12.20.3 CuttingsIntervalLithology

Citation

Citation

An ISO 19115 EIP-derived set of metadata attached to ensure the traceability of the CuttingsIntervalLithology.

CodeLith

String64

An optional custom lithology encoding scheme.

If used, it is recommended that the scheme follows the NPD required usage. With the numeric values noted in the enum tables, which was the original intent for this item.

The NPD Coding System assigns a digital code to the main lithologies as per the Norwegian Blue Book data standards.

The code was then derived by lithology = (main lithology * 10) + cement + (modifier / 100).

Example: Calcite cemented silty micaceous sandstone: (33 * 10) + 1 + (21 / 100) gives a numeric code of 331.21.

However, the NPD is also working through Energistics/Caesar to potentially change this usage.)

This scheme should not be used for mnemonics, because those vary by operator, and if an abbreviation is required, a local look-up table should be used by the rendering client, based on Lithology Type.

Color

String64

STRUCTURED DESCRIPTION USAGE. Lithology color description, from Shell 1995 4.3.3.1 and 4.3.3.2 colors with the addition of: frosted. e.g., black, blue, brown, buff, green, grey, olive, orange, pink, purple, red, translucent, frosted, white, yellow; modified by: dark, light, moderate, medium, mottled, variegated, slight, weak, strong, and vivid.

Compaction

String64

STRUCTURED DESCRIPTION USAGE. Lithology compaction from Shell 1995 4.3.1.5, which includes: not compacted, slightly compacted, compacted, strongly compacted, friable, indurated, hard.

Hardness

String64

STRUCTURED DESCRIPTION USAGE. Mineral hardness. Typically, this element is rarely used because mineral hardness is not typically recorded.

What typically is recorded is compaction. However, this element is retained for use defined as per Mohs scale of mineral hardness.

Kind

LithologyKindExt

The geological name for the type of lithology from the enum table listing a subset of the OneGeology/CGI defined formation types.

LithPc

VolumePerVolumeMeasure

Lithology percent. Represents the portion of the sampled interval this lithology type relates to.

The total of the lithologies within an interval should add up to 100 percent.

If LithologySource in geology is:

1. "interpreted" only 100% is allowed.
2. "core" or "cuttings" then recommended usage is that the creating application uses blocks of 10%. i.e. 10, 20, 30, 40, 50, 60, 70, 80, 90, 100.

Ideally the input application should enforce a total of 100% for each defined depth interval.

If the total for a depth interval does not add up to 100%, then use the "undifferentiated" code to fill out to 100%.

MatrixCement

MatrixCementKind

STRUCTURED DESCRIPTION USAGE. Lithology matrix/cement description. Terms will be as defined in the enumeration table.

e.g., "calcite" (Common) "dolomite", "ankerite" (e.g., North Sea HPHT reservoirs such as Elgin and Franklin have almost pure ankerite cementation) "siderite" (Sherwood sandstones, southern UK typical Siderite cements), "quartz" (grain-to-grain contact cementation or secondary quartz deposition), "kaolinite", "illite" (e.g., Village Fields North Sea), "smectite","chlorite" (Teg, Algeria.).

Permeability

String64

STRUCTURED DESCRIPTION USAGE. Lithology permeability description from Shell 4.3.2.5.

In the future, these values would benefit from quantification, e.g., tight, slightly, fairly, highly.

PorosityFabric

String64

STRUCTURED DESCRIPTION USAGE. Visible porosity fabric description from after Shell 4.3.2.1 and 4.3.2.2: intergranular (particle size greater than 20m), fine interparticle (particle size less than 20m), intercrystalline, intragranular, intraskeletal, intracrystalline, mouldic, fenestral, shelter, framework, stylolitic, replacement, solution, vuggy, channel, cavernous.

PorosityVisible

String64

STRUCTURED DESCRIPTION USAGE. Lithology visible porosity description.

Defined after BakerHughes definitions, as opposed to Shell, which has no linkage to actual numeric estimates.

The theoretical maximum porosity for a clastic rock is about 26%, which is normally much reduced by other factors.

When estimating porosities use: more than 15% "good"; 10 to 15% "fair"; 5 to 10% "poor"; less than 5% "trace"; 0 "none".

Roundness

String64

STRUCTURED DESCRIPTION USAGE. Lithology roundness description from Shell 4.3.1.3. Roundness refers to modal size class: very angular, angular, subangular, subrounded, rounded, well rounded.

SizeGrain

String64

STRUCTURED DESCRIPTION USAGE. Lithology grain size description. Defined from Shell 4.3.1.1.(Wentworth) modified to remove the ambiguous term pelite.

Size ranges in millimeter (or micrometer) and inches.

LT 256 mm LT 10.1 in "boulder"

64-256 mm 2.5–10.1 in "cobble";

32–64 mm 1.26–2.5 in "very coarse gravel"

16–32 mm 0.63–1.26 in "coarse gravel"

8–16 mm 0.31–0.63 in "medium gravel"

4–8 mm 0.157–0.31 in "fine gravel"

2–4 mm 0.079–0.157 in "very fine gravel"

1–2 mm 0.039–0.079 in "very coarse sand"

0.5–1 mm 0.020–0.039 in "coarse sand"

0.25–0.5 mm 0.010–0.020 in "medium sand"

125–250 um 0.0049–0.010 in "fine sand"

62.5–125 um .0025–0.0049 in "very fine sand"

3.90625–62.5 um 0.00015–0.0025 in "silt"

LT 3.90625 um LT 0.00015 in "clay"

LT 1 um LT 0.000039 in "colloid"

Sorting

String64

STRUCTURED DESCRIPTION USAGE. Lithology sorting description from Shell 4.3.1.2 Sorting: very poorly sorted, unsorted, poorly sorted, poorly to moderately well sorted, moderately well sorted, well sorted, very well sorted, unimodally sorted, bimodally sorted.

Sphericity

String64

STRUCTURED DESCRIPTION USAGE. Lithology sphericity description for the modal size class of grains in the sample, defined as per Shell 4.3.1.4 Sphericity: very elongated, elongated, slightly elongated, slightly spherical, spherical, very spherical.

Texture

String64

STRUCTURED DESCRIPTION USAGE. Lithology matrix texture description from Shell 1995 4.3.2.6: crystalline, (often "feather-edge" appearance on breaking), friable, dull, earthy, chalky, (particle size less than 20m; often exhibits capillary imbibition) visibly particulate, granular, sucrosic, (often exhibits capillary imbibition).

Examples: compact interlocking, particulate, (Gradational textures are quite common.) chalky matrix with sucrosic patches, (Composite textures also occur).

uid

String64

Unique identifier for this instance of CuttingsIntervalLithology.

From: CuttingsIntervalLithology.

To: MatrixCementKind

Dependency

From: CuttingsIntervalLithology.

To: LithologyKindExt

Dependency

From: CuttingsIntervalLithology.Qualifier

0..*To: LithologyQualifier

Association

From: CuttingsIntervalLithology.Shows

0..*To: CuttingsIntervalShow

Association

From: CuttingsGeologyInterval.CuttingsIntervalLithology

0..*To: CuttingsIntervalLithology

Association