Imperial College London

Dr Margaret "Daisy" Pataki

Central FacultyCentre for Languages, Culture and Communication

Teaching Fellow in Global Challenges
 
 
 
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m.pataki

 
 
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Location

 

Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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16 results found

Jacquemyn C, Pataki MEH, Hampson GJ, Jackson MD, Petrovskyy D, Geiger S, Marques CC, Machado Silva JD, Judice S, Rahman F, Costa Sousa Met al., 2021, Sketch-based interface and modelling of stratigraphy and structure in three dimensions, Journal of the Geological Society, Vol: 178, Pages: 1-17, ISSN: 0016-7649

Geological modelling is widely used to predict resource potential in subsurface reservoirs. However, modelling is often slow, requires use of mathematical methods that are unfamiliar to many geoscientists, and is implemented in expert software. We demonstrate here an alternative approach using sketch-based interface and modelling, which allows rapid creation of complex three-dimensional (3D) models from 2D sketches. Sketches, either on vertical cross-sections or in map-view, are converted to 3D surfaces that outline geological interpretations. We propose a suite of geological operators that handle interactions between the surfaces to form a geologically realistic 3D model. These operators deliver the flexibility to sketch a geological model in any order and provide an intuitive framework for geoscientists to rapidly create 3D models. Two case studies are presented, demonstrating scenarios in which different approaches to model sketching are used depending on the geological setting and available data. These case studies show the strengths of sketching with geological operators. Sketched 3D models can be queried visually or quantitatively to provide insights into heterogeneity distribution, facies connectivity or dynamic model behaviour; this information cannot be obtained by sketching in 2D or on paper.

Journal article

Costa Sousa M, Silva J, Silva C, De Carvalho F, Judice S, Rahman F, Jacquemyn C, Pataki M, Hampson G, Jackson M, Petrovskyy D, Geiger Set al., 2020, Smart modelling of geologic stratigraphy concepts using sketches, Smart Tools and Applications in computer Graphics (STAG) 2020, Publisher: The Eurographics Association, Pages: 89-100

Several applications of Earth Science require geologically valid interpretation and visualization of complex physical structures in data-poor subsurface environments. Hand-drawn sketches and illustrations are standard practices used by domain experts for conceptualizing their observations and interpretations. These conceptual geo-sketches provide rich visual references for exploring uncertainties and helping users formulate ideas, suggest possible solutions, and make critical decisions affecting the various stages in geoscience studies and modelling workflows. In this paper, we present a sketch-based interfaces and modelling (SBIM) approach for the rapid conceptual construction of stratigraphic surfaces, which are common to most geologic modelling scales, studies, and workflows. Our SBIM approach mirrors the way domain users produce geo-sketches and uses them to construct 3D geologic models, enforcing algorithmic rules to ensure geologically-sound stratigraphic relationships are generated, and supporting different scales of geology being observed and interpreted. Results are presented for two case studies demonstrating the flexibility and broad applicability of our rule-based SBIM approach for conceptual stratigraphy.

Conference paper

Zhang Z, Geiger S, Rood M, Jacquemyn C, Jackson M, Hampson G, De Carvalho FM, Silva CCMM, Silva JDM, Sousa MCet al., 2020, Fast flow computation methods on unstructured tetrahedral meshes for rapid reservoir modelling, Computational Geosciences, Vol: 24, Pages: 641-661, ISSN: 1420-0597

Subsurface reservoir models have a high degree of uncertainty regarding reservoir geometry and structure. A range of conceptual models should therefore be generated to explore how fluids-in-place, reservoir dynamics, and development decisions are affected by such uncertainty. The rapid reservoir modelling (RRM) workflow has been developed to prototype reservoir models across scales and test their dynamic behaviour. RRM complements existing workflows in that conceptual models can be prototyped, explored, compared, and ranked rapidly prior to detailed reservoir modelling. Reservoir geology is sketched in 2D with geological operators and translated in real-time into geologically correct 3D models. Flow diagnostics provide quantitative information for these reservoir model prototypes about their static and dynamic behaviours. A tracing algorithm is reviewed and implemented to compute time-of-flight and tracer concentrations efficiently on unstructured grids. Numerical well testing (NWT) is adopted in RRM to further interrogate the reservoir model. A new edge-based fast marching method is developed and implemented to solve the diffusive time-of-flight for approximating pressure transients efficiently on unstructured tetrahedral meshes. We demonstrate that an implementation of the workflow consisting of integrated sketch-based interface modelling, unstructured mesh generation, flow diagnostics, and numerical well testing is possible.

