bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationship between frictional strength and fault gouge generation from direct shear testing under constant normal displacement control
Authors: Crawford B. R. , Smart B. G. D. , Ngwenya B. T. 
Published: December 2007

Abstract
The production of frictional wear debris (fault gouge) under optimum non-dilatant conditions conducive to maximum dynamic fragmentation has been undertaken utilising a novel direct shear machine. A wide variety of sedimentary lithologies have been tested under constant normal displacement control and a mechanistic model for the evolution of frictional resistance developed. X-ray diffraction quantitative mineral identification and laser diffraction particle sizing technologies have been employed to characterise the induced debris distributions. A relationship is presented between the frictional strength of the sliding surfaces and the specific surface area of the induced cataclastic debris.
An estimation of bulk moduli of sandstones as a function of confining pressure using their petrographic and petrophysic description
Authors: Vincké O. 
Published: December 2007

Abstract
In a previous paper, we developed a model to estimate the terminal bulk modulus of sandstones using their petrographic and petrophysic description. The above mentioned model is summarized. A method which is introduced in the previous formulation is then developed to estimate the evolution of the bulk modulus as a function of confining pressure. The role played by the cement and the cracks is emphasized. We test the model using a basic data set in which the bulk moduli have been measured for 17 different sandstones for confining pressures up to 100 MPa.
Numerical Simulation of Three-Dimensional Natural Convection in Porous Media
Authors: Holst P.H. , Aziz K. 
Published: December 2007

Abstract
The equations of motion and the energy equation are developed for the prediction of temperature and velocity fields in the problem of natural convection in porous media. The equations are made suitable for numerical computation by introducing a vector potential which is the counterpart of stream function in two dimensions. This vector potential has previously been used by one of the authors to solve previously been used by one of the authors to solve the Navier-Stokes equation in three dimensions. The partial differential equations are solved by finite difference methods employing Alternating Direction Implicit Procedure [ADIP] and Successive Over Relaxation [SOR] methods. The model may be used when the heated side is vertical, horizontal or inclined. The detailed structure of three-dimensional cells predicted by this model is compared with previous two-dimensional studies conducted by the authors.
Analytical solutions are possible and available for the linearized partial differential equations for this problem. Such solutions only predict the onset of convection and fail to reveal what happens after convection sets in.
This is the first attempt in solving these equations for the case where nonlinear terms are not neglected and the predictions are carried out as a function of time and all three space directions.
The results are presented in the form of contour maps and show the interesting structure of convection cells in porous media.
Introduction
Natural convection is a phenomena conceivable in a petroleum reservoir subjected to fire or steam flooding. It is the result of adverse temperature gradients generating buoyancy forces that in turn cause fluid motion. A mathematical analog of the physical phenomena may be obtained by writing mass, force and energy balances on a differential volume of porous media. If Darcy's law is employed to porous media. If Darcy's law is employed to relate fluid flow to potential gradients and the Boussinesq approximations [fluid properties independent of temperature except where they contribute to buoyancy] are assumed to be applicable, the three balances reduce to two nonlinear partial differential equations. The two-dimensional form of these equations has been solved by a number of investigators. The reader is referred to Karra's thesis for a comprehensive literature review on the subject. In order to apply the mathematical model with some degree of confidence, an experimental verification is desirable if not necessary. As any experimental verification would presumably involve a three-dimensional apparatus, a study as to the effect of the third dimension on the solution was clearly indicated.
Comparison of borehole breakouts from laboratory and field tests
Authors: Martin C. D. , Martino J. B. , Dzik E. J. 
Published: December 2007

Abstract
Laboratory testing of granite blocks containing a circular borehole was carried out with uniaxial and biaxial loading conditions, and with borehole diameters ranging from 5 to 103 mm. Borehole breakouts were also investigated in situ using borehole diameters ranging from 75 to 3500 mm. Results show that the same strength-scaling law cannot be applied to both laboratory and in situ breakouts.
Basin Scale Rock Mechanics: Field Observations of Sand Production
Authors: Moricca G. , Ripa G. , Sanfilippo F. , Santarelli F. J. 
Published: December 2007

ABSTRACT
Sand production is very common in the gas wells of the Adriatic Sea. Accurate field surveys have been conducted before and after sand production has occurred in wells where no sand control methods had been initially introduced. Unlike the numerous other papers dealing with sand production, this one describes the sand production observed in low permeability gas-bearing formations which include a significant amount of clays. The main parameters inducing sand production are identified and an empirical correlation is established which enables its prediction. Moreover, the influence of parameters such as depth, drawdown, depletion, gas rate, water gas ratio etc. on the occurrence of sand production is determined. The paper also reports the results of a sand flow test performed in a gas field situated in the surveyed area. Finally, these results are discussed in terms of geological history of the Northern Adriatic Basin.
Interaction and Link-up of Hydraulic Starter Fractures Close to a Perforated Wellbore
Authors: Weijers L. , de Pater C. J. 
Published: December 2007

