bluuebunny/crossref_metadata_2025 huggingface dataset:
Electro-osmotic chemical treatment of clay with interbedded sand
Authors: Chien Shao-Chi , Ou Chang-Yu , Lo Wei-Wen
Published: October 2012

Electro-osmotic chemical treatment is a ground improvement method that injects chemical solutions into the soil during electro-osmosis to increase soil strength. However, previous studies have shown that the electro-osmotic chemical treatment method is inadequate when applied to clay with interbedded sand. The reason was that the injected chemical solutions may leak from the interbedded sand during electro-osmosis, resulting in poor improvement of the clay. In this study, a small-scale test cell (0·23 m wide, 0·44 m long, 0·32 m deep) with a pair of electrodes were designed to develop an appropriate electro-osmotic chemical treatment process for clay strata with sand layers. A clay stratum overlying a sand layer was used to make the conductivity of the sand layer relatively high. The results show that the permeability coefficient of the interbedded sand could be effectively reduced to 10−5–10−6 m/s by first injecting sodium silicate into the sand by pressure, followed by injecting calcium chloride by electro-osmosis. The calcium chloride could therefore effectively be flowed in the clay during electro-osmosis after decreasing the permeability coefficient of the interbedded sand, resulting in strength improvement of the clay. The strength of the clay was increased by up to 20 times the original strength near the cathode region.
Reducing driving forces for pressed-in piles
Authors: Gorasia Rohit Jay , McNamara Andrew Martin , Rettura Domenico
Published: October 2012

Pile jacking techniques use static loading to install sheet piles with minimal environmental effects, such as noise and ground vibrations, which are often associated with other methods of driven piling. This paper describes a series of 20g centrifuge tests conducted to investigate two methods of reducing the large driving forces that can be associated with jacked sheet piles in stiff clay. In practice, pre-auguring at the clutch positions and water jetting techniques are routinely carried out prior to the installation of sheet piling in order to reduce the driving forces. However, these methods are known to contribute to ground movements and can detract from the advantages of jacked sheet piles. The tests involved driving model sheet piles, which were modified either by installing driving shoes to the base of the pile, or by ribbing the profile of the pile shaft. The driving forces of the modified piles were compared with those of a plain pile. The tests showed that the use of driving shoes and ribs can lead to the reduction of driving forces at greater depth.
Heterogeneity and soil element testing
Authors: Wood D. Muir
Published: October 2012

Studies of strains within granular assemblies using digital image correlation have shown that as the resolution of observation becomes finer so the detail of the local variations of strains becomes more complex. The scale of this observed complexity is typically of the order of a few (5–10?) particles. The notion of a localised shear band of uniform shear or volumetric strain is not easily supported. In addition, studies reveal somewhat regular patterns of heterogeneity within samples which have been subjected to uniform external boundary deformations. A heterogeneous state is the natural state for granular materials. These observations have implications for the scales that should be adopted for testing of granular materials either in single-element or in physical model tests. Testing of a single element of a size that just accommodates a single region of ‘localisation’ will inevitably impose constraints on the particles in this region. On the other hand, one can envisage a representative element that is uniformly heterogeneous. Such an element would need to have dimensions that are large in comparison with the dimensions of the building blocks of the patterns of heterogeneity. These would define a length scale that is two orders of magnitude greater than typical particle sizes.
A conceptual model for the chemo-mechanical degradation of granular geomaterials
Authors: Buscarnera G.
Published: October 2012

A conceptual model is presented, the main aim of which is to elucidate the microscopic origins of the chemo-mechanical coupling in granular geomaterials. The study focuses on the interplay between the inelastic response under high compressive stresses and the chemical reactions leading to mineral dissolution. Chemical and mechanical processes are incorporated within a thermodynamic framework in which energy storage mechanisms depend on microstructural properties. Coupling between the two processes is reproduced through a simplified microscopic idealisation that establishes a link between the evolving microstructure (i.e. particle size geometry) and a chemical state variable. The mechanical implications at the continuum scale are finally derived through statistical homogenisation. The results disclose a relation between the evolution of the elastic properties of a chemically weathered geomaterial and the yielding threshold under high compressive stresses. Such dependency is obtained as an emergent property by advocating that the main contribution to the mechanical dissipation derives from the brittle breakage of the mineral compounds. This result stresses the importance of identifying the key physical processes that regulate macroscopic inelastic phenomena and can constitute a conceptual springboard for the development of chemo-mechanical models.
Investigation of the reduction in uncertainty due to soil variability when conditioning a random field using Kriging
Authors: Lloret-Cabot M. , Hicks M. A. , van den Eijnden A P.
Published: October 2012

