bluuebunny/crossref_metadata_2025 huggingface dataset:
Appraising Feasibility of Tertiary Recovery with Carbon Dioxide
Authors: Kelm C. H.
Published: December 2007

Amoco Production Company has been and is continuing to investigate the potential for recovering tertiary oil by CO2 flooding. Tonight I will discuss a method for appraising the feasibility of tertiary recovery with carbon dioxide.

This method was applied initially to the evaluation of eleven Amoco operated properties in seven fields in the Permian Basin. These projects, which are currently being waterflooded, encompass 2300 producers and 1600 injectors. In addition, several other properties are currently being evaluated using this same approach.

In the evaluation of a plan of depletion, the basic components necessary for determining economics are estimated costs and predicted performance. Accurate estimates of these two parameters are especially critical in appraising tertiary recovery with CO2 because of high initial costs, extremely high operating costs, and the long lead times required for flood implementation. Compounding the risk associated with it being a high cost project, CO2 tertiary flooding is a complex process. For example, waterflooding was a "forgiving" process. If water breakthrough occurred prematurely, we handled it fairly simply. But with CO2 it may be a different story and to top it off, CO2 tertiary flooding a waterflood project may prove detrimental to waterflood performance should the tertiary flood be unsuccessful.
The Impact of Measurement Error on Deliverability Projections for Tight Gas Wells
Authors: Hale Brent W. , Mahmood Alice M.
Published: December 2007

Many papers have been written attempting to describe the basic parameters of a tight gas reservoir. Normally, a reservoir is described using a combination of geological and transient pressure data. This paper does not propose specific methods for measuring or for interpreting the required data. It relates parameters measured by initial well tests to long term deliverability projections.

Partly because data is subject to error, various interpretations can result. This paper discusses the impact of measurement error on deliverability projections for tight gas wells. It relates measurement error to long term interpretation error so that long term interpretation error can be minimized.
Uinta Basin Lenticular Sandstone Reservoir Characteristics
Authors: Boardman Charles R. , Knutson Carroll F.
Published: December 2007

Previous analysis of production curves, from tight gas sand wells in the Uinta Basin of Utah, identified three types of performance - linear, intermediate and near radial. Six wells were selected, covering this distribution, and an attempt was made to determine dynamic reservoir gas volumes, and to compare these "production" volumes with volumes calculated from several different lenticular sand models.

Volumes of the 29 tight gas sandstones present in these six wells were approximated by using long term pressure buildups to calculate present pressures (and permeabilities). Then reservoir volumes were calculated using p/z vs cumulative production plots extrapolated to zero pressure. The average reservoir volume is interpreted to be about 240,000 cubic feet per foot of net pay.

The "production" volumes are compared with the equivalent calculated volumes using four different modeling techniques.

Reservoir Volume, 106 cu ft. Sum of All Wells Well C Production Volume 75.3 10.8 Knutson Model Volume 60.7 – Knutson/Ward Model Volume 86.0 – Baker Model Volume 10.6 Gidley et al Model Volume 136.1 –

The Knutson/Ward and Baker models seem to provide the best approximation of the "production" data. This approximation may have been better if a more sophisticated pressure buildup analysis had been used.

Apparent reservoir permeabilities, assuming radial flow, range from .009 to .052 millidarcies and actual sandstone matrix permeabilities are interpreted to range from .06 to .21 millidarcies.
The Operational Excellence Roadmap: A Tool for Implementing Operational Excellence in Major Capital Projects
Authors: Dehmer S.
Published: December 2007

To achieve world-class performance, major capital projects must successfully implement Operational Excellence (OE): the systematic management of safety, health, environment, reliability, and efficiency. When compared to operations, implementation of OE in capital projects provides unique challenges because it will vary depending upon the project phase (e.g., design, construction, etc.). A special tool, the OE Roadmap, was developed to assist projects in addressing these implementation challenges.
Determination of Fluid Corrected Porosity in Tight Gas Sands and in Formations Exhibiting Shallow Invasion Profiles
Authors: Kukal Gerald C.
Published: December 2007

Log-core correlations from four Upper Cretaceous wells in Rocky Mountain basins demonstrate that the axiom "high porosity - shallow invasion, low porosity - deep invasion" is not valid in tight gas sands. The data suggests that the zone of flushing is typically much shallower than the density tool depth of investigation. This results in too high density interpreted porosity in low permeability gas sands. The discrepancy is generally 3-4% porosity in gas sands having 8-12% porosity as determined from core analysis.

Rigorous log quality control was maintained in the field. This included monitoring of the before and after density calibration record, multiple repeat runs over the cored intervals, slow logging speed, monitoring of tool stability, and digital logging. Whole core Boyle's Law helium porosity and grain density measurements were made on every foot of potential reservoir sand. Core measurements are depth shifted to log data using a combination of core gamma, lithologic description, and a plotted core data overlay. A crossplot of core porosity versus density log calculated porosity is presented for each well. Log calculated porosities are based upon bulk density, the grain density value of each correlated core measurement, and the customary assumed fluid density of 1.00 g/cc.