ABSTRACT
A hydraulic fracture treatment in a cased-perforated well may result in the initiation of inclined starter fractures from each perforation. We performed scaled model tests and observed that link-up of starter fractures was affected by the confining stress difference and the pressure in the fracture during a treatment. A large stress difference in the plane perpendicular to the perforations prevents starter fractures from linkage. Also, fracture linkage is affected by the cementation of the well. Fluid flow in the annulus between borehole and casing may results in better linkage, but the fracture may grow through the annulus and avoid the perforations.
Deformation Characteristics of Weakly Cemented Sandstone
Authors: Nikraz H. R. , Press M. , Evans A. W. 
Published: December 2007

Abstract
This paper reports the finding of a investigation carried out to evaluate the deformation characteristics of saturated sandstone aquifers in the Collie Coal Basin under conditions anticipated during dewatering operations.
A drained triaxial compression test technique for various combinations of confining pressure and back pressure was designed to examine the applicability of the effective stress theory suggested to Terzaghi (1), with particular reference to the Collie sandstone. Further, the results obtained were utilised to characterise the strength and deformability properties of the Collie sandstone.
Real-Time Microseismic Monitoring: Automatic Wave Processing and Multilayered Velocity Model for Accurate Event Location
Authors: Senfaute G. , Bigarré P. , Josien J. P. , Mathieu E. 
Published: December 2007

Abstract
At the Provence colliery, France, the remote microseismic monitoring used for the prevention of dynamic phenomena is an integral part of a strategy for exploring zones where there are risks of violent instability or rockbursts. Precise location, in real time, of the hypocentres associated with daily microseismic activity is one of the main objectives in the interpretation of data to optimise countermeasures. A study has been carried out with the purpose of calibrating an inclined wave propagation multilayered model. This article describes the operational microseismic monitoring network, the method used to calibrate the velocity model, the results obtained and the undeniable contribution which it makes to the quality of data interpretation.
Parametric or Nonparametric Analysis of Induced Seismicity Sequences
Authors: Lasocki Stanislaw 
Published: December 2007

Abstract
Methods of the seismic risk analysis in either natural or induced seismicity can be divided into the parametric methods and the nonparametric ones. Within the presented work correlations between ten functions representing nonparametric traits of the local sequence of induced seismicity, a risk function issued from the parametric model and the number of strong events in the sequence were studied. The analysis showed that the parametric approach to time-varying processes like the triggered seismicity process may give more reliable results than the nonparametric inference.
Storing Liquid Natural Gas in a Depleted Reservoir: Preliminary Results of a Feasibility Study
Authors: Brignoli M. , Santarelli F. J. , Zausa F. 
Published: December 2007

Abstract
Some rock mechanics laboratory tests at low temperature on both poorly consolidated sand and drilling cement samples have been performed. These may be useful when examining the feasibilty of storing LNG in depleted reservoirs as an alternative to more traditional methods; in the paper is presented a list of some of the questions which need to be answered in order ensure the feasibility of such a project and particular attention is given to the rock mechanics aspects of the problem. Variations of in-situ stress state due to thermal effects and behaviour of both rock and cement at low temperature are examined and some conclusion derived from simple models are given.
Sealing of Boreholes using Natural, Compatible Materials: Granular Salt
Authors: Finley Ray E. , Zeuch David H. , Stormont John C. , Daemen Jaak J. K. 
Published: December 2007

Abstract
Granular salt can be used to construct high performance permanent seals in boreholes which penetrate rock salt formations. These seals are described as seal systems comprised of the host rock, the seal material, and the seal rock interface. The performance of these seal systems is defined by the complex interactions between these seal system components through time. The interactions are largely driven by the creep of the host formation applying boundary stress on the seal forcing consolidation of the granular salt. The permeability of well constructed granular salt seal systems is expected to approach the host rock permeability (&lt;10-21 m2 (10−9 darcy)) with time. The immediate permeability of these seals is dependent on the emplaced density. Laboratory test results suggest that careful emplacement techniques could result in immediate seal system permeability on the order of 10−16 m2 to 10−18 (10−4 darcy to 10−6 darcy). The visco-plastic behavior of the host rock coupled with the granular salts ability to "heal" or consolidate make granular salt an ideal sealing material for boreholes whose permanent sealing is required.
Mechanisms of Chalk Compaction
Authors: Powell Benjamin N. , Lovell Gary L. 
Published: December 2007

