HIGH RESOLUTION X-RAY CT SCANNING

X-Ray CT Imaging (CT scanning) is a well-established screening tool (more than 30 years) for both whole core in liners, preserved samples, core plugs and side- wall cores. CT scanning allows the presence of fractures, bedding, nodules etc. to be visualized. It is important to be aware of the presence of heterogeneity and damage present in samples that are being considered for use in advanced core studies such as SCAL. 

 

High Resolution X-Ray CT scanning provides unrivalled visualisation of the internal structure of whole core and plugs in 2D & 3D plus a borehole image log (BHI), 3600 view

High Resolution X-Ray CT Scanning

Core Technical Services (CTS) work in partnership with Geotek Limited utilising an MSCL-XCT system which is custom designed for core and as such, has unique advantages over the medical CT scanners used as standard by other service providers. The key advantage is voxel resolution which is an order of magnitude superior. In house personnel have more than 30 year’s experience with X-Ray CT imaging of core.

The key applications and deliverables are;

  • High resolution characterisation of the internal structures & fabric of core materials

  • Orientation of whole core in liner to facilitate band sawing and plugging

  • Core orientation / reconciliation with bore hole image logs (BHI), 360o view

  • Structural analysis of core – bedding, fractures, paleo transport direction / sediment movement

  • Detailed characterisation of preserved core sections prior to plugging for advanced studies

  • Detailed characterisation of core plugs before inclusion in advanced studies

  • Monitoring integrity of sleeved (mounted) core plugs as they progress through the analytical sequence – scanning pre-extraction, post-extraction and post analysis for one fixed price

  • Enhanced interpretation of routine core analysis (RCA) and special core analysis (SCAL) data

  • Mercury free core plug bulk volume (for porosity determination)

  • Optimising value of information from rotary sidewall cores (RSWC)

 

 

Why choose Core Technical Services as your provider of High Resolution X-Ray CT scanning?

 

Resolution - Up to 10x higher than medical systems

 

Flexibility- Innovative scanning methods such as laminography

 

Experience - Our team has 30+ years and many hundreds of cored wells

 

Cost - Ask for a quote and compare to your existing provider

 

During early March 2018, CTS installed a Geotek MSCL-XCT core scanning system at our Aberdeen premises. This system is capable of generating high resolution (down to 80 microns) X-Ray CT images of reservoir core material (whole core in liner, preserved core, core plugs including rotary sidewall core). 

 

The instrument differs from a medical CT scanner (as universally employed by the core analysis industry) in that the Geotek instrument is specifically designed for core material and can provide resolution up to an order of magnitude higher. In addition, the instrument is contained within a closed cabinet (incorporating safety interlocks) allowing it to be safely operated in any environment.

Much of the value to be obtained from CT scan data is derived from post-acquisition processing (somewhat to seismic). Various commercial (proprietary) and free-ware programs are available for such processing. The true value and potential of CT scanning on core is rarely utilised mainly due to restrictions imposed by resolution and the possibility of post processing of the raw scan data due to delivery of data in a medical format.

 

The CT scan service provided addresses both these issues.

The ability to extract “unwrapped” core images which are analogous to borehole image logs is of significant benefit for the purpose of structural analysis of core and reservoir.

 

The whole core CT scanning service removes the need for white light 360 degree core imaging. Moreover, CT scanning can reveal fine structures that are not visible to the human eye in white light.

                                                                                          

   

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                               Whole Core Unwrapped 360 Degree Image                               Dense laminations Isolated from CT Data Volume

            

All scanning is supervised by personnel who have CT scanning experience from the 1980's to present day - many hundreds of projects. Great care and attention will be taken during handling of the samples.

CT scans are provided in digital format. CTS will review the entire data volume for each sample and select images which provide most relevant detail of the sample condition and create an image album with accompanying information on sample ID and brief description.

 

The Raw scan files can also be provided to the client user who can review the images using Freeware.

All SCAL plugs must be CT scanned as part of the sample screening / selection process.

 

The previous SCAL studies noted the heterogeneity of the rock and value of X-Ray CT scanning.

CTS typically scan each plug prior to extraction, post extraction / drying and post analysis (potentially at additional steps during SCAL) to ensure only robust data is utilised for the purposes of reservoir evaluation. This means that each plug can be scanned at least twice times for a single fixed price.

 

                                                                               Plug Deliverable 

    

Additional Notes on CT File Formats;

 

  • Images files are supplied as standard TIFF stack

  • Videos of are supplied standard MP4 video files

 

 

Scanning of a whole core or plug's results in a file "stack" each file is a    slice through the object (the core in this case), so a 1 m core section consists of a  “stack” of about 1000 tiff files which the viewing software stitches together into a seamless volume, and then allows  rendering  for  different  views.,  slices  etc.  The  total data volume can be very large - usually sent out a hard drive (new and not re-used for security concerns) with the entire project on it.

 

In terms of viewing and management software, CTS use freeware, principally Image  J  and Drishti. Both require an element of of practice, but CTS issue guide notes for  this purpose. These software were developed for general application in image analysis but are very suitable for X-Ray CT data review.

 

In summary, there is no cost to the software required for viewing of these data. With a little practice, videos can be created by the user, static images extracted, data volumes created and even colour rendered – as X-Ray images are grey scale.

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