Journal article

Zhang Z, Geiger S, Rood M, Jacquemyn C, Jackson M, Hampson G, De Carvalho FM, Silva CCMM, Silva JDM, Sousa MCet al., 2020, Fast flow computation methods on unstructured tetrahedral meshes for rapid reservoir modelling, 16th European Conference on the Mathematics of Oil Recovery (ECMOR), Publisher: SPRINGER, Pages: 641-661, ISSN: 1420-0597

Conference paper

Jacquemyn C, Rood M, Melnikova Y, Salinas P, Jackson M, Hampson Get al., 2018, My Geology Is Too Complex for My Grid: Grid-Free Surface-Based Geological Modelling, EAGE annual conference and exhibition

Conference paper

Jacquemyn C, Rood MP, Melnikova Y, Salinas P, Jackson MD, Hampson GJet al., 2018, My geology is too complex for my grid: Grid-free surface-based geological modelling

Building spatially realistic representations of heterogeneity in reservoir models is a challenging task that is limited by predefined pillar or cornerpoint grids. Diverse rock types are ‘averaged’ within grid cells of arbitrary size and shape; continuity of baffles, barriers or high-permeability streaks is often lost; large features are over-resolved and small features are under-resolved or omitted. We present a surface-based modelling workflow using grid-free surfaces that allows creation of geological models without the limitations of predefined grids. Surface-based modelling uses a boundary-representation approach, modelling all heterogeneity of interest by its bounding surfaces, independent of any grid. Surfaces are modelled using a NURBS description. These surfaces are efficient, and allow fast creation of multiple realizations of geometrically realistic reservoir models. Surfaces are constructed by (1) extruding a cross section along a plan-view trajectory, or (2) using geostatistical models. Surface metadata is created to allow automatic assembly of these individual surfaces into full reservoir models. We demonstrate this surface-based approach using common elements such as facies belts, clinoforms, channels and concretions, which are combined into reservoir models that preserve realistic geometries. This is applied to a coastal-plain and overlying shoreface succession, analogous to an upper Brent Group reservoir, North Sea (e.g. SPE10-model).

Conference paper

Jacquemyn C, Rood MP, Melnikova Y, Salinas P, Jackson MD, Hampson GJet al., 2018, My geology is too complex for my grid: Grid-free surface-based geological modelling

© 2018 Society of Petroleum Engineers. All rights reserved. Building spatially realistic representations of heterogeneity in reservoir models is a challenging task that is limited by predefined pillar or cornerpoint grids. Diverse rock types are ‘averaged’ within grid cells of arbitrary size and shape; continuity of baffles, barriers or high-permeability streaks is often lost; large features are over-resolved and small features are under-resolved or omitted. We present a surface-based modelling workflow using grid-free surfaces that allows creation of geological models without the limitations of predefined grids. Surface-based modelling uses a boundary-representation approach, modelling all heterogeneity of interest by its bounding surfaces, independent of any grid. Surfaces are modelled using a NURBS description. These surfaces are efficient, and allow fast creation of multiple realizations of geometrically realistic reservoir models. Surfaces are constructed by (1) extruding a cross section along a plan-view trajectory, or (2) using geostatistical models. Surface metadata is created to allow automatic assembly of these individual surfaces into full reservoir models. We demonstrate this surface-based approach using common elements such as facies belts, clinoforms, channels and concretions, which are combined into reservoir models that preserve realistic geometries. This is applied to a coastal-plain and overlying shoreface succession, analogous to an upper Brent Group reservoir, North Sea (e.g. SPE10-model).