Abstract
A scanning electron microscope study of textures in several companion pairs of uncompacted and experimentally compacted Ekofisk chalk samples has documented two principal mechanisms of chalk matrix compaction. The dominant mechanism — which we have quantified through processing and analysis of digitized backscattered electron images — is simple grain displacement, which results in larger pore spaces being partially filled in by single calcite rhombohedra and other small fragments of bioclasts as the matrix porosity becomes more homogeneous with compaction. A second mechanism — which we have quantified by counting intact coccoliths in 100 secondary electron images per sample — involves the mechanical breakup (cataclasis) of bioclasts. The second mechanism contributes to the first. However, it clearly played a more significant role in the natural process of compaction over geologic time and is likely to be of only secondary importance relative to simple grain displacement during production-related compaction of the reservoir.
Changes in Mechanical Properties of Chalk Caused by Deformation and by Pore Pressure
Authors: Risnes R. , Gjesdal S. A. , Landaas T. L. , Madland I. 
Published: December 2007

Abstract
A laboratory study on weak high porosity outcrop chalk has been performed in order to see how mechanical strength is affected when the material is strained beyond the elastic limit. Both tensile and compressive strength and Young's modulus are considerably reduced, although there is some strain hardening in compressive strength with increasing degree of deformation.
A second part of the study addresses the possibility of causing damage when the pore pressure is increased like in stimulation operations. Samples that were pressurized, when locked in an oedometer cell, became weaker than samples with no pressure cycle.
Behaviour of Chalks
Authors: Siwak J. M. , Pecqueur G. , Mikolajczak A. 
Published: December 2007

Abstract
In order to study the behaviour of chalk, four chalks were tested under different loading conditions. We present, in this paper, the behaviour of these chalks under hydrostatic, oedometric, deviatoric, proportional and torsional tests. It appears that the behaviour of chalk can be predicted from Lade's model with a differenciation between after and before the pore-collapse. We observed that Lade's model agrees with chalk's case. The simulation of the torsional tests were made by fmite element analisys. From Chang's model and the one of Lade's model, the results give some good agreement between simulations and experimental tests.
Geophysical Monitoring during a Hydraulic Fracture in a Fractured Reservoir: Tiltmeter and Passive Seismic Results
Authors: Schemeta J. E. , Minner W. B. , Hickman R. G. , Johnston P. A. , Wright C. A. , Watchi N. 
Published: December 2007

Abstract
UNOCAL and Japan National Oil Corporation jointly carried out a hydraulic fracture operation in the Monterey Formation in the Newlove 110 well, located in the Santa Maria basin in central coastal California, USA. The treatment well was monitored by an array of tiltmeters to measure the surface deformation, and with a 3-component oriented geophone to monitor microseismic events during the stimulation. There is good agreement between the results of the two monitoring programs, each showed the procedure produced a vertical fracture with an azimuth of about N 60° E. This orientation also agrees well with the regional data from tectonic stress and fracture orientations.
Heterogeneous Stress Orientations in the North Sea Basin
Authors: Cowgill S. Mark , Meredith Philip G. , Murrell Stanley A. F. , Brereton N. Robin 
Published: December 2007

Abstract
The orientations of stress induced wellbore breakouts in the North Sea Basin are diiectionally heterogeneous. Few obvious trends are apparent. Consistent orientations can only be observed in relatively small geographic domains. In constrast, more consistent orientations are observed when the data are divided into separate chronostratigraphic intervals. We propose that the stress distribution within each domain is controlled by the superimposition of the local geological structure and the effects of palaeostress fields onto the present day tectonic stress field.
Some Field Observations Of Heterogeneity Of Reservoir Rocks And Its Effects On Oil Displacement Efficiency
Authors: Elkins Lincoln F. , Skov Arlie M. 
Published: December 2007

Abstract
Ten to possibly thousand fold ratios of horizontal permeability to vertical permeability are required in two "clean" sand reservoirs to match actual water-free product ion of oil and. gas of wells having bottom water. Layer models with average permeabilities of cores at similar stratigraphic position in the reservoir rather than values selected from the permeability frequency distribution and with highly restricted cross flow yield the best match between actual and calculated dilution of wet gas by injected gas in two cycling projects. These same reservoir modeling concepts yield reasonable agreement with actual performance of the Seeligson enriched gas drive test without assumption of serious viscous fingering with gravity segregation.

