Acoustic Televiewers

Acoustic televiewers (ATV) were developed my Mobil Research in the mid-1960s to make an ultrasonic image of the inside of boreholes for fracture characterization. This technology that was truly developed before its time and only a small portion of the potential information could be utilized. In the 1980s Colleen Barton with the Rock Physics Group at Stanford started digitizing the analog ATV data and developed interactive software to process this digital data. Her first software was developed on mainframes followed by software on Macintosh based systems. In the 1990’s, TNO in Belgium developed the first digital ATV system for Petroleum and the ODP program. Advanced Logic Technologies (ALT) developed an MS Windows based interactive software to process this digital data (WellCAD) and obtained rights to TNO’s slimhole Acoustic Televiewers sensor thus creating the Facsimile 40 (FAC40). ALT followed this development with a digital optical borehole imager (OBI) or optical televiewer that acquired a RGB color image of the borehole wall using a downhole CCD camera.

ALT subsequently developed the next generation of acoustic borehole imagers (ABI40) using their own higher resolution sensor head design and downhole processor. The ABI40’s were the first acoustic televiewers that could be used for ultrasonic casing inspection. ALT has continued to be the leader in slimhole acoustic and optical imaging tools with new models being introduced at regular intervals. All of ALT’s imaging tools contain a 3-axis Fluxgate magnetometer and inclinometers or 3-axis accelerometers to sense tool orientation. Images can be obtained non-oriented or oriented to magnetic north or high side of the drill hole. The deviation sensors also allow the borehole path to be determined as well.

Southwest Exploration is a leader in acoustic and optical televiewer imaging with ALT tools. SwExp started with ALT’s FAC40 and OBI Mark I model tools initially and now has a total of 8 imaging tools including ALT’s latest model ABI43 and OBI Mark 4 tools. SwExp has applied these tools in the full-spectrum of applications ranging from:

Fracture characterization of ground water / environmental applications;
Rock mass characterization for engineering and mining applications;
Lithologic and structural geologic applications;
Orientation of core;
Insitu stress analysis; and
Steel casing thickness evaluation.

The single biggest issue impacting borehole imaging data quality is tool centralization. To this regard, SwExp utilizes more than 8 different styles of tool centralizers to insure the best quality data in a wide variety of applications. SwExp has used acoustic televiewers to capture excellent data in boreholes ranging from NX sise (76 mm dia.) boreholes ~2400 m deep an inclined ~45° to water wells ~18” in diameter. SwExp has utilized these tools on back pack portable equipment to helicopter portable equipment and large truck mounted systems at projects in North and South America.

SwExp has extensive experience with advanced processing algorithms to optimize image quality post-acquisition and to pick, classify and display image features not recognized by new users of this technology. SwExp can extract the maximum amount of information available from acoustic televiewers and provide a variety of data presentations to optimize use of this information. Due to the years of experience with this equipment and ongoing interaction with ALT, we have developed extensive QA/QC procedures to minimize potential data quality pitfalls during both acquisition and processing.

Our imaging tools are 40mm to 43 mm (1.6” to 1.7”) in diameter and ~2m (6-7.5’) in length.

Interactive software, (WellCAD) allows for image orientation, optimization and picking and ranking of the fractures and also allows the operator to create 3 dimensional cylindrical projections of the inside of the borehole wall. It is not uncommon to see bit scratches from tri-cone drilling or core spin marks from coring operations while collecting the data or with minor post processing steps. We  provide a WellCAD Reader with all the data files so our clients can utilize the virtual borehole feature of WellCAD and rotate, expand and visualize the 3D projection from any view.

Real time print-outs and processed data can be obtained in the field in recent years due to the significant increase in computer processor speeds. What used to take ½ the day to import can now be imported and printed in a matter of minutes.

Optical and Acoustic televiewers are a mature technology that is widely accepted in the petroleum and mining industries.

We can also provide complimentary borehole video surveys in appropriate environments (dry holes and or clear fluid).

We encourage early interaction with clients on proposed applications of the borehole imaging tools. They can provide suggestions for drilling, borehole fluid, and borehole preparation that will help insure optimal borehole image quality at time of acquisition as well as make suggests for complimentary borehole geophysical services that can greatly improve the amount and type of information obtained from these surveys.

• OBI_40 Optical Televiewer
• ABI-40-Full Waveform Acoustic Televiewer
• ABI-43 Full Waveform Acoustic Televiewer