Articles

Magnetotelluric studies of lithospheric structure beneath Western Canada: insights into plate tectonics both past and present

Martyn Unsworth

Electromagnetic (EM) methods were originally developed for mineral exploration owing to the large contrast in electrical resistivity between many ore bodies and the host rock. They have subsequently found application in a range of fields including geothermal exploration, hydrogeology and environmental geophysics. In addition to applied studies, EM methods are…

A New Perspective on Shallow Water Flow (SWF) Prediction and the Prevention of Sinking Well-Heads in Deepwater Settings

Selim Simon Shaker

A new study integrating the seismic velocity profile with a proposed subsurface geopressure partition sheds light on a possible cause of shallow water flow (SWF) sands and sinking well heads in deepwater settings. The Bureau of Ocean Energy Management (BOEM), previously known as MMS, reported 157 cases of SWF in…

Signal Processing and Physics-Based Approaches to Seismic Data Regularization

Aaron Stanton

In recent years seismic data interpolation has been a major focus area for geophysical research. These efforts aim to compensate for inadequate spatial sampling of sources and receivers to precondition the data for prestack migration. Interpolation algorithms rely on a variety of signal processing strategies with the underlying assumption that…

Introduction To January Focus: Oil Sands

David Gray

Strategies to fill in the details for an oil sands reservoir: Kinosis example

Dragana Todorovic-Marinic, David Gray and Jan Dewar

In developing an oil sands play, the task facing the geoscientist is to build a detailed characterization of a three-dimensionally complex reservoir to position horizontal wells precisely and optimally. There is usually no shortage of data to examine. In fact, terabytes of information about the reservoir are often collected. The…

Characterization of the Albian Lower Grand Rapids Formation, Cold Lake, Alberta

Tammy Willmer and Garrett Quinn

The Alberta Energy Regulator estimates 10.0 billion m3 (62.9 billion barrels) of bitumen initially in place within the Albian-aged Lower Grand Rapids Formation (LGR) in the Cold Lake Oil Sands Region (Marsh and Honarvar, 2014). Despite this significant resource estimate, development of the zone lags behind other bitumen reservoirs in…

Microseismic Monitoring Applications in Heavy Oil Reservoirs

Ted Urbancic and Katie Jeziorski

Heavy oil or partially depleted conventional reservoirs typically require some form of stimulation to mobilize the oil. For more than a decade, steam injection programs in heavy oil reservoirs such as Cyclic Steam Stimulation, Huff and Puff, SAGD or some combination thereof have utilized microseismic monitoring to track steam movement…

A New Approach to Pore Pressure Predictions Generation, Expulsion and Retention Trio: Case Histories

Selim Simon Shaker

A comprehensive framework and fresh perspective to pore pressure prediction methods and algorithms based on the established geological building blocks is presented. Applying the suggested four subsurface zones is the backbone of this pore pressure prediction approach. Determining the boundary of the four subsurface zones utilizing seismic data is crucial…

2b or not 2b? Interpreting Magnitude Distributions from Microseismic Catalogs

David Eaton

The Gutenberg-Richter b value, the slope of a logarithmic cumulative magnitude distribution graph, provides an indication of the relative abundance of large-tosmall magnitude events. Numerous studies have demonstrated that earthquake catalogs for seismically active fault systems typically show a long-term b value in the range of 0.75 to 1.25, depending…

Introduction To December Focus: A glimpse into the future of seismic imaging?

