bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Investigation of Leak-off Test Data for Estimating In-situ Stress Magnitudes: Application to a Basinwide Study in the North Sea
Authors: Edwards S.T. , Meredith P.G. , Murrell S.A.F. 
Published: December 2007

Abstract
The leak-off test (LOT) procedure has been examined within the theoretical framework pertaining to hydraulic fracturing stress measurements (HFSMs). LOT records have then been compared with the results of HFSMs where both measurements have been made in the same boreholes. From this comparison, we make recommendations on the use of LOT data, and suggest a new method of estimating the minimum horizontal stress magnitude () from LOT pressure/volume plots. In-situ stress magnitudes have been investigated by applying these methods to data from over 1000 LOTs in North Sea boreholes. The results of this investigation imply that tectonic stress increases significantly with depth in some parts of the North Sea. which is consistent with the mapped distribution of borehole breakouts.
P. 357
The Influence Of The Reservoir Stress-Depletion Response On The Lifetime Considerations Of Well Completion Design
Authors: Addis M.A. , Choi X. , Gunning J. 
Published: December 2007

Abstract
The selection of horizontal wells as barefoot and multilateral well candidates requires consideration of the well integrity over the producing life of the field. The evaluation of the production lifetime of a well requires that both the mechanical and chemical changes which the well experiences be modeled and predicted during the well design. The mechanical changes which the well will experience during production is primarily a function of stress and strength changes; the stress changes which result from depletion, the stress-depletion response, are addressed in this paper. Stress-depletion responses from reservoirs in the Gulf Coast region and in the North Sea have been collated and show a range of stress reductions which fields undergo accompanying the field-wide pore pressure depletion. The stress-depletion response of a field only addresses the minimum stress changes, consequently, the maximum horizontal stress change accompanying depletion can only be estimated using models.
The ability to predict the stress-depletion response of a field requires an understanding of what processes control the initial stress magnitudes, and the boundary conditions which the reservoir experiences during the production lifetime. The factors which define and influence the stress-depletion response of reservoirs are addressed, specifically the geological boundary conditions. The ability to model and predict the stress-depletion response of the reservoirs is then discussed, specifically focusing on the role and influence of the overburden surrounding the reservoir on the predicted response. Analytical and numerical models illustrate the influence of the material properties in the reservoir and overburden, and the reservoir size on the stressdepletion response. The ability to predict stress changes during depletion is erratic primarily due to insufficient data.
Uncertainty in the pre-production estimation of the stress- depletion response of the reservoir has a considerable impact on the predicted stability of wells in the reservoir interval. The ability to determine an accurate stress-depletion response is a principal consideration for reliable stability predictions and design recommendations for horizontal and multilateral wells.
P. 433
Investigating the Mechanics of Microcrack Damage Induced under True-Triaxial Unloading
Authors: Pettitt W.S. , Young R. Paul , Marsden J. Robert 
Published: December 2007

Abstract
The stress path experienced by a rock mass, during and immediately after excavation is complex and cannot be replicated by a simple loading of samples to induce microcracking. We have simulated excavation stresses in the laboratory by true-triaxial unloading. To do this we have utilised an existing polyaxial system at Imperial College and modified it to undertake acoustic emission (AE) monitoring. We have then used triaxial strain, measurements, three- dimensional ultrasonic surveys and Ali studies to investigate laboratory induced cracking. In particular we have developed and applied a moment tensor inversion procedure to located AE. This allows a direct analysis of the mechanics driving the cracking. We present and compare results from two tests (triaxial loading and triaxial unloading) using Springwell sandstone to show the capabilities of the laboratory and processing techniques. The AE source mechanisms in both tests are shown tu have a significant isotropic component. The mechanics of the cracking fits neither a Mode I tensile or shear source, but a combination of the two. The mechanism orientations agree with cracking parallel to.
P. 509
Micromechanical Modelling of Acoustic Emissions
Authors: Hazzard J.F. , Maxwell S.C. , Young R.P. 
Published: December 2007

