Hilde Grude Borgos

Automated Geometry Extraction From 3D Seismic Data

Classification tools are widely used in both 3D and 4D reservoir characterization, for example in mapping of 3D structures, lithological properties and production effects [1]. In this work we extent the application area of the classification methodology into automated interpretation of seismic reflectors. By classifying the seismic signal along reflectors we gain an improved automated interpretation that performs well also in structurally complex regions. Based on this classification methodology, we demonstrate automatic extraction of seismic reflectors and geo-bodies, and automatic fault displacement estimation.

Automated Structural Interpretation Through Classification of Seismic Horizons

A novel method for extracting geometry primitives from seismic data is presented. All events in the 3D seismic cube will be detected and can be combined into geometric primitives based on similarities in the local wave form. No assumptions of continuity in the geometric primitives are required. The geometric primitives can therefore represent faulted horizons, which furthermore facilitates quantification of the fault displacement.

Extracting Horizon Patches And Geo-bodies From 3D Seismic Waveform Sequences

Summary A methodology for automated 3D interpretation is presented. Sequences of horizons (seismic events) are constructed from pre-computed horizon primitives. These horizon primitives are subsequently used to generate geobodies. Classification techniques can be applied to automatically group seismic events into classes of similar seismic waveform when performing seismic interpretation, as described by Borgos et al. (2003). In this work we describe how the classification approach can be used to extract a set of geometry primitives, constituting building blocks that the seismic interpreter can apply to construct a structural description of the reservoir. These primitives can be either surface segments or closed volumes, referred to as geobodies. Attributes from the classification are stored along with the primitives, allowing a later refinement of the reservoir description through further classification.

Automated Horizon and Geobody Extraction Using 3D Seismic Waveform Sequences

B014 Automated Horizon and Geobody Extraction Using 3D Seismic Waveform Sequences H.G. Borgos* (Schlumberger) O. Gramstad (Schlumberger) G.V. Dahl (Schlumberger) P. Le Guern (Schlumberger) L. Sonneland (Schlumberger) & J.F. Rosalba (Petrobras) SUMMARY A methodology for automated 3D interpretation is presented. Sequences of horizons (seismic events) are constructed from pre-computed horizon primitives. These horizon primitives are subsequently used to generate geobodies. Classification techniques can be applied to automatically group seismic events into classes of similar seismic waveform when performing seismic interpretation as described by Borgos et al. (2003). In this work we describe how the classification approach can be used to

Super‐resolution mapping of thin gas pockets

Improved resolution in seismic prospecting implies better resolving power of objects in the subsurface. It is well known that resolution is directly related to the frequency bandwidth of the seismic measurement. Various criteria for the resolving power exist, like the Rayleigh criterion [1]. Under certain conditions the resolution can be improved beyond the limits of i.e. the Rayleigh criterion. These conditions can be the availability of additional information about the scene being analyzed. Procedures that enable such improved resolution are referred to as superresolution. We will present a seismic super-resolution procedure and apply this to map thin gas pockets with resolution better than the sampling rate.

A New 3D Seismic Stratigraphic Methodology Applied to an Offshore Brazil Case

Seismic stratigraphic interpretation is a powerful method for analyzing the depositional history of the subsurface. However, the lack of support of such interpretation methods in the state-of-the-art tools limits its application. A novel technology allowing a highly automated procedure for seismic stratigraphic interpretation is presented (figure 1). The technology includes an automated high resolution extraction step of all the stratigraphic primitives prior to the interactive session. The technology supports a “dual domain” concept that enables to interpret transparently in the seismic domain and the chronostratigraphic time domain. The interpreter controls this mapping by selecting the appropriate set of stratigraphic primitives to define this transformation. The high resolution extraction step, referred to as extrema classification in figure 1, is based on Borgos et al., 2003, 2005. The output from this classification results in extrema patches (figure 1) from which the stratigraphic primitives might be defined. The method can be extended to active tectonic basins by including fault patches in the mapping between the seismic domain and the chronostratigraphic time domain (Pedersen et al., 2003, 2005). Figure 1 illustrates how faults supplement extrema patches to define the geological model.

Novel Workflow for Shale Gas Reservoir Characterization

Shales may contain significant volumes of organic matter and constitutes the key source rock for hydrocarbon reservoirs. Today these types of organic rich shales are being economical exploited in situ and have become recognized as unconventional reservoirs. The current reservoir characterization technology has been evolved over decades focusing on sandstone - and carbonate – rocks. This technology is not directly applicable for shale reservoir characterization. One important difference is that permeability and porosity in shales are order of magnitude different from sandstone - and carbonate – rocks, another that we are describing the source - rock it. We will in this paper propose a new procedure for characterization of shale reservoirs. The workflow is highlighted in figure 1. Input data is typically cores, well-logs and surface seismic data in addition to micro-seismic data .The core, well-logs and seismic data are integrated in a hierarchical fashion that allows characterization of key features in the shales. The total organic content (TOC) in the shales is an example of such a feature. Loseth et. al has in a recent paper that acoustic impedance (AI) in organic-rich claystones decreases nonlinearly with increasing TOC percent. Further claystones mixed with low-density organic matter have significant higher intrinsic anisotropy than otherwise similar non-organic claystones.

A New Automated 3D Seismic Stratigraphic Methodology

H043 A New Automated 3D Seismic Stratigraphic Methodology P. Le Guern* (Schlumberger) B. Savary (Schlumberger) H.G. Borgos (Schlumberger) G. Vaaland Dahl (Schlumberger) E. Monsen (Schlumberger) L. Sonneland (Schlumberger) A.R. Dias Elias (Petrobras) & J.F. Rosalba (Petrobras) SUMMARY Seismic stratigraphic interpretation is a powerful method for analyzing the depositional history of the subsurface. However the lack of support of such interpretation methods in the state-of-the-art tools limits its application. A novel technology allowing a highly automated procedure for seismic stratigraphic interpretation is presented. The technology includes an automated high resolution extraction step of all the stratigraphic primitives. The technology supports a

Geological Process Controlled Interpretation Based on 3D Wheeler Diagram Generation

B015 Geological Process Controlled Interpretation Based on 3D Wheeler Diagram Generation E.M. Monsen* (Schlumberger) H.G. Borgos (Schlumberger) P. Le Guern (Schlumberger) & L. Sonneland (Schlumberger) SUMMARY The techniques of a new seismic stratigraphic interpretation paradigm are presented whereby geology is made explicit and is brought into the interpretation process through interactive use of an automatically generated 3D Wheeler diagram. The Wheeler diagram explicitly captures the geological context throughout the interpretation process and provides a great tool for fast QC and data understanding. EAGE 69 th Conference & Exhibition — London UK 11 - 14 June 2007 Introduction Chronostratigraphy is the

New quality metric for validation of velocity models

Summary The crucial analysis step in seismic processing is to establish an optimal velocity model. The quality of the velocity model has a major influence on the quality of the final processing result. The quality of the velocity model can be measured by how well the velocities NMO-correct the common reflection-point gathers (CRP). However, after transformation of the CRP-gathers to zero offset, it is impossible to validate the quality of the velocity model without invoking the prestack CRP-gathers. It is prohibitive to pass an undecimated prestack seismic data volume to the interpretation stage. As a result of this, the interpreter has no means to assess the quality of the velocity model. This might lead to pitfalls and misinterpretations. We propose a new compact quality metric for the velocity model that allows the interpreter to relate all seismic events in the zero-offset cube to quality measures of the NMOcorrection that resulted in these seismic events. The primitives of the quality measure are Residual Wavefront Normals (RWN) computed for every wavefront in the prestack gathers.