Spatial variability of soil properties is inherent in soil deposits, whether as a result of natural geological processes or engineering construction. It is therefore important to account for soil variability in geotechnical design in order to represent more realistically a soil's in situ state. This variability may be modelled as a random field, with a given probability density function and scale of fluctuation. A more convenient way to deal with the uncertainty of a soil property due to spatial variability, by constraining the generated random field at the locations of actual field measurements, is presented in this article. Conditioning the random field at known locations is a powerful tool, not only because it more accurately represents the observed variability on site, but also because it uses the available field information more efficiently. In situ cone penetration test (CPT) data from a particular test site are used to determine the input statistics for generating random fields, which are later constrained (conditioned) at the locations of actual CPT measurements using the Kriging interpolation method. The results from the conditional random fields are then analysed, to quantify how the number of field measurements used influences the reduction of uncertainty. It is shown that the spatial uncertainty relative to the original (unconditional) random field reduces with the number of CPTs used in the conditioning.
Multiscale ‘tomography-to-simulation’ framework for granular matter: the road ahead
Authors: Andrade J. E. , VlahiniĆ I. , Lim K.-W. , Jerves A.
Published: October 2012

A roadmap is presented to transition seamlessly from an image to a predictive computational model for granular materials. So far, constitutive modelling in granular materials has been based on macroscopic experimental observations. Here, the point of departure is the basic granular scale where kinematics, contact forces and fabric control the macroscopic mechanical behaviour of the material. New computational and analytical tools are presented that allow for more accurate measurement of kinematics and inference of contact forces, directly from imaging tools (e.g. high-energy tomography). These grain-scale data are then used to construct powerful multiscale models that can predict the emergent behaviour of granular materials, without resorting to phenomenology, but can rather directly unravel the micro-mechanical origin of macroscopic behaviour. The aim of these tools is to furnish a ‘tomography-to-simulation’ framework, where experimental techniques, imaging procedures, and computational models are seamlessly integrated. These integrated techniques will help define a new physics-based approach for modelling and characterisation of granular soils in the near future.
3D assessment of fracture of sand particles using discrete element method
Authors: Cil M. B. , Alshibli K. A.
Published: October 2012

Shearing or compression of granular materials causes particles to translate and rotate relative to each other, interlock or fracture depending on their mineralogy, morphology, porosity, applied stresses and boundary conditions. Conventional soil plasticity theories consider mainly the stress level and density to predict soil failure and ignore the influence of particle fracture. However, recent research has shown that there is a strong relationship between granular particle fracture and plastic yielding and hardening. In this study, the fracture of individual silica sand particles was modelled by adopting the bonded particle model concept within the framework of the discrete element method (DEM). Individual three-dimensional (3D) particles were generated as an agglomerate of a large number of small spherical sub-particles that were connected by parallel bonds that resist moment and tension at contact points. The tensile strength variation observed when testing natural silica sand was achieved by changing the shape of the particle, the size and distribution of the spherical sub-particles and their bond strength. The onset and propagation of cracks through the particle were investigated using DEM and verified experimentally using 3D synchrotron micro-computed tomography images of sand. The behaviour across the scale from a single particle to a laboratory-size specimen is also presented and discussed.
Scale effects in rockfill behaviour
Authors: Alonso E. E. , Tapias M. , Gili J.
Published: October 2012

The particle sizes in large rockfill structures such as dams prevent laboratory testing. The prediction of field behaviour requires the development of models that integrate size effects. A distinct element method model was developed in which grains are characterised by aggregations of a maximum of 14 elementary spherical particles (the resulting particle shape approaches real geometries and allows a reasonable breakage evolution) and the particle breakage criterion involves the subcritical propagation of fissures in the grain. Time effects are included through the velocity of crack propagation, a function of stress state and defect size, which is introduced as a random set of varying lengths. The model was used to simulate the stress–strain response, the evolution of grain size distribution and creep behaviour under oedometric conditions. The model has been used to simulate size effects in the range 0·28–56·0 cm of initial particle size (uniform distributions were tested). Compressibility and creep were partially validated by comparing calculations with test results covering a reduced range of particles. The paper presents the evolution of short-term compressibility and creep indices in terms of particle size. The model is a useful and novel tool with which to extrapolate laboratory results from scaled grain size distributions to prototype dimensions.
Limonite – a weathered residual soil heterogeneous at all scales
Authors: Airey D. , Suchowerska A. , Williams D.
Published: October 2012

