Rockfield Software Ltd

King's Lynn, United Kingdom

Rockfield Software Ltd

King's Lynn, United Kingdom

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Lobao M.C.,University of Swansea | Lobao M.C.,Black and Veatch Ltd. | Eve R.,Rockfield Software Ltd. | Owen D.R.J.,University of Swansea | De Souza Neto E.A.,University of Swansea
Engineering Computations (Swansea, Wales) | Year: 2010

Purpose - The mechanical response of the skeleton of a porous medium is highly dependent on its seepage behaviour as pore pressure modifications affect the in situ stress field. The purpose of this paper is to describe how u-p formulation is employed using an explicit time integration scheme where fully saturated and single-phase partially saturated analyse are incorporated for 2D and 3D cases. Design/methodology/approach - Owing to their inherent simplicity, low-order elements provide an excellent framework in which contact conditions coupled with crack propagation can be dealt with in an effective manner. For linear elements this implies single point integration which, however, can result in spurious zero-energy modes which necessitates introduction of a stabilization technique to provide reliable results. Findings - The success of the modelling strategy ultimately depends on the inter-dependence of different phenomena. The linking between the displacements components, network and pore pressures represents an important role in the efficiency of the overall coupling procedure. Therefore, a master-slave technique is proposed to link seepage and network fields, proving to be particularly attractive from a computational cost point of view. Another development that has provided substantial savings in CPU times is the use of an explicit-explicit subcycling scheme. Originality/value - Significant reduction in computational cost is achievable using a master-slave procedure to link seepage and fracture network-flows and an explicit-explicit subcycling scheme. Special attention is focused on the investigation of the influence of plastic zones in oil production problems. © Emerald Group Publishing Limited.


Grant
Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: NMP-2008-1.1-1 | Award Amount: 4.93M | Year: 2010

The main scientific aims are to radically improve understanding of the human mechanotransduction system and tissue engineered nanobiosensors. This will be achieved through systematic integration of new developments from converging scientific areas by involving academic and industrial participants who are experts in cognitive sciences, microneurography, brain imaging, cell biology and mechanics, tissue engineering, skin physics (tribology and mechanics), microengineering, multi-scale multi-physics modelling, information processing, robotics, prosthetics and medical rehabilitation. The project will build on existing discriminative touch research in order to understand affective touch mediated by the human fingerpad. Sensors capable of detecting directional force and temperature will be developed since a combination of these modalities is critical to the affective component of the neurophysiological response evoked in taction. This next generation of sensors will include NEMS arrays and hybrid bio-NEMS systems. They will be integrated into a robotic finger with articulation controlled by neural network information processing that will allow artificial exploration of a surface to be achieved in ways that mimic human haptic behaviour and affective response. The impact of the project will include alleviating the effects of human touch and vision disabilities, improving the quality of life, security printing, brand protection, smart packaging, space exploration and also the evaluation of products such as textiles and skin creams using the instrumented robotic finger. The consortium includes industrial participants who will undertake specific technical exploitation activities in order to maximise the commercial impact of the research.


Angus D.A.,University of Leeds | Kendall J.-M.,University of Bristol | Fisher Q.J.,University of Leeds | Segura J.M.,University of Leeds | And 5 more authors.
Geophysical Prospecting | Year: 2010

In this paper, we investigate production induced microseismicity based on modelling material failure from coupled fluid-flow and geomechanical simulation. The model is a graben style reservoir characterized by two normal faults subdividing a sandstone reservoir into three compartments. The results are analysed in terms of spatial and temporal variations in distribution of material failure. We observe that material failure and hence potentially microseismicity is sensitive to not only fault movement but also fluid movement across faults. For sealing faults, failure is confined to the volume in and around the well compartment, with shear failure localized along the boundaries of the compartment and shear-enhanced compaction failure widespread throughout the reservoir compartment. For non-sealing faults, failure is observed within and surrounding all three reservoir compartments as well as a significant distribution located near the surface of the overburden. All shear-enhanced compaction failures are localized within the reservoir compartments. Fault movement leads to an increase in shear-enhanced compaction events within the reservoir as well as shear events located within the side-burden adjacent to the fault. We also evaluate the associated moment tensor mechanisms to estimate the pseudo scalar seismic moment of failure based on the assumption that failure is not aseismic. The shear-enhanced compaction events display a relatively normal and tight pseudo scalar seismic moment distribution centred about 106 Pa, whereas the shear events have pseudo scalar seismic moments that vary over three orders of magnitude. Overall, the results from the study indicate that it may be possible to identify compartment boundaries based on the results of microseismic monitoring. © 2010 European Association of Geoscientists & Engineers.


