Articles

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…

Collaborative Studies of Regional Seismicity in Northeast British Columbia

Amir Mansour Farahbod, John F. Cassidy, Honn Kao and Dan Walker

This article documents a recently-initiated, collaborative study of seismicity in northeast British Columbia. Induced seismicity is a topic of increasing, and global interest, in particular with respect to shale-gas extraction activities. There are many important questions regarding linkages between induced seismicity and hydraulic fracturing (HF) activities. Addressing these questions requires…

Interpretation of Microseismic Using Geomechanical Modeling of Multiple Hydraulic Fractures Interacting with Natural Fractures – Application to Montney Shale

Ahmed Ouenes, Yamina Aimene and John Nairn

This paper describes the application of a new geomechanical workflow for modeling the interaction between hydraulic and natural fractures. The geomechanical workflow combines the meshless Material Point Method (MPM) with Continuous Fracture Modeling (CFM). The distribution of the natural fracture density is estimated from a time lapse 3C seismic that…

The Jordan-Risha High Productivity 3D Survey

Jack Bouska

In January 2010, BP signed an agreement to explore and appraise the 7,200 sq km Risha Concession, located in Eastern Jordan, bordering Syria, Iraq and Saudi Arabia. A short Exploration and Appraisal period mandated acquisition of 5000 sq.km. of high fold 3D data, to be completed within the first 18…

Introduction to October Focus: Seismic Interpretation

Ayon Kumar Dey

This issue of the RECORDER focuses on modern seismic interpretation through four interesting articles. Highlighted are critical elements such as best practices and the importance of integrating the earth mechanics for a better subsurface understanding. I invite you to come along to see the present and future of seismic interpretation.

Chasing Density – An Introduction to Seismic Acquisition, Processing, and Interpretation Methods Leading to Quantitative Interpretation

Brian Schulte and David Manthei

Natural fracture characterization from 3D structural attributes

Damien Thenin and Ron Larson

As seismic interpretation continuously evolves, it seems that interpreters have not kept pace with technological innovation provided in commercial software: workflows may be more persistent than technologies. Despite having access to 3D seismic for close to three decades, the majority of an interpreter’s time is spent picking inline and crosslines…

Optimising resource plays – an integrated “GeoPrediction” approach

S. O'Connor, S. Mildren, M. Kemper, C. Malaver, J. Gallop and S. Green

A mechanical earth model (or “MEM”) is a fundamental tool for considering the relationships between stress, strength and elastic properties of unconventional resources. The ultimate aim of these MEM’s is to aid the targeting of producible “sweet spots” so that an intelligent stimulation plan can be developed that leads to…

Offshore East Coast: Model-based Water-Layer Demultiple Breathes New Life into Old Data

Key Seismic Solutions Ltd.

This article describes recent development and application of a model-based water-layer demultiple technique. We discuss some application details such as the water-bottom Green’s function and the necessity of a two-step prediction to handle both shot-side and receiver-side multiples. This method is tested using a finite difference synthetic dataset and then…

3D Seismic Image Processing for Interpretation of Faults and Horizons

Dave Hale

Fault surfaces are an important aspect of subsurface geology that we can extract from 3D seismic images. Estimates of fault slips are important as well, as they enable correlation across faults of subsurface properties. Moreover, with estimated fault slips, we can undo faulting apparent in 3D seismic images. After unfaulting,…

Introduction to September Focus: University Geophysical Research

Rob Holt

Whilst brainstorming ideas for future focus topics for the RECORDER this Spring with the other members of the CSEG RECORDER committee, I proposed an edition focused on geophysical research at Canadian universities, largely because I was wondering what the hot topics are in research these days, and who is working…