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Stein J.A.,Geotrace
Hart's E and P | Year: 2011

The newly developed concept of offset vector tile processing for wide-azimuth data provides fracture information at a much lower cost in oil and gas exploration projects. The two necessary functions for this technology to work are a well-sampled wide-azimuth acquisition and a wide-azimuthal seismic processing system that includes an orthorhombic migration and velocity analysis. It is possible to measure the propagation velocities of these compressional waves in different directions and determine the fracture orientation. This new technology can be used to determine fracture orientation, based on the use of offset vector tiles (OVT), orthorhombic prestack time migration, and careful analysis of the generated offset migrated gathers (OMG). Through a process called a surface-fitting algorithm, it is possible to find these velocities. Source


Stein J.A.,Geotrace
75th European Association of Geoscientists and Engineers Conference and Exhibition 2013 Incorporating SPE EUROPEC 2013: Changing Frontiers | Year: 2013

The correct imaging of Fractured Reservoirs common in many unconventional plays involves the extension of the migration algorithms to include azimuthal anisotropic (HTI) corrections. More often than not vertical anisotropy (VTI) is also present demanding the extension of the algorithms to an orthorhombic anisotropy. The set of anisotropic parameters derived in our original work (Wojslaw & Stein 2010) had a shortcoming. It overlooked the effect of the overburden, effectively describing RMS-like anisotropy and projecting (or foot-printing) into the deeper layers the effects of the shallow ones. This produces an overestimation of the anisotropy values and an incorrect fracture orientation. This paper will describe the layer stripping methodology and its applications to a real exploration situation that removes the effect of the overburden. Copyright © (2012) by the European Association of Geoscientists & Engineers All rights reserved. Source


Yu J.H.,Geotrace | Pottorf M.,Geotrace
72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010: A New Spring for Geoscience. Incorporating SPE EUROPEC 2010 | Year: 2010

For a typical prospect evaluation, the three main technical elements are migration, reservoir and trap. Traditionally geoscientist employs structural interpretation to assess the trap or seal integrity. In this paper we focus on how to use pore pressure to evaluate the seal integrity since without a proper trap mechanism or seal integrity, the hydrocarbons would continue to migrate out of the reservoir and result in no prospect. To be able to extract accurate pore pressure from seismic data, we must understand the causes and mechanisms of abnormal pressure. When they are better understood, a mathematical model can be built to estimate the formation pore pressure. We present a systematic workflow to condition the input seismic data and build a well-calibrated pressure model to estimate a high density high resolution (HDHR) 3D pore pressure volume from seismic data. This calibrated pressure model is unique because it takes into account burial depth, temperature gradient and shale diagenesis as well as the compaction and loading and off-loading trends. We discuss how to visualize and interpret pore pressure with seismic data and demonstrate the usefulness of this calibrated pressure model with real case studies for seal capacity evaluation. © 2010, European Association of Geoscientists and Engineers. Source


Wojslaw R.,Geotrace | Stein J.A.,Geotrace | Langston T.,Geotrace
74th European Association of Geoscientists and Engineers Conference and Exhibition 2012 Incorporating SPE EUROPEC 2012: Responsibly Securing Natural Resources | Year: 2012

A generalization of the standard semblance equation is used to develop a 5D noise elimination algorithm. After explaining the methodology we illustrate its power by applying it to a real seismic data set. Additionally, we will compare the results to the 3D version of the same program and show that the inclusion of the extra dimensions greatly benefits the noise cancelation process. Source


Wojslaw R.,Geotrace | Stein J.A.,Geotrace | Langston T.,Geotrace
74th European Association of Geoscientists and Engineers Conference and Exhibition 2012 Incorporating SPE EUROPEC 2012: Responsibly Securing Natural Resources | Year: 2012

A generalization of the standard semblance equation is used to develop a 5D interpolation algorithm. After explaining the methodology, we demonstrate its effectiveness by applying it to two onshore data sets. Both datasets have numerous acquisition skips and irregularities due to cultural obstructions or permitting issues and, as acquired, are full of 5D holes. The first is a structurally complex supra salt survey and has additional coverage and regularity issues resulting from the merging of two 3D surveys with different acquisition parameters and vintages. The second survey is a project on which azimuthal orthorhombic migration will be performed requiring appropriate offset/azimuth coverage and distribution. We will show how the technology described in this paper can address complex coverage issues by regularizing and interpolating the input data in all five dimensions to optimize velocity modeling and migration. This approach pushes toward the ultimate goal of yielding the best possible results to satisfy the exploration requirements envisioned with the acquisition of these 3D surveys. Source

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