bluuebunny/crossref_metadata_2025 huggingface dataset:
Naphtha Injection and Reproduction in Qatif Field: A Case History
Authors: Al-Habbash I. I. , Gutek A. M. H.
Published: December 2007

A large refinery naphtha storage project has been successfully operated by the Arabian American Oil Company in Saudi Arabia. Variations in the liftings of refinery naphtha precipitated the need for underground storage to support existing surface tankage. Facilities consisting of a pipeline from the refining center at Ras Tanura to a Gas Oil Separation Plant in the Qatif field and injection pumps were put in place. Injection into the south domes of two highly porous carbonate reservoirs occured in two separate cycles over a combined interval of 7 years. Total injection into Reservoir I and Reservoir II has been 194 and 9.7 million barrels (3.1 and 1.5 million m3) respectively. Intermittent reproduction has recovered 50 percent of the stored naphtha, with crude contamination increasing on an individual well basis from initial rates of 10 percent to more than 40 percent as naphtha reproduction continued. During naphtha injection, reservoir pressure responses of approximately 200 psi (1379 kPa) were observed in wells offsetting the injectors. Acid stimulations and light hydrocarbon soak treatments were successfully used to eliminate the adverse effects of wellbore plugging during the injection and reproduction phases of the project.
Evaluation of Two-Phase Flow Test Pipeline Configurations for an Offshore Oil Field
Authors: Brill J. P. , Sifferman T. R. , Schmidt Zelimir , Sharma Yugdutt , Dutta-Roy Kunal
Published: December 2007

In a major oilfield in Saudi Arabia, detailed information on individual well performance is required for operating and planning purposes. Complete design data can only be obtained through the addition of extensive facilities for periodic testing of all production in the field. Three different test pipeline configurations were considered. Variables included pipe diameter, pipeline length, oil production rate, gas/liquid ratio, and water cut. Lengths up to approximately 10 miles (16.1 km) were considered.

Three types of analyses were undertaken. The first analysis included steady state pressure losses in not only the horizontal segments but also the vertical risers and downcomers at the platforms. The second set of calculations involved transient simulations for both increasing and decreasing flow rates. Finally, slug length and period predictions for both normal and "severe" slugging were performed. Severe slugging occurs only at very low flow rates and negative pipeline inclination angles.

Pressure drop calculations based on the Beggs & Brill correlation, with a rough pipe friction factor, showed that 10 in. (25.4 cm) pipelines were adequate for most cases. Transient simulation results indicated that, in general, less than two hours were required to reestablish steady state flow for both increasing and decreasing rates. Normally occurring slugs were found to vary in average length from about 200 to 600 ft (61 to 183m)with a maximum possible slug length of approximately 2500 ft (762 m). Liquid slug lengths for severe slugging varied from about 100 to 800 ft (30. 5 to 244 m depending on the pipeline length and riser height.
Drillstem Testing of High-Pressure and Temperature Wells on Land is Made Safer by Using Annulus Pressure Operated Testing Tools
Authors: Hushbeck D. F. , Henderson J. L.
Published: December 2007

Often on high pressure or high temperature wells, drillstem testing is considered too dangerous and thus bypassed. With the development of annulus pressure operated tools for offshore use come new techniques of drillstem testing that have proved to he safer than conventional testing methods. These tools and techniques can he used on high pressure and temperature wells on land to perform safe and efficient drillstem tests.

The annulus pressure responsive (APR) system of testing tools has been used offshore for years primarily because of its simple operation by varying annulus pump pressure. This operating method allows a drillstem test to be conducted with a closed system (the rams are closed during the test), and no pipe rotation or manipulation is necessary to control the test. The possibility of a leak in the test string is reduced and safeguards can be incorporated into the test string so that if a leak to the annulus occurs, the increase in pressure will trip a safety valve and close the well in. The full opening arrangement in the APR system also lends itself well to high pressure testing, allowing for greater drawdown to occur. The full opening feature also allows for perforating under-balanced, and treating through the tools.

Case histories will show how the APR system of testing tools can be utilized on land to achieve safer and more accurate test results.
Removal of Oil-Phase Muds From Wells in the Anadarko Basin
Authors: Goode D. L. , Phillips A. M. , Williams D. A. , Stacy A. L.
Published: December 2007

Oil-phase drilling muds are widely employed in the Anadarko Basin where they offer improved temperature stability and drilling efficiency in these hot, geopressured zones.

Diesel/mutual solvent remedial treatments have been used in the Anadarko wells to remove oil-phase mud from the wellbore area and fractures. These treatments reduce the mud viscosity in a reversible manner such that subsequent exposure of the mud to water can cause an increase in mud viscosity and potential plugging of the well. The diesel/mutual solvent leaves the exposed zone in an oil-wet state which can lower the productive capacity of the well. In addition, the diesel/mutual solvent treatments are expensive and particularly hazardous at the high surface treating pressures encountered.

