HEF’s standard service is the processing and interpretation of borehole image data. We are able to process data for any dipmeter or borehole image tool from any logging contractor and can handle data from both new and old wells from a variety of raw data types, including scanned paper prints and digital tapes. Our interpretations identify and quantify bedding and fracture textures as well as sedimentary, stratigraphic, and structural features. Interpretations can be augmented with HEF’s advanced service offerings, which include the integration of core images, structural analysis, fracture and stress analysis, stratigraphic analysis, and advanced reports.

Common Borehole Image Tools

While we can process any borehole image log acquired by any logging contractor, some of the common image tools and types we see are listed below:

Tool Type	Tool Acronym
Multi-pad water-based resistivity image	FMI, XRMI, STAR, CMI, ERMI, MCI, BIT, RIT, EMI, HMI
Single pad water-based resistivity image	FMS
Multi-pad oil-based resistivity image	Dual OBMI, ORMI, OMI, EIT, NGI, GXPL
Single pad oil-based resistivity image	OBMI
Acoustic / ultrasonic image	UBI, CBIL, ECBIL, UMI, CAST, UXPL
LWD / MWD image (resistivity/gamma ray/density)	RAB, ADN, GVR, STARTRAK, ONTRAK, AFR
Imaged dipmeter	HEXDIP, SED, SDT, SHDT, HDT

 

At the workstaion - At HEF, every job is thoroughly quality-checked and features are hand-picked.

Standard Workflow

Every well is different, each presenting its own unique processing challenges, but consistency is vital. We employ a standard set of processing steps and checks to ensure the data is correct and there are no issues with the logging tool. This guarantees the highest quality image interpretation possible. 

 To serve our client's needs we typically employ the following workflow:
  • Receipt of raw borehole image data, via FTP, CD, direct download/upload from the logging contractor 
  • Quality check and feedback on borehole image data to the client (usually within minutes of receipt of the data)
  • Processing of borehole image data (see processing stages below)
  • Interpretation of borehole image data
  • Review of interpretation by second analyst
  • Discussion on interpretation with client
  • Deliverables provided based on client's specific requirements

Borehole Image Processing Stages

Similar to seismic or conventional petrophysics processing, borehole image processing cannot be a black-box workflow. There are many stages that require thought and consideration leading to a time-tested process with checks and balances along the way to ensure quality is maintained and the computed dipmeter answer is correctly oriented.

HEF employs the following processing stages:
  • Depth shifting to put the image data on depth with the openhole logs
  • Preprocessing to re-orient images to true north and depth shift data to put it on depth in time 
  • Automatic accelerometer correction to correct for stick-and-pull and other depth errors
  • Image generation via static normalization of the image pads (histogram normalization that assigns
     the lightest color to the most resistive features of the entire well and the darkest color to the most
     conductive features)
  • Image button equalization on the static image, which attempts to limit differences from button
     to button when required
  • Dynamic image normalization over a 2 metre window (re-normalization in a sliding window to
     enhance local contrast)
  • Manual correction of accelerometer errors that were missed by the accelerometer correction
  • Verification of tool orientation quality through comparison to driller’s surveys and verifying |
     magnetometer and accelerometer
     accuracy by re-computing the field strength and relative orientations as the tool sweeps through
     the respective field
  • Manual correction of image artifacts as needed to deal with bad buttons, gain corrections and
     other cosmetic image issues
  • Manual correction of depth mismatches between odd and even pads and flaps or between
     multiple tools or passes within the borehole

After these stages, all of which are verified and conducted by one of our many experienced analysts, geological feature interpretation can begin. We pick a wide variety of bedforms and fracture types, and every interpretation is seen in its entirety by at least two of our interpreters to ensure that the standard remains consistent from well to well, field to field, and year to year.