Borehole Imaging (Borehole Imaging References & Additional Information)

Borehole Imaging References & Additional Information

Borehole Imaging References & Additional information

References

Antoine, J-N., and Delhomme, J-P. (1993), "A Method to Derive Dips from Bedding Boundaries in Borehole Images", in SPE Formation Evaluation, (June), pages 96-102 Society of Petroleum Engineers, Richardson, TX.

Halliburton Energy Services, Video tape: Finding Solutions with Downhole Video, 1998.

Maddox, S. Gibling, G.R., and Dahl, J.(1995) Downhole Video Services Enhance Conformance Technology, SPE Paper 30134, presented at The Hague, The Netherlands, European Formation Damage Conference, (May).

Murphy, D.P. (1996) "Advances in MWD and formation evaluation for 1996."World Oil, (March), pages 37-47

Serra, O. (1989), Formation MicroScanner Image Interpretation, published by Schlumberger Educational Services.

Ward, S.L., Allen, T. T., Chavers, R.D., Robertson, T.N., and Schultz, P.K, (1994) "Diagnosing Production Problems with Downhole Video Surveying At Prudhoe Bay." Journal of Petroleum Technology (November), pp.973 – 978 Society of Petroleum Engineers, Richardson, TX.

Whitaker, J.L. and Linville, G. D., SPE Paper 35680, Well Preparation – Essential to Successful Video Logging, presented at Anchorage Alaska at 1996 SPE Western Region Meeting

Zemanek, J., Caldwell, R.L., Glenn. E.E. Jr., Holcomb, S.V., Norton, L.J. and Straus, A.J.D. (1967). "The Borehole Televiewer—A New Logging Concept for Fracture Location and Other Types of Borehole Inspection." Journal of Petroleum Technology (June), pp. 762 - 774. Society of Petroleum Engineers, Richardson, TX.

The following web sites provide useful information on the logging tools discussed in this IPIMS treatment.

 

Baker Atlas web pages at

http://www.bakeratlas.com

DHV International, Incorporated web pages at

http://www.dhvi.com

Halliburton Energy Services
web page at

http://www.halliburton.com

Hitwell Video Inc. web pages at

http://www.hitwellvideo.com

Schlumberger Oilfield Services web pages at

http://www.slb.com

BOREHOLE IMAGING REFERENCES & ADDITIONAL INFORMATION

Imaging Tools Quick Reference

Here is a listing of some of the companies that provide borehole imaging services, as well as tool names and associated acronyms.

Acoustic Imaging Tools	Service	Acronym
Baker Atlas	Circumferential Borehole Imaging Log	CBILTM
Halliburton	Circumferential Acoustic Scanning Tool	CASTTM
Schlumberger Resistivity Imaging Tools	Ultrasonic Borehole Imager	UBITM
Baker Atlas	Simultaneous Acoustic/Resistivity tool	STARTM
Halliburton	Electrical Micro Imaging tool	EMITM
Schlumberger	Azimuthal Resistivity Imager tool	ARITM
Schlumberger Video Tools	Fullbore Formation MicroImager tool	FMITM
Halliburton /  DHV International	Downhole Video	DHVTM
Schlumberger /  Hitwell Video Inc.	Video Scan Acquisition System	VSASTM

 

 

E.5. Best Practices

Best Practices for Downhole Video Systems

The downhole video system is constrained primarily by the clarity of the downhole fluid, though hole size, pressure, temperature, and depth are also factors that will influence the outcome of the job. The following factors should be considered in order to obtain optimum video quality from the downhole video system.

Fluid Clarity

Downhole video cameras require a clear medium such as clear water, dry gas or air. Drilling mud does not provide sufficient clarity.
Fluid clarity differs from well to well, so it is absolutely necessary to test the fluid before attempting to run a video service. Sample the fluid at the wellhead, rather than the pump or holding tank because fluid clarity can change considerably as it moves through pumps tanks, and lines. Avoid sampling from the kelly hose, which is often a source of particulate matter that reduces visibility.

Sample the fluid at least 24 hours prior to testing it, to allow sufficient time for oil/water mixtures to stratify. If a fluid sample has to settle for a day before you can see through it, then you should plan on shutting-in the well for a similar period to enable the camera to see through the fluid at the bottom of the well. If the fluid is not clear after 24 hours, then remedial action may be needed to clear up the fluid sufficiently to view the object or zone of interest. When the wellbore fluid is air or gas, well preparation may still be needed to clean up the well, though these fluids are usually less complex than water/oil mixtures.