A laboratory investigation was performed in which alternative mud removal systems were tested. An Aqueous-Based Cleanup System has been developed to remove oil-phase muds following drilling. The system incorporates 2% KCl with an organic solvent and a surfactant blend. The treatment irreversibly reduces oil-phase mud viscosity while suspending mud solids for removal from the reservoir. The Aqueous-Based Cleanup System restores the mud-damaged zone to a water-wet state for maximum hydrocarbon productivity. This system offers a less expensive and safer alternative to the diesel/mutual solvent treatments.

This paper presents laboratory data comparing the effects of several mud removal systems on oil-phase muds and their associated wetting tendencies. Anadarko Basin case histories of Aqueous-Based Cleanup System treatments are presented. Significant production increases were achieved with the treatments.
An Approximation of Continuity of Lenticular Mesaverde Sandstone Lenses Utilizing Close-Well Correlations, Piceance Basin, Northwestern Colorado
Authors: Peterson R. E. , Kohout Julie
Published: December 2007

Mesaverde Group sandstone units in 13 closely-spaced wells in the central and southern Piceance Basin of Colorado were correlated utilizing wireline log response quantitatively and qualitatively. Based on these correlations, the environmental subdivisions of the Mesaverde Group were characterized as follows:Paralic (upper mixed-marine) zone, occuring in the uppermost Mesaverde Group, includes thick sandstone units which are interpreted to be regionally continuous.Fluvial zone, containing point-bars 20 to 30+ ft thick, is interpreted to be correlatable to a maximum of 6,300 ft.Paludal zone has insufficient data to adequately characterize the sand units. However, 63 percent of the units are correlatable across at least 139 ft.

An approximation of the dimensional characteristics of Mesaverde sandstone units has potential applications in designing hydraulic fracturing treatments and estimating gas reserves more accurately.
The Prediction of Hydraulic Fracture Azimuth Through Geological, Core, and Analytical Studies
Authors: Clark J. A.
Published: December 2007

Results of 10 different methods for determining the maximum horizontal principal stress direction at the DOE's Multi-Well Experiment site in the Piceance Basin, Colorado show remarkable consistency. The methods included surface geological observations (e.g. fracture mapping, lineament analysis, and faulting), analyses of oriented core from the Multi-Well Experiment (e.g. strain relaxation, differential strain analysis, acoustic velocity anisotropy, natural fractures), and computer modeling of expected stresses caused by topographic loads. The mean direction predicted for the maximum horizontal principal stress is N79.6°W. The very small standard deviation about this prediction of 5.5° indicates the extreme consistency among the methods. Similar methods could be utilized in other low permeability reservoirs to determine stress orientation and hence hydraulic fracture propagation direction.
A Method for Selection of Optimum Proppant in the Cotton Valley
Authors: Clark H. C.
Published: December 2007

Numerous laboratory tests on Cotton Valley core samples have been conducted that compare Ottawa sand and sintered bauxite in terms of their ability to perform as a propping agent under varying closure stresses. Computer simulation has also been used as an aid in selecting the optimum proppant type and pack configuration for a given fracture treatment. However, in spite of the information obtained from these sources, there remains some uncertainty as to the value of closure stress at which a high strength proppant should be incorporated into the fracture treatment design.

Data obtained from Cotton Valley wells indicates that the producing rate was significantly reduced beyond the normal decline when a certain closure stress was reached. An examination of offset wells that experienced a lesser closure stress or were fractured with bauxite reveals that this abnormal decline is not present. This comparison indicates the fracture conductivity, and consequently the producing rate, were significantly altered as a result of sand crushing.
A New Approach to Air-Hole Interpretation in the Canyon Sands of Central Texas
Authors: Foret R. P. , Diggons W. F. , Grace L. M.
Published: December 2007

The Canyon Sands of Central Texas have been exploited by air-drilling techniques since the mid-1950's, and the activity level has increased because of tight gas prices and the prospect of eventual deregulation. This paper introduces a new approach to air-hole interpretation which combines old and new techniques and provides additional information for the exploitation of this area.

The Canyon Sands are characterized by low permeabilities, high clay content, and small amounts of water production. Previous methods of evaluation include an FDC* Density/CNL* Neutron log and a Temperature survey.

Advances have been made in establishing an accurate neutron porosity, and the addition of an Induction log has allowed a Three-Perm Coriband* log to be computed. The Audio* log is run in combination with the Induction log to confirm temperature anomalies and to find previously overlooked gas entries.