Limonite is a residual soil produced by the decomposition of magnesium silicate (olivine) rocks in tropical environments. During weathering most of the original rock is leached away leaving only its iron content, which is precipitated out in the form of iron sesqui-oxides to create a soft and highly porous soil. The predominant mineral present in limonite is goethite, which forms acicular nanoparticles that agglomerate to produce a silty sand with porous particles. The void ratio varies from 2 to 6, with higher values being a consequence of structure-supported voids. An extensive set of laboratory tests have been performed on a limonite soil profile which extends 50 m to rock. These data show that there is no pattern to shear strength with depth, with the shear strength equally likely to be 50 or 200 kPa through much of the profile. It is argued that the shear strength parameters for failure mechanisms, having any significant length, should be based on average values. The letter presents scanning electron microscopy photographs showing the fundamental particles, the results of triaxial tests comparing natural and reconstituted behaviour which show the effects of microstructure on the meso-scale response, and field data to show site variability.
Experimental micromechanics: grain-scale observation of sand deformation
Authors: Andò E. , Hall S. A. , Viggiani G. , Desrues J. , Bésuelle P.
Published: October 2012

Strain localisation plays a key role in the deformation of granular materials. Such localisation involves bands of just a few grains wide, which dominate the material's macroscopic response. This grain-scale phenomenon presents challenges for continuum modelling, which is the rationale behind models that explicitly take micro-scales into account. These in turn require micro-scale experimental analysis. In this work, X-ray tomography is used to image a small sample of oolitic sand while it deforms under triaxial compression. Grains are followed with a technique combining recent developments in image correlation and particle tracking. From these rich data, the evolution of the material in a subvolume of a thousand grains inside the sample (which contains 53 000 grains) is presented. The subvolume is chosen to lie inside the shear band that appears at the sample scale. Three-dimensional (3D) grain kinematics are analysed in three increments: the beginning of the test, the peak of the sample's macroscopic axial stress response and the residual stress state. When the sample's deformation is homogeneous (increment one) or fully localised (increment three), the kinematics of the grains in the subvolume appear to be representative of the kinematics occurring at the sample scale, allowing micro-mechanical observations to be made. In the transition from homogeneous to localised deformation (increment two), however, the scale of observation requires a zoom out of the subvolume to the sample scale in order to capture the complex mechanisms at play.
An experimental assessment of displacement fluctuations in a 2D granular material subjected to shear
Authors: Richefeu V. , Combe G. , Viggiani G.
Published: October 2012

In a granular material, a macroscopically homogeneous deformation does not correspond to a homogeneous displacement field when looking at the individual grains. The deviation of a grain displacement from the value dictated by the continuum field (referred to as ‘fluctuation’) is likely to hold valuable information about the characteristic length(s) involved in the grains' rearrangement, which is the principal mechanism of irreversible deformation for granular materials. This paper shows a selection of results from a series of shear tests on a two-dimensional analogue granular material. The route opened by the pioneering work of Radjaï and Roux is followed, and the same framework is used to analyse the experimental data on displacement fluctuations. Digital image correlation has been used to measure and characterise the displacement fluctuations. The analysis of their spatial organisation reveals the emergence of a minimum-length scale; that is, in the order of 10 times the mean particle size.
How to connect two scales of behaviour in constitutive modelling of geomaterials
Authors: Nguyen G. D. , Einav I. , Korsunsky A. M.
Published: October 2012

Localised failure of geomaterials involves deformation at two scales: a narrow localisation zone and the surrounding bulk. The behaviour associated with both scales should be properly taken into account in the development of constitutive models. This article presents a general constitutive modelling framework to connect these two scales, each of which is associated with a different stage of the material behaviour. It is demonstrated how this approach can be applied to any geomaterial model and how it could help obtain solutions independent of the spatial discretisation in numerical analysis.
A particle refinement method for simulating DEM of cone penetration testing in granular materials
Authors: Mcdowell G. R. , Falagush O. , Yu H.-S.
Published: October 2012

Discrete-element modelling of cone penetration testing (CPT) of granular materials in a calibration chamber has been performed. It was established that simulating the entire chamber with a realistic particle size requires too many particles. Simulating a segment of the chamber partly solves the problem, but the number of particle contacts at the cone tip is unrealistically small. A particle refinement method was therefore developed whereby particles nearer the cone tip were smaller than those further away. This was found to give a pronounced effect on the ability to model CPT in soils using the discrete-element method.
Dynamic fragmentation of rock clasts under normal compression in sturzstrom
Authors: Rait K. L. , Bowman E. T. , Lambert C.
Published: October 2012