By combining plots of all four wells, a non-linear trend is established for conversion of apparent density porosity to true porosity. The trend has the characteristic of closure to unity for the higher and very low porosity values, with greatest divergence from unity in the middle porosity range. Formations having higher water saturations show less divergence in the middle porosity range.

An iterative mathematical model is developed for calculation of "Sxo" and effective porosity. The "Sxo" is actually the average water saturation of the zone investigated by the PGTK density tool and the CNTA thermal neutron tool. This system provides more reliable porosities and may have application as an indicator of potential formation producibility. The technique also has application in other shallow-invasion type borehole environments, e.g., air-gas drilled holes, oil base systems, and underbalanced drilling systems.
Driving the Standards Along the Nile
Authors: Refaat H. , Elassar C. , Othman A. , Mourad S. , Hammouda M. , Nabil K. , Nosseir M. , McJarrow S. , El Kordy W. , El Khatib H. , Farouk K. , Nassar M.
Published: December 2007

Egypt has the highest Road Fatality Rate worldwide. Roads claim at least 50% of the lives lost in the Petroleum Industry. During 2004, an initiative was set up to develop a cross industry committee. The aim was to create a strong, collaborative approach on Road Safety across our companies, the wider industry as well as the in community. The objectives were to:

Raise awareness of progress and share lessons learned in monthly meetings. Adopt common industry standards. Influence contractors to adopt safer standards and improved performance. Influence local communities. Influence the issue on a National scale.

Membership has grown to 11 companies including key industry majors plus Joint Ventures. Working groups set out to develop detailed plans in 3 areas:
Impact of High Salinity of Produced Water on the Technical Feasibility of Biotreatment for E&P Onshore Applications
Authors: Baldoni-Andrey P. , Lesage N. , Segues B. , Pedenaud P. , Dehaene P. L.
Published: December 2007

Hydrocarbon production generates aqueous effluents that may contain traces of either hydrocarbon or chemical products, which have to be eliminated according to regulations and to the operator's policy, to reduce the potential impact of their discharge on the environment. These waters could also contain a large amount of salt. The aim of this work is to evaluate the feasibility of the biotreatment of saline (200 g/L TDS) produced water. A Sequencing Batch Reactor (SBR), a trickling filter and a chemostat reactor were compared in terms of total organic carbon (TOC) removal. Results pointed out the biodegradability of the produced water containing high concentration of salt. However continuous operation with SBR could lead to a loss of biomass. TOC removal in the SBR is higher than in trickling filter or chemostat reactor.
A Variational Approach to the Prediction of the Three-Dimensional Geometry of Hydraulic Fractures
Authors: Clifton Rodney J. , Abou-Sayed Ahmed S.
Published: December 2007

A computational method is outlined for modeling the three-dimensional development of hydraulic fractures due to the injection of a non-Newtonian fluid at the well bore. The rock formation is modeled as an infinite, homogeneous, isotropic, clastic solid with in situ stresses that vary with depth. This three-dimensional problem is made two-dimensional by reducing the elasticity problem to an integral equation that relates pressure on the crack faces to crack openings and by neglecting the component of the fluid velocity in the direction perpendicular to the fracture plane. Variational principles are used to derive the discrete form of the governing equations that are used for the computations. Preliminary computations indicate that the essential features of the approach are suitable for use in a numerical method for predicting the three-dimensional geometry of an advancing crack.
Characteristic Behavior of Finite Radial and Linear Gas Flow Systems - Constant Terminal Pressure Case
Authors: Carter Robert D.
Published: December 2007

Gas well rate-time behavior under constant terminal pressure conditions, which is influenced by reservoir boundaries, is treated. It is shown that the variation of the quantity μ(p)cg(p) over the range of average reservoir pressure traversed during depletion influences the rate behavior. Numerical solution results are given in the form of log-log type curves and representative semilog decline curves. It is further shown that the solution for constant pc is a limiting case which may often be used to approximate rate-time behavior adequately during the transient stage of producing history, but which may only be appropriate for late time behavior when the pressure range traversed is suitably small. Results are presented for both real and ideal gas cases and are expressed in terms of a correlation parameter related to the pressure range traversed. The conditions under which this parameter may be used as an exact correlator and those under which it may be used as an approximate correlator are stated. Liquid and rock compressibility effects and turbulent flow are ignored.
Cementing of an Offshore Disposal Well Using a Novel Sealant That Withstands Pressure and Temperature Cycles
Authors: Pedersen R. O. , Scheie A. , Johnson C. , Hoyos J. C. , Therond E. , Khatri D. K.
Published: December 2007

A dedicated injector well, located in the Grane field in the Norwegian North Sea, was chosen as a candidate for application of a novel new sealant. The injector well, drilled for disposal of cuttings and produced water, was selected because of expected temperature and pressure cycling during the injection operation, and the risk of cement sheath integrity failure. This paper will discuss the design, execution, and evaluation of this injector well.