Thornton D.A.,Rockfield Software Ltd | Thornton D.A.,Chevron | Crook A.J.L.,Three Cliffs Geomechanical Analysis
Rock Mechanics and Rock Engineering | Year: 2014

Reconstruction of geological structures has the potential to provide additional insight into the effect of the depositional history on the current-day geomechanical and hydro-geologic state. Accurate modeling of the reconstruction process is, however, complex, necessitating advanced procedures for the prediction of fault formation and evolution within fully coupled geomechanical, fluid flow and temperature fields. In this paper, a 3-D computational approach is presented that is able to forward model complex structural evolution with multiple intersecting faults that exhibit large relative movement within a coupled geomechanical/flow environment. The approach adopts the Lagrangian method, complemented by robust and efficient automated adaptive meshing techniques, an elasto-plastic constitutive model based on critical state concepts, and global energy dissipation regularized by inclusion of fracture energy in the equations governing state variable evolution. The proposed model is validated by comparison of 2-D plane strain and 3-D thin-slice predictions of a bench-scale experiment, and then applied to two conceptual coupled geomechanical/fluid flow field-scale benchmarks. © 2014 Springer-Verlag Wien.


Thornton D.A.,Rockfield Software Ltd. | Thornton D.A.,Chevron | Crook A.J.L.,Three Cliffs Geomechanical Analysis
47th US Rock Mechanics / Geomechanics Symposium 2013 | Year: 2013

Reconstruction of geological structures has the potential to provide additional insight into the effect of the depositional history on the current day geomechanical and hydro-geologic state. Accurate modeling of the reconstruction process is however complex, necessitating advanced procedures for the prediction of fault formation and evolution within fully coupled geomechanical, fluid flow and temperature fields. In this paper, a 3-D computational approach is presented that is able to forward model complex structural evolution with multiple intersecting faults that exhibit large relative movement within a coupled geomechanical/flow environment. The approach adopts the Lagrangian method, complemented by robust and efficient automated adaptive meshing techniques, an elasto-plastic constitutive model based on critical state concepts, and global energy dissipation regularized by inclusion of fracture energy in the equations governing state variable evolution. The proposed model is validated by comparison of 2-D plane strain and 3-D thin-slice predictions of a bench-scale experiment, and then applied to two conceptual coupled geomechanical/fluid flow field-scale benchmarks. Copyright 2013 ARMA, American Rock Mechanics Association.


Roberts D.T.,Rockfield Software Ltd. | Roberts D.T.,University of Cardiff | Crook A.J.L.,University of Leeds | Cartwright J.A.,University of Oxford | Profit M.L.,University of Cardiff
49th US Rock Mechanics / Geomechanics Symposium 2015 | Year: 2015

Polygonal faults are thought to potentially compromise the integrity of regional caprocks and are widely developed in mudrocks that are targeted for unconventionals exploration. Polygonal Fault Systems (PFS) contain networks of exclusively normal faults that intersect bedding planes at a wide variety of azimuths. This fact alone suggests a non-tectonic origin and recent arguments focus on a constitutive control on PFS formation. Geomechanical forward modelling has the potential to shed light on the evolution of material and stress state as geological structures form. The evolution of polygonal faults is studied here using the finite strain forward modelling code ELFEN FM. More specifically the recently suggested diagenetic trigger for PFS formation is investigated, and the process of incorporating this into a critical-state based model is outlined and discussed. The results demonstrate the formation of PFS in both 2D plane-strain and full 3D simulations as validation of both the genetic argument and the computational approach. PFS are additionally observed to be sensitive to subtle horizontal stress anisotropy e.g. around salt diapirs or larger tectonic faults. As such, there is the potential for these fault networks to act as 'paleo-stress piezometers'. This study investigates this by incorporating subtle stress anisotropy into the model and observing the influence on fault alignment. Results indicate that even for subtle stress anisotropy, preferential fault alignment is observed and this is consistent with observation. Copyright 2015 ARMA, American Rock Mechanics Association.


Segura J.M.,University of Leeds | Fisher Q.J.,University of Leeds | Crook A.J.L.,Rockfield Software Ltd | Dutko M.,Rockfield Software Ltd | And 6 more authors.
Petroleum Geoscience | Year: 2011

