Acoustic and Optical Televiewers [PDF ]

Televiewers provide the most comprehensive and accurate information available for structural, resource and geotechnical assessment. The time and money saved pays for itself - the knowledge gained pays dividends.


In-situ Structural, Resource and Geotechnical Analysis

 

Acoustic (ATV) and Optical (OTV) Televiewers provide a unique opportunity to visualize, orient and measure borehole features in-situ while under naturally occurring pressure, temperature and stress conditions.

 

Precision depth, azimuth and dip control are accomplished with integrated tilt-meters and 3-component magnetometers; providing attitude reference which enables borehole and "true" feature orientation.  The resulting data provides accurate 3D representations and modeling for geotechnical, structural or resource applications.  Acquiring this information throughout a drilling program presents a significant opportunity for real-time information gain and saving for structural and resource geologists, project managers, geophysicists and/or geotechnical and mining engineers.  

Acoustic and Optical Televiewers are a cost-effective and reliable alternative to oriented core, especially when core recovery is an issue.  Televiewers provide the opportunity for:

  • Defining in-ditu strike, dip and aperture of fractures, veins, bedding and contracts;
  • Obtaining information from areas with missing core or low core recovery (low RQD);
  • Detailing fracture and fault zones regarding depth, size, frequency and attitude;
  • Depicting the in-situ stress field orientation. 

The Optical Televiewer (OTV) acquires a 360° high-resolution digital image of the borehole wall. This oriented and seamless image can be viewed "unwrapped" and in a 3-D "virtual core" for the entire borehole (Figure 1)

 

Optical Televiewer

Figure 1: OTV Log

Figure 1

In-situ OTV cleary Depicting bedding, geology fabric and open fractures that are oriented and measureable. 


 The Acoustic Televiewer (ATV) continuously images the borehole wall with acoustic waves enabling quantified measurement of open borehole features.  Fractures, breakouts and other acoustically visible features can be precisely measured in terms of position, depth, aperture, length and orientation.  
 
 

 Acoustic Televiewer

Virtual Core

Unwrapped View

 3D Borehole

Cross-Section of

Oriented Borehole

 Figure 2: ATV Core  Figure 3a: 3D Borehole  Figure 3b: Cross-section of borehole

 Figure 2

 Figure 3

  ATV data is used to measure the depth of features as well as aperture, length, strike, and dip (Figure 2). Oriented ATV data can be depicted as virtual core or borehole, rotated in 3D with cross-sections and unwrapped for maximum visualization, measurement and analysis capability eg. Breakout Analysis (Figure 3). 

 

 

Employing OTV or ATV probes independently provides exceptionally accurate data; combining both in a complementary fashion provides an unparalleled in-situ solution.  This high-resolution data set provides a common information base for multiple and diverse applications that can be leveraged throughout the project lifecycle.  

 

The following is a partial list of ATV and/or OTV benefits:

  • Orient core and features with true strike and dip;
  • Bore deviation (directional) measurement;
  • Fracture zone characterization, modeling and analysis;
  • Regional stress field evaluation;
  • High-resolution diameter (Caliper).

 DGI has successfully helped our customers by:

  • Identifying and orienting mineralized vein intersections;
  • Visually inspecting paste fill lines, well casings and screens;
  • Identifying or validating zones of groundwater flow;
  • Defining structural geology;
  • Conducting geotechnical investigations for civil engineering, hydroelectric and mining projects.

Wulff Plot

Figure 4: Wulff Plot

Figure 4

OTV and ATV data can be identified, classified and analyzed with "true" orientation.