This suite of logs ensures better treatment and, therefore, greater production. Well stimulation and design are further enhanced by Producibility logs. The overall air-hole package is the most up-to-date wireline method for the interpretation of air-drilled gas wells.
The Relation Between Recovery Deformation and In-Situ Stress Magnitudes
Authors: Blanton T. L.
Published: December 2007

In this paper a theoretical basis is developed for calculating in situ stress magnitudes from recovery deformations measured in rock. The constitutive theory used assumes that the rock is linearly viscoelastic, homogeneous, and non-aging. These assumptions yield explicit integral equations relating strain as a function of time to stress history, which is taken to be instantaneous unloading of the rock. Solutions are obtained for recovery of isotropic and transversely isotropic core in which time-dependent behavior is contained in creep compliance terms and Poisson's ratio terms are constant. The main results for both cases are equations that allow calculation of horizontal principal stresses from vertical stress, principal recovery strains, and material properties that do not depend on time. For the isotropic case, the only material property required is Poisson's ratio. For the transversely isotropic case, two Poisson's ratio terms as well as the ratio of creep compliances are required. This last solution assumes that the vertical stress is parallel to the axis of material property symmetry.
Numerical Solution for Height and Elongated Hydraulic Fractures
Authors: Palmer I. D. , Carroll H. B.
Published: December 2007

Vertical hydraulic fractures, used to enhance the release of natural gas, can reach thousands of feet in length, while extending only a few hundred feet in height. When a payzone is bounded above and below by zones which have a substantially higher minimum in-situ stress, conditions are optimal for restricting a fracture's vertical growth. By theoretically calculating the height and shape of a fracture, our goal is to study how well higher stress zones adjacent to a blanket payzone confine the vertical growth.

Previously we presented a model1 for fracture expansion which assumed an elliptical fracture perimeter. The fracture height was determined by applying at the wellbore a fracture mechanics criterion, involving a critical stress intensity factor. When this criterion is applied to all points of the fracture perimeter, the entire fracture shape may be determined. This is the approach of this paper. As it turned out, the elliptical fracture shape gave a reasonable approximation for height and bottomhole pressure, and the previous model was able to predict, by way of a parameter study, fracture height growth in a variety of likely situations.

The effects of leakoff, previously neglected, are now included.
Microcomputer Models for the Design of Hydraulic Fractures
Authors: Cleary M. P. , Keck R. G. , Mear M. E.
Published: December 2007

This paper describes approximate models which yield credible descriptions of hydraulic fracturing processes and are amenable to calculations on microcomputers. These models provide the basis for both analysis of conventional fracturing treatments and for proposing/designing new procedures suitable to varied reservoir conditions. Satisfying a shortterm need for realistic analysis that offer improved fracture designs, the models also admit considerable upgrading as more detail/realism is described by more complex simulators. The two levels of analysis presented are:

Lumped models, in which the spatial variation is represented by integral coefficients. Although simple enough for use on a microcomputer or programmable calculator, the models are detailed enough to describe geometries varying from long Perkins & Kern-type, through circular shapes, to high CGD (Christianovich et al.)-type fractures. More complex pseudo-three-dimensional (P3DH) models (which require at least a small microcomputer for proper implementation); these divide the 3D problem into coupled sets of equations governing one-dimensional lateral fluid flow and two-dimensional growth of vertical cross sections. A major feature is a refined mesh that moves with the fracture, rather than one fixed to the reservoir; the result is detailed tracing of evolving geometry, pressure distribution and flow throughout the job and after shut-in.

Although not as complex as our full 3D simulations under development, these approximate models contain most important elements governing fracture evolution. They compute such significant design evaluation quantities as length, height, width and pressure variation with specified injection rate (or vica versa). To date, the models have produced many significant results that aid in explaining observed pressure profiles and may, in the future, be used at the wellhead for real-time control of fracturing operations.
A Method for Evaluation of Formation Damage Due to Fracturing Fluids
Authors: Volk L. J. , Gall B. L. , Raible C. J. , Carroll H. B.
Published: December 2007

The extent of formation damage due to invasion of fracturing fluids during the hydraulic fracturing process was studied. An apparatus, which can simulate reservoir conditions, is described for measuring permeability before and after fluids are pumped across the surface of a core. Dynamic fluid loss was also measured of fluid which passes through the core plug.

After the fluid pump schedule was completed, high gas pressure was applied in the reverse direction from fluid leak-off to measure fluid cleanup and the extent of core damage. The system had a wide dynamic range and the measurements have been automated.
Recent Petroleum Mergers and Acquisitions: An Oil Analyst's Perspective
Authors: Petrie T. A.
Published: December 2007

The last several years have seen the most active period of petroleum related merger and acquisitions activity in the several decades since World War II. When the history of the current era is written, an important chapter will address the substantial, de facto restructuring of the petroleum industry which is occurring as a result of recent acquisitions and mergers.

The comments contained herein are based on analysis of some 42 announced proposals and actual transactions in the last five years. In all, these deals represent total market values at the time of announcement of some $36 billion.. By way of comparison, the total energy components now account for approximately 17°Lof the Standard and Poors 400 industrial index and have an aggregate market value of the order of $170 billion.

Breaking these deals down by the nature of the transaction, seven, and nearly all of the very largest deals, represent defenses against hostile or unsolicited offers by third parties, seven are internally or management initiated reorganizations/rationalizations of corporate businesses, another nine or part of the corporate liquidations, and the remaining 20 are outright sales of the entire company.
A New Model for Well Test Data Analysis for Naturally Fractured Reservoirs
Authors: Lai C. H. , Bodvarsson G. S. , Tsang C. F. , Witherspoon P. A.
Published: December 2007

A new model for the analysis of constant rate well test data from naturally fractured reservoirs is presented. The model considers three sets of orthogonal fractures with fluid flow from the fractures to the well and from the rock matrix to the fractures. In comparison to other models for naturally fractured reservoirs the present model allows fully transient fluid flow from the rock matrix to the fractures and a cubic geometry of the matrix blocks.

