Articles
Shear-wave sourced 3-D VSP Image Interpretation of Tight Gas Sandstones in Rulison Field, Colorado
Prajnajyoti Mazumdar and Thomas L. Davis
Exploration and development of tight-gas sandstone reservoirs relies heavily on understanding the distribution of sandstone bodies in the subsurface. Shear-wave sourced 3-D vertical seismic profiling (VSP) data are used for sandstone detection and fractured interval delineation. We apply anisotropic Kirchhoff 3-D prestack depth migration to the shear wave VSP reflection…
Isostasy and Gravity Modelling: Integrating Potential Field Data in Interpretation Workflows
David Close
Potential field data, namely gravity and magnetic data, provide a relatively low cost means of mapping regional geological trends and structures. Magnetic data are typically of most value in regions where igneous and metamorphic rocks are common and they have proved particularly vital for understanding the structure and age of…
Shear-wave sourced 3-D VSP Depth Imaging of Tight Gas Sandstones in Rulison Field, Colorado
Prajnajyoti Mazumdar and Thomas L. Davis
Rulison Field, Piceance Basin, Colorado was approved for development drilling to 10-acre spacing in 2003. The down spacing and hydraulic fracturing within this unconventional reservoir has increased its production five fold in less than a decade. A significant portion of the gas production is from low permeability fluvial discontinuous sandstones…
Tight Gas Geophysics: AVO Inversion for Reservoir Characterization
David Close, Simon Stirling, David Cho, and Frederik Horn
A general discussion of some of the critical steps in AVO inversion workflows is included with a Western Canadian case study in this paper. We use the case study to illustrate that the ratio of the compressional and shear wave velocities (Vp/Vs) is a useful indicator of quartz-clay ratios in…
Robust Workflows for Seismic Reservoir Characterisation
Patrick Connolly
In the talk I describe a workflow for seismic reservoir characterisation. The specific problem I address is the estimation of net-to-gross from a clastic reservoir, however the workflow is adaptable for a variety of other applications.
The three main components of the workflow are:
- Extended elastic impedance analysis followed…
A Possible Origin of the Hawaiian Islands
J. Tuzo Wilson
It is noted that different physicists and geologists have in recent years espoused not less than four groups of theories of the physical behavior of the Earth’s interior. Recent observations of submarine geology, heat, and rock magnetism have tended to support some form of continental drift rather than the older…
Model-based Seismic Inversion: Comparing deterministic and probabilistic approaches
Dennis Cooke and John Cant
The target audience of this article is the geoscientist who desires to learn more about seismic inversion and its limitations. The content is especially relevant to those using seismic inversion to help build static reservoir models for field development and/or estimate probabilities for presence of hydrocarbons. The viewpoint and experience…
Logical considerations in applying pattern recognition techniques on seismic data: Precise ruling, realistic solutions
Hosein Hashemi
In this paper, comprehensive method and necessary considerations in seismic pattern recognition procedures are reviewed. In pattern recognition experiments, it is essential to decide about many parameters like picking representative objects with all possible spatial variations, minimum size of training set, knowledge on prior probabilities, seismic attribute redundancy reduction, choice…
Airborne electromagnetic methods: applications to minerals, water and hydrocarbon exploration
Richard Smith
Electromagnetic methods have a transmitter that carries a current that varies in magnitude as a function of time. This current has an associated (primary) magnetic field that has a similar time dependence. According to Faraday’s law of induction, this time varying field induces currents in conductive features in the ground.…
Looking beneath the noise: experience with high-resolution seismic acquisition and pre-stack process
David C. Henley, Malcolm B. Bertram, and Kevin W. Hall
Historically, the design of land seismic surveys has been subject primarily to two influences: the overall dimensions and station spacing of the survey for both sources and receivers has been governed by the depth and configuration of the geological target zone; and suppression of the ever-present source-generated coherent noise has…
The influence of spatial sampling on resolution
Mark S. Egan, Joe Seissiger, Antoun Salama, George El-Kaseeh
... Characterization of a heavy oil reservoir using Vp/Vs ratio and neural network analysis
Carmen C. Dumitrescu and Larry Lines
The Oil Sands reservoir related to the Long Lake South (LLS) Project is contained within the McMurray Formation, which is the basal unit of the Lower Cretaceous Mannville Group. The McMurray Formation directly overlies the Subcretaceous Unconformity, which is developed on Paleozoic carbonates of the Beaver Hill Lake Group, and…
Magnitude Determination, Event Detectability, and Assessing the Effectiveness of Microseismic Monitoring Programs in Petroleum Applications
Adam Baig and Ted Urbancic
Magnitudes and locations are the first-order output for microseismic events recorded during hydraulic fracture stimulations and longer term reservoir based extraction operations (eg., CSS, SAG-D, CO2 sequestration). The magnitude describes the strength of an event and tells us about the dynamics of the fracturing processes and the distribution of magnitudes…
Sensitivity measurements for locating microseismic events
John C. Bancroft, Joe Wong, and Lejia Han
The first-arrival clock-times from a number of receivers are used to estimate the clock-time and location of a microseismic event. The 3D analytic solution is based on a 2D Apollonius method which requires four receivers that are non-coplanar or non-collinear. These restrictions are typically violated when receivers are placed in…
The old and new in noise removal, wavefield representation and data regularization
Mauricio Sacchi, Sam Kaplan and Mostafa Naghizadeh
Traditional noise removal methods based on Fourier analysis, Radon transforms, and prediction filtering have occupied an important place in our arsenal of methods for noise attenuation. They all rely on different assumptions and, in general, on a simple signal model. An open problem in seismic data processing is the establishment…
Impact of Microseismic Location Uncertainties On Interpreted Fracture Geometries
Shawn Maxwell
Microseismic imaging of hydraulic fracturing is a growing technology throughout North America, and especially in the WCSB. Microearthquakes associated with hydraulic fracture stimulations are used to image the fracture network induced by the injection, and provide unique information about the fracture geometries. In an article in the March 2009 issue…
Gaussian-beam polarization-based location methods using S-waves for hydraulic fracturing induced seismicity
Xueping Zhao, David S. Collins, and R. Paul Young
We propose a new method to locate hydraulic fracturing induced seismicity using three-component S-waveforms. The method requires only time intervals around the peak amplitude of the S-wave and does not depend on the arrival-time picking accuracy. The initial-value for the ray tracing is along the direction of wave propagation obtained…
Classification of microseismic events via principal component analysis of trace statistics
Jeffrey F. Tan, Robert R. Stewart, and Joe Wong
Prior to microseismic hypocenter location, an event-classification technique must be used to identify “good” events warranting further investigation from “noise” events that are generally not of interest. A passive-seismic monitoring system may record tens or hundreds of thousands of microseismic traces daily, so the event classification method must be precise…
Lessons Learned from Simultaneous Source Investigations
Craig J. Beasley
Dealing with external interferences imposed on a desired seismic signal is fundamental to achieving the goals of a seismic survey. Whether it be related to Earth transmission effects or external noise, this is the stuff of acquisition, processing and, ultimately, interpretation of seismic data. From time-to-time, geophysicists have taken a…
What Comes Up Must Have Gone Down the Principle and Application of Up-Down Deconvolution for Multiple Attenuation of Ocean Bottom Data
Yi Wang, Sergio Grion and Richard Bale
Up-down deconvolution is a method for attenuating all free surface multiples from ocean bottom seismic data, by exploiting the separation into up and down-going wavefields from combining hydrophone and geophone data. We describe the method and show its application both to a synthetic dataset provided to us by Chevron and…