Stress modeling indicated that as wellbore temperature decreased from bottomhole static to injection temperature and as bottomhole pressure cycled between static and dynamic conditions, conventional cement would fail in tension and create a microannulus. In view of these challenges, a redesigned the cement program, which incorporated stress analysis calculations and mechanical-properties testing provided a sealant material that would resist failure due to excessive wellbore stresses. The redesign required three steps;. Firstly, it was necessary to calculate temperature and pressure variations expected in the wellbore during injection. Next, temperature and pressure variations in the wellbore were evaluated using numerical analysis. Finally, a sealant was engineered so that its integrity would be maintained when exposed to repeated temperature and pressure cycles. The chosen sealant material incorporated flexible and expanding materials within an optimized particle size distribution blend. The sealant's mechanical properties were engineered in line with expected stresses to minimize the Young's modulus and improve bonding properties.

The cuttings-disposal injector well was drilled, cased, and cemented using the new sealant material. Since placement, the well has been logged with sonic and ultrasonic tools and these data indicated an excellent bonding response. The well has now been used as an injector for more than two years with no indication of fluid communication in the annulus or loss of cement sheath integrity.

Significantly, since this first application, which incorporated the successful of modeling of the expected stresses and the engineering of a sealant to manage these stresses, further injector wells have been cemented utilizing the same engineering approach.
Hole Cleaning During UBD in Horizontal and Inclined Wellbore
Authors: Zhou L.
Published: December 2007

This paper is an extended work of SPE 90038. Aerated non-Newtonian flow and inclined wellbore section were added to the previous model to study hole cleaning problem while drilling underbalanced well. This new mechanistic model for cuttings transport is developed by combining two-phase hydraulic equations, turbulent boundary layer theory and particle transport mechanism. It is shown that the model is useful for predicting minimum annular velocity and cuttings bed thickness in horizontal and inclined wellbore geometry. Effects of temperature, bottom hole pressure, liquid flow rate, gas injection rate, cuttings size and density, inclination angle and Rheological properties of drilling mud on hole cleaning are analyzed using this mechanistic model. Model is validated by available experimental data. Computer simulation indicates that cuttings bed thickness is very sensitive to the liquid phase flow rate. It dominates cuttings transport efficiency. However, during underbalanced drilling, increase of liquid phase fraction may not always be feasible while trying to keep low ECD. Meanwhile, injection of gas has positive effects on cuttings transportation depending on the flow patterns and drilling mud viscosity. Elevated temperature causes a significant increase of bed thickness and it is important to recognize this negative effect, especially when drilling HTHP wells. The effect of pressure on cuttings concentration is negative. Larger size and heavier cuttings make hole cleaning more difficult and require higher pump rate for low viscosity fluids. Increases of liquid phase density results in better hole cleaning. The range of hole angles from about 35 – 60 deg (from vertical) is the most difficult for cuttings transport. Frictional pressure losses in a deviated wellbore highly depend on cutting bed thickness. Simulation results are compared to available experiment data and show good agreement. In summary, this paper presents a model which is useful for practical hole cleaning during UBD.
World-Record ERD Well Drilled from a Floating Installation in the North Sea
Authors: Hjelle A. , Teige T. G. , Rolfsen K. , Hanken K. J. , Hernes S. , Huelvan Y.
Published: December 2007

The well 34/8-A-6 AHT2 was drilled from the Visund Field Floating Production and Drilling Unit (FPDU) in the North Sea, and set on production in October 2005. The well was drilled to 9082 m/29796 ft measured depth and has an Along Hole Depth (AHD) reach of 7593 m/24911 ft, which is a world record for Extended Reach Drilling (ERD) from a floating installation.

The 34/8-A-6 AHT2 is also the longest Down hole Instrumentation and Control System (DIACS) installation worldwide, with the lower isolation packer set at 8560 m / 28084 ft measured depth. The well includes three hydraulically operated flow valves, which are used as down hole chokes to optimize the production from the separate zones in the reservoir.

Subsea developments in combination with ERD wells can increase oil production and lower total development cost. The drilling progress was 108 m/day from seabed to total depth, according to the Rushmore drilling performance definition, and the payback time for this well was less than two months. Experiences gained on this well indicate that even longer wells can be drilled from subsea locations in the near future.
A Steamflood Experiment in a Utah Tar Sand
Authors: Johnson Lyle A. , Fahy L. John , Romanowski Leo J.
Published: December 2007