The model has been used to develop type curves for the analysis of drawdown and build-up tests as well as pressure transient data from observation wells. The reservoir systems considered include an infinite and a finite (no-flow outer boundary) system and a system with a constant pressure outer boundary. The effects of wellbore storage and skin are illustrated. The model is applied to field data to illustrate the method of analysis and the applicability of the model.
Viscosity Stability of Aqueous Polysaccharide Solutions
Authors: Glass J. E. , Soules D. A. , Ahmed H. , Egland-Jongewaard S. K. , Fernando R. H.
Published: December 2007

The viscosity stability of carbohydrate polymers under thermal-oxidative, mechanical and acid-catalyzed hydrolysis is examined and compared with the performance of a synthetic water-soluble polymer, hydrolyzed (30%) poly(acrylamide) (HPAM). Under thermal-oxidative conditions HPAM is the most stable polymer and the carbohydrate polymers prepared by fermentation systhesis (i.e., Xanthan gum (XCPS) or Sclerotium glucanicum polysaccharide, (SGPS) are more stable than non-fermentation polysaccharides (i.e., guar gum, hydroxyethyl cellulose, cellulose sulfate ester, etc.). In acid catalyzed hydrolysis the same differential performance between fermentation and non-fermentation carbohydrate polymers is observed. This difference is correlated with an ability to form helical aggregates which protects the repeating acetal linkage in carbohydrate polymers from oxygen and proton attack. Additives that disrupt hydrogen bonding among pyranose units and therefore disrupt helical aggregate structures in fermentation polymers decrease their solution viscosity stabilities. A molecular weight dependence is not observed under either thermaloxidative or acid catalyzed degradation conditions, but a dependence is observed in mechanical degradation. Lower molecular weight polymers are more stable. For mechanical stability, a rigid-rod conformation is sufficient for stability; some non-fermentation polymers exhibit stability equivalent to fermentation polymers. Less mechanically stable carbohydrate polymer solutions (i.e., hydroxyethyl cellulose, xanthan gum in a 4M urea or SGPS in alkaline solutons) are more stable than conformationally and segmentally flexible synthetic water-soluble polymers (i.e., HPAM or polyethylene oxide).

The influence of oxygen as an antagonist to polymer stability is investigated in the presence of two stabilizing additives, magnesium oxide (MgO) and tetraethylenepentamine (TEPA). In oxygen saturated solutions thickened with non-fermentation carbohydrate polymers, both function effectively, primarily by inhibiting the formation of hydroperoxide groups. In aqueous systems containing oxygen scavengers, MgO is ineffective; TEPA continues to be effective due to its ability to chelate transition metals, modify the scavenger's activity and intercede in the synergistic interaction of these activators with oxygen. The use of either of these additives in field applications can result in well bore problems.
Selection Criteria and Formation of a Surfactant Slug for High-Temperature, Moderate Salinity Reservoir Conditions
Authors: Sharma A. K. , Pithapurwala Y. K. , Shah D. O.
Published: December 2007

The main objective of this investigation was to formulate a surfactant system for a water-flooded reservoir at 80°C and having a salinity in the range of 20-30 gms/liter. The equivalent alkane carbon number (EACN) of the crude oil at 80°C was found to be 9.3 as determined by a comparison of its optimal salinity with those of pure hydrocarbon oils. Isopropyl alcohol, isobutyl alcohol, secondary butyl alcohol and tertiary amyl alcohol (TAA) were employed as cosolvents in this study. The optimal salinity at 80°C of a petroleum sulfonate (TRS10-80), crude oil and any of the above alcohol containing system was found to be less than 1.3%. A phosphated ester (KF AA-270) was used as a cosurfactant with TRS10-80 in the weight ratio of 2/5 which increased the optimal salinity in the range of 25-35 gms/liter. However, the addition of this cosurfactant decreased the solubilization parameters drastically. In order to improve the solubilization of brine and oil in the middle phase microemulsion, inorganic salts such as Na2CO3 and sodium tripolyphosphate were added to the formulation. The partitioning of alcohol in various phases was determined by gas chromatography. It was found that only TAA partitioned in the excess oil phase and middle phase whereas other alcohols partitioned in the middle and excess brine phase. Displacement tests were carried out at 80°C in sandpacks and Berea cores. The tertiary oil recovery efficiency was 92% when 0.2 PV of TAA containing surfactant slug was injected while the tertiary oil recovery efficiency was poor in systems containing other alcohols. It is concluded that the choice of alcohol and its partitioning behavior are important criteria for designing formulations for high temperature reservoir conditions. In the present study, the partitioning of alcohol in the oil phase seems to correlate with greater oil displacement efficiency for the surfactant system studied. It is proposed that the mass transfer of alcohol (TAA) from the aqueous surfactant slug to the oil phase in porous media promotes the oil displacement presumably due to the ultra-low IFT associated with this mass transfer process.

