bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of Hydrate Formation in Natural Gas Systems
Authors: Rossi L. F. S. , Gasparetto C. A.
Published: December 2007

In this work a computational algorithm was developed to predict conditions of hydrate formation in natural gas systems, including the effect of inhibitors. The model utilizes Peng-Robinson equation of state and was developed with the objective of fast processing intended for quick results with simple field computing equipment or processor controllers. Development is based on van der Waals and Platteeuw [15] model wich accounts for the interactions between water molecules forming the crystal lattice and gas molecules. Description of such interactions utilizes the spherically symétrie potential of Kihara along with the contributions by Parrish and Prausnitz [10], John et alii [3], and Munckei alii [8]. From statistical and classical thermodynamics it is produced a reletionship between fraction of crystal lattice ocupation by the gas mixture and systems pressure and temperature. From this relationship is produced a curve indicating the region of viable hydrate formation.
Numerical Simulation of Pressure Transients in Naturally Fractured Reservoirs with Unsteady-State Matrix-to-Fracture Flow
Authors: Nanba T.
Published: December 2007

Pressure transient behaviors in a naturally fractured reservoir with unsteady state matrix to fracture flow (transient interporosity flow) are simulated using a multiple interacting continua (MINC) method. The numerical method is verified by comparison with the analytical solutions.

In this paper, the pseudosteady state interporosity behavior in an actual field is explaind by using a concept of a matrix block skin. The behavior is also explained by introducing a concept that fractures contributing to interporosity flow are sparsely distributed in a reservoir. This new concept is numerically modeled by MINC method with a proximity function.

This paper also discusses the relationship between pressure transient behaviors and water imbibition performances.
Improved Formation Imaging with Extended Microelectrical Arrays
Authors: Safinya K. A. , Le Lan P. , Villegas M. , Cheung P. S.
Published: December 2007

Formation imaging using microelectrical arrays is an extremely powerful tool that enables the log analyst, geologist, geophysicist and petroleum engineer to better evaluate complex reservoirs. To date, electrical formation imaging tools with high spatial resolution can image only part of the borehole wall at any one time; attempts to increase borehole coverage have been achieved but with a small degradation of image resolution. A new formation imaging tool has been developed to provide real-time wellsite images of the borehole wall with unprecedented borehole coverage at a resolution of 0.2 in. The borehole coverage of this new tool is 80% in an 8-in. borehole, which represents an increase by a factor of two over previous generation tools. This increase has been achieved while also improving the spatial resolution of the tool. This paper describes the applications of the new tool and the improvement in interpretation of the images. Four tools have been built and tested successfully in wells throughout the world. Examples are given of a fractured formation, a reverse fault, a braided sand and a horizontal well to demonstrate the improvement in the data interpretation.
Multiple-Probe Formation Testing and Vertical Reservoir Continuity
Authors: Goode P. A. , Pop J. J. , Murphy W. F.
Published: December 2007

This paper introduces a strategy and methodology for the wireline measurement of permeability that is consistent with the geological structure observed at the wellbore. The strategy involves new technology; real-time data acquisition and interpretation in parallel utilizing high resolution borehole images and a multiprobe formation tester. The multiprobe tester differs from its single probe counterpart in that it has an additional two probes, displaced from the flowing probe, at which the pressure is monitored. In homogeneous formations this configuration permits the direct determination of both horizontal and vertical mobilities; in laminated formations such a tool allows the study of potential permeability barriers and their effect on vertical fluid movement. As part of the method, we introduce a new interpretation for the multiprobe tester based on flow regime identification using the pressures obtained at the observation probes.

Application of the method is demonstrated using data obtained from two field tests. In addition to electrical and nuclear logs, electric borehole images were obtained over the intervals of interest. The borehole images were used at the wellsite to identify several potential barriers to vertical flow and to choose the test points for the multiprobe formation tester. Subsequently these intervals were tested to determine the effect of the barriers on vertical communication. Additional multiprobe measurements were made in relatively unstratified zones to allow a comparison.

The results of one example indicate that features appearing as permeability barriers at the wellbore may not have large lateral extent and therefore do not act as barriers to vertical flow. The other example shows that the converse may also be true, in that, features which are observed to be thin at the wellbore can have considerable lateral extent and be significant barriers.
Typical Sand Production Problems: Case Studies and Strategies for Sand Control.
Authors: Morita N. , Boyd P. A.
Published: December 2007

This paper presents analyses of five typical sand problems commonly observed in the field. The causes and progress of these sand production problems are explained using field data to help field engineers gain a better understanding of the various sand problems encountered. Strategies for minimizing these sand problems are also discussed.
Outcrop Gamma Ray Logging: Truck-Mounted and Hand-Held Scintillometer Methods Are Useful for Exploration, Development, and Training Purposes
Authors: Jordan D. W. , Slatt R. M. , D’Agostino A. , Gillespie R. H.
Published: December 2007

Reliable, reproducible gamma-ray logs of outcrops have been generated by two techniques with the objective of better visualizing interwell-scale lateral continuity (and discontinuity) of strata and to demonstrate reliability and potential pitfalls in subsurface wireline log correlations. One innovative technique was developed which uses a standard gamma-ray sonde run from a logging truck to log vertical cliff or quarry faces. The second technique employs a hand-held gamma-ray scintillometer to log more easily accessible outcrops.

