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3. Manage data in Correlator

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1.

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Prepare correlation data

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Data directories

Correlator is relatively flexible in terms of data file content and formats. Its import functions allow you to specify the only columns it really requires: depth and data. However, having the data files in a consistent format makes the process simpler and reliable. The following are the recommendations should be considered to be best practices on the JR.

• Use the Correlator Downloader application to download data from the LIMS database. Refer to the separate user guide for that application.
• Create a folder for each site (example in Fig. 3.1-1).
• Download one file for each data type and hole into the site folder. Append data for each new core measured using the Append core feature in Correlator Downloader.
• Create an images folder in each site folder where you place all reduced section images for the hole.
  • Batch-download the cropped section half images for a hole into a separate folder.
  • Use the R script provided to crop and reduce the images, then move the reduced images to the images folder in the correlation data site folder.
  • A separate user guide describes how to use the R script.
• If you have existing affine and splice tables for the site, place them in the site folder as well.

Figure 3.1-1. Example of a site folder with correlation data.

Image Added

Special case of specifying data types

One of the primary objectives of stratigraphic correlation is to correlate section data from a new hole rapidly to the data from one or more previous holes to check if coring gaps in previous holes are recovered in the current hole. If coring gaps are not covered adequately due to the change in water depth (mostly due to tides, but also other environmental and operations factors), you want to provide relative coring offset (drill down interval) instructions to the drillers in near-real time.

In order to achieve this objective, we implemented a special task multisensor logger (STMSL), also referred to as ‘fast track’, with the same type of magnetic susceptibility (MS) instrument as the one mounted on the primary whole-round multisensor logger (WRMSL). The two instruments are the same for all practical purposes, however, users have found that slight differences in the data may exist (normally negligible compared to the overall analytical error). In any case, the ultimate goal is to measure all sections on the WRMSL in the sequence they are recovered to provide a consistent final MS data set. The STMSL is only and specifically used to measure selected sections from a new hole as needed, thus out of sequence, to provide rapid assessments and instructions to the driller.

Here comes the trick: In order to be able to correlate data from the STMSL with data from the WRMS in Correlator, the two data sets must be imported as two different data types, MSTL and STMSL, even though they are in fact both MS.
The Correlator Downloader application assists you with that: make sure you check the Split by instrument check box when downloading MS data, which results in two separate data files. When importing to Correlator, you assign the explicit custom names WRMSL STMSL for the two data files and you'll be able to correlate them.

3.2. Summary of Data Manager functions

When launching Correlator, you land on the Data Manager page. If you arrive there for the first time, you have only one function available:

• Root: right-click to add data

As soon as the first data file is imported, Correlator creates a data directory for the site, using the site name from the data file, and the following data group folders:

• One folder for each imported data type. Within each data type, the imported data are represented by a line item for each hole.
• The Section Summaries folder described above, which needs one file and list item per hole.
• The Saved Tables folder where Correlator saves affine and splice tables for the site.

Here, the functions available at each directory level are summarized for general reference (Table 3.2-1).

Table 3.2-1. Summary of data management functions.

3.3. Import primary correlation data

(Update)

(Correlator will not allow you to import two files for the same data type). The new data type labels will stick in the data type list for future use in your session.
Now you can correlate the STMSL data rapidly acquired on critical sections from a new hole to the WRMSL data from previous holes using the TIE and SET methods.
 However, because Correlator was not designed to correlate different data types (usually makes no sense) the affine table currently only keeps track of the SHIFT core, with the assumption that the REF core tie point is from the same data type as the SHIFT tie point. An arrow can therefore not be drawn.

(Move up from 2.6.)

3.1. Import primary correlation data

(Update)

3.2. Import core section summary files

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