Abstract
Micromechanical models of high porosity chalk and low porosity granite are presented to examine the mechanics of cracking and failure that occur in the rocks when they are subjected to stress. The models are run dynamically (with low numerical damping) to allow for dynamic fracture propagation and so that acoustic emission (AE) information can be obtained. Seismic parameters such as source location, magnitude and crack type are calculated internally within the models. It is also shown how it is possible to calculate this information externally through waveform inversion of synthetic AE. These methods are used to compare the acoustic behaviour of compacting chalk models with different porosities. It is shown that low porosity chalks are more seismically active than those with high porosities. The methods are also applied to observe the cracking and eventual macrofailure that occurs in axially loaded granite samples. The micromechanics of tensile cracks occurring during loading of the granite are examined directly by observing the particle motions at the source, and indirectly by recording waveforms and calculating seismic parameters.
P. 519
Elastoplastic Finite Element Analysis of Inclined Wellbores
Authors: Zervos A. , Papanastasiou P. , Cook J. 
Published: December 2007

Abstract
An effective finite element model which can be used for elastoplastic analysis of inclined wellbores is presented. The same discretised model can be used for any wellbore inclination and azimuth by varying only the applied initial stress field or boundary conditions. The model is applied for calculating the optimum drilling mud-pressure assuming an elastoplastic rock behaviour and different failure criteria. The rock material parameters were derived from triaxial compression tests. The results show that the difference in mud- pressure predictions between elasticity and plasticity depends strongly on the employed failure criteria. The difference between elasticity and plasticity becomes more pronounced with a criterion which allows the material near the borehole wall to reach a critical plastic strain determined from the calibration tests. In such a case differences from 45% to 80% were encountered. Calibration factors given by the ratio of plasticity predictions over the elasticity predictions have been derived and can be used with analytical models for quick field wellbore stability computations.
P. 535
Measurement of Velocity Changes Induced In Cores By Saturation Changes, Water Flood, and Drawdown.
Authors: Jones C. , Somerville J.M. , Smart B.G.D. , Hamilton S.A. 
Published: December 2007

Abstract
4 D seismic measurements are used to monitor changes during the production and stimulation of a reservoir. Parameters such as the type of fluid fill, porosity and pressure distribution are obtained from the results. Interpretation is difficult and is complicated by stress sensitive matrix properties, and phase sensitive fluid properties. Interpretation depends on some theoretical scheme such as Gassmann's equation. Such formulations require a detailed knowledge of the velocity of sound in the fluids present and compression and shear wave velocities in the matrix. These velocity values are obtained from a combination of field and laboratory measurements.
P. 555
Direct Observation and Modeling of Sand Production Processes in Weak Sandstone
Authors: Nicholson E.D. , Goldsmith G. , Cook J.M. 
Published: December 2007

Abstract
Sanding experiments were carried out on weak sandstones with uniaxial compressive strengths in the range of 2 MPa to 25 MPa. The sandstones were either reservoir rocks or those with appropriate physical and mechanical properties to be good model materials.
The experiments involved simulating a perforation or openhole well, by flowing fluid/gas down a hole in a cylindrical rock sample. No radial flow component was present. The flow velocity could be varied, while the sample was hydrostatically stressed to values up to 70 MPa. Deformation of the hole, and the initiation and subsequent flow of sand are viewed and monitored using a specially designed optical method.
Significant differences in behavior were seen for the different rock types. The weakest rock showed compactant behavior, whereas the stronger rocks showed a more brittle response with the formation of breakouts in sanding tests.
The data will be used in the future in the elastoplastic modeling of the perforation geometry.
Experiments of this type provide a simple route to direct observation of sanding in experimental perforations or openhole wells, and give new insight into the mechanisms of failure and the diversity of these mechanisms with different rock types.
P. 97
A Constitutive Model For Swelling Shales
Authors: Molenaar M.M. , Huyghe J.M. , van den Bogert P.A.J. 
Published: December 2007

Abstract
The main operational parameters controlling borehole stability in drilling shales are the density and the chemical composition of the drilling fluid. The density of the drilling fluid provides support of the borehole wall, while the chemical composition of the drilling fluid can be adopted to reduce the infiltration rate and to maintain hole stability for prolonged exposure time of the drilling fluid to the shale.
To describe the interaction between the drilling fluid composition and the mechanical behaviour of shales, an electro-chemo-mechanical formulation of quasi-static finite deformation of swelling compressible porous media has been derived from the theory of mixtures. The model presented in this paper, which is applicable to biological tissues and synthetic hydrogels also, consists of an electrically charged porous solid, saturated with an ionic solution. The mixture as a whole is assumed electro-neutral.
Four phases following different kinematic paths are defined: solid, fluid, anions and cations. Balance laws have been derived for each constituent and for the mixture as a whole. A Lagrangian form of the second law of thermodynamics has been derived to formulate the constitutive relations for the swelling behaviour of shales as well as the transport equations for the fluid and the ions.
P. 127
Application of Yield Design For Understanding Rock Cutting Mechanism
Authors: Challamel N. , Sellami H. 
Published: December 2007

