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Sault Ste. Marie, Canada

Bale R.,Key Seismic Solutions | Marchand T.,Key Seismic Solutions | Wilkinson K.,Key Seismic Solutions | Wikel K.,Petrobank Energy and Resources | Kendall R.,Tesla Exploration Ltd
Leading Edge | Year: 2013

The use of shear-wave splitting analysis as a tool for fracture analysis is well established. In this article, we discuss the analysis of shear-wave splitting in a relatively new context-shallow heavy oil plays where we believe stress is the dominant cause of the shear-wave splitting, rather than macroscale fracturing. There is clear laboratory evidence in the literature for shear-wave splitting caused by differential stress, which we believe supports this viewpoint. We are particularly interested in the use of shear-wave splitting technology for monitoring reservoir stress changes which correlate with thermal production for heavy oil reservoirs. This article also takes a fresh look at some well-established characteristics of split shear waves as they appear in wide-azimuth multicomponent data, and in particular the relative merits of the radial and transverse amplitude signatures. We describe a recently developed method, which combines both radial and transverse analysis to improve the effective azimuthal coverage. This approach is beneficial when the survey has been coarsely acquired, as we demonstrate on a heavy oil example. The article concludes with a case study at Kerrobert, a reservoir in the Canadian heavy oil region where thermal recovery methods are in use, and where shear-wave splitting is being utilized to help characterize the resulting stress changes in the reservoir. © 2013 by The Society of Exploration Geophysicists.

Wikel K.,Petrobank Energy and Resources
73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 | Year: 2011

3D converted wave data have been used in the past as an indicator of fractures and differential stress, although the emphasis has historically been on fractures. Recently, industry has been analyzing stress directions and stress changes based on the direction of fast converted mode (PS1) and the time lag between the fast and slow converted modes (PS1/PS2) in the near surface. In the compliant near surface of NE Alberta the data provided from converted wave seismic data rotated into fast and slow shear directions allows us to evaluate cap rock integrity and areas where the cap rock may deviate from the regional faulting regime. This information is extremely useful in discerning the cap rocks ability to maintain integrity during shallow high pressure bitumen and heavy oil recovery. In addition to this, the changes in PS1 direction and PS1/PS2 time lag with time can assist us in monitoring reservoir changes and recovery of bitumen. This paper is an overview of a case study from Petrobanks pilot THAI facility near Conklin, Alberta, and the results of a converted wave cap rock integrity study.

Wikel K.,Petrobank Energy and Resources | Kendall R.,Petrobank Energy and Resources | Bale R.,CGG Veritas | Grossman J.,CGG Veritas | DeMeersman K.,CGG Veritas
First Break | Year: 2012

Recent observations of shear-wave splitting in the near surface have been interpreted as a consequence of the stress state rather than the presence of fractures. The analysis of such shallow anisotropy measurements from shear-wave splitting on converted-wave data allows us to evaluate caprock integrity and detect areas where the stress in the caprock may deviate from the regional faulting regime. This information is vital in discerning whether the caprock is able to withstand recovery of shallow in-situ bitumen and heavy oil. Moreover, using time-lapse multi-component data, we can use the changes in splitting azimuth and time delay to monitor overburden and reservoir changes occurring during production. Here we show that converted-wave splitting changes, observed at the Conklin Demonstration Project between 2008 and 2009, can be directly correlated to changes occurring in the overburden. Additionally, we show that the stress state of the overburden, and in particular the transition from one stress regime to another with depth, is considerably more complex than has generally been assumed. © 2012 EAGE.

Kendall R.,Petrobank Energy and Resources | Wikel K.,Petrobank Energy and Resources
73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 | Year: 2011

The compressional and shear velocities of bitumen sand decrease dramatically with increasing temperature. The THAI process can be monitored using timelapse seismic and the results indicate that the combustion front is moving primarily from the toe area of the producing wells towards the heel area. We have also observed a rogue anomaly that suggests some of the upgraded oil has been pushed down into the bottom water system and is being swept away due to hydrodynamic forces. Multidimensional interpolation can be used to dramatically reduce the bin size and hence increase the trace count of coarsely sampled 3Ds. The integrity of the interpolated data is sufficient for monitoring THAI combustion-style production using time-delay 4D methods. The implications for production monitoring of enhanced oil recovery is substantial using interpolation.

Kendall R.,Petrobank Energy and Resources | Wikel K.,Petrobank Energy and Resources
SEG Technical Program Expanded Abstracts | Year: 2011

In-situ recovery of bitumen resources in Northwestern Canada occurs in the near surface deeper than 75m and typically less than 600m. The recovery method patented and used by Petrobank is known as Toe-to-Heel-Air-Injection THAI®, which is an in-situ combustion process that is used for the recovery of bitumen and heavy oil. It combines a horizontal production well with a vertical air injection well placed at the toe. This is an in-situ combustion process which burns the heavy end asphaltenes of the bitumen to mobilize and upgrade oil in-situ, while recovering up to 65% of the bitumen. Because of the shallow depth of operation in combination with the properties of bitumen, where the oil is part of the formations matrix, this process produces large changes in the reservoir and also in how the formation carries and distributes a load Wikel, 2011. Therefore, this affects how the reservoir and overburden distribute regional and local stresses. This requires monitoring of the reservoir during combustion and for stress changes in the formation of interest. In addition to this, the overburden must be monitored and studied to ensure cap rock integrity through time. This will help us avoid well damage or surface venting of pressure. Time lapse multi-component studies are well suited for this purpose. Data from the Conklin THAI pilot show that the combustion front is moving toward the heels of the wells in a non-uniform pattern Kendall, 2011 and that regional stress anomalies in the overburden are responsible for changes in the faulting regime in the reservoir Wikel, 2011. In addition to this, new data has shown that front movement has changed with time and operational improvements. Also, stress directions and magnitudes in the reservoir and overburden have changed as the front has progressed from 2008-2011. Well deformation in the area can be directly attributed to stress changes in the overburden. These changes have implications for how the pilot is managed in the future. Examples from past and new data sets will be shown along with drilling and operational data from the pilot facility. © 2011 Society of Exploration Geophysicists.

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