Examples are presented from the Jackfork Group (Pennsylvanian), Arkansas of outcrop gamma-ray logging of both laterally continuous and discontinuous turbidites in structurally simple and complex settings. We have found that by using these examples, the following common wireline log correlation problems can be clearly explained to engineers and geoscientists, and understood, because the strata from which the logs were measured can be visualized and discussed at the outcrop: (1) the reliability of subsurface log correlations can be greatly improved by understanding expected subsurface depositional geometries and lateral fades changes, (2) wireline log correlations in strati-graphically and structurally complex settings, such as many oil or gas fields, may not be reliable without sufficient coring and special logging in addition to well testing, and (3) correlations and stratigraphic and reservoir quality interpretations of subsurface wireline logs in both oil/gas fields and in exploration areas can be improved by comparing the subsurface logs with outcrop gamma-ray logs of nearby analogous strata.
Flowline Storage Effect on Wireline Formation Tester
Authors: Yildiz T. , Desbrandes R. , Bassiouni Z.
Published: December 2007

The design of wireline formation testers (WFT) features a flowline full of drilling fluid. The compressible drilling mud in the flowline results in a "flowline storage effect" (FLSE) similar in nature to the well bore storage effect.

This paper presents a 3-D analytical model that includes the FLSE. The model is used to investigate the importance of this effect and its impact on pressure response. It shows that the response of the WFT is a combination of fluid decompression in the flowline and flow from the formation. Due to decompression of drilling mud in the flowline, the sandface flow rate is not constant and gradually increases from zero to the piston displacement rate. Slow pressure buildup observed in some field tests is partially due to the FLSE.

A laboratory experimental setup is used to investigate the effect of different parameters on the WFT response. Type curves based on the FLSE model are constructed and result in permeability values that are in good agreement with measured values.
A Case Study of Scaling Up 2D Geostatistical Models to a 3D Simulation Model
Authors: Harris D. E. , Perkins R. L.
Published: December 2007

This paper reviews the procedure used in a recent simulation study in which results from two-dimensional (2D) cross-sectional geostatistical models were scaled up to a three-dimensional (3D) simulation model. Geostatistics (which included fractals) were used in the cross-sectional models to incorporate the effects of fine-scale heterogeneities in the coarsely-gridded, full-field model. Areal and vertical variograms were developed from well log data and used in the realizations. The geostatistical models were modified after the conditional simulations to preserve the integrity between each geostatistical model and the known geologic model. For this waterflood simulation study, the scale-up process involved matching the flood-front velocities and bypassed/trapped oil saturation values in the geostatistical models to those properties in the coarsely-gridded models. Although the scale-up procedure was specific to this reservoir study, the overall process can be modified for application in other studies.
Measurement of Velocity Profiles in Upwards Oil/Water Flow Using Ultrasonic Doppler Velocimetry
Authors: Morriss S. L. , Hill A. D.
Published: December 2007

An experimental study used pulsed ultrasonic Doppler techniques to determine fluid velocities in two-phase oil-water vertical pipe flow.1 The data acquisition system was based on a medical ultrasound instrument, modified as needed, and a microcomputer. Measurements were made in a pipe with an inside diameter of 7.25 in. [18.4 cm], part of the Multiphase Flow Loop in the Department of Petroleum Engineering at The University of Texas at Austin. This pipe is 42 ft [12.8 m] long and can be inclined at any angle. The ultrasonic measurements gave reasonable qualitative results in all regimes of which the flow facility is capable: the Doppler frequency was generally proportional to the phase velocities. More theoretical and experimental work is needed, though, to improve the quantitative accuracy and to increase the measurement range: measured velocities were generally too low, and the range limit is estimated to be approximately 6 to 12 cm into the flow, depending on the regime. Backflow is measured on the low side when the pipe is inclined from the vertical.
A Comparison of Cementation Logging Tools in a Full-Scale Simulator
Authors: Hayman A. J. , Gai H. , Toma I.
Published: December 2007

Acoustic cementation logging tools have been run in a full-scale cement flow loop and the logs compared to a physical examination of the cement in the annulus. In the flow loop the complete cycle of cementing operations — mud and spacer circulation, and cement placement — was carried out. The flow loop included artificial formation and double string sections.