The reduction of fluid pressure during reservoir production promotes changes in the effective and total stress distribution within the reservoir and the surrounding strata. This stress evolution is responsible for many problems encountered during production (e.g. fault reactivation, casing deformation). This work presents the results of an extensive series of 3D numerical hydro-mechanical coupled analyses that study the influence of reservoir geometry and material properties on the reservoir stress path. The stress path is defined in terms of parameters that quantify the amount of stress arching and stress anisotropy that occur during reservoir production. The coupled simulations are performed by explicitly coupling independent commercial geomechanical and flow simulators. It is shown that stress arching is important in reservoirs with low aspect ratios that are less stiff than the bounding material. In such cases, the stresses will not significantly evolve in the reservoir, and stress evolution occurs in the over- and sideburden. Stiff reservoirs, relative to the bounding rock, exhibit negligible stress arching regardless of the geometry. Stress anisotropy reduces with reduction of the Young's modulus of the bounding material, especially for low aspect ratio reservoirs, but as the reservoir extends in either or both of the horizontal directions, the reservoir deforms uniaxially and the horizontal stress evolution is governed by the Poisson's ratio of the reservoir. Furthermore, the effect of the stress path parameters is introduced in the calculation of pore volume multiplier tables to improve non-coupled simulations, which otherwise overestimate the average reservoir pore pressure drawdown when stress arching is taking place. © 2011 EAGE/Geological Society of London.


Baird A.F.,University of Bristol | Kendall J.-M.,University of Bristol | Verdon J.P.,University of Bristol | Wuestefeld A.,NORSAR | And 4 more authors.
Geophysical Journal International | Year: 2013

Hydraulic overpressure can induce fractures and increase permeability in a range of geological settings, including volcanological, glacial and petroleum reservoirs. Here we consideran example of induced hydraulic fracture stimulation in a tight-gas sandstone. Successful exploitation of tight-gas reservoirs requires fracture networks, either naturally occurring, or generated through hydraulic stimulation. The study of seismic anisotropy provides a means to infer properties of fracture networks, such as the dominant orientation of fracture sets and fracture compliances. Shear wave splitting from microseismic data acquired during hydraulic fracture stimulation allows us to not only estimate anisotropy and fracture properties, but also to monitor their evolution through time. Here, we analyse shear wave splitting using microseismic events recorded during a multistage hydraulic fracture stimulation in a tight-gas sandstone reservoir. A substantial rotation in the dominant fast polarization direction (ψ) is observed between the events of stage 1 and those from later stages. Although large changes in ψ have often been linked to stress-induced changes in crack orientation, here we argue that it can better be explained by a smaller fracture rotation coupled with an increase in the ratio of normal to tangential compliance (ZN/ZT) from 0.3 to 0.6. ZN/ZT is sensitive to elements of the internal architecture of the fracture, as well as fracture connectivity and permeability. Thus, monitoring ZN/ZT with shear wave splitting can potentially allow us to remotely detect changes in permeability caused by hydraulic stimulation in a range of geological settings. © The Authors 2013. Published by Oxford University Press on behalf of The Royal Astronomical Society.


Carneiro Molina A.J.,Rockfield Software Ltd | Curiel-Sosa J.L.,University of Sheffield
Finite Elements in Analysis and Design | Year: 2015

This paper presents a multiscale finite element homogenization technique (MFEH) for modelling nonlinear deformation of multi-phase materials. A novel condensation technique to relate force variations acting on the representative volume element (RVE) - involving antiperiodicity of traction forces at RVE corners - and displacement variations on boundary-nodes is proposed. The formulation to accommodate the condensation technique and overall tangent modulus is presented in detail. In this context, the effective homogenised tangent modulus is computed as a function of microstructure stiffness matrix which, in turn, depends upon the material properties and geometrical distribution of the micro-constituents. Numerical tests concerning plastic materials with different voids distributions are presented to show the robustness of the proposed MFEH. © 2014 Elsevier B.V. All rights reserved.


Profit M.L.,Rockfield Software Ltd | Dutko M.,Rockfield Software Ltd | Yu J.,Rockfield Software Ltd
49th US Rock Mechanics / Geomechanics Symposium 2015 | Year: 2015

Hydraulic fracturing in tight gas reservoirs is a complex physical process with interactions between tracking fluid flow in a confined channel, fracture propagation in reaction to an initial and evolving stress state, proppant transport inside an advancing fracture and finally gas production over the life-time of the well. This paper outlines the modelling methodology of a combined Finite Element (FE) and Discrete Element (DE) technology which is used in the software package ELFEN to simulate hydraulic fracturing. Current FE/DE technologies require a fine mesh in the region of the advancing tip to satisfactorily capture stress concentrations. The developments are centred on the capability to simulate fracture propagation within a geometry fracture insertion rather than element splitting framework. A local remeshing scheme is adopted instead of a traditional global remeshing procedure in which a fine mesh is maintained only adjacent to fracture tips to readily cut down on computational cost. The newly developed technology is demonstrated on simulating fluid driven fractures in single and multiple stimulated wells. Copyright 2015 ARMA, American Rock Mechanics Association.

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