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About The Data
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Core Analysis Data
The original data set used for this project was contained in books that were used as
exhibits in various company applications to designate a particular region and formation
as a Tight Gas Formation under regulations established by the Federal Energy Regulatory Commission (FERC).
Typical information contained in these books included images of well header information, an image
of a pertinent well log through the depth interval of interest, and any available core analysis data.
Some books also contained information such as depth to the top of a particular unit,
tops picked within the Dakota, and perforation intervals; however this data was not present in every area.
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The original analyses were not done specifically for the applications, but had been
produced previously for some other reason. Most core analyses were performed in the
late 1950’s and early 1960s, although a few were older or younger, and they were
performed by different companies, so they showed significant variability in content
and format. Some records contained copies of the original analyses, while others
only contained the tabular data that had been abstracted from the original analyses.
Original analyses contained useful information that was often non-quantitative in
nature (eg., lithologies, notable features, non-numerical measurement designations
such as TSTM for too small to measure). Where available, we made efforts to capture
this information in the database in notes and remarks columns.
For each core analysis well we have a data set that includes basic well data,
the core analysis data, image files of well records, and, in many cases image files
of well logs. In addition, we digitized available well logs to create a reasonably
complete suite of LAS files for the Dakota core analysis wells. For all wells with logs,
the top of the Dakota was picked, and where possible, we made picks of tops of several
units within the formation. Some wells had pre-existing data on formation tops, either
from scout cards, records from the NM OCD, or the application books. We noted that
several different methods seemed to be in use for defining the various units of interest,
so we eventually elected to have two workers familiarize themselves with the subsurface
stratigraphy and log curves and pick tops for three sets of wells. This ensured that we at
least had a consistent choice of top for the entire study area.
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