Three tools were used in the flow loop: a sonic tool and two ultrasonic pulse-echo tools. The sonic tool measures the attenuation of sonic waves along the casing and is sensitive to shear coupling between casing and cement. The ultrasonic tools measure the damping of a thickness-mode resonance and the acoustic impedance. One ultrasonic tool samples every 45 degrees in azimuth; the other provides complete coverage using a rotating probe.

Conditions such as channeling, good and contaminated cement, mud and water were created in the flow loop. The logs were consistent with the subsequent physical examination, within the resolution limits of each tool. Very thin annulus and highly contaminated cement posed interpretation problems. Of the tools investigated, the rotating ultrasonic tool provided the most accurate predictions of cement distribution and quality.

The results illustrate the advantages and limitations of the different types of tools, and will be a useful aid in the interpretation of cementation logs.
Computers And The Petroleum Engineer
Authors: Gillette J.M.
Published: December 2007

What are some of the uses a petroleum engineer can make of electronic computers? How can he learn to use them? This paper answers these questions in terms to be understood by the reader who is not a computer expert. The computer expert may find here one or two ideas of how he may extend the use of computers in his company.

How many times have you had to estimate an answer because there was neither time nor manpower to develop a more exact answer? If the answer is, "Too many times," then you can use a computer. For example, you, as petroleum engineers can use computers for calculation of design factors for process units, prediction of water flooding in a reservoir, or optimization and control of process units.

What is a computer? A computer is a device capable of accepting data, performing prescribed operations on these data, and supplying the results. A computer is shown schematically in Fig. 1. Four sections [central processor, input, output and auxiliary memory] make up the total computer system. Data are moved between the section and within the central processor under control of the central processor control unit. In a stored program computer, the control unit interprets and executes a program stored in the internal memory.

The input, output and auxiliary memory sections may consist of any one or all of the device listed in Fig. 1. The size and cost of a compute will depend upon the number and type of devices in the three sections and upon the speed with which operations are performed. There are many commercial computers available today. They range in size from the IBM 7090 to the Monrobot XI. For example, the Computer Characteristics Chart published by Adams Associates lists 61 computers.

Comparison of computers is not within the scope of this paper; however, a few facts to illustrate the range of sizes should be of interest. [See Table 1.]

Somewhere in the wide range of available computers, there is one, or perhaps several, to fit your needs. A word of caution — seek the advice of an expert before taking a selection.

How do you make a computer perform a given job? Computers operate by executing a program. A program is a series of instructions detailing each step the computer is to perform. An instruction for a computer consists of a series of code digits which the control unit interprets and executes. For example, the instruction 60 1423 1527 would be interpreted by the IBM 650 to mean RESET and ADD to the accumulator [60], the number stored in the memory location with the address of 1423, and go to the memory location with the address of 1527 to find the next instruction. A series of such instructions is a machine language program.
Testing of Subsea Gate Valves in Sand Slurry
Authors: Norland S. O.
Published: December 2007

Three gate valves from different manufacturers have been performance tested in a test loop. Anticipated production rates on the Statfjord Satellite Fields (SSF) have been simulated. The testing was part of the pre-qualification of the Christmas tree valves for this project. The tests were performed in order to determine the expected cycle life and failure mode while operating in a sand slurry environment. The valve’s ability to hold gas liquid pressure was monitored throughout the test.

On completion of the tests, the valves were disassembled and inspected for wear and tear, and the gates subjected to a material analysis.

Information gained from the tests has proved to be very useful for the development of SSF.

Four main discoveries were made during the testing: (i)- Grease in the valve cavity traps and accumulates sand.(ii)- The ability to operate in a sand slurry is dependent on the geometry of the valve internals.(iii)- Valves designed for API class II sandy service do not necessarily perform satisfactorily when test conditions are changed from those specified in API spec 14D.(iv)- Gates with tungsten carbide coating on high alloy steel performed better than those on low alloy steel.
Prediction of In-Situ Shaped-Charge Penetration Using Acoustic and Density Logs
Authors: Halleck P. M. , Wesson D. S. , Snider P. M. , Navarette M.
Published: December 2007

This paper presents the findings of a joint research project studying the relationships between rock acoustic properties and shaped charge penetration. The project was based on results from API project 89-36 in which a relationship between compressional wave velocity and penetration depth was found to be valid regardless of overburden stress. Two new charges were used in this study and the scope was expanded to include testing in three sandstones (dominantly quartz), three limestones (dominantly calcite), and a quartzite. The target properties studies were also expanded by measuring shear velocity (Vs) as well as compressional velocity (Vp). Penetration was correlated with a range of calculated parameters available from sonic and density logs such as bulk modulus, compressional impedance, and shear impedance. Well logs from a number of actual wells were reviewed to determine the values of these parameters for typical reservoir rocks.

