A. Levannier

Schlumberger (British Virgin Islands)

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Samita Santoshini

Schlumberger (British Virgin Islands)

Azeddine Benabbou

Schlumberger (British Virgin Islands)

Johanna Lofi

Université de Montpellier

Thomas Viard

RIKEN Center for Advanced Intelligence Project

N. Denchik

Géosciences Montpellier

Simon D. Harris

Schlumberger (British Virgin Islands)

Osama Khan

Schlumberger (British Virgin Islands)

Sheleem Kashem

Schlumberger (British Virgin Islands)

Colin Daly

Schlumberger (United Kingdom)

Denis Neyens

imaGeau (France)

Cooperative Institutions

Schlumberger (British Virgin Islands)

Centre National de la Recherche Scientifique

Géosciences Montpellier

Université de Montpellier

Milieux environnementaux, transferts et interactions dans les hydrosystèmes et les sols

Bureau de Recherches Géologiques et Minières

École Nationale Supérieure des Mines de Nancy

Université de Lorraine

Schlumberger (United Kingdom)

IFP Énergies nouvelles

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Electrical Monitoring of Fresh Water Displacement in a Brackish Aquifer During Aquifer Storage and Recovery: Forward and Inverse Modeling Results

AGU Fall Meeting Abstracts (2003)

A. Levannier J. P. Delhomme

Specific storage

Water storage

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Citations (1)

Depogrid: Next Generation Unstructured Grids for Accurate Reservoir Modeling and Simulation

SPE Russian Petroleum Technology Conference (2018)

Samita Santoshini Simon D. Harris Sheleem Kashem A. Levannier Azeddine Benabbou

Abstract As the oil and gas industry is moving toward tapping reserves in more complex structural environments, there comes the challenge for the reservoir modeling platform to accurately and robustly build and simulate a model to aid in making more trustworthy reserve estimates and field development plans. The 3D geocellular model sits at the core of an integrated seismic-to-simulation workflow, within which one can characterize and predict the behavior of reservoirs and can make confident quantitative decisions about one's assets. In structurally complex areas, the construction of accurate 3D models is often impeded by fundamental limitations of standard geocellular modeling technologies. With these limitations in mind, a new cut-cell unstructured grid has been developed that honors the geological structure precisely, enables accurate property modeling in a flattened, un-faulted, pseudo-depositional space, and can be simulated directly in a next-generation simulator; we call this unstructured grid built in depositional space a ‘depogrid’. The polyhedral, cut-cell nature of the depogrid arises when the regularly gridded volume in depositional space is cut by the structural model features (faults and unconformities) before being forward-deformed into geological space. By construction, the grid cell columns are orthogonal to the local stratigraphy, yet they can accurately represent complex structures and volumes, independent of the grid resolution. A next-generation high resolution reservoir seamlessly consumes the globally unstructured grid topology, with the structural complexity and non-neighbor connections, and honors the flow dynamics accurately. This ensures a more geologically consistent simulation model, realistic parameters to tune for history matching workflows and the ability to make reliable predictions. We present some particular reservoir modeling and simulation considerations where the depogrid approach improves on typical gridding technologies. The seismic-to-simulation workflow is then applied to several structural examples to demonstrate how the depogrid is best suited to model the geological structure and properties in a variety of reservoirs and subsequently improves the accuracy and efficiency of field development planning and risk mitigation.

Reservoir Simulation

Unstructured grid

10.2118/191615-18rptc-ms

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Citations (5)

Complex Geological Modeling Using Unstructured Grids: Quality Assurance Approaches and Improved Prediction