The best way to determine clarity is to actually look through a sample of any fluid that will come between the camera and the target (Whitaker and Linville,1996). Downhole video imaging is best used in liquids that have a turbidity value of less than 11 Nephelometric Turbidity Units (NTUs), measured by a device that includes both transmission and scattering methods in the measurement. (By comparison, tap water has a turbidity value of approximately 1 NTU.)

Generally, still camera systems require more light and a clearer viewing medium than full-motion cameras. Consequently, clean-up procedures are even more important with still cameras than with full-motion systems. If a brine solution will be used, it should be pre-mixed and placed in a holding tank at least one day prior to being filtered and pumped downhole. Brine should be filtered down to 5 microns, using two filter units in parallel, so that one unit can be cleaned while the other is 'on line'.

Hole Size

Minimum hole size must accommodate the diameter of the video tool, which ranges from 1-11/16 inch to 2-3/8 inches, depending on the tool model.

Pressure

Most video tools are pressure-rated to 10,000 psi.

Temperature

Some video tools are capable of operating in temperatures ranging from 32 to 400 degrees F, depending on the tool model. Some tools have even been utilized in geothermal wells, where temperatures surpassed 500 degrees F. Some tools may have a higher tolerance to short exposures at high temperatures than their tolerance to prolonged exposures at slightly lower temperatures.

Depth

Depending on the tool model, maximum depths range from 14,000 to 18,000 feet.

Additional Information

For further details, consult the SPE articles by Maddox, Gibling, and Dahl, (1995) and by Whitaker and Linville (1996), listed in the references. Contact your local service representative for specific information regarding operating parameters and limitations of each particular tool.

 

Exercises & Solutions

Exercise 1.

The three borehole imaging technologies are:

• ______________ ,
  
• ______________ , and
  
• ______________ .
  

The three borehole imaging technologies are:

• Downhole video,
  
• Acoustic imaging, and
  
• Resistivity imaging.
  

Exercise 2.

As a formation evaluation tool, the downhole video camera is used to find the depth, orientation, and size of ______________ , as well as characterizing the type of ____________ produced by each perforation in the well.

As a formation evaluation tool, the downhole video camera is used to find the depth, orientation, and size of fractures, as well as characterizing the type of fluid produced by each perforation in the well.

Exercise 3.

The most important influence on the success of a downhole video survey is __________________.

For this reason, drilling mud is or is not an acceptable medium for downhole video applications.

The most important influence on the success of a downhole video survey is clarity of the borehole fluid.

For this reason, drilling mud is or is not an acceptable medium.

Exercise 4.

The acoustic imaging tool employs a _____________________ to generate ultrasonic pulses.

The acoustic imaging tool employs a rotating transducer to generate ultrasonic pulses.

Exercise 5.

Though acoustic imaging tools have _________ resolution than microresistivity tools,
they can be run in a variety of drilling fluids, including:

• __________  muds,
  
• __________  muds,
  
• __________  muds, and
  
• __________  muds.
  

Though acoustic imaging tools have poorer resolution than microresistivity tools,
they can be run in a variety of drilling fluids, including:

• Fresh-water muds,
  
• Salt-water muds,
  
• Oil-based muds, and
  
• Polymer muds.
  

Exercise 6.

Acoustic imaging tools may be used in both _______ and ________ hole applications.

Acoustic imaging tools may be used in both open and cased hole applications.

Exercise 7.

Acoustic imaging measurements may be somewhat limited by:

 ___________,

 ___________, and

 ___________________.

Acoustic imaging measurements may be somewhat limited by:

• Heavy muds,
  
• Tool eccentering, and
  
• Large-diameter wellbores.
  

Exercise 8.

Resistivity imaging tools utilize articulating ___________ containing multiple ____________ to measure the formation _________________ at the borehole wall.

Resistivity imaging tools utilize articulating  pads containing multiple electrodes to measure the formation microconductivity or microresistivity at the borehole wall.

Exercise 9.

Currents measured by the resistivity imaging tool vary according to formation conductivity, which reflects changes in:

• _____________,
  
• __________,
  
• __________,
  
• _______________ , and
  
• ___________.
  

Currents measured by the resistivity imaging tool vary according to formation conductivity, which reflects changes in:

• Fluid properties,
  
• Permeability,
  
• Porosity,
  
• Rock composition
  , and
  
• Grain texture.
  

Exercise 10.

Three factors which affect the resistivity imaging tool are:

· ___________________ ,

· ___________________ , and

· ___________________ .

Three factors which affect the resistivity imaging tool are:

·
Open hole environment,

·
Water-based mud, and
·
Tool centralization.