Shaped charge penetration can be correlated and predicted in situ using certain acoustic rock properties. The effects of the target stress can be accounted for by the corresponding change in the rock’s acoustic properties. Penetration decreases with increasing values of all parameters studied, but on to a plateau level. Further increases in the acoustic parameters above these critical values, due either to using different target materials or to increasing stress, cause little further penetration decrease. The best correlation appears to be with bulk modulus. Many of the actual wells studied have values of bulk modulus above this critical level, and thus penetration depths for the studied charges should be equal to the plateau value in many reservoirs. It is speculated that this minimum penetration corresponds to the hydrodynamic penetration by the supersonic portion of the jet.

These findings will allow more accurate estimates of the downhole performance by using the acoustic and density logs from the well. Downhole penetrations can be estimated without regard for rock compressive strength, stress, or overburden. Given only a curve for penetration of the specified charge vs. an acoustic parameter, in situ penetration can be estimated in the actual formation. It is anticipated that the theoretical models of shaped charge penetration can be improved using these observations.
Improved System Test for Perforators
Authors: Wesson D. S. , Gill B. C. , Navarette M.
Published: December 2007

The current API RP-43 procedures for deep penetrating shaped charges require that they be tested to Section 1 (Evaluation of Perforating Systems Under Surface Conditions, Concrete Targets) and Section 2 (Evaluation of Perforators Under Stress Conditions, Berea Targets).1 The Section 2 procedures compare charges and estimate penetration in natural rock under simulated downhole conditions. This test is conducted on a single charge.

The objectives of the Section 1 (Concrete Target) procedures are to estimate the hole size in the perforated casingto test the system.

The primary objective of a system test is to determine if the single charge performance on the Section 2, test will be representative of the shots in actual field hardware. Many variables of the system can effect actual field performance.2 This paper discusses one factor that can adversely effect shaped charge performance in a perforator system: explosive interference.

For the purposes of this paper, explosive interference is defined as the reduction of shape charge performance under single shot performance as a result of geometric and explosive factors in a gun system. Many factors can contribute to explosive interference in a perforating system. These factors are not the subject matter of this paper; rather, this paper focuses on detecting explosive interference with modified API RP-43 Section 1 procedures.

Explosive interference in a gun system can range from very severe to very slight. Severe interference may be obvious by the condition of the gun carrier and the casing hole size. Penetration reductions of 50% or more have been observed with this type of explosive interference. However, observations made on modified API Section 1 tests have shown "slight interference" can reduce overall penetration by as much as 35%. This interference can not be detected by observation of the gun, casing, or standard Section 1 concrete penetration data.

After performing many API RP-43 Section 1 tests with high shot density perforators (over 4 spf), an improved API RP-43 Section 1 test procedure has been used successfully to determine whether significant explosive interference exists in a perforating gun system. This modified procedure assures that field perforator systems do not have an explosive interference problem that reduces perforator performance significantly below published Section 2 data.
Environmental Protection and Regulatory Compliance at the Elk Hills Field
Authors: Chappelle H. H. , Donahoe R. L. , Kato T. T. , Ordway H. E.
Published: December 2007

Environmental protection has played an integral role in the development and operation of the Elk Hills field since production at the maximum efficient rate was authorized in 1976. The field is located in a non-attainment area for California and National Ambient Air Quality Standards for two criteria pollutants and their associated precursors, is home to four endangered species, and operates within the California regulatory framework. Environmental protection and regulatory compliance is a multi-faceted program carried out through a substantial commitment of resources and workforce involvement. This paper describes the actions taken and resources employed to protect the environment, specific technologies and projects implemented, and the ongoing nature of these efforts at Elk Hills.
Coiled-Tubing-Life Modeling
Authors: Newman K. R. , Newburn D. A.
Published: December 2007

The use of coiled tubing (CT) is increasing rapidly in the oilfield service industry. Large CT sizes are being developed to meet new service requirements. The CT is being pushed closer to its performance limits for many of these services. To avoid CT failures in the field, it is important that these limits are well understood.

There are three major types of CT limits: Life limits due to low cycle fatigue and corrosion of the CT.Pressure and tension limits of the CT [1].Diameter and ovality limits.