Simon D. Harris Samita Santoshini Stewart W. Smith A. Levannier Osama Khan

Abstract The vast majority of grids for reservoir modeling and simulation workflows are based on pillar gridding or stairstep grid technologies. The grids are part of a feature-rich and well-established modeling workflow provided by many commercial software packages. Undesirable and significant simplifications to the gridding often arise when employing such approaches in structurally complex areas, and this will clearly lead to poor predictions from the downstream modeling. In the classical gridding and modeling workflow, the grid is built in geological space from input horizon and fault interpretations, and the property modeling occurs in an approximated ‘depositional’ space generated from the geological space grid cells. The unstructured grids that we consider here are based on a very different workflow: a volume-based structural model is first constructed from the fault/horizon input data; a flattening (‘depositional’) mapping deforms the mesh of the structural model under mechanical and geometric constraints; the property modeling occurs in this depositional space on a regular cuboidal grid; after ‘cutting’ this grid by the geological discontinuities, the inverse depositional mapping recovers the final unstructured grid in geological space. A critical part of the depositional transformation is the improved preservation of geodetic distances and the layer-orthogonality of the grid cells. The final grid is an accurate representation of the input structural model, and therefore the quality checking of the modeling workflow must be focused on the input data and structural model creation. We describe a variety of basic quality checking and structurally-focused tools that should be applied at this stage; these tools aim to ensure the accuracy of the depositional transformation, and consequently ensure both the quality of the generated grid and the consistent representation of the property models. A variety of quality assurance metrics applied to the depositional/geological grid geometries provide spatial measures of the ‘quality’ of the gridding and modeling workflow, and the ultimate validation of the structural quality of the input data. Two case studies will be used to demonstrate this novel workflow for creating high-quality unstructured grids in structurally complex areas. The improved quality is validated by monitoring downstream impacts on property prediction and reservoir simulation; these improved prediction scenarios are a more accurate basis for history matching approaches.

Unstructured grid

10.2523/iptc-19303-ms

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Citations (1)

Time-lapse downhole electrical resistivity monitoring of subsurface CO 2 storage at the Maguelone shallow experimental site (Languedoc, France)

International journal of greenhouse gas control (2015)

Philippe Pézard N. Denchik Johanna Lofi H. Perroud Gilles Henry

10.1016/j.ijggc.2015.12.005

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Citations (16)

Complex Geological Modeling Using Unstructured Grids: Quality Assurance Approaches and Improved Prediction

International Petroleum Technology Conference (2019)

Simon R. Harris Samita Santoshini Stewart Smith A. Levannier Osama Khan

Unstructured grid

10.2523/19303-ms

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Citations (1)

Complex Geological Modeling and Quality Assurance Using Unstructured Grids

Simon D. Harris Samita Santoshini Sheleem Kashem Thomas Viard A. Levannier

Abstract Conceptual limitations of existing gridding technologies often lead to undesirable simplifications to the modeling of structurally complex areas, and consequently poor predictions. We present a structural modeling and gridding workflow that limits these modeling compromises. A volume-based 3D structural model based on fault and horizon surfaces is constructed from input data that has undergone basic quality checking using a variety of techniques. The critical step in the grid creation is the definition of a flattened (‘depositional’) space that deforms the structural model mesh under mechanical constraints. A 3D ‘unstructured’ grid is created in the depositional space, based on ‘cutting’ a property-populated, regular cuboidal grid by the geological discontinuities. The tectonic consistency and better preservation of geodetic distance make the flattened space ideal for a range of property modeling approaches. The forward-deformation of the grid into true geological space tends to preserve the layer-orthogonality of the grid columns and makes the grid more suited to numerical simulation approximations. The final grid is unstructured, high quality and an accurate representation of the input structural model. The 3D structural model, depositional space transform and grid geometries all provide valuable information on the structural quality of the input data. The stretching and deforming of the orthogonal local axes in the transformation from depositional space to geological space are used to focus further effort on structural model quality assurance (QA). The key step in generating accurate property population and simulation models is the application of QA metrics on the grid geometry; the transformation from depositional space to geological space is used to generate a set of grid properties that highlight potential structural inconsistencies or data quality issues back in the structural model. We present several examples based on a range of structurally complex models, and demonstrate the downstream impact of applying this QA workflow throughout the stages of input data validation, structural model creation and grid creation.