Sturzstrom are massive and catastrophic long run-out rock avalanches that occur in mountainous areas around the world. The dynamic fragmentation of rock clasts is considered by some to be a key mechanism leading to long run-out behaviour in sturzstrom, but details on the micromechanics of the process are lacking. It is hypothesised here that the high strain rates applied to rock clasts at depth within a sturzstrom in motion promote dynamic fragmentation. The kinetic energy of the fine material generated during fragmentation is postulated to decrease effective stress in the system via a disruption of load transfer between heavily loaded particles (i.e. the strong force network). This results in a reduction in effective friction within the system, leading to longer run-out or greater clast spreading than would otherwise occur. The discrete element method is utilised via PFC3D to investigate this behaviour by placing a single brittle cluster of particles within a cubic arrangement of non-breakable clusters, each of which is hexagonally close packed. This system is placed under varying normally applied strain rates while determining the effect of fragmentation rate on the behaviour of near particles. It was found that strain rate is directly related to the fragmentation process where, so long as a load is applied sufficiently quickly, particles will dynamically fragment rather than simply split or crush. The strain rate tests indicate an abrupt change from a static to dynamic regime where the process of bond breakage changes from fracture to explosive fragmentation and kinetic energy dominates frictional dissipation of energy.
Steel sections subject to a long-duration blast
Authors: Clubley Simon K.
Published: October 2012

This paper examines the dynamic pressure effects of a long-duration blast load on small-diameter circular and angular structural steel members for a Mach stem region where a shock wave travels at near the speed of sound. In complicated flow fields, where fully coupled analyses are not reasonably practicable, the correct application of translational drag loads is vital. The variability in drag coefficient for members of the same shape can differ greatly, owing to stagnation of the flow and the level of flow field obstruction. To investigate this effect, this paper details a simplified experimental trial conducted in the world's most powerful blast tunnel, the US large-blast thermal simulator at White Sands Missile Range, New Mexico. Four assemblies were examined based upon hollow steel sections mounted at different angles and positions. The experiment indicated a drop in drag coefficient for shielded circular members in close proximity of approximately 40%. The drag force on unshielded sections was lower in magnitude than initially expected; this was attributed to an absence of flow stagnation and reduced boundary layer effects. Comparative square and angled sections displayed approximately 50% higher values than circular members.
Global ballast water management and the “same location” concept: a clear term or a clear issue?
Authors: David Matej , Gollasch Stephan , Pavliha Marko
Published: October 2012

The United Nations recognized the transfer of harmful organisms and pathogens across natural barriers as one of the four greatest pressures to the world's oceans and seas, causing global environmental changes, while also posing a threat to human health, property, and resources. Ballast water transferred by vessels was recognized as a prominent vector of such species and was regulated by the International Convention for the Control and Management of Ship's Ballast Water and Sediments (2004). Permanent exceptions from ballast water management requirements may apply when the uptake and discharge of ballast water occur at the “same location.” However, the “same location” concept may be interpreted differently, e.g., a port basin, a port, an anchorage, or a larger area even with more ports inside. Considering that the Convention is nearing the beginning of enforcement, national authorities all around the world will soon be exposed to applications for exceptions. Here we consider possible effects of different interpretations of the “same location” concept. We have considered different possible extensions of the same location through environmental, shipping, and legal aspects. The extension of such areas, and the inclusion of more ports, may compromise the Convention's main purpose. We recommend that “same location” mean the smallest practicable unit, i.e., the same harbor, mooring, or anchorage. An entire smaller port, possibly also including the anchorage, could be considered as same location. For larger ports with a gradient of environmental conditions, “same location” should mean a terminal or a port basin. We further recommend that IMO consider the preparation of a guidance document to include concepts, criteria, and processes outlining how to identify “same location,” which limits should be clearly identified.
«Smart Wells» is a Key to Production Enhancement from Low Permeable Reservoirs
Authors: Gulyaev Danila , Ipatov Andrey , Krichevskiy Vladimir
Published: October 2012

Recently the problems of the expansion of "smart wells" in Russia are discussed a lot, but there are still only few real global achievements in this direction. The major reason of the delay of transferring well-known western technology "smart wells" in Russian reality is its high unit cost. However an increase of hydrocarbons production and recovery from low permeable reservoirs using complex completion wells can't be achieved without moving to modern automated systems of «online» wells monitoring and layers control.
First Channel Fracturing Applied in Mature Wells Increases Production from Talinskoe Oilfield in Western Siberia
Authors: Kayumov Rifat , Klyubin Artem , Yudin Alexey , Enkababian Philippe , Leskin Fedor , Davidenko Igor , Kaluder Zdenko
Published: October 2012