Introduction
The effects of heterogeneity off reservoir rocks on fluid displacement efficiency remain as a very important unsolved problem in this period of rapidly growing application of fluid injection for increased recovery of oil. Hypotheses of reservoirs ranging from non-connecting layers characterized by permeability frequency distribution, irrespective of spatial origin of cores, to reservoirs so heterogeneous they are nearly homogeneous have been offered as bases for evaluation of actual oil recovery projects. Since we are forever barred from knowing the actual variation arid continuity of rock properties, it is imperative that we test our simplified models against performance of actual reservoirs to select those assumptions most appropriate as guides to judgment. This paper presents two types of field observations having a bearing on these models:Determination that 10 to possibly1000 fold ratio of horizontal permeability to vertical permeability is required to match water coning performance of a number of wells in "clean" sand reservoirs in contrast with very low ratios usually observed in small core plugs. Possibly cross flow between layers in laboratory fluid flow models or calculated mathematically for multilayer systems with equal horizontal and vertical permeabilities may not be representative of actual reservoirs in which gross anisotropy appears to be much greater than that of small cores.Agreement between actual dilution of gas streams by injected gas in two cycling projects and that calculated with assumption of parallel flow in separate layers is reasonable if permeabilities assigned to individual layers are average permeabilities of cores from different wells at the same relative vertical position in the reservoir section rather than values from the permeability frequency distribution.
Most performance features of the current Seeligson enriched gas drive project are adequately matched by this parallel layer type analysis.
Evaluation Of Cement Systems For Permafrost
Authors: Morris E.F. 
Published: December 2007

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.

Abstract
Cementing of casing in the permafrost on the Alaskan North Slope presents new problems to many operators. Primarily, the cement system must be kept from freezing until after the setting reaction is complete. Different types of systems have been suggested and used to solve this problem. High alumina cement systems, however, appear to be the most satisfactory at this time.
This paper presents data of several systems proposed for permafrost cementing and attempts to point out the merits and disadvantages of each.

Introduction
Cementing of pipe set through the permafrost in Alaskan North Slope wells introduces permafrost in Alaskan North Slope wells introduces new problems. The permafrost section is reported to vary from unconsolidated sands and gravels with ice lenses to some areas of icefree, consolidated rock. A broad definition of permafrost is that formation from surface to a depth where the temperature is at 32 degrees F or below. This depth may vary from 500 feet to 2000 feet. The permafrost temperature may range from 15 degrees F up to 32 degrees F. Conventional cement systems, commonly used in oil well cementing are not satisfactory under these conditions. Conventional cement slurries will freeze, preventing the development of set cement when placed in the low-temperature environment.
Operators on the North Slope requested a cement system that could be mixed, pumped and conventionally placed behind the pipe set through the permafrost. The cement should set to adequate compressive and bond strengths, sufficient to support the pipe and prevent the circulation of drilling fluids up the annulus as drilling is continued. It was further requested that the cement system and placement technique be kept as simple as possible due to the adverse working conditions present on the North Slope.
Conventional laboratory methods commonly used for designing and testing cement systems were not adequate to develop reliable cement systems for permafrost cementing. A test method more closely resembling permafrost conditions and one that could be readily reproduced was needed. A model was developed which met these requirements.
Unenclosed Gas Plants for Colder Climates
Authors: Kyllo M.A. , Phillips M.D. 
Published: December 2007

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.

Abstract
Construction of unenclosed gas processing plants is suitable for cold processing plants is suitable for cold weather operation provided appropriate winterizing procedures are followed. The result should be a safer operating plant with less investment. plant with less investment

Introduction
Hudson's Bay Oil and Gas Company Limited is a producing company employing 875 people. It was formed through an agreement between what is now Continental oil Company in the United States and the Hudson's Bay Company Limited. The Hudson's Bay Company was incorporated in 1670 under a charter given by King Charles II. It is the oldest company in existence in North America.
Hudson's Bay Oil and Gas operates seven sour gas plants and one sweet gas plant in Alberta. These vary in size plant in Alberta. These vary in size up to our largest, the Kaybob South Gas Processing Plant which is designed to Processing Plant which is designed to produce 2080 long tons of sulphur, produce 2080 long tons of sulphur, 25,000 bbls. of condensate and 6,800 bbls. of LPG per day. This plant is located on 54.5 degrees North Latitude and is subject to severe winter conditions. It is this plant and our Edson Gas Plant, about 60 plant and our Edson Gas Plant, about 60 miles south of the Kaybob South Plant, which will be discussed in this paper.

Discussion
Winter temperatures in North Central Alberta will drop to 60 degrees F below zero on occasion. Minimums of 40 degrees F below are expected. Unless proper design precautions are taken, temperatures at this precautions are taken, temperatures at this level can make a plant inoperable.
One of the first decisions to be made in plant design is the extent of housing for the plant. The plants being considered in this paper are basically unhoused. only process pumps containing water, compressors, firing ends of boilers and other small equipment containing water are housed. One major reason for this decision is safety. The gas we handle contains up to 17% hydrogen sulphide, which is extremely poisonous. poisonous.