The tertiary oil recovery for surfactant slugs having different alcohols correlated with surfactant breakthrough in the produced fluids. It was observed that the higher surfactant recovery in the produced fluids and a delayed surfactant breakthrough corresponded to a greater oil recovery.
Limiting Conditions for the Use of Hydrolyzed Polyacrylamides in Brines Containing Divalent Ions
Authors: Zaitoun Alain , Potie Brigitte
Published: December 2007

This paper summarizes the main parameters acting on the stability of hydrolyzed polyacrylamides in brines containing divalent ions. For dilute solutions the critical hydrolysis degree τc2+ above which the polymer may be precipitated by Ca ions is τc = 35% at room temperature and 33% at 80°C. For τ < 60% the precipitated polymer redissolves at high CaCl2 or NaCl concentrations. Intrinsic viscosity measurements of the solutions near the precipitation point show a slow decrease in coil expansion and an increase in the Huggins constant as expected near θ conditions. Neither precipitation phenomena nor viscosity can be predicted from the divalent-ion content without taking into account the overall ionic environment.
A Comprehensive Fracture Diagnostics Instrumentation Fielding Program
Authors: Hart C. M. , Engi Dennis , Morris H. E.
Published: December 2007

Economic development of low permeability gas reservoirs often necessitates the use of massive hydraulic fracturing. Assessment of the effectiveness of the induced fracture requires knowledge of the dimensions, orientation, and spatial characteristics of thefrac-ture in relation to the gas-bearing formation. |A comprehensive characterization of fracture propagation not only aids in fracture treat?ment design for the reservoir, but can also help specify well spacings which will minimize interference of drainage patterns and thus maximize economic-recovery potential.

This paper presents an approach to the development of a comprehensive fracture diagnostics program. The fracture diagnostics subprogram for the Multi-Well Stimulation Experiment I is discussedin detail, including fielding descriptions and operational pro?cedures. Synopses of measurement techniques are given with emphasison the fracture parameters one would expect to estimate from the individual instrumentation systems.
Microscopic Analysis of Dry Cement Blends
Authors: Reeves N. K. , Bailey D. E. , Caveny W. J.
Published: December 2007

With the use of a microscope equipped with polarization and fluorescence, and simple laboratory techniques, the presence of and/or contamination by cementing additives can be confirmed in field-blended cementing compositions. The initial learning process involved in this procedure is observing and learning the appearance of neat cements and the various additives using plain, polarized and fluorescence light microscopy. When individual characteristics such as color, sixe, shape and texture of each additive are noted, these can easily and euickly be qualitated when viewed under the microscope, whether they are present as the only additive in a blend or with various other additives.
Continuous Cleanup of Oilfield Waste in an Environmentally Acceptable Manner
Authors: Wally R. F. , Dowdy S. A.
Published: December 2007

After several years of research and field testing, a process has been developed which can economically treat reserve pit waste. This continuous process converts the reserve pit contents into two environmentally acceptable products: a relatively dry, non-leachable cake-like solid material, and water which is purified for recycle or release directly into the environment.
A Comparative Analysis of Reactivities of Commercial Iron and Zinc Compounds Used in the Removal of H2S From Drilling Fluids
Authors: Evers J. F. , Olson G. A.
Published: December 2007

Five commercial H2S scavengers for drilling fluids were experimentally tested for scavenging ability under various conditions of pH, pressure and temperature. These consisted of both iron and zinc based compounds. Conditions were: pressures of 500 psi, 1000 psi, and 1500 psi, temperatures of 100°F and 200°F, and pH of 6.4 and 12.0.

The zinc reactions were quick, predictable, and irreversible under normal well conditions. The iron scavenger had somewhat higher reactivity (gm H2S/gm scavenger) than most zinc scavengers when tested at pH 12, and much higher reactivities when tested at a pH of approximately 6.5.
Estimation of Distance to a Slanted Flow Barrier From Pressure Transient Test Data
Authors: Azari Mehdi , Ershaghi Iraj
Published: December 2007

The analytical solution of the wellbore pressure in a reservoir which is located near a slanted fault were derived using the method of images and by applying the principle of superposition to the Kelvin's point source solution. The solutions show that the inclination of the flow barrier causes additional pressure drop beyond what is usually considered in the concept of a single mirror image well. The extra pressure drop causes gradual changes on the slope of semi-log plots of pressure versus time. In many cases the behavior resembles that of wells in completely bounded systems. Using the general solution presented in graphical forms, one may estimate the distance to the fault.
Evaluation of the Use of High-Strength Crosslinked Hydrochloric Acid System for Mission Canyon Stimulation: SEM/EDS Analysis
Authors: McLane J. E. , Scott M. A.
Published: December 2007

Core samples examined from the Mission Canyon Formation, McKenzie County, North Dakota were subjected to Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS) analysis. The interval of the core samples studied from well "A" were 9122–9125 feet, 9140–9143 feet and 9171–9174 feet. Those samples studied from well "B" were taken from intervals 9471–9474 feet and 9556–9559 feet. This preliminary study was carried out to evaluate the Mission Canyon formation for a successful stimulation treatment.