These limits are interrelated in some ways but can be analyzed separately. The corrosion effect on the CT must be considered for the first two limits; but, the fatigue life of the CT does not significantly affect the pressure and tension limits.
New Plate Pack Design Leads to Increased Separation Efficiency of a Centrifuge
Authors: Plat R. , van den Broek W. M. G. T.
Published: December 2007

Centrifugation is a very efficient technique for the de-oiling of production water. The high efficiency is the result of the large acceleration inside the centrifuge in combination with the effect of the built-in plate pack, usually a conical disc stack. To study possibilities for the improvement of centrifuge performance a new plate pack type is developed.

In this paper the working principle of both the disc stack centrifuge and the centrifuge with the new plate pack is described. A design of the new plate pack, with vertical plates parallel to the centrifuge axis, is presented. Results of a computer simulation program indicate that this design will lead to an increased efficiency of the centrifuge. Use of the plate pack instead of the disc stack will cause a decrease of the oil concentration of the centrifuge effluent of about 25%. Experiments with the new plate pack confirmed this. Further improvement of the plate pack may lead to a decrease of the oil concentration of more than 40%.
A Thermodynamic Study of Borate Complexation With Guar and Guar Derivatives
Authors: Dawson J. C.
Published: December 2007

Borate–crosslinked galactomannan gels are commonly used as fracturing fluids. These fluids are reversible gels having crosslink junctions that easily dissociate causing the gels to be both thermal and shear thinning. Rheological measurements and 11B NMR analysis were used to examine the nature of these crosslink junctions. The NMR data suggests that a 1:1 borate polymer complex forms in abundant quantities. The primary structure of the crosslink junction may be an ionic association between the complex and adsorbed cations on the second polymer chain. Steady and oscillatory shear measurements were also made to examine the properties of the crosslink junction.
The Fractal Nature of Geological Data Sets: Power Law Processes Everywhere!
Authors: Garrison J. R. , Pearn W. C. , von Rosenberg D. U.
Published: December 2007

Geological features such as lithologie beds, fractures, folds, sedimentary structures, and pore networks are evident at a variety of scales and require that a length scale be specified in order to establish a frame of reference. Recently, it has been demonstrated that such apparently self-similar, scaling objects and features could be described as stochastic natural fractals. These natural fractals exhibit structures and features whose distributions are exponential (i.e., they exhibit power-law behavior) and can be described in terms of apparent or effective fractal dimensions. This paper presents a sampling of geological data sets whose distributions can be described as natural fractals: reservoir rock/pore systems, sand layers in mixed-lithology sequences, sandstone grain-size, and fault systems. The Arun Limestone, San Andres Dolomite, Norphlet Sandstone, Lobo Sandstone, and Spraberry Sandstone all exhibit fractal rock/pore networks with fractal pore size-frequency distributions. An example of a Tertiary deep-water sand/shale sequence from off-shore Gulf of Mexico exhibits a fractal sand thickness, and both the sand and shale thickness-frequency distributions are fractal, as well. A carbonate sand/carbonate mud sequence from Saudi Arabia also exhibits a fractal sand thickness-frequency distribution. Samples of a Tertiary Gulf of Mexico deep-water sandstone and a West African deltaic sandstone exhibit fractal grain size-frequency distributions. The amplitude and residue thickness of styolites from a Limestone from Abu Dhabi illustrate an example of fractal data sets from structural geology. Most geological objects and features, common to petroleum and mineral exploration and production, can probably be described statistically in terms of fractal geometry, and their fragmentation and irregularity can be characterized by fractal dimensions.
Key Gas Well Blowout Due to Waterhammer Phenomenon
Authors: Blick E. F. , Saleem S.
Published: December 2007

A theory based upon the "waterhammer effect" is developed to explain the cause of the blowout of the Key 1–11 well on October 4,1981, operated by Apache Corporation in Wheeler County, Texas. The real cause of the accident was not known. The operating pressures before blowout were not sufficient to stretch 778′​′″ casing 80 feet and to cause this accident. However, this analysis shows that high pressures generated due to waterhammer appear to be the probable cause. It was assumed that the tubing suddenly ruptured (possibly from corrosion), causing a pressure wave to develop in the KCl water in the annulus between the 278′​′″ tubing and 758′​′″ casing. The upward moving wave reflected off the wellhead and moved downward. Depending upon the amount of gas on top of the water in the annulus, pressures up to 30,000 psi were computed. Pressures of these magnitudes were shown to stretch the 758′​′″ casing in excess of 80 feet which correlates with the evidence at the blow-out site.
Heat Transfer During Two-Phase Flow in Wellbores: Part I—Formation Temperature
Authors: Hasan A. R. , Kabir C. S.
Published: December 2007

Heat loss from the wellbore fluid depends on the temperature distribution in the formation. Formation temperature distribution around a well was modeled by Ramey (1962) by assuming a vanishingly small wellbore radius. The assumption, while robust for some cases, could lead to unrealistic predictions of early-time behavior. This paper uses a rigorous model of heat transfer developed with consideration for the appropriate boundary conditions; that is, the heat transfer at the formation/wellbore interface is represented by the Fourier law of heat conduction. The superposition principle is used to account for the gradual change in heat transfer rate between the wellbore and the the formation.