In the last two decades, hydraulic fracturing has become a routine completion practice in most oilfields producing from the low- and medium-permeability Jurassic formations in western Siberia. To optimize hydraulic fracture conductivity, operators and service companies were progressively decreasing polymer loading in fracturing fluids, developing new polymer-free fluids, implementing foams as fracturing fluids, increasing proppant size and concentration, enhancing polymer breaker performance, increasing breaker concentration, and implementing the tip screenout technique. All these methods have some positive impact on proppant pack conductivity but lead to higher risk of premature screenout. The intrinsic limitations stem from the fact that conductivity is created by the proppant pack, which physically limits permeability. The new channel fracturing technique allows development of an open network of flow channels within the proppant pack; thus, the fracture conductivity is enabled by such channels rather than by flow through the pores between proppant grains in the proppant pack. The channel fracturing technique is capable of increasing fracture conductivity by up to two orders of magnitude.

Talinskoe field, located near Nyagan, Russia, produces from a series of Jurassic sublayers at depths of 2270 to 2700 m. Several oil-saturated sandstone sublayers are separated by shale barriers, and their development is conducted separately. For some wells, production from bottom sublayers JK10 and JK11 became uneconomical due to injection water breakthrough or low liquid rates. Production in these wells was switched to upper layers JK2 through JK9 after perforation and stimulation operations. Five of these wells were stimulated with the channel fracturing technique. Six-month of post-frac production data were compared with production data from eight offset wells stimulated recently via conventional hydraulic fracturing. The wells stimulated with the channel fracturing technology showed an average productivity index about 51% higher. This production effect still remains positive. The absence of screenouts confirmed reliability in proppant placement observed in other projects worldwide.

The successful implementation of the channel fracturing technique in brownfield development is described in detail with a theoretical and operational review, results from laboratory experiments, and analysis of the production results in comparison with conventional fracturing.
New Software for Processing of LWD Extra-Deep and Azimuthal Resistivity Data
Authors: Sviridov M. , Mosin A. , Antonov Yu. , Nikitenko M. , Martakov S. , Rabinovich M.
Published: October 2012

In petroleum exploration, reservoir navigation is used for reaching a productive reservoir and placing the borehole optimally inside the reservoir to maximize production. For proper well placement, it is necessary to calculate in real-time parameters of the formation we are drilling in, and the parameters of formations we are approaching. Based on these results, a decision to change the direction of drilling could be made. Modern logging while drilling (LWD) extra-deep and azimuthal resistivity tools acquire multi-component, multi-spacing, and multi-frequency data that provide sufficient information for resolving the surrounding formation parameters. These tools are generally used for reservoir navigation and real-time formation evaluation. However, real-time interpretation software very often is based on simplified resistivity models that can be inadequate and lead to incorrect geosteering decisions.

The core of the newly developed software is an inversion algorithm based on a model of transversely-isotropic layered earth with an arbitrary number of layers. The following model parameters are determined in real time: horizontal and vertical resistivities and thickness of each layer, formation dip, and azimuth. The inversion algorithm is based on the method of the most-probable parameter combination. The algorithm has good performance and excellent convergence due to its enhanced capability of avoiding local minima. This capability enables interpretation of real-time resistivity data, including azimuthal and extra-deep measurements.

A graphical user interface was developed to provide an interactive environment for each stage of the resistivity data interpretation process: preview of input resistivity logs, initial preprocessing and filtering of raw data, creation of initial guess, running inversion and viewing inversion results, and quality control indicators. Applications of the developed software will be shown on a series of synthetic examples and field data from the North Sea. This newly developed software is currently in use for real-time reservoir navigation and post-well analysis.
Digital Core Analysis - The Future of Petrophysics
Authors: Grachev Nikolai
Published: October 2012

The increasing complexity of collectors developed makes new demands on geological samples investigation methods. A breakthrough in high-performance calculations for multi-physical processesmade it possible to perform digital core analysis based on microanalysis and X-ray computed tomography allowing the study of the volume distribution of density inhomogeneties, physico-chemical and petrophysical properties of rocks. Data obtained by such methods can be used for quality control, laboratory research optimization, reservoir properties description of formation based on sludge and unconsolidated cores, characterization of cracks, cavities, the matrix porosity, distribution of salts in carbonates of Eastern Siberia, upscaling core – layer. As a result, companies in the industry can get the potential effect of the introduction of digital technology in the form of faster decision-making, refining the project design and economic model in the design of field development.
The New Multipurpose Neutron Generator MANK
Authors: Kirgizov D. I. , Kosarev V. E. , Lukhminsky B. E. , Teplyakov A. V.
Published: October 2012

