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Stein J.A.,Geotrace | Wojslaw R.,Geotrace | Langston T.,Geotrace | Boyer S.,Geotrace
Leading Edge (Tulsa, OK) | Year: 2010

Using a modern wide-azimuth land survey, we demonstrate the power of offset vector tile (OVT) processing and subsequent analysis of offset vector gathers (OVG) to identify potential anisotropy and fracture characteristics of certain reservoirs of interest. Migration of the inherently azimuth-limited OVT gathers and the accompanying velocity updating scheme, based on surface fitting in offset and azimuth, yields robust measurements critical to this analysis. Both the kinematic and dynamic aspects of the processing are considered and contrasted. The results of the processing and analysis are then confirmed by comparison to the values predicted from two wells in the area. © 2010 Society of Exploration Geophysicists.


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.


Wang H.,Geotrace | Sun Y.,Geotrace | Boyer S.,Geotrace | Yu G.,Geotrace | And 2 more authors.
74th European Association of Geoscientists and Engineers Conference and Exhibition 2012 Incorporating SPE EUROPEC 2012: Responsibly Securing Natural Resources | Year: 2012

Shallow Water Demultiple (SWD) is a very challenging problem for marine seismic data processing. In shallow water environments, water bottom reflections are recorded only on a few near offset traces because critical reflection angle is reached quickly. In very shallow water, water bottom reflections may disappear completely. This poses a limitation to any convolution based demultiple methods such as Surface Related Multiple Elimination (SRME) and SWD to predict first order multiple. In this paper we propose a way to enhance these aforementioned methods by modeling the water bottom reflection and then adding it to the recorded seismic data. The modified data can then be used to predict first order multiple using SRME and/or SWD. We call these methods enhanced SRME and enhanced SWD, respectively. We will also demonstrate that an optimal way to perform the multiple elimination is to cascade the enhanced SWD followed by SRME. We call this methodology Cascaded Enhanced Shallow Water Demultiple (CESWD). Our test results show that enhanced SWD is better than enhanced SRME, and CESWD is better than enhanced SWD. Finally a comparison of these methods is presented by applying them to a real data example. The enhanced methods produce better than their conventional counterparts.


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.


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.


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

We present a methodology that allows the simultaneous determination of velocity and true eta in a production setting. Rather than deal with non-hyperbolic gathers by higher-order moveout equations, we take a new approach of using a different velocity function for each offset (Hellman, et al., 2012). At each analysis location, interval velocities are inverted from the near-offset rms velocities and then traveltimes are determined by anisotropic ray tracing through the implied model determined by the velocity and eta picks. These raytraced traveltimes are inserted into the hyperbolic moveout equation and rearranged to form offset dependent velocities, which are used to move out the gathers. Etas and velocities are iterated until the updated gather is flat. A primary benefit of the method is that the eta values are completely decoupled from the non-hyperbolic effect of the layered overburden, so that the derived etas are geophysical, and not "effective". The velocities and etas are not necessarily picked on the same grid, allowing the processor to control the velocities in a much finer grid than is necessary for the anisotropy. The final set of picks can then be re-gridded to be on the same grid for further processing steps. Copyright © (2012) by the European Association of Geoscientists & Engineers All rights reserved.


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.


Smith M.E.,United Technologies | Yu G.,Geotrace | Yang W.,Geotrace | Pottorf M.,Geotrace
75th European Association of Geoscientists and Engineers Conference and Exhibition 2013 Incorporating SPE EUROPEC 2013: Changing Frontiers | Year: 2013

We used a model based inversion solving for Vp, Vs and Density and computed Young's modulus and Poisson's ratio to determine rock brittleness/ductility and total organic carbon (TOC) from rock properties. Although the lower Eagle Ford shale appears fairly consistent in its properties, we note specific variations in those rock properties that suggest they can be used to improve prospecting for hydrocarbons in the Eagle Ford shale play. Copyright © (2012) by the European Association of Geoscientists & Engineers All rights reserved.


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.


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

Using any model-based pre-stack inversion process requires three types of input data: wavelet, initial model and seismic gathers. In this paper we analyze the impact of the errors possible, such as wavelet estimation errors, initial model errors and seismic signal to noise ratio (SNR), using the non-linear conjugate gradient method for inversion to P-wave velocity (Vp), S-wave velocity (Vs) and density () data. Using this synthetic model response as the recorded seismic data, we compare the inversion results to the Vp, Vs and density from actual well data for three zones of interest. Improper rock properties from the inversion will lead to incorrect conclusions about the viability of a prospect. We arrive at conclusions about the impact of wavelet, initial model and seismic SNR required for acceptable inversion. We also offer suggestions for future research and development to increase the accuracy of the inversion results. © 2010, European Association of Geoscientists and Engineers.

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