The results of the new analysis are in agreement with the classical work of Ramey for large times (dimensionless time, tD > 10). However, significant differences are noted between the proposed solution and that of Ramey’s log-linear approximation at small (tD < 1.0) times. These differences may have considerable effect on certain applications, such as static earth temperature estimation from temperature logs, and bottomhole temperature estimation for cyclic steam injection.

We also present an approximate algebraic expression for the rigorous integral solution of dimensionless formation temperature, TD. This simplified expression is accurate for most engineering calculations. Use of this solution is shown in the second part of the paper where the wellbore fluid temperature distribution is computed during two-phase flow.
The Character of Coal Fracture Treatments in Oak Grove Field, Black Warrior Basin
Authors: Palmer I. D. , King N. S. , Sparks D. P.
Published: December 2007

Forty-three gel fracture treatments are analyzed in this report - in both Mary Lee/Blue Creek seams and in Black Creek seams. Although 12/20 sand concentrations were added to 10 ppg, there were virtually no screen-outs, presumably because pad volumes were so high (almost 50%). The Black Creek fractures are vertical, with substantial height growth, and are characterized by high treating pressures but relatively low fracture propagation pressures. There is conspicuous erosion by 12/20 sand of the fracture "entry region": perforations, perforation/fracture junction, or near-wellbore fracture constriction. It is postulated that erosion is conspicuous because (a) not all perforated zones are taking fluid, (b) the overall perforation/fracture junction may be more complex when subfractures from Black Creek seams join up to form the main fracture, or (c) the fluid, sand, and products of erosion are not confined to the coal seams. There are relatively few proppant-induced pressure increases, again possibly due to the fact that the 12/20 sand and products of erosion are not confined to the coal seams. The constant behavior of shut-in pressure with time in the majority of cases is consistent with an absence of any poroelastic effect (although about 25% of cases are consistent with a poroelastic effect). Approximately half of the Mary Lee/Blue Creek fractures are just like the Black Creek fractures and are interpreted similarly. The other half are different and exhibit high fracture propagation pressures. They are probably T-shaped fractures. A T-fracture is confined to a coal seam (there might be a T-fracture in more than one seam). Shut-in pressures measured throughout such fracture treatments are greater than 1 psi/ft, but generally decrease with time. In general the high pressure T-fractures are shallower than the low pressure vertical fractures. They do not show any correlation with a prominent fault block, which contradicts a previous finding. There are more proppant-induced pressure increases. In the high pressure Mary Lee/Blue Creek cases, the pressure drops at final shut-in range from small ( ~ 100 psi) to large ( ~ 750 psi). The former appear to be consistent with an elevated fracture tip resistance (or apparent fracture toughness). The latter are consistent with a near-wellbore flow constriction (discrete offsets/obstructions, or multistrands, or tortuous fluid flow path due to T-fracture geometry). The pressure decline after shut-in is not any faster in the high pressure Mary Lee/Blue Creek cases than in the low pressure cases. The most likely explanation is a reduction in coal permeability due to (a) high ambient in-situ stress, (b) damage by the high fracturing pressures. Gas production appears better, by more than 50%, in low pressure Mary Lee/Blue Creek cases than in high pressure cases. This is consistent with the notion that a vertical fracture is a more effective stimulation than a T-fracture.
Fractured Reservoir Simulation and Field Development, Natih Field, Oman
Authors: Dijkum C. E. van , Walker T.
Published: December 2007

Further development of the fractured Natih field requires a good understanding of the historical contributions from gas/oil gravity drainage and water/oil displacement. A history match of the field has been made using a fractured reservoir simulator, which apart from dual porosity, can model dual permeability and block-block interaction. Several studies aimed at describing the reservoir in detail were required before simulation could start. The history match shows that gas/oil gravity drainage has been about twice as effective as water/oil displacement. This figure is in good agreement with the gas and water sweep data derived from recent gas saturation and water saturation measurements in the field. Prediction runs show that promoting gas/oil gravity drainage by lowering the fracture oil rim is an attractive way to further develop the Natih field.
Horizontal Wells in the Water Zone: The Most Effective Way of Tapping Oil from Thin Oil Zones?
Authors: Haug B. T. , Ferguson W. I. , Kydland T.
Published: December 2007

Oil production from thin oil zones sandwiched between a gas cap and an active aquifer is often limited to uneconomic rates due to water and gas coning. Horizontal wells seem to provide a promising solution to the coning problem. In order to avoid premature gas breakthrough, the horizontal wells should normally be positioned as far away from the GOC as possible. This assumption has been examined further; wells completed below the WOC have been compared to wells in the oil zone. This strategy relies upon oil coning into the well completions through the water zone; the so called "inverse coning" process.