Abstract
This paper deals with the analysis of the response of rock material subjected to the cutting action of a PDC (Polycristalline Diamond Compact) cutter. Following a phenomenological characterization, we show the importance of the maximum loading in understanding the rock cutting mechanism. This parameter is analytically approached using the formalism of the yield design. Cutting tests carried out in Vosges sandstone at atmospheric pressure showed the existence of additional forces acting on the cutter and not predicted by the model. These forces, related to the rock microstructure, induce a change of the rock failure. As they cannot be neglected at this solicitation scale for many geomaterials, they are a major stake of rock cutting.
P. 153
Predicting Rock Mechanical Properties from Wireline Porosities
Authors: Edimann K. , Somerville J.M. , Smart B.G.D. , Hamilton S.A. , Crawford B.R. 
Published: December 2007

Abstract
The rock mechanical behaviour of reservoir rocks is important in the design and implementation of drilling and production programmes. Traditionally rock mechanical properties are obtained from direct measurement on core samples or from mechanical calculations on acoustic wireline log measurements. This paper reports the rock mechanical properties of many different reservoir rocks of different porosities. This has led to the development of a new method of predicting rock mechanical properties directly from porosity. The paper discusses the measurement of experimentally derived porosity, elastic moduli and fracture strength parameters and the intetpretation of these mechanical properties results into direct correlations with porosity. The application of these results to obtain continuous rock mechanical property plots of the reservoir from wireline derived porosity is discussed. The practical use of these rock mechanical property profiles in drilling, production and enhanced reservoir simulation is also emphasised.
Porosity (), modulus of elasticity (E), Poisson's Ratio (v), uniaxial compressive strength (UCS), cohesion (), angle of internal friction (), and triaxial stress factor (k), were measured on samples from a wide range of North Sea reservoirs using a conventional triaxial testing machine. This paper describes the procedure used and presents the correlations obtained from plotting each of the rock mechanical properties against porosity. The derivation of wireline porosities along with empirical corrections are presented and the results of applying the correlations to these wireline derived porosities to produce continuous rock mechanical property plots are discussed. Logs were calibrated to core-measured values to reveal realistic elastic and inelastic moduli profiles. The continuous property logs provide a reasonable estimate of the possible behaviour at discrete points throughout the reservoir interval, but they are limited in their description of the behaviour of individual beds as coherent bodies. A technique has been developed to pick out these individual beds and assess how they will perform as Rock Mechanical Coherent Units, i.e. sets of beds that perform in a similar or dissimilar manner to adjacent layers. Finally a discussion on how the results are used to aid production and generate enhanced reservoir simulation will be presented.
P. 169
A Mathematical Model of the Steam Drive Process Applications
Authors: Neuman C.H. 
Published: December 2007

This paper was prepared for the 45th Annual California Regional Meeting of the Society of Petroleum Engineers of AIME, to be held in Ventura, Calif., April 2–4, 1975. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor of the appropriate journal, provided agreement to give proper credit is made.
Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Introduction
Previously reported calculations of Previously reported calculations of oil displacement by continuous steam injection either ignore the effects of gravity override or simulate them numerically. This paper describes a theoretical analysis of the problem that leads to a relatively simple solution. A steam zone is assumed near the overburden. Calculations include (1) the rates of steam zone thickness increase vs time since steam first arrived, (2) the steam zone areal increase rate, and (3) total oil displaced (from the steam and underlying hot water zones). The mathematical derivation is to be submitted to the SPE Journal.
Equations describing the steam drive process are presented, applied in an process are presented, applied in an example, and discussed as to limits of validity. Predicted and observed steam drive behaviors are compared for Chevron's Ten Pattern Steam Flood in the Kern River Field, California. Also discussed are methods of application for economic and engineering analysis.