The first Laramie Energy Technology Center steamflood experiment in a Utah Tar Sand, LETC TS-1S, was conducted in the Northwest Asphalt Ridge deposit located near Vernal, Utah. Following completion of construction in April 1980, steam injection was initiated in the center well of two concentric inverted five spot patterns. The zone chosen for the experiment was a 45 foot (14 m) thick sandstone in the Rimrock Member of the Mesaverde Formation. The pattern area was 0.25 acres (1012 m2) and contained a 12% API (986 kg/m3) bitumen with a viscosity greater than 106 centipoise (103 Pa.s) at reservoir conditions. The average oil saturation was 78.9 percent of the pore volume. During the 160 days of operation, 65,700 barrels (10.4 dam3) of water equivalent steam were injected at 360 to 530 psig (2.5 to 3.7 MPa) and 180 to 650 BPD (29 to 103 m3/d). Total production during the test amounted to 1,150 barrels (183 m3) of oil and 6,250 barrels (994 m3) of water.
New Storage Phenomena in High Drawdown Gas Well Buildup
Authors: Fligelman Haim , Cinco-Ley H. , Ramey H. J.
Published: December 2007

Strange behavior has been noticed in pressure buildup curves for gas wells producing from very low permeability, high drawdown formations. The typical unit slope on a log-log graph of real gas pseudopressure m(p) vs time for wellbore storage-dominated data becomes very steep (greater than unity) before going through a transition to the semilog straight line. A study of this behavior was made by means of a one-dimensional radial mathematical model wherein wellbore storage is treated rigorously. It was detected that buildup cases characterized by moderate to high pressure drawdown before shut-in always exhibit a shift of the conventional log-log graph to a larger value of the dimensionless wellbore storage constant, compared to the liquid solution. The typical unit slope in the wellbore storage control period is still preserved, and after that period, the buildup curve coincides smoothly with the constant physical properties liquid case. In extreme pressure drawdown cases, in addition, a more significant shift is also followed by a steepening towards the liquid solution.
Drawdown Testing for High Velocity Gas Flow
Authors: Fligelman Haim , Cinco-Ley Heber , Ramey Henry J.
Published: December 2007

As the slope and intercept of the conventional semilog graphing are sensitive to gas and well properties, the calculation of conductivity and skin effect for cases of high velocity flowrate can yield erroneous results.

A sensitivity analysis of the transient response of a well located in an infinite medium while a non-Darcy flow caused by high fluid velocity is presented. A rigorous material balance on the wellbore is included.

The analysis of simulated drawdown tests produced several important conclusions. Gas and formation properties such as gas gravity, initial pressure, temperature, and permeability can lead to significant errors if not considered correctly. The rate-dependent pseudoskin factor is not simply an additive term as are the other skin factor components. The radius of invasion of the damaged region around the well remains a significant factor ëven for long times in cases where turbulence is considered. The effect of high velocity is more pronounced in a production case than in an equivalent injection case, and the slope of the conventional semilog straight line may be greater (production) or less (injection) than 1.151. Although wellbore storage was handled in a rigorous manner, for high pressure drawdown cases the shape of log-log drawdown curves of mD(1,tD) vs tD are similar to the liquid log-log graphs. Thus log-log type-curve matching can be a useful technique for detecting the beginning of the semilog straight line. New correlating groups which consider a variety of possible conditions were found. A correction procedure for analyzing drawdown tests when data for only one flowrate are available is suggested.
Recovery of CO2 from Flue Gas for Enhanced Oil Recovery
Authors: Sears John T. , Waltermire Debbie M. , Marcus Steven R.
Published: December 2007

The present study was initiated to investigate the problems associated with recovery of CO2 from flue gases for enhanced oil recovery. In particular, MEA and activated K2CO3 absorbing solutions were evaluated.

In MEA, amine sulfite and amine sulfate are the dominant impurities formed with minor amounts of higher thiosulfates and oxidized amines. In activated potassium carbonate solutions, only sulfites and sulfates ions were found, without higher oxidation products. The absorption rate of CO2 in these solutions decreases with increasing loading of CO2 in almost a linear fashion. The absorption coefficients obtained were linear with respect to active uncombined solution species, in agreement with theory of chemical-reaction control at low CO2 partial pressures. The coefficients ranged from 50 × 10−5 lb mole/ft2-sec for 20% MEA to 2 × 10−5 for 9% K2CO3 (8% K2SO4, 0.9% MEA) at zero CO2 loadings. It was found that addition of EAE rather than MEA as an activator increased the absorption rate by a factor of 2-4. At high CO2 loadings, the absorption rate of EAE-activated potassium carbonate and MEA have almost the same values.

Alternative absorption systems were analyzed in a preliminary cost evaluation. It is recommended that a K2CO3 (EAE activated) solution be the process of choice. The impurity level in the recovered CO2 was estimated to be ≤ 100 ppm non-condensible gases, 20-200 ppm SO2, and < 20 ppm NOX. There is little cost differential between an amine process and a K2CO3 process; the final decision should be based on operating experience, operating ease, and corrosion problem minimization. The estimated cost of recovery was 0.88ȼ/MCF CO2 (available at 1 atm. pressure) for extraction from a large stream of flue gas.
Implementation of Smart Solutions in the Persian Gulf: Optimized Drilling and Completion in South Pars 6–8
Authors: Johannessen B. , Teigen A. S. , Vestvik J.
Published: December 2007

This paper will cover the drilling and completion optimizations implemented in the South Pars field, which has resulted in more than two years of saved rig time compared to the budgeted time.