In this study, production from the 12 m thick oil zone in the Troll West Gas Province has been simulated with a 500 m horizontal well completed in the water zone below the WOC. The effects of various rock and fluid parameters have been evaluated, and a correlation for time to gas breakthrough has been developed based upon the simulation results.

The calculated gain in oil production with the well below the WOC ranged from 15% to over 50% in this study, depending on the reservoir and operating conditions. Based upon cumulative oil production considerations, an optimal completion depth of 3-4 m below the WOC was determined. Cone behaviour was shown to be dominated by permeability level, fluid mobilities, completion depth and liquid production rate. The primary disadvantage with these wells is the sustained increased water cut.
Water Coning Calculations for Vertical and Horizontal Wells
Authors: Yang Weiping , Wattenbarger R. A.
Published: December 2007

Most authors have concentrated on correlations for critical rate and breakthrough time in vertical and horizontal wells. WOR (water-oil ratio) has also been addressed in vertical wells. However, WOR performance in horizontal wells has not received much attention. The purpose of this work is to develop a method suitable for either hand calculation or simulation to predict (1) critical rate, (2) breakthrough time, and (3) WOR after breakthrough in both vertical and horizontal wells.

An extensive sensitivity analysis of water coning was performed using numerical simulation. From this analysis, an empirical coning correlation was developed based on the basic flow equations and regression analysis. The format of the correlation is similar to Addington’s gas-coning correlation. It predicts critical rate, breakthrough time and WOR after breakthrough.

WOR performance at variable rate production conditions has also been evaluated in this work. It was found that WOR has hysteresis, (i.e., WOR not only depends on the current production rate, but also the previous production history). However, given sufficient time after rate changes, hysteresis disappears. At such conditions, the correlations can also give a good estimation of WOR for variable rate cases.

This correlation provides a hand calculation method of coning prediction for both vertical and horizontal wells. It can also be used as a coning function for 3-D coarse grid reservoir simulation. The correlation was tested and found to be reliable and accurate in predicting WOR, as well as critical rate and breakthrough time when water-oil mobility ratio is smaller than 5 or viscous forces are not dominating.
Numerical Simulation of Oil Displacement in Pattern Floods With Fractured Wells
Authors: Konoplyov V. Y. , Zazovsky A. F.
Published: December 2007

The effect of fracture length, orientation and conductivity on waterflooding performance in repeated fractured well patterns is considered. It’s found that for fixed well spacing density there is an optimum fracture length which provides maximum of oil recovery at a fixed time of production, because of oil recovery at breakthrough changes for the worse with the increase of fracture length. For the developed oil field, aggravation may be connected with unfavorable orientation of fractures in well pattern. If orientation of fractures is in accordance with well pattern, with fixed well spacing density the aggravation due to increasing fracture length can be connected with the finite fracture conductivity.

The cleanup of fracture and zone invaded by the viscous fracturing fluid, when putting the well into production, is investigated. The increase in fracture length is shown to leads to slowing-down fracture cleanup and invaded zone washout and as a result to extreme relationship between well productivity factor and fracture length.

Fully implicit numerical simulator based on the method of lines, was developed for solving multi-phase flow problems. The main advantage of this method is in the efficient simulation of transient processes with great difference in time or space scales.
Extending Gas Well Velocity Limits: Problems and Solutions
Authors: Castle M. J. , Teng D. T.
Published: December 2007

Production from North Rankin A platform (NRA) aims to meet the objective of supplying contract gas/LNG whilst maximising the condensate yield. This paper describes current efforts to increase production of selected wells through an extension of tubing flow velocity limits. By doing so, condensate rich wells can be produced preferentially at higher rates and overall flexibility between wells with regards to maintaining contractual gas production can be improved.

Arguments used to define a new limit to tubing flow velocity are presented together with the agreed basis for allowable sand production. Also discussed are the monitoring practices undertaken to ensure a long term field trial is completed safely. Here, particular emphasis was placed on proving the reliability of sand monitoring by performing field comparison trials of available systems prior to the commencement of the high rate trial.
Hydrocarbon-Producing Formations of Salin, Irrwaddy, and Martaban Basins, Myanmar (Burma)
Authors: Khin J. A.
Published: December 2007

Hydrocarbon producing formations of the Salin, Irrawaddy and Martaban basins of Myanmar are Upper Tertiary (Pliocene, Miocene and Oligocene) in age. Almost all the producing oil and gas fields are located in these three sedimentary basins.