OUTLINE OF GRAVITY OVERRIDE MODEL
Steam injected during steam flooding rises to the top of the injection interval, causing the steam zone to grow downward as well as areally. The vertical rate is determined by the rate of steam condensation from heat diffusion into the overburden and the liquid-filled underlying reservoir. The rate of areal growth is determined by the balance between the net energy injected as steam and that required from steam condensation to sustain vertical growth. The amount of oil displaced from below the lower steam interface can be predicted from the temperature profile there and a critical temperature. The latter depends on the flow properties of the reservoir and fluids. The model presented here is like that of Marx and Langenheim in that neither assumes a particular areal geometry.
Design and Operation of a Supercritical CO2 Pipeline-Compression System Sacroc Unit, Scurry County, Texas
Authors: West James M. 
Published: December 2007

The SACROC Unit is in the second year of a carbon dioxide miscible flood that is the largest secondary recovery project of this type ever undertaken. To accomplish this flood, over 35 million tons of carbon dioxide will be used for injection into the reservoir. The total cost of the project when finalized will be in excess of $175,000,000. This cost includes purchase of CO2, conversion of over 200 producing wells to CO2 injectors, expansion of surface facilities and the construction and operation of the CO2 Pipeline-compression system. The magnitude and innovative nature of the project has demanded a major engineering, planning and design effort involving the coordination of many fields of engineering and various technical specialties. This paper will give a brief account of the overall CO2 delivery facilities to include the basic design considerations and some of the studies that were conducted for each aspect of the project.
The focal point of the CO2 transport project is the SACROC Unit in Scurry County, Texas. (Referring to Figure No. 1). It might be noted that the name SACROC was derived from the initials of the "Scurry Area Canyon Reef Operators Committee", a task group that was activated for essential work required prior to the formation of the SACROC Unit. The Canyon Reef field was discovered in 1948 with major development beginning in 1949 and extending through 1951. During this period, over 1,000 wells were drilled to develop more than 50,000 acres. The surface extent of the field is about 6 miles wide by 12 miles long.
Waterflood operations were started in 1954. By 1972, over 280 million barrels of oil had been produced by waterflood.
Cementing of Well Casings for Pollution Control
Authors: Runyan E.E. 
Published: December 2007

Abstract
This paper discusses the importance of obtaining a good cement job in well completions, and the three areas vital to obtaining this effective wellbore cement seal. These three areas are (1) formation cement interface (2) casing cement interface, and (3) the cement sheath itself.
An operator is interested in getting best cement job possible for several reasons:shut off and/or protect fresh and salt-water zones,segregate producing zones,eliminate communication between gas-oil, oil-water, or gas-water contacts,stabilize the casing string, andseal well fluids in wellbore to prevent surface or subsurface pollution. prevent surface or subsurface pollution.
The steps involved in obtaining a good wellbore seal are (1) good borehole conditions, (2) good wellbore cleanup prior to cementing, (3) removal of excess filter cake from permeable formations, (4) selection of correct cement composition for given well conditions, (5) proper centralization of the well casing, and proper centralization of the well casing, and (6) preparation of the external casing surface for maximum cement bonding.
Several field case histories are presented to show the effectiveness of proper cementing practices, particularly the effectiveness of practices, particularly the effectiveness of resin-sand coating of the casing in producing an extremely strong bond between cement and casing. The application of the Cement Bond Log for evaluation of the final cement job is also presented. The paper concludes that potential presented. The paper concludes that potential problems of fluid leakage and their consequences problems of fluid leakage and their consequences can be minimized by the proper use of known technology.

Introduction
The cementing of oil, gas, gas storage, injection, and disposal wells throughout the industry has received a great amount of attention over the past 50 years in both research and field development areas. This attention and research is continuing. Probably no other aspect of the completion operation has been as widely studied and discussed. Yet, cementing problems continue. Partially, this is due to problems continue. Partially, this is due to the complexity of the problem, but unfortunately, it is also partly due to failure to properly apply known technology.
The cementing operation is designed to (1) shut off and/or protect fresh and saltwater zones, (2) segregate producing zones, (3) eliminate communication between gas-oil, oil-water, or gas-water contacts, (4) stabilize the casing string, and (5) seal well fluids in the wellbore to prevent environmental contamination.