The Mission Canyon formation is predominantly fractured dense carbonate of the lower middle Mississippian and a member of the Madison group, see fig. 1. Problems have been encountered in stimulating the Mission Canyon due to a variety of factors. Out of many, a few important ones are the release of fines and their migration due to acid reaction, the presence of clay minerals and the availability of various other acid insoluable mineral assemblages.

A limited number of Mission Canyon cores were available for this study. This paper will discuss the in depth SEM/EDS analysis. Information is now available to aid in the selection of a more effective system to stimulate the Mission Canyon Formation. The effectiveness of a high strength, crosslinked hydrochloric acid system in various counties namely, Billings, Williams and McKenzie in North Dakota has been studied. Scrutiny of the crosslinked acid jobs pumped indicates that small volume jobs (1000-5000 gallons) in the Dickinson area using high strength (15%–20%) crosslinked hydrochloric acid at low rates, (4 to 8 barrels per minute) have been more successful, wheras large volume jobs have not produced encouraging results.

This paper will provide insight for optimizing acidizing systems that suspends fines and prevents their migration thus making stimulation in the Mission Canyon Formation more successful.
Rate Gyro Surveying of Wellbores in the Rocky Mountains
Authors: Wright John
Published: December 2007

The introduction of a rate gyro surveying system was made in the Rocky Mountain area in April 1982. This paper describes that system as well as its accuracy and durability.

It appears there has been a significant increase in accuracy and durability, with a decrease in survey time over conventional free gyro systems. This assessment is made from data accumulated over 100 field surveys, many runs in a 1400 foot test well and hundreds of hours on a laboratory test stand.

The Eastman Whipstock rate gyro system employs a single floated rate integrating gyroscope gimbled with a single precision accelerometer. This configuration is rotated about the tool axis 360° for every survey measurement. From this rotation the gyro measures a component of the earths horizontal spin vector, which by definition points true north, and the accelerometer measures a component of the earths gravity. The information is then processed to provide inclination, borehole azimuth and tool face. This method provides increased accuracy by producing readings which are independent of those taken previously and by eliminating C-independent sensor bias. Additionally this configuration allows a pressure barrel outside diameter of only 1 3/4″ (45.0mm).
The Application of Mud Motors for Surface Hole Drilling
Authors: Foret Gary , Kerr Jim
Published: December 2007

Mud motor drilling with mill-tooth or insert-type bits in the surface upper hole can often result in increased rates of penetration and less hole deviation -- two factors that can often mean cost savings to the operator.

Most people associate mud motors with two different types of drilling -- controlled directional and long-interval straight-hole drilling. Using mud motors is now the norm rather than the exception in drilling a directional section, and in the last five years, mud motors, when used with diamond or PCD type bits, have gained wide acceptance in many long-interval drilling applications. The reasons for the increased use of mud motors in straight-hole drilling are higher rates of penetration (ROP) than traditional methods, less hole deviation, and much improved tool performance, resulting in savings for the operator.

Recent case histories in the Rocky Mountain Region show that these same reasons apply to a section of the hole not often associated with mud motors, but nevertheless where mud motors are now providing a viable alternative to rotary drilling -- the surface or upper hole. Drilling a large (12¼″, 17½″, 26″) surface hole with a mud motor and mill-tooth or insert-type bits can, in many cases, 1) increase ROP, and 2) maintain a straighter upper hole which helps minimize subsequent problems as the hole depth increases. In some cases, rates of penetration have been improved even when drilling single pass large diameter hole, thus also eliminating the need for hole opening operations, and adding to cost savings.
Positive Displacement Downhole Motors and Diamond Compact Bits Reduce Drilling Costs in Overthrust Wells
Authors: Wood J. E.
Published: December 2007

Recent technological advancements made in synthetic diamond bits, coupled with positive displacement downhole mud motor technology now enable operators to use these two products and technologies in deep overthrust wells to reach total depth in fewer days at lower cost per foot.

Straight-hole drilling programs using high speed, low torque motors and synthetic/natural diamond bits have been economically utilized in a number and variety of well types in the Overthrust belt.
One-Dimensional Modeling of Steam Injection in Tar Sands
Authors: Chen C. S. , Hutchinson H. L.
Published: December 2007

A one-dimensional numerical model of steam injection was developed and used to simulate experimental steam and hot water injection in the Asphalt Ridge Tar Sands. The model described a three-phase flow system of water, steam and oil with interphase mass transfer of water. The mass and energy balance equations were solved simultaneously by a semi-implicit Sequential Solution method.