Conference paper

Zhang Z, Geiger S, Rood M, Jacquemyn C, Jackson M, Hampson G, De Carvalho FM, Marques Machado Silva CC, Machado Silva JD, Sousa MCet al., 2017, A Tracing Algorithm for Flow Diagnostics on Fully Unstructured Grids With Multipoint Flux Approximation, SPE Journal, Vol: 22, Pages: 1946-1962, ISSN: 1930-0220

Flow diagnostics is a common way to rank and cluster ensembles of reservoir models depending on their approximate dynamic behavior before beginning full-physics reservoir simulation. Traditionally, they have been performed on corner-point grids inherent to geocellular models. The rapid-reservoir-modeling (RRM) concept aims at fast and intuitive prototyping of geologically realistic reservoir models. In RRM, complex reservoir heterogeneities are modeled as discrete volumes bounded by surfaces that are sketched in real time. The resulting reservoir models are discretized by use of fully unstructured tetrahedral meshes where the grid conforms to the reservoir geometry, hence preserving the original geological structures that have been modeled.This paper presents a computationally efficient work flow for flow diagnostics on fully unstructured grids. The control-volume finite-element method (CVFEM) is used to solve the elliptic pressure equation. The flux field is a multipoint flux approximation (MPFA). A new tracing algorithm is developed on a reduced monotone acyclic graph for the hyperbolic transport equations of time of flight (TOF) and tracer distributions. An optimal reordering technique is used to deal with each control volume locally such that the hyperbolic equations can be computed in an efficient node-by-node manner. This reordering algorithm scales linearly with the number of unknowns.The results of these computations allow us to estimate swept-reservoir volumes, injector/producer pairs, well-allocation factors, flow capacity, storage capacity, and dynamic Lorenz coefficients, which all help approximate the dynamic reservoir behavior. The total central-processing-unit (CPU) time, including grid generation and flow diagnostics, is typically a few seconds for meshes with O (100,000) unknowns. Such fast calculations provide, for the first time, real-time feedback in the dynamic reservoir behavior while models are prototyped.

Journal article

Zhang Z, Geiger S, Rood M, Jacquemyn C, Jackson M, Hampson G, De Carvalho FM, Machado Silva CCM, Silva JM, Sousa MCet al., 2017, Flow diagnostics on fully unstructured grids, Pages: 772-787

Flow-diagnostics are a common way to rank and cluster ensembles of reservoir models based on their approximate dynamic behaviour prior to commencing full-physics reservoir simulation. Traditionally, flow diagnostics are carried out on corner-point grids inherent to geocellular models. The novel "Rapid Reservoir Modelling" (RRM) concept enables fast and intuitive prototyping and updating of reservoir models. In RRM, complex reservoir heterogeneities are modelled as discrete volumes bounded by surfaces that can be modified using simple sketching operations in real time. The resulting reservoir models are discretized using fully unstructured 3D meshes where the grid conforms to the reservoir geometry. This paper presents a new and computationally efficient numerical scheme that enables flow diagnostic calculations on fully unstructured grids. Time-of-flight and steady-state tracer distributions are computed directly on the grid. The results of these computations allows us to estimate swept reservoir volumes, injector-producer pairs, well-allocation factors, flow capacity, storage capacity and dynamic Lorenz coefficients which all help approximate the dynamic reservoir behaviour. We use the Control Volume Finite Element Method (CVFEM) to solve the elliptic pressure equation. A scalable matrix solver (SAMG) is used to invert the linear system. A new edge-based CVFEM is developed to solve hyperbolic transport equations for time-of-flight and tracer distributions. An optimal reordering technique is employed to deal with each control volume locally such that the hyperbolic equations can be computed in an efficient node-by-node manner. This reordering algorithm scales linearly with the number of unknowns. The total CPU time, including grid generation and flow diagnostics, is typically below 3 seconds for grids with 50k unknowns. Such fast calculations provide, for the first time, real-time feedback on changes in the dynamic reservoir behaviour while the reservoir m

Conference paper

Koehn D, Rood MP, Beaudoin N, Chung P, Bons PD, Gomez-Rivas Eet al., 2016, A new stylolite classification scheme to estimate compaction and local permeability variations, Sedimentary Geology, Vol: 346, Pages: 60-71, ISSN: 0037-0738