Improvements introduced to the drilling process and the technologies and equipment utilized to achieve the success will be discussed, as well as the decision to change the "standard South Pars completion solution" commonly used by all other operators in the same field.

The previous best drilling and completion times by the other operators in the field have all been surpassed, and the total operational time spent on each well have been reduced to almost half of the original budget estimate of 72 days per well (Figure 1). We will try to shed some light on the planning process and the fit for purpose technical solutions that have lead to the best overall well times so far in the South Pars field.
Lifting of Heavy Oil with Inert-Gas-Operated Chamber Pumps
Authors: Dewan John T. , Elfarr John
Published: December 2007

Lifting of heavy oil is currently carried out almost exclusively by rod pumps. Severe problems are often encountered, such as rod floating and overloading due to high fluid viscosity, pump sticking and erosion with high sand production, heavy crude plugging, and gas locking under steam flood conditions. Special rod pumps alleviate some of these problems but installation and maintenance expense typically remains high.

This paper describes an unconventional gas lift system which can replace rod pumping for shallow (<3,000 ft.) heavy oil production. It circumvents all of the aforementioned problems and in addition has advantages in adjusting to variable production rates, in steam injection and in ease of well cleanout.

The heart of this system is an insert chamber downhole, whose only moving parts are two standing valves. Produced fluid entering the chamber is periodically expelled into a production annulus by pressurized gas injected from the surface down a small injection string. Natural gas, inert gas, or even air can be used for pumping. This paper analyzes the operation of the chamber lifting system and shows how to optimize the system design and the operating variables to obtain maximum production at minimum cost.

With the close spacing of thermal wells (2-5 acres), the combination of a single inert gas generator and associated compressor to supply a large number of wells equipped with chamber pumps is feasible. Several types of inert gas generators are described. Capital and operating costs of chamber and rod pumping for a 170 well system are compared. The economic return is far greater for chamber pumps when bottomhole conditions are such that steam locking of rod pumps occurs.
High-Speed Drillstring Telemetry Network Enables New Real-Time Drilling and Measurement Technologies
Authors: Reeves M. , Macpherson J. , Zaeper R. , Bert D. , Shursen J. , Armagost K. , Pixton D. , Hernandez M.
Published: December 2007

A real-time, bi-directional, drill string telemetry network has been proven reliable over the course of seventeen field trial wells, including seven wells within the U.S. The network has demonstrated simultaneous upward and downward data rates of up to 57,000 bits per second, with reliability comparable to current mud pulse telemetry technology.

The network utilizes unique inductive coupling coils and armored coaxial data cables embedded within premium double-shouldered drilling tubulars to provide high bandwidth telemetry without impacting drilling operations.

U.S. field trials have included multiple vertical and directional gas wells drilled to depths exceeding 14,000 feet in the Arkoma region of southeastern Oklahoma. The drilling environment has involved extremely harsh vibrational conditions, including air hammer drilling and multiple jarring events.

During these trials, a leading oilfield service company has deployed a number of different downhole measurement-while -drilling (MWD) tools interfaced directly to the drill string telemetry network. This interface allows real-time surface control and interrogation of the downhole tools and transmission of high-density, low-latency drilling dynamics, formation evaluation and directional MWD data at previously impossible speeds.

In a recent well, the operator elected to eliminate their usual mud pulse transmission tool, utilizing the telemetry drill string network and compatible MWD tools as the primary downhole data source.

This paper builds on prior publications and provides details of the latest field trials, including, for the first time, information on the development and performance of network enabled MWD tools. A summary of the mechanical and electrical design considerations associated with tool conversion is offered.

Observations regarding mud-pulse and drill string telemetry performance, including operational differences, rig time impact, added value and deployment issues are provided.

Finally, this paper provides details, and value propositions, of downhole measurement and drilling applications that are enabled by the availability of a reliable telemetry drill string network.
Technological Improvements in Wells Drilled With a Pneumatic Fluid
Authors: Mellott J.
Published: December 2007

Most of the technological improvements seen in the drilling of wells with a "pneumatic fluid" (hereafter referred to as air) have come from the mining industry which is primarily associated with shallow large bore wells. The oil and gas industry has failed to make the same technological improvements in "air drilling" as compared to wells drilled with liquid systems. Air drilling has remained a "step child" and treated as an art rather than a science. One of the primary differences has been the failure to treat it as a integrated system like liquid drilling. In "air drilling" components are pieced together with little regard to other components.A air drilling system is actually more complex than a liquid one and requires more engineering to be successful. Because the pneumatic fluid is compressible there many improvements that can be made to manipulate downhole pressure and velocity which cannot be done in a liquid system. It is actually advantageous to divert a portion of the pneumatic fluid into the wellbore before it reaches the bit. However to do this with consistency and divert the proper volumes at the proper depth a Pneumatic Fluids Drilling Model must be utilized which is rarely done. This paper presents new technology which has been proven in theory and practice to improve air drilling performance. The technological improvements include a model which accurately demonstrates downhole pressures, velocities and kinetic energy throughout the system so that various drillstring and wellbore geometry as well as pneumatic fluid volumes can evaluated quickly. The model demonstrates the effects of diverting a portion of the pneumatic fluid into the wellbore above the bit. The paper also describes a new tool the "downhole air diverter" or DHAD) which is deployed in the drillstring that can accurately divert the optimum amount of pneumatic fluid based on model recommendations. As a result of using this new technology to manipulate bottom hole pressures at the bit the energy normally lost to friction can be used beneficially resulting in lower surface compression cost, less hole erosion, higher penetration rates, longer bit life and a higher percentage of wells reaching TD without converting to incompressible fluids.