The results of the linear numerical simulator showed moderate agreement with the observed results from the steam and hot water injection experiments. The simulator predicted that (1) changes in relative permeability, thermal expansion coefficient of oil and oil viscosity are important factors affecting oil recovery from tar sands; (2) the oil response time is decreased with increasing steam injection rate and quality, and is decreased by reducing steam injection temperature.
Compressed Air and Foam, Cleanout Technique for Old Open Hole Completions
Authors: Dahlgaard C. C.
Published: December 2007

Compressed air and drilling foam is being used successfully in circulating out mud, grit, cavings and spent acid from shallow(1700 ft.) open hole completions in the Kevin-Sunburst Field. Many of the wells cleaned out have shot holes and low bottom hole pressures. The technique is cost effective and usually prevents cleanout induced formation damage.
Procedures To Improve Pre-Frac Well Testing and Analysis
Authors: Branagan Paul , Cotner Gene
Published: December 2007

This paper presents the results of a study designed to determine well testing procedures required to overcome the effects of formation damage from drilling, completion and other fluids in order to permit the derivation of realistic values of original formation permeability. A variety of possible drilling, completion and well testing conditions was modeled using a numerical multiphase reservoir simulator. Results indicate the possible lengths of the tests that may be required for various expected permeability ranges and how to allocate drawdown to buildup time for a fixed testing time to optimize results.
High-Volume Electrical Submersible Pumping in the Sulphate-Scaling Environment of the Piper Field
Authors: Macdonald B A , Engwall S J
Published: December 2007

Electrical Submersible pumping is currently one of only three artificial-lift methods practicable in the North Sea production environment. The pump installations from multi-well platforms involve operating deep-set units in highly deviated wells with high rates of oil and water production. The majority of the fields in the North Sea employ deaerated seawater injection as a means of reservoir-pressure support. The resultant breakthrough of injection water in the producing well creates an environment for potential scale formation.

This paper presents the original design concepts and experience gained from the initial installation in Piper field well PO7. The use of a soft-start facility and the scale-inhibitor squeeze technique to extend pump life is discussed and conclusions drawn for future installations, which will total 12 units by 1986.
Small-Diameter Inertial-Grade Sensors Significantly Enhance Wellbore Survey Accuracy
Authors: Morgan D G , Uttecht G W
Published: December 2007

Tests with a new directional-survey instrument show a significant enhancement in the accuracy of defining a wellbore trajectory. Several prototype systems developed over the previous two years by Gyrodata Inc., in conjunction with Incosym Inc., a developer of guidance systems and components for the aerospace industry, have successfully undergone tests in the laboratory and in the field. The testing period, which included both land and offshore operations, indicates that the original design objective for borehole position uncertainty less than 1.7 feet per 1,000 feet of hole has been met. Although prototype development has been completed to the extent that criteria for manufacturing have been established, an ongoing testing programme is in effect to verify field accuracies and system application in a wider range.

The Gyrodata Wellbore Surveyor employs an inertial grade-rate gyro adapted from the aerospace industry. In combination with its other sensors and electronics, the device can sense the orientation of the earth's spin vector at each independent survey station. As a result, the major systematic errors associated with conventional gyros-geographical reference and unaccountable drift - are eliminated. Other sources of inaccuracy are minimized by the system's measuring techniques and operational procedures, and additional benefits arise from faster survey speed and increased reliability. A true north reference device can also employ a small outside diameter since it requires only one gyro and one accelerometer.
Test Installation of Subsea Production System and Flowlines in Deep Water
Authors: Madsen T , Andersen S , Vetaas L
Published: December 2007

PREFACE

The subject for discussion in this paper is the marine operations as they were performed during the research project:

CIB – DIVERLESS INSTALLATION AND MAINTENANCE OF SUBSEA PRODUCTION SYSTEMS IN DEEP WATER

The project commenced in January, 1981, with participation of six oil companies: AGIP, Chevron, Fina, Hispanoil, Norsk Hydro, and Total.

A single-well Subsea Production System (SPS) was installed in 300m of water depth for test purposes in the Onarheimsfjord on the west coast of Norway in the autumn of 1982. Two different ways of connecting flowlines to the SPS were tested; a remote off-bottom pull-in operation featuring the "J"-method.

All operations were performed diverless, a remotely operated observation vehicle (ROV) and an Atmospheric Diving Suit (ADS) beingused for general assistance and back-up.

In order to optimise the operations, extensive analyses had been performed on the equipment and on the operational plan. These analyses included a failure mode and effect analysis (FMEA) on equipment and operations in general as well as computer simulations of the flow line operations.

The objective of the test was to gain experience related to operations in deep water, state limitations in today's level of technology.

The paper gives a review of the test and planning phase. The problems related to deep waters are pin-pointed, and some results are given.
Flexible Dynamic Riser for Floating Production Facility in The North Sea
Authors: Pettenati C , Dumay J M
Published: December 2007

For several fundamental reasons such as growing economical constraints, decreasing size of discoveries, deeper-water exploration, improvement of subsea technology, the trend for future offshore developments has recently been very much in favour of the floating-production facility concept.