Unstructured grid

10.2118/193202-ms

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Citations (12)

Near-surface CO 2 leak detection monitoring from downhole electrical resistivity at the CO 2 Field Laboratory, Svelvik Ridge (Norway)

International journal of greenhouse gas control (2014)

N. Denchik P.A. Pezard Denis Neyens Johanna Lofi Frédérick Gal

Electrical Resistivity Tomography

Water well

10.1016/j.ijggc.2014.06.033

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Citations (19)

Microgravity investigation of an aquifer storage and recovery site in Abu Dhabi

First Break (2007)

C. C. Bradley Mohammed Y. Ali Ibrahim Shawky A. Levannier Mohamed A. Dawoud

In this case study paper microgravimetry is used to investigate the geological structure of an area proposed for an aquifer storage and recovery (ASR) project in northeastern Abu Dhabi Emirate in the UAE. This study is a joint collaboration between the Environmental Agency - Abu Dhabi (EAD), Schlumberger Water Services, and the Petroleum Institute. The goal of the project is to explore the geological structure underlying the aquifer and to see if gravity can be used to help further delineate the lower aquifer boundary. The test site, approximately 4 km2 in area, contains an aquifer 50 m below the surface which is bisected by a thrust fault running approximately north to south.

Abu dhabi

Aquifer properties

Thrust fault

10.3997/1365-2397.25.1113.27712

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Citations (10)

Geological Modeling in Structurally Complex Settings Using a Depositional Space and Cut-Cell Unstructured Grids

A. Levannier A. Chabbert Martin Neumaier Azeddine Benabbou Thomas Viard

Abstract Historically it has been a challenge to rapidly produce a geomodel that can honor the detailed form of complex faulting and folding, while enabling sensible property modeling and that is tailored to fluid flow simulations. In structurally complex areas, the construction of accurate 3D geological models is often impeded by the complexity of the fault framework, the resulting layer segmentation, "multi-z" horizons in compressive settings and steeply dipping to overturned layers. In particular, standard geocellular models, such as pillar grids, may fail to honor complex structural features. To address those issues, methodologies using a mapping between the geological space and a 3D parametric space — often referred to as depositional space — have been described in the literature for geological grid construction and property population. Using case examples of structurally complex settings, we illustrate a depositional unstructured grid construction workflow. Compared to known methodologies, the depositional space is computed using a geomechanically-based approach. We illustrate that the methodology allows for complex structural configurations to be effectively modeled and transformed into a geocellular model honoring the full structural complexity. Our depositional unstructured model can then be populated with properties and used directly for flow simulations.

Unstructured grid

10.2118/183960-ms

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Citations (10)

Integrated Onshore‐Offshore Investigation of a Mediterranean Layered Coastal Aquifer

Ground Water (2012)

Johanna Lofi Philippe Pézard Frédéric Bouchette Olivier Raynal Pierre Sabatier

Most of the Mediterranean coastal porous aquifers are intensively exploited. Because of climatic and anthropogenic effects, understanding the physical and geological controls on groundwater distribution and flow dynamics in such aquifers is crucial. This study presents the results of a structural investigation of a system located along the coastline of the Gulf of Lions (NW Mediterranean). A key aspect of this study relies on an onshore‐offshore integrated approach combining outcrops, seismic profiles, and borehole data analysis. This multidisciplinary approach provides constraints on pore‐fluid salinity distribution and stratigraphic organization, which are crucial in assessing the modes of groundwater/seawater exchanges. Onshore, Lower Pliocene deposits dip gently seaward. They are unconformably overlain by Holocene clays in the lagoons. Offshore the Pliocene deposits either outcrop at the seabed or are buried below nonconsolidated sands infilling paleo‐valleys. Beneath the lido, the groundwater salinity distribution consists of salty pore water, overlying fresher pore water. Active circulation of groundwater masses is inferred from the geophysical results. In particular, offshore outcrops and paleo‐valleys may play an important role in salt water intrusion.

Outcrop

10.1111/j.1745-6584.2012.01011.x

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Citations (36)