The geological structures of the producing fields are discussed individually, on the basis of the findings of geological field surveys, gravity and seismic data and drilling results.

The tectonic of the three basins are also presented in respect of the movements of the Indian and Asian plates along the Sumatra – Andaman – Arakan – Himalayan trench or sub-duction zone.

The lithology of the formations and reservoir characteristics of the producing horizons are discussed, on the basis of well logs, cores and pressure/temperature measurements.

The paper also attempts to analyse the source and migration of tertiary oil and gas based on organic and isotope geochemistry, to assist in further explanation of hydrocarbons in Myanmar.
Petroleum Engineering Education: Oil Industry Viewpoint
Authors: Rye John G.
Published: December 2007

Publication Rights Reserved

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and considered for publication in one of the two SPE magazines with the paper.

There is a continual need in the oil industry for Petroleum Engineers to work as operational, staff and research engineers and as supervisors or managers with a technical background. This paper explores the methods of hiring and training used by the larger companies in developing engineers to fill these career opportunities.

Suggestions are made by the author on "How the universities and colleges teaching Petroleum Engineering can improve the academic curriculum and educational counseling in order to better prepare their graduates for work in the oil industry."

Introduction

One of the primary objectives of the Petroleum Engineering schools should be to prepare students to perform engineering work which will be profitable to themselves and to the industry in which they will be working. Therefore, it is important that the students studying Petroleum Engineering and the men teaching this profession keep in mind, "What does the oil industry expect and look for in the graduate Petroleum Engineer?" In order to better understand this question, it is necessary to investigate the hiring practices and training methods employed by the larger companies in the oil industry. This is true because a large proportion of the new graduates are employed by oil companies or corporations of at least fairly large size as opposed to very small companies or self-employment. In fact, many Petroleum Engineers working for small companies or self-employed have received previous training with a larger oil company.

CAREER POSSIBILITIES

The career possibilities for a graduate Petroleum Engineer can be broken down into three general categories:General Operational and Staff Engineering The largest number of Petroleum Engineers are included in this group which is defined as those engineers whose work is primarily concerned with engineering problems and the operational procedures to carry their engineering work through to completion in the field.Supervisors and Managers with an Engineerin
Formulation of an Environmentally Safe Oil Based Drilling Fluid
Authors: Yassin Abu Azam Md. , Kamis Azmi , Abdullah Mohammad Omar
Published: December 2007

The usage of oil especially diesel oil as the continuous phase of drilling mud is widespread when drilling through sensitive producing formation and troublesome shale zone.

Diesel oil is harmful to the environment-particularly marine environment in offshore application due to extensive legislation now exist in many countries to regulate this form of oil pollution. The use of palm oil derivative could be considered as an alternative based fluid which is harmless to the environment. Tests have been undertaken to evaluate the characteristics of palm oil derivative as the base fluid in the oil based mud and its toxicity effect on marine life and results obtained showed that palm oil derivative is a suitable alternative to formulate oil based drilling mud with the necessary rheological properties, compatible with existing mud additives and non-toxic to the marine life.
Optimization of Perforation Distribution for Horizontal Wells
Authors: Landman M. J. , Goldthorpe W. H.
Published: December 2007

In a high permeability reservoir, significant pressure drop can occur in a horizontal well, causing nonuniform inflow due to the variation in pressure drawdown along the well. A mathematical model is described for investigating how perforation distribution affects the performance of a horizontal well producing under steady state inflow. The model couples the Darcy flow into each perforation with the one-dimensional momentum equations for pipe flow. The perforated well is treated like a pipe manifold with T-junctions representing the perforations along the wellbore. A number of examples are presented demonstrating how the model may be used to determine the optimal perforation distribution for different production requirements.
Borehole Instability on the Northwest Shelf of Australia
Authors: Kingsborough R. H. , Williams A. F. , Hillis R. R.
Published: December 2007

Wellbore instability poses a significant problem for many wells drilled on the Northwest Shelf of Australia. With the discovery of the Wanaea and Cossack oilfields, research work has focused on an investigation involving the measurement of shale properties, analysis of operations and well logs and the application of this information to the analysis of wellbore stress and instability.
Effect of Some Design Parameters on Well Completion Stresses
Authors: Mclver D. B.
Published: December 2007

Some recent experience is presented of the structural analysis of subsea completions subjected to bending loads. The paper looks at the stresses and internal loads induced near the mudline in the wellhead, conductor and casing and, in particular, the effect of cement shortfalls and different soil conditions are explored.

The insight obtained to structural performance by this type of analysis is shown to be invaluable and can lead to the design of more efficient structures. As a result, safety can be improved.