This paper presents conclusive data from bottom hole pressure tests demonstrating that the surge effect (Venturi Effect) which is used at the surface to draw pneumatic fluids away from the wellhead can also be created downhole to lower annular bottom hole pressures. By lowering this bottom hole pressure more velocity is created with less air and less friction. Case studies are presented demonstrating how this technology has been used successfully in the field under various wellbore conditions resulting in higher penetration rates, improved wellbore stability, longer bit life and overall reduced drilling cost.
Use of Lightweight Solid Additives To Reduce the Weight of Drilling Fluid in the Riser
Authors: Cohen J. H. , Deskins G.
Published: December 2007

This paper describes the first phases of development of a drilling system for offshore wells based on the use of lightweight solid additives (LWSA) to reduce the density of drilling fluid within the riser above the seafloor. Equipment and procedures were tested to pump LWSA down to the bottom of the riser without damage, separate them from the mud after the fluid mixture returns to the surface, recycle LWSA for immediate re-use, as well as several other problems. Initial developments and tests are described that successfully addresses many of these issues.

In offshore wells, particularly in deep water, the problem of maintaining a safe range of mud weights is compounded by the additional pressure that drilling mud in the riser exerts on the formation. If the effective weight of mud in the riser can be reduced, the range of safe mud weights is effectively widened at the formation, resulting in fewer casing strings and safer operations. Mud with high concentrations of LWSA might be pumped down from the surface through special lines and then injected into the riser at the mud line. The mixture of mud and LWSA flowing up the riser then weighs less than pure mud.

LWSA were developed and tested as spheres produced from different materials including glass, composites, and epoxy resins. Tests showed that LWSA could withstand high pressures existing at the bottom of risers. LWSA were able to be separated from oilfield muds using conventional oilfield shale shakers and hydrocyclones. Muds with LWSA could be pumped with conventional mud pumps without excessive pressure losses. LWSA were recirculated many times with minimal breakage, demonstrating that they could survive in commercial operations.

Significant cost savings will be possible in drilling offshore wells if remaining problems with LWSA can be addressed. In addition to reducing the number of casing strings required, drilling with LWSA would reduce tension load requirements on the riser and mud storage requirements on the drilling vessel, which will reduce the size of drillships or increase depth capability of existing vessels.
An Algorithm for the Analysis of Shaly Gas Sands
Authors: Saldaña Miguel A. , O'Brien William J. , Brown Susan L. , Gobran Brian D. , Sanyal Subir K.
Published: December 2007

This paper describes an approach for analysis of shaly sands and a program for TI-59 calculators based on the theory of the neutron-density crossplot. The program calculates porosity, flushed zone water saturation, and amounts of dispersed, laminar and structural shale. Also, formation water saturation is determined using three shale models. The most appropriate value can then be selected according to the relative amounts of the shale types.
Estimation of QV Profile in a Sedimentary Type Geothermal Reservoir
Authors: Ershaghi Iraj , Ghaemian Shahed
Published: December 2007

In-situ determination of Qv (effective concentration of clay-exchange cations) of sedimentary rocks using geophysical well logs is discussed with application to geothermal reservoirs. A method is proposed based on the solution of equations relating formation rock and fluid properties and the conductivity of mud filtrate to the data obtained from S.P. (Spontaneous Potential) and resistivity logs.

The application of the proposed method to some wells in the Cerro Prieto Geothermal field in Mexico is discussed.
CO2 Injection as an Immiscible Application for Enhanced Recovery in Heavy Oil Reservoirs
Authors: Khatib Ala K. , Earlougher R. C. , Kantar Kutluyil
Published: December 2007

Most field applications and pilot tests of CO2 injection are for miscible drive, and are therefore confined to light oil reservoirs. However, it has been known for decades that as CO2 dissolves in heavy oil, it swells the oil and reduces its viscosity. Core displacement tests in the fifties indicated that substantial additional recovery of heavy oil, and in some cases light oil, was possible with carbonated water. Until recently, unfavorable economics discouraged field application, and yet in 1976 a field project was commenced in southern Arkansas.