Rob Holt

Slowly, inexorably, prestack depth migration (PSDM) is replacing prestack time migration (PSTM) as our seismic imaging workhorse, just as prestack time migration previously replaced poststack time migration. We saw this first in the Canadian Foothills, where anisotropic PSDM is required to correctly position the images of our hydrocarbon-bearing reservoirs beneath…

Resolving small-scale near-seabed velocity anomalies using non-parametric autopicking and hybrid tomography

Juergen Fruehn, Stuart Greenwood, Victoria Valler, Dejan Sekulic

High resolution tomographic inversion has conventionally been preceded by picking of 2nd and 4th order residual moveout of depth migrated gathers. However, this type of picking assumes that the residual moveout behaviour can adequately be characterized with a parametric fit of a simple curve to the form of moveout exhibited…

Multicomponent PSDM Velocity Model building using OBC Data from the Albacora Field

T. Krishnasamy, L. D’Afonseca, P. Guillaume, O.J. Birkeland, T.M.G. Santiago, C. Guerra, R. Lima

The Albacora field is located in the Campos Basin offshore Brazil. It contains several reservoirs, mainly sandstones and carbonates. The geology is complicated with salt bodies of various thicknesses. The thickness of these salt bodies can vary from 50 m to 1000 m (Lima et al., 2009). To add to…

Reverse-time depth migration in elastic media

Zaiming Jiang

The main objective of this paper is to sketch a reverse-time migration workflow. The migration is based on an elastic model of the earth, is driven by elastodynamic equations, and processes mutlicomponent seismic records. It works with shot gathers and is a prestack migration. As a typical depth migration, the…

Least squares migration of converted wave seismic data

Aaron Stanton and Mauricio D. Sacchi

Least squares migration permits the estimation of subsurface models that honor the recorded primary seismic wavefield. In addition, it permits us to include regularization constraints that reduce sampling and illumination artifacts. Least squares migration utilizing one-way wave equation migration has been mainly restricted to imaging via scalar wave propagation operators.…

How much can I stretch and squeeze?

David Cho and David Nordin

Well to seismic ties is a fundamental step in seismic interpretation. It relates subsurface measurements obtained at a wellbore measured in depth and seismic data measured in time. A time-depth relationship is typically computed by integrating the slowness function measured at a wellbore. Mis-ties are often present and adjustments to…

Integrating Production Analysis with Microseismic and Fracture Modeling to Characterize Hydraulic Fractures

Chris R. Clarkson

There are now multiple geophysics- and engineering-based methods for the evaluation of hydraulic fracture stimulation effectiveness associated with multi-fractured horizontal wells (MFHWs) completed in unconventional gas and light oil reservoirs. These methods, which can be classified according to the timing of data collection relative to the main hydraulic fracture stimulation,…

Introduction to November Focus: Induced Seismicity

Mostafa Naghizadeh

As professional geophysicists and engineers it is mandatory to put public safety above any other aspects of our professional practice. The widespread usage of hydraulic fracturing (HF) of unconventional resources (shale gas) has created multiple questions in the public mind about the short and long term effects on residents near…

Basic Geomechanics for Induced Seismicity: A Tutorial

Douglas R. Schmitt

We are increasingly accessing the earth’s crust to extract water, minerals, hydrocarbons, and geothermal energy and to dispose of waste CO2 and liquids. All of these activities result in changes to the subsurface pore pressures either stabilizing a geological formation or nudging it closer to failure. Such failure becomes a…

Alberta Telemetered Seismograph Network (ATSN): Real-time Monitoring of Seismicity in Northern Alberta

David W. Eaton

The term induced seismicity is generally defined as earthquake activity that is brought about by human activities, including fluid injection or withdrawal, reservoir impoundment and mining (Majer et al., 2012). A related concept is triggered seismicity, which represents activation of a pre-existing zone of weakness such as a fault that…

Preparing to Monitor and Distinguish Natural and Induced Seismicity near Norman Wells, Northwest Territories

Scott Cairns, Honn Kao, Amir Mansour Farahbod and David Snyder

In the winter of 2012, representatives of Aboriginal Affairs and Northern Development Canada and the National Energy Board visited three Sahtu communities in the Northwest Territories (NWT) of Canada to provide information about hydraulic fracturing. At the time, those communities expressed concerns about the environmental impact this technology would have…