This type of development has been for several years successfully implemented in various parts of the world where weather conditions are favourable, for both early-and permanent-production applications (Brazil, Mediterranean Sea etc….).

So far in a more hostile environment such as the North Sea, only two producing fields have been developed using this approach : Argyll (1975), Buchan (1980).
A Case History of Polycrystalline Diamond Compact Bit Performance in the Tuscaloosa Trend
Authors: Moore S. O. , Lynch B. W. , Talbot K. J.
Published: December 2007

This case history documents the performance of Polycrystalline Diamond Compact (PDC) bits relative to conventional roller cone and natural diamond bits in drilling a deep (14,500 ft – 18,000 ft) shale-chalk sequence in 65 wells in the Tuscaloosa Trend of South Louisiana. PDC bits were used on rotary for drilling this sequence with varying degrees of success in conjunction with four different drilling programs. Included are discussions on variables which affected the performance of the PDC bits studied. Data presented originates from company bit records and photographs compiled during normal field operations.
Effect of Pattern Configuration on Oil Recovery by In-Situ Combustion
Authors: Huang Kuo-Lon , Aziz Khalid
Published: December 2007

A numerical investigation of the effect of pattern configuration on oil recovery by in situ combustion is presented. The patterns considered were inverted 5, 7, 9 and 13 spot. The data used for the base case were typical of the Athabasca area of Alberta, Canada. The sensitivity results are presented for changes in well density, pay thickness, initial oil saturation, oil viscosity, absolute permeability, water-oil ratio and air injectivity. All results are compared at the time of steam breakthrough.

The numerical results presented in this paper show that hexagonal (7 and 13 spot) patterns perform better than square (5 and 9 spot) patterns for most situations. As the oil mobility is reduced, the relative performance of square patterns tends to improve.

The results presented should be of value in the design of in situ combustion projects.
In-Situ Combustion Pilot Operations in the Wabasca Heavy Oil Sands Deposit of North Central Alberta, Canada
Authors: Alderman J. H. , Fox R. L. , Antonation R. G.
Published: December 2007

General American Oils, Ltd. conducted a wet institu combustion pilot in the Wabiskaw Formation of the Wabasca Heavy Oil Sands Deposit from February, 1981 until February, 1983. The purpose of this test was to assist in determining if this process would be economically feasible in the Wabiskaw Formation.

A single 20 acre (8.09 hectare) inverted seven spot was chosen as the pattern for the pilot. The operational concept was that the producing wells would be cyclic steamed to stimulate them at the same time that the wet insitu combustion process was being conducted. To monitor the movement of the combustion front, a series of 3-D seismic surveys were scheduled. The initial survey was conducted prior to air injection and was used as a reference to compare to the surveys conducted after ignition of the pilot.

The pilot performance using cyclic steam and wet insitu combustion as well as the results of the 3-D seismic monitoring are discussed in this paper. The well completions and surface facilities design as well as operational concepts to allow year round operation in a muskeg environment are also discussed.

Additional information was also gathered on the rock and fluid properties of the Wabiskaw. Even though the project was terminated after two years of the planned five year program because of the poor performance exhibited using air injection, the information gathered will help in the design of future Wabiskaw pilots.
Well Test Interpretation in Heterogeneous Reservoirs With Skin and Afterflow: Some New Theoretical Solutions and General Field Experience
Authors: Niko Helmut
Published: December 2007

Some new analytical solutions for dimensionless pressure vs. dimensionless time are presented. It is deomonstrated how these new solutions, together with existing ones, can be used for unravelling reservoir heterogeneity patterns, quantitative interpretation of selected field tests, and well test design. The field tests cover both naturally fractured carbonates and layered sandstones.

Two examples of well test interpretation in naturally fractured formations reinforce the conclusions of other authors, namely that well test interpretation based only on 2 parallel semi-log straight lines is questionable in cases with afterflow.

The new analytical solutions refer to stratified and heterogeneous systems with interlayer cross-flow. In both cases after-flow and skin factor are included. It is shown how the type curve can be used in certain long pressure build-ups to gain information on the average reservoir pressure in a stratified system. In the pressure behaviour of a heterogeneous system with interlayer cross-flow, there is often quite a long transition zone before the system behaves like a single reservoir. This requires careful planning of test duration. In particular, the early part of the transition zone, looked at in isolation, may give a false impression of pressure stabilisation, which could lead to the interpretation of small drainage areas or a gross over-estimation of the system permeability.
Porosity Reduction in Sandstone
Authors: Dibble W. E. , Nur Amos , Potter J. M.
Published: December 2007

Porosity reduction in siliceous sedimentary rocks is worthy of detailed study because the processes involved control the final porosity and permeability observed in all oil and gas reservoirs. In addition, porosity reduction and petroleum generation and migration may also be related.

The effects on porosity reduction of the major porosity-controlling variables are virtually unknown and have been the subject of new experimental studies. Cores of St. Peter Sandstone have been subjected to high effective stress at room temperature and with fluid flow occurring at various rates. Relatively rapid pressure solution occurs even at room temperature in a flowing system.