Резюме

A new multi-purpose hardware-software system based on high-frequency pulsed neutron generator (MANK) is described. The main differences between this device from other devices of pulsed neutron logging (PNL) include: two probes, with each probes consists of a three epicadmium and thermal neutron counters, an variable frequency and duration of the fast neutron pulses. The device can measure the slowing-down time of neutrons, and determine the porosity of the reservoir with high sensitivity and weak influence of lithology, mineralization of the borehole and formation fluids. It is also possible the measurement of macro cross-section of thermal neutron capture (Sigma). There was completed computer (Monte-Carlo) optimization of the device, obtained a series of modeling and borehole measurements, obtained a set of interpretation charts for main parameters,
Dynamic Underbalance Perforating maximizes Well's Productivity by Minimizing Completion Damage on a Western Siberia Oil Field
Authors: Pickles M. , Lavdannikov P. , Amanov M. , Khabibullin T.
Published: October 2012

In Russia many operators are challenged with the goal to increase production on oil and gas fields by drilling new wells or by using enhanced completion designs in the old ones. The latter is significantly less expensive, hence is preferable. The transition from completion to production on new and workover wells requires optimal clean up and the removal of the perforation damage to achieve maximum productivity.

Perforating in the low formation pressure West Salym field has historically been performed overbalanced using wireline or with static underbalance using tubing conveyed perforating (TCP) with immediate well kill to remove guns. These perforating techniques, do not provide sufficient cleanup of the perforation tunnels and leave out significant perforation skin. A novel tubing conveyed perforating (TCP) technique using the dynamic underbalance effect combined with an afterperforation inflow testing was applied in the West Salym field. The goal was to achieve maximum productivity and to record the pressure transient. Deep penetrating charges were also used to bypass near wellbore damage and maximize potential results.

A customized TCP test string was designed for 7 in. (178mm) casing that had two sets of gauges installed at different depths, and a production valve for the in-flow surge. The test string allowed to conduct a perforation inflow test to estimate post perforation skin, productive zone permeability and reservoir pressure.

The operations were performed on 10 wells (5 workover wells and 5 new wells). Inflow pressure data on 5 wells, which allowed us to make conclusive estimates of skin, showed negative values. Improved productivity exceeded expected values by 10% on average.

Dynamic underbalanced perforating has enabled us to obtain clean perforation tunnels and resulted in an average 50% production increase in comparison to the average field production.
Aerated Underbalanced Drilling System Development
Authors: Al-Yami Abdullah S. , Schubert Jerome
Published: October 2012

Texas A&M University recently has established a new method to develop a drilling expert system to provide consultations related to best practices and trouble shooting in aerated underbalanced drilling. The drilling expert system is based on Bayesian network.

A Bayesian network is defined as "probabilistic graphical model that represents a set of random variables and their conditional independencies via a directed acyclic graph (DAG)." To the best of the authors' knowledge, this paper is the first study that shows the use of such method in aerated underbalanced drilling engineering.

The paper demonstrates the use of Bayesian network to develop the advisory system for aerated underbalanced drilling. To develop this system, we reviewed the literature and interviewed experts to find best practices in aerated underbalanced drilling. The advisory system can be used as a training tool for engineers to show them basic designing steps for aerated UBD.
Flow Induced Vibration In Subsea Production Systems
Authors: Smeulers Jan , Díez Néstor González , Slot Harmen
Published: October 2012

In the design of subsea flow systems, integrity and reliability are of paramount importance. As the equipment must be designed to operate at a large variety of conditions, inherent to the many processes, evaluation of the integrity is complex. Flow induced pulsations and vibrations can cause serious design and production problems, especially in subsea gas production systems. Mechanical vibrations can be induced by internal and external flow through a complex process that is affected by numerous factors such as the piping geometry, flow conditions and fluid properties. In the current subsea pipe system design, only the external flow induced vibrations are being addressed properly. Contemporary subsea production systems and piping are becoming more vulnerable for fatigue problems caused by internal flow induced vibrations and noise. This is mainly because of the increased complexity of offshore gas production project and subsea template designs and high production velocities. To ensure reliable operation over the entire life cycle of the project, it is important to understand if and how flow-induced vibrations affect the integrity of the subsea production system.
First Hydraulic Fracturing from a Supply Vessel in Russian Caspian Sea
Authors: Stenin V. P. , Delia S. V. , Levchenko V. S. , Vereschagin S. , Butula K. K. , Enkababian P.
Published: October 2012

