to set, the pump head required to initiate flow can be considerably higher than that necessary for the normal operation of the line. The necessary head which can be related to the shear strength of the oil in its gelled condition is affected by the previous shear and thermal history of the oil as well as the temperature present in the pipeline. The lower the temperature of the oil, the greater the head necessary to fracture the gel. Therefore, provision to accommodate restarting of the line must be incorporated into the design of any facilities transporting such an oil.

There are many alternate approaches to the problem, which can be considered either separately or in combination with one another depending on the economics associated with them. Those most often included are:heat tracing of the line to maintain an elevated temperature, which can certainly be most useful over short distances,
The Great Lloydminster Oil Rush
Authors: Burge Edgar
Published: March 2010

Perhaps because of my Canadian citizenship, Schlumberger Well Surveying Corporation transferred me to Canada when they first opened an office in this country in 1946. The manager was to be Charlie Bailey, with offices in the Burns Building in Calgary. I was to be the field engineer, located in Lloydminster. The way had been paved for us with a smooth layer of promises by Andrei A. Perebinossoff who, in two months, had become a legend as Mr. "Perry" in all the small towns of Alberta, where a presumably, all the future oil exploration would occur. Arriving dressed like a World War I flying ace (perhaps piloted by his friend Roy Graves of Dowell Incorporated) or striding into a beer parlor like a movie director from Hollywood in his French beret, breeches and riding boots and exuding his unique blend of French-Russian-American charm, "Perry" presented a picture of Schlumberger well logs never seen in Canada before or since.

Largely due to the impression left by Perebinossoff, the Canadian branch immediately operated in the black, but there were other reasons. Our logging truck came cheap, having already been written off as obsolete in California. Also, brilliantly, "Perry" had hired Hughie Gough and Arne Thorson of Okotoks as truck drivers and operators. These two, after rebuilding the truck in Casper, Wyoming, to suit our winter conditions, were apparently willing to carry it on their backs if necessary to maintain our reputation for service.

Our competition was the logging service offered by Halliburton, which became Welex a few years later. We felt that we had the better logs, but we had to admit that they had earned the loyalty of their clients, That loyalty was hard to win over to our side. We were the late-comers, by several months at least. So began a long period of friendship, mutual respect and rivalry with Halliburton's Bob Wark, Stan Nelner, Jack Pettinger and Harold Fairbanks. Stan is still with Welex, in Europe. We all believed that the client's interests came first and we would call in our competition rather than make a well wait, if we were very busy.

The Lloydminster oil boom of the late 1940s was something to experience. When we arrived, there was only one hotel and only one hotel room allowed per company; no rooms for mere families no houses and no office space to be had. However, it did have a very large, busy, dripping beer parlor, which served as a sort of oil forum and labour exchange. Perebinossoff had told me not to get an office, but to operate from the beer parlor in order to be part of the oil picture, but after a week or so I had to give up and rent part of a shack for office space. My wife, and daughter got a room in the Brunswick Hotel in Vermilion and I became a commuter.
Leak Detection — “A Necessity In Today''s Industry ”
Authors: Muth R.B. , Bratrud T.F.
Published: March 2010

Present methods of detecting gas leaks during testing of well heads, tubular goods, flowlines and even complete gas plants are woefully inadequate. If leaks are allowed to continue, the resulting high costs, both financial and in human life, can be disastrous.

A unique method of leak detection is now being employed to record leaks as low as 0.0001 ce/sec (1 SCF in 10 years). With this innovative technology, the oil and gas industry is now able to eliminate the presence of dangerous gases to a degree not possible prior to this development. The process involves the use of a tracer gas (helium) and a portable mass spectrometer tuned to respond to the molecular weight of this gas.

To date, the method has seen widespread use on production platforms in the North Sea, with outstanding success. Its reputation for providing a reliable and safe means of leak detection remains untarnished.

Details of the process and up-to-date job histories will be presented in the paper.

Introduction

In today's petroleum industry, the demands on systems used in the transfer of hydrocarbons are rising steadily. Gas production facilities, chemical plants and oil refineries are operating more efficiently, and at higher capacities. Because these facilities deal with toxic and flammable gases at high pressures, safety standards require a high level of system integrity. This means leaks must be detected and repaired.

Various methods have been used for leak detection, with limited success. Hydrostatic testing is not acceptable for establishing the leak integrity of a gas flow system due to the differences in gas and liquid flow regimes (Santeler/Moller(1)). Methane and H2S gas can closely simulate operating conditions, but the techniques and instruments used do not provide accurate and reliable results. The demand for a safer, more sensitive and quantitative method of leak detection led to the techniques described in this paper.

The use of the helium mass spectrometer to detect leaks is not a novel idea-the technology has been available for over thirty years. Its use has been mainly confined to the high vacuum industry, with specialized applications in space simulation apparatus and nuclear breeder research. Initial development was tied in closely with the manufacture of mercury-are rectifiers and hermetically sealed meters for the aircraft industry. Work has progressed to include the testing of intermediate heat exchangers, as outlined by Hopkins(2) for use in liquid fast breeder facilities, but the methods used were centered around vacuum techniques. Pressurized systems, although as prone to troublesome leaks as vacuum systems, had never received the benefits of advancements in helium leak detection.
Trends In PIP And COR Planning
Authors: Parsons R.B.
Published: March 2010

Now that the PIP and COR rules seem to be taking shape (more than two years after the introduction of PIP and COR!), industry operators and investors are in a better position to do some productive planning in order to optimize their PIP benefits.

This month, Tax Topics examines some of the opportunities that are currently available for such planning.

Introduction

With the enactment of the legislation to give effect to the exploration and development grant programs of the federal and Alberta governments, applicants for grants are now better able to plan the operating structure through which they and their participants will carry on qualified exploration and development activities. The governing legislation is set out in the Canadian Ownership and Control Determination Act (COCDA), the Petroleum Incentives Program Act (PIPA) and the Alberta Petroleum Incentives Program Act (APIPA).

It is to be noted, however, that the references herein to the regulations issued under the COCDA are based on the draft thereof issued by the Minister of Energy, Mines and Resources ("Minister ") in the spring of 1982. However, it appears that by virtue of Section 62 of the COCDA, these draft regulations may be relied upon by applicants for a control and ownership certificate under that statute. As of the date of writing, the "final" regulations had not been issued. It is understood that these "final" regulations will differ to some degree from the existing draft, but apparently not in a substantive way.

The purpose of this article is to identify certain specific situations which, in the author's view, illustrate some of the planning techniques that can be used to good advantage. In this context, the focus will be on three broad categories of objectives, as follows:shifting control of an entity to Canada;increasing or maintaining the Canadian ownership rate (COR) of an entity; andincreasing the costs which qualify for grants under the PIP A or APIPA, as the case may be (referred to hereafter as "PIP grants ").

It is a fundamental precondition of eligibility for PIP grants that the applicant therefore be controlled in Canada and have a minimum COR of 50%(1). Thus, for entities that are not controlled in Canada, a fundamental question will be whether access to PIP grants will warrant a shift in control to Canadians. As will be illustrated, this will likely be an issue primarily for those entities that have a high COR to begin with.

For an entity that is Canadian controlled, a primary planning objective will be to increase its COR so as to qualify it for PIP grants or increase the PIP grant levels to which it is entitled. A complementary planning objective for these entities is to ensure that arrangements entered into with non-eligible persons (NEP)(2) do not have a downward impact on the PIP grants to which they would otherwise be entitled.

Access to PIP grants can also be an issue for a NEP as well as ensuring that the arrangements entered into with qualified applicants reflect the value of the NEP's contribution to the venture.