We modeled the geometrical roughening of bedding-parallel, mainly layer-dominated stylolites in order to understand their structural evolution, to present an advanced classification of stylolite shapes and to relate this classification to chemical compaction and permeability variations at stylolites. Stylolites are rough dissolution seams that develop in sedimentary basins during chemical compaction. In the Zechstein 2 carbonate units, an important lean gas reservoir in the southern Permian Zechstein basin in Germany, stylolites influence local fluid flow, mineral replacement reactions and hence the permeability of the reservoir. Our simulations demonstrate that layer-dominated stylolites can grow in three distinct stages: an initial slow nucleation phase, a fast layer-pinning phase and a final freezing phase if the layer is completely dissolved during growth. Dissolution of the pinning layer and thus destruction of the stylolite's compaction tracking capabilities is a function of the background noise in the rock and the dissolution rate of the layer itself. Low background noise needs a slower dissolving layer for pinning to be successful but produces flatter teeth than higher background noise. We present an advanced classification based on our simulations and separate stylolites into four classes: (1) rectangular layer type, (2) seismogram pinning type, (3) suture/sharp peak type and (4) simple wave-like type. Rectangular layer type stylolites are the most appropriate for chemical compaction estimates because they grow linearly and record most of the actual compaction (up to 40 mm in the Zechstein example). Seismogram pinning type stylolites also provide good tracking capabilities, with the largest teeth tracking most of the compaction. Suture/sharp peak type stylolites grow in a non-linear fashion and thus do not record most of the actual compaction. However, when a non-linear growth law is used, the compaction estimates are similar to those making use of the rect

Journal article

Jackson MD, Hampson GJ, Rood D, Geiger S, Zhang Z, Sousa MC, Amorim R, Brazil EV, Samavati FF, Guimaraes LNet al., 2015, Rapid Reservoir Modeling: Prototyping of Reservoir Models, Well Trajectories and Development Options using an Intuitive, Sketch-Based Interface, Publisher: Society of Petroleum Engineers

Abstract Constructing or refining complex reservoir models at the appraisal, development, or production stage is a challenging and time-consuming task that entails a high degree of uncertainty. The challenge is significantly increased by the lack of modeling, simulation and visualization tools that allow prototyping of reservoir models and development concepts, and which are simple and intuitive to use. Conventional modeling workflows, facilitated by commercially available software packages, have remained essentially unchanged for the past decade. However, these are slow, often requiring many months from initial model concepts to flow simulation or other outputs; moreover, many model concepts, such as large scale reservoir architecture, become fixed early in the process and are difficult to retrospectively change. Such workflows are poorly suited to rapid prototyping of a range of reservoir model concepts, well trajectories and development options, and testing of how these might impact on reservoir behavior. We present a new reservoir modeling and simulation approach termed Rapid Reservoir Modeling (RRM) that allows such prototyping and complements existing workflows. In RRM, reservoir geometries that describe geologic heterogeneities (e.g. faults, stratigraphic, sedimentologic and/or diagenetic features) are modelled as discrete volumes bounded by surfaces, without reference to a predefined grid. These surfaces, and also well trajectories, are created and modified using intuitive, interactive techniques from computer visualization, such as Sketch Based Interfaces and Modeling (SBIM). Input data can be sourced from seismic, geocellular or flow simulation models, outcrop analogues, conceptual model libraries or blank screen. RRM outputs can be exported to conventional workflows at any stage. Gridding or meshing of the models within the RRM framework allows rapid calculation of key reservoir properties and dynamic behaviors linked with well trajectories and developmen

Conference paper

Koehn D, Toussaint R, Ebner M, Gomez-Rivas E, Bons P, Rood Det al., 2014, Stylolite stress inversion, EGU General Meeting 2014

Conference paper

Clark JD, Yepes O, Pataki M, Schweller Wet al., 2008, Integrating seismic, well and core data for stratigraphic interpretation of reservoir architecture and facies distribution in deepwater slope valleys: Landana Field, Block 14, Angola, AAPG International Conference 2008

Conference paper

Pataki MEH, 2007, The influence of mica on quartz pressure solution and stylolite development in Plio- Pleistocene and Jurassic sandstones

Thesis dissertation

Pataki MEH, Boles JR, 2007, Muscovite, illite and organic material drive quartz pressure solution and stylolite development in Plio-Pleistocene, Jurassic and Ordovician sandstones, Geological Society of America, Pages: 506-506

Conference paper

Boles JR, Israelachvili J, Alcantar N, Anzalone A, Meyer E, Greene W, Pataki Met al., 2005, Pressure solution and mica in quartzose sandstone: Observations and experiments, 15th Annual VM Goldschmidt Conference, Pages: A311-A311, ISSN: 1872-9533

Conference paper

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