Rakushechnoe-8 is one of the exploration wells drilled in the Northern Caspian Sea. The understanding of the geometry and performance of the propped fracture completion in the Apt formation was considered critical for the economical development of this offshore oilfield. Because of this, and the potential risk of fracture breaking into the water zone below, no resources were spared and robust engineering methods were applied for the first time in Russian offshore operations to determine the formation productivity without and with a hydraulic fracture completion in place. This case history will detail how a planned joint engineered approach provided critical information for the reservoir and production teams to determine the formations potentials, ensuring at the same time reliable and safe offshore operations.

After a detailed feasibility and engineering study, a local supply vessel was converted into a stimulation vessel to meet the maritime regulation requirements and projected needs of the Russian Federation. As part of the Project Readiness Assessment, the 4000-HHP strong frac equipment was mock-assembled on the dock, tested, and all the hazards evaluated before sailing. The joint engineering team prepared a rigorous plan for multi source data collection before, during, and after treatment operations. The plan included running dipole cased hole acoustic measurements before and after the frac treatment, bottomhole pressure gauges, a complete mini-frac test, multiple post mini-frac temperature logging runs, production logging runs, and well testing and sampling operations before and after the frac. Finally, a novel vertical seismic profile and micro-seismic measurement was employed to further understand the hydraulic fracture behavior in the Apt formation.

The data analyzed before the main fracture treatment enabled safe placement of all 49 tons of 16/20 mesh Intermediate Strength Proppant (ISP) through the drillstem test string obtaining a Cfd = 2.7 deemed optimal for the formation.

Post frac measurements and semi numerical modeling indicated that the mechanical model created before the mini frac required some additional modifications and that the propped fracture remained within the target zone. The acoustic and microseismic post frac measurements and well-test results correlated with the expected fracture effective half-lengths and conductivity, confirming that the preparation and execution involved with attaining accurate measurements provided significant value.
Turbulent Flow Laminarization Under Conditions Of Spatial and Heat Deformations in Pipelines
Authors: Alginov R. A. , Kharlamov S. N.
Published: October 2012

Investigation represented below is devoted to flows in channels with complicated wall configuration, containing cross-section variation along pipes (so-called convergent and divergent pipes) as well as under conditions of intensive heat supply to wall. Investigation was carried out in terms of original two-parametric k-L turbulence model adapted for internal flows on the basis of experimental data [1]. Obtained results are compared with experimental ones. Effects of laminarization are fixed, practical recommendations on use of these effects are given.
Implementation of the Upgraded Shut-Off Valves for Protecting Productive Formations
Authors: Kuznetsov Vasiliy Leontievich , Nurgaliev I. F. , Kutko R. O.
Published: October 2012

Annotation

The Vankor Field is being developed as network of horizontal production wells, with lateral filter length of not less than 1,000 m. The completion systems options include Equalizer™(Schlumberge), ResFlow (Baker Hughes) systems as well as various designs of slotted and screen filters made by Russian manufacturers.

With the purpose of achieving planned oil production capacities and oil recovery factors, it is critically important to save formation reservoir properties and prevent clogging of bottomhole formation zone.

For this purpose we analyzed the market of technologies used to eliminate contact of killing fluid with bottomhole formation zone during intervention and workover operations, and selected bottomhole shut-off valves for the Vankor Field conditions.

The main challenge of shut-off valves design selection is the functional possibility of conducting geophysical surveys using coiled tubing in lateral hole below packer set interval without prior retrieval of the packer.

By the time of selection, the Halliburton serial shut-off valves completely complied with these conditions but the implementation process was complicated by problems related to setting of shut-off valve in the G-6 packer seat due to complex wellbore profiles and deviation angles up to 90 degrees.

This publication describes the result achieved by joint operations of ZAO Vankorneft Oil and Gas Production Department specialists and Halliburton design engineers, which enabled us to successfully apply shut-off valves in the Vankor field wells.
Integrated Reservoir Fluid Characterization: A Case Study of Multilayered Yuzhno-Tambeyskoe Gas Condensate Field
Authors: Filippova J. , Mezentsev D.
Published: October 2012

Article contains the comparison of traditional and authors suggested methodologies for the composition of fluid modeling of multilayer gascondensate fields. Conditions of practical applications, benefits and constrains were denoted for green low-studied and operated fields.

