An Efficient Approach for Earth Model Updates

Suter, Erich; Cayeux, Eric; Vefring, Erlend H.; Næsheim, L.I.; Friis, Helmer André; Escalona, Alejandro; Kårstad, T.

doi:10.2118/136319-ms

Cited by 3 publications

(2 citation statements)

References 11 publications

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“…Such developments are important to speed up and streamline the earth modelling process when targeting real-time workflows. Rudimentary discussions of the strategy were presented in [5] [6].…”

Section: Main Contributions Of This Papermentioning

confidence: 99%

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A Novel Method for Locally Updating an Earth Model While Geosteering

Suter¹,

Cayeux²,

Friis³

et al. 2017

IJG

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Earth models are important tools for support of decision making processes for optimal exploitation of subsurface resources. For geosteering and other realtime processes where time is a major constraint, effective model management is decisive for optimal decision support. During drilling, subsurface information is received which should optimally be used to modify the 3D earth model. Today this model is typically not altered during the operation. We discuss the principles of a novel method that enables a populated earth model grid to be locally modified when the topology (connectivity) of the geological structure is locally altered. The method also allows local updates of the grid resolution. The modelled volume is split into closed regions by the structural model. Each region is individually discretized and obtains its own subgrid. Properties are stored in separate functions, e.g. for each layer, and transferred into each subgrid via a mapping. A local update of the geological structure implies that only subgrids in regions that are directly affected by the updated structure must be discarded and rebuilt, and the rest of the populated earth model grid is retained. Our focus is on decision support for optimal well placement while geosteering. The proposed method aims to manage multiple model realizations that are never fixed and always locally updated with the most recent measurements and interpretations in real-time, and where each realization is always kept at an optimal resolution.

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Section: Main Contributions Of This Papermentioning

confidence: 99%

“…Potential strategies include that the function is represented over a grid, or is a uniform value as in[12]. The function could also be a complex analytical function, or a multi-resolution function as suggested in[5] [13][14]. A property function can be constructed from grid-based property distributions that are imported from external tools.…”

mentioning

confidence: 99%

A Novel Method for Locally Updating an Earth Model While Geosteering

Suter¹,

Cayeux²,

Friis³

et al. 2017

IJG

View full text Add to dashboard Cite

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A Novel Method for Multi-Resolution Earth Model Gridding

Suter

Friis

Vefring

et al. 2017

SPE Reservoir Simulation Conference

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Earth models are important tools for support of decision making processes for optimal exploitation of subsurface resources. In earth modelling applications, massive amounts of information result from collecting and interpreting measurements and simulating physical scenarios at various scales and resolutions. The size of an earth model grid is a consequence of its scale and resolution. The grid size is a major factor for the computational efficiency when managing the model and performing various model based simulations. The grid is controlled by the geological structure, and the resolution of the grid is therefore controlled by the resolution of the geological structure (the number of structural elements). We discuss principles for a multi-resolution framework for earth model gridding where the aim is to allow automatic, local control of the resolution of a populated grid by locally controlling the resolution of the geological structure. The structure is ordered in a hierarchical manner, and splits the subsurface into a nested set of regions that are ordered in a corresponding hierarchical fashion. Each region can be separately gridded. The method is based on a recent method for local updates of the connectivity (topology) of the geological structure and of the resolution of a populated grid. Similar to existing strategies for multi-resolution modelling in other sciences and applications, the proposed method allows local control with the trade-off between numerical accuracy and grid size. The method should allow to locally change the model resolution even during a modelling exercise; subsurface volumes of high interest can be represented at fine resolution, whereas in volumes of less interest, details can be omitted. The method also enables local updates and local scale uncertainty management of the geological structure. The aim of the proposed method is to develop an effective methodology that supports real-time earth model based workflows such as geosteering where multiple grid realizations are never fixed and always updated with the most recent measurements and interpretations, and where each realization is always kept at an optimal resolution.

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New Geosteering Technology Boosts Wellbore Data and Seismic Properties Integration: A Case History From Norway

Cossa

Manassero

Mele

et al. 2019

SPE Europec Featured at 81st EAGE Conference and Exhibition

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In a deep-water green field's development, horizontal wells are drilled to exploit the reservoir with the aim of reducing drilling cost and time to first oil. During geosteering operations, Ultra Deep Azimuthal Electro-Magnetic (E.M.) measurements permit investigating the reservoir around the borehole up to a maximum depth of 30 m, in a good resistivity contrast environment. Acquired data are inverted on a vertical section, providing multi-boundary reservoir mapping along well path. With such a depth of investigation, the reservoir mapping is an excellent bridge between conventional logging-while-drilling (LWD) and seismic images. The integration of acquired wellbore data with high-resolution attributes, from seismic inversion, maximizes well placement results when operating in complex subsurface geology and expands the perspectives of geosteering application. A workflow to calibrate the reservoir structural and stratigraphyc setting has been assessed, via integration of seismic and Borehole Data. Enhancement of reservoir geometry interpretation during geosteering provides revised structural surfaces suitable for a quick update of the velocity model and a depth-calibration of all the seismic attributes used to steer wells. We describe an application of the workflow to an infill well, targeting channel and crevasse splays deposits drilled through a structurally complex oil field in the Norwegian offshore. The availability of seismic attributes (probabilities of facies and petrophysical properties) allowed improving the overall results of the well placement operation. Reservoir mapping identifies in real time Geo-bodies crossed by the well and within the range of investigation of Ultra Deep E.M. tool based on tool configuration, frequencies analysed and resistivity contrasts of the rocks. Stratigraphic correlation with offset wells, using conventional LWD data supported by Image Log interpretation, allowed allocating resistivity boundaries in terms of stratigraphic surfaces. These data are then integrated in near real time to depth calibrate maps, update the velocity model, hence the depth image of seismic attributes. After depth calibration, Geo-bodies recognized on seismic show a good correspondence with those identified on the resistivity inversion and a detailed correlation of the heterogeneous fluvial sand was possible, even in presence of minor faults. In this challenging structural and stratigraphic environment, the correlation supported decision making during well operations to target the well on the pay sand. The application proves that a detailed stratigraphic interpretation is an achievable goal in real time to steer successfully the well and to be used afterwards in a detailed reservoir model update.

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An Efficient Approach for Earth Model Updates

Cited by 3 publications

References 11 publications

A Novel Method for Locally Updating an Earth Model While Geosteering

A Novel Method for Locally Updating an Earth Model While Geosteering

A Novel Method for Multi-Resolution Earth Model Gridding

New Geosteering Technology Boosts Wellbore Data and Seismic Properties Integration: A Case History From Norway

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