Two techniques have been field-tested. These are "huff-and-puff" CO2 injection for stimulation of the producing wells and either alternate or simultaneous injection of CO2 and water.

Both process mechanisms are discussed and are illustrated, where possible, by the results of field tests in the United States. These have been in sandstone reservoirs containing light oils and heavy oils. Several other pilot or field projects are in the planning stage. A planned field demonstration project of both processes, in different test areas of a fractured limestone reservoir (oil 9° - 15°) in Turkey, is summarized.

The possible range of candidate reservoirs is discussed, and general economic comparison with steam injection is given. The obvious candidates are heavy oil reservoirs that are too deep for current steam injection technology and economics.
Stimulation of the North Coles Levee Field with A Retarded HF-Acid
Authors: Hall Bobby E. , Tinnemeyer Art C. , Underwood Porter J.
Published: December 2007

The North Coles Levee field is located in the San Joaquin Valley, approximately halfway between the cities of Bakersfield and Taft, California. Production, from the Stevens Sand, has significantly declined, partly due to migration and/or swelling of fines. Nine wells in this field have been acidized with the sequential hydrofluoric acid (SHF) system within the last twelve months.

Six of these treatments were termed successful with an average production increase of 2.8 for all nine wells.

Presented in this paper are reservoir characteristics, production history and production data on the North Coles Levee field.
Gas Hydrates in Oil Systems
Authors: Mohammadi A. H. , Ji H. , Burgass R. W. , Bashir A. , Tohidi B.
Published: December 2007

Extensive studies have been conducted on hydrate formation in gaseous systems; however, little information is available on hydrate risks in oil systems. This is partly due to difficulties in measuring the hydrate stability zone in oil systems, as well as problems associated with compositional representation of such systems. Furthermore, it is reported that hydrate formation pose less risks in oil systems than gas systems, partly due to the presence of natural inhibitors, formation of water in oil emulsions, and possibly oil wet pipeline walls. However, little is known of the nature and mechanism of the natural inhibition and the response of the system to an increase in the water cut.

In this communication, we present details of two experimental set-ups specifically designed to study the hydrate risks in oil systems. They include a visual high pressure kinetic rig for measuring the hydrate stability zone, crystal size, distribution and the rate of hydrate formation and dissociation, and a glass micromodel for visual observation of hydrate formation / dissociation in micro-scale. We report some of the recently obtained experimental results using the above experimental equipment. The results show that the existing techniques should be revisited for generating reliable data in oil system. We also demonstrate that proper characterization of the heavy end and taking into account the possibility of wax formation may play a role in improving the reliability of predictive techniques. The results provide better understanding and evaluation of risks associated with hydrate formation in pipelines carrying oil.
Predicting Oil Displacement By Thermal Methods
Authors: Moss Jon T.
Published: December 2007

Oil displaced by heat fronts associated with Thermal Oil Recovery methods is calculated using a graphical correlation of three-phase permeability data. Previous investigations were based on the two-phase flow of steam and oil behind the heat front and hot water and oil ahead of the condensation front. In situ combustion displacement has not been adequately studied, except to some extent by numerical methods and laboratory experiments, due to the complexity of gas, oil and water three-phase flow. The solution developed herein combines fluid flow with Marx-Langen-heim heat loss to predict heat front velocity and oil displacement.
A Parallel Adaptive Finite Difference Algorithm for Reservoir Simulation
Authors: Hoang H. M. , Kleppe J.
Published: December 2007

Adaptive finite difference methods for problems arising in flow of porous medium applications are being considered. Such methods have proved useful for overcoming limitations of computational resources and improving the resolution of the numerical solutions to a wide range of problems. By local refinement of the computational mesh where need to improve the accuracy of solutions, yield better solution resolution than is possible with traditional fixed-grid approaches, representing more efficient use of computational resources.

In this paper, we present a parallel adaptive cell-centered finite difference algorithm for black-oil reservoir simulation models. This is an extension of the adaptive mesh refinement methodology first developed by Berger and Oliger (1984) for the hyperbolic problem.

The material in this paper is subdivided into three parts. First we explain the methodology and intricacies of adaptive finite difference scheme. Then we extend a finite differential cell-centered approximation discretization to a multilevel hierarchy of refined grids, and finally we are employing the algorithm on parallel computers.

Our algorithm is fully adaptive in time and space through the use of sub-cycling, in which finer grids are advanced at smaller time steps than coarser one. When coarse and fine grids reach the same advanced time level, they are synchronized to ensure that the global solution is conservative and satisfy the divergence constraint across all levels of refinement.

The results in this work show that the approach presented is robust, and stable, thus demonstrating the increased solution accuracy due to local refinement and reduced computing resource consumption.
A Hybrid Approach To Improve Reserve Estimates in Waterdrive Gas Reservoirs
Authors: Yildiz T.
Published: December 2007

The conventional reserve estimate methods for waterdrive reservoirs are well established. Typically, the techniques proposed by Havlena and Odeh and McEwen are used. In general, the reserves estimated from the Havlena-Odeh and McEwen procedures are not unique since the recorded historical production data is simultaneously solved for aquifer parameters and reserves. Normally, multiple combinations of reserves and aquifer parameters match the field data equally well. Hence, a range of reserves rather than a unique value is found. The upper and lower limits of the reserve range may vary several folds.