As prerequisite for application of integrated approach: Basis of experimental determination of reservoir fluids composition's were described, causes and scopes of mistakes were analized.Possibility for integrated fluid model availability were justified.Basis for composition, matching and monitoring were configured for integrated fluid modeling of gascondensate field. Suggested technique could be applyed for reserves calculation, designing of field's development, designing of surface facility of transport and preparations.

Composition and employment of integrated fluid modeling of field can allow to get composition's properties of unstudied layers, to find mistakes data and correct them, to simplify preparation data for calculation gathering and treatment systems.
Increase of certainty of calculation of hydrocarbon reserves on the basis of fuzzy petrophysical compositions method
Authors: Ivanovich Kobrunov Aleksandr , Evgenevich Kuleshov Vladislav
Published: October 2012

The problem of parameter assessment characterizing oil-and-gas content, and its adequacy to real data which the geologist interpreter has is considered.

The necessity to appeal to this problem is connected with the existing methods of finding such parameters don't consider: the real character of geological-geophysical data and the specific errors arising at parameter assessment of oil-and-gas content and forecasting of their values;the uncertainty of conclusions concerning all parameters including volumetric data of hydrocarbon reserves on the field.

One of the main tasks of oil-and-gas field geology is calculation of hydrocarbon reserves which is nowadays carried out on the basis of three-dimensional geological-geophysical models. One of the key parameters influencing accuracy of reserve calculation is an authentic definition of factors of porosity and oil content which are calculated by means of field and geophysical methods of research. The last methods don't allow establishing the size of porosity and oil content but they estimate the sizes of geophysical parameters which are connected by correlation dependences with collector properties of breeds. To find the concrete expressions of these dependences and their parameters we use statistical data processing and finally we sometimes use replacement of the real experimental material with the received laws and some integrated assessment of Correlation ratio measure, i.e. the general for all dependence as a whole. According to the accepted technology the found law in the form of the coupling equations between parameters is transferred on the studied object. This way is often the source of erroneous conclusions which can bring: from incorrectly chosen conditions of opening and modes of well operation to mistakes in drill site and the conclusions about reserves and resources of hydrocarbon raw materials in the regions.
Potential to Increase Oil Reserves Due to Non-used "Lost" Deposits Located at Presently Operated Fields of OAO "Samaraneftegas"
Authors: Arkhipov V. S. , Zubova Yu. A. , Krainiy Yu. D. , Manasyan A. E. , Ustinov A. S.
Published: October 2012

Presently the objective to expand the resource basis of the now-operated hydro-carbon reserves remains rather acute. The experience in building-up the oil reserves is given on the basis of revealing previously non-operated reservoirs at the field that are presently operated. The practical efficiency of considered approach is proved. The search and start-up of these now not-operated reservoirs allows to build-up the amount of active reserves and to produce oil using the low-cost measures.

The paper presents the basic results of a system work with the same subject for the last two years. In 2010 they have opened and commissioned 6 new reservoirs at 5 fields that contain 1,364 million of tons of recoverable oil; the growth in oil production rate has made 843 t/d. In 2011 they have opened 14 new reservoirs at 13 fields, of which 11 pools were included into state balance. The build-up in recoverable reserves by industrial category C1 has made 1,681 million tons, the oil production rate growth - 801 t/d.
Integration of Conceptual Considerations in Geological Model of Riphean Carbonate Reservoir in Yurubcheno-Tokhomskoe Field
Authors: Kutukova N. M. , Birun E. M. , Malakhov R. A. , Savichev K. S. , Yatsenko V. M.
Published: October 2012

Carbonate reservoirs usually demonstrate considerable structural complexity and their high heterogeneity makes it difficult to predict their quality. Quite often productivity levels obtained in wells located close to each other and drilled to carbonate reservoirs differ from each other by a factor of ten or much more. Another issue is related to interpretation of log data in carbonate reservoirs: not always logs are sufficient to identify reservoirs and non-reservoirs and determine how much any component of the reservoir (fractures, cavities and matrix) contributes to the reservoir's effective capacity. High variety of poro-perm properties of carbonate reservoirs imply that geology and simulation modeling of hydrocarbon fields and making any forecasts for them bring about considerable difficulties and make it inevitable to use specific approaches to modeling process. Using as a case study one of the least clear fields by their geology in East Siberia, namely the Yurubcheno-Tokhomskoye field, the article describes an integrated approach to determining the reservoir's conceptual model and creating geological and simulation models.