To pick the best solution out of the multiple realizations, statistical parameters are calculated for all the matches. The solution with some minimum statistical indicator is considered to be the best solution. Among the statistical indicators suggested are the standard absolute relative error, normalized sums of squares of differences, standard deviation, normalized standard deviation, curvature, and coefficient of variation.

The reserve estimate based on some minimum statistical indicator may not be reliable. The best reserve estimate corresponding to the minimum standard absolute relative error may differ from those corresponding to the minimum normalized standard deviation or the minimum coefficient of variation.

In this paper, a hybrid approach making use of available methods is employed to narrow the reserve range estimates in waterdrive gas reservoirs.
Avantages linguistiques, scolaires et cognitifs de l'immersion française
Authors: Lazaruk Wally
Published: December 2007

Abstract:

A survey of research on French as a second language (FSL) education in Canada suggests that French immersion (FI) students enjoy significant linguistic, academic, and cognitive benefits. We organize our summary of the advantages of FI around these three themes, comparing students’ proficiency in French and English across various FI programs, and assessing their overall academic achievement. Our review shows that FI programs enable students to develop high levels of proficiency in both French and English, at no cost to their academic success. Cognitive research associates bilingualism with heightened mental flexibility and creative thinking skills, enhanced metalinguistic awareness, and greater communicative sensitivity. Because cognitive benefits are contingent on a bilingual learner's proficiency in both languages, it may be that FI programs, which promote heightened proficiency in both French and English, foster in their students an underlying cognitive advantage.
Design of an Antibiotic Delivery System Based on a Bioresorbable Bone Substitute
Authors: Vogt S. , Schnabelrauch M. , Weisser J. , Kautz A. R. , Büchner H. , Kühn K.‐D.
Published: December 2007

In the current study a new composite material comprising calcium sulphate, calcium carbonate, and tripalmitin was developed as a bioresorbable drug carrier for the local antibiotic therapy. Device fabrication can be simply performed by compression moulding of the components. The evaluated bone substitute material based on a calcium sulphate/calcium carbonate composite exhibits an excellent biocompatibility and a therapeutically useful release profile. It, therefore, represents a promising new antibiotic delivery system for the efficient prevention and treatment of bone infections.
Kinked Star‐Shaped Fluorene/ Triazatruxene Co‐oligomer Hybrids with Enhanced Functional Properties for High‐Performance, Solution‐Processed, Blue Organic Light‐Emitting Diodes
Authors: Lai W.‐Y. , He Q‐Y. , Zhu R. , Chen Q.‐Q. , Huang W.
Published: December 2007

A novel series of kinked star‐shaped oligofluorene/triazatruxene hybrids are conveniently prepared via a powerful microwave‐enhanced multiple coupling methodology. Constructing kinked star‐shaped architectures can effectively suppress crystallization and aggregation. The resulting materials are highly amorphous, showing stable amorphous morphology against crystallization. A triazatruxene core endows the materials with elevated highest occupied molecular orbital (HOMO) levels that are well matched to the anode work function, leading to a significantly improved hole‐injection property. They hybrids are highly luminescent in both solution (quantum yield is 0.52–0.80) and the solid‐state (quantum yield is 0.45–0.76) with bright blue emission. Remarkably, solution‐processed devices displaying single‐layer electroluminescence (EL) based on these oligomers exhibit efficient blue EL and demonstrate striking color stability, almost unchanged with increasing driving voltage. The best device performance has a rather low turn‐on voltage (3.3 V) and a high device efficiency (2.16 % @ 2382 cd m–2) as well as a high brightness (7714 cd m–2 @ 10 V) with CIE coordinates of (0.16, 0.15); it shows remarkably better EL performance than devices based on linear oligofluorene or polyfluorene counterparts. The results prove that an oligomer with kinked star‐shaped architecture is extremely promising for efficient and stable blue EL. The reasons for the enhanced functional properties and the improved color stability are discussed in relation to the chemical structures and components.
Gold‐ vs. Platinum‐Catalyzed Polycyclizations by O‐Acyl Migration. Solvent‐Free Reactions
Authors: Moreau Xavier , Goddard Jean‐Philippe , Bernard Matthieu , Lemière Gilles , López‐Romero Juan Manuel , Mainetti Emily , Marion Nicolas , Mouriès Virginie , Thorimbert Serge , Fensterbank Louis , Malacria Max
Published: December 2007

Polycyclic derivatives incorporating a cyclopropyl group have been efficiently synthesized from propargyl acetates using platinum(II), gold(I) and gold(III) catalysis. These reactions which are also viable for the preparation of medium‐sized rings, proceed with a complete diastereocontrol and can also be run in neat conditions.