A Practical Lithology Reference Standard

Paul Maton (POSC)and

Gary Masters (POSC)

Outline

• Introduction• Business Objectives, Motivation and

Work flows• Resources• Lithology in WITSML 1.3• Enhanced Lithological Classification• Conclusions

Objectives and Requirements

• Provide evolving dictionary in XML of lithological terminology for use in:– end-2004 WITSML Version 1.3 Mudlog and Core

specifications– revised lithological classification, 2Q05– next WITSML Mudlog version 1.3.1, late 2005?

• Improve or simplify existing specification(s)

• Lithological terminology needed for POSC exchange standards

• Easy maintenance and extensibility

Business Drivers

• Operator Point of View– Standard vocabulary and semantics for

lithologies will improve the following processes• Assimilating results of outsourced work• Information exchanges with partners, regulators• Reduction of ambiguity and uncertainty in data • Common nomenclature used for mudlog, core and other

rock sample descriptions

• Service Company Point of View– Enable use of same nomenclature and

classifications in services and software for many customers

• Cost savings in software engineering and maintenance• Cost savings and consistency in information produced

Use Cases

• Mudlog– Rapid wellsite description of rock cuttings

• Core analysis– Full description of petrographic and

quantitative properties (porosity, permeability, density, etc.)

• Detailed Rock description and analysis– Optical and electron microscopy analysis

Available Resources

• Landmark Graphics– List of Lithology Classes with Qualifiers and

Symbol Codes

• Norwegian Petroleum Directorate– Reporting requirements for Digital Well Data:

Lithological Codes

• Shell– 1995 Standard Legend

• Statoil– Current Listing of Lithological codes

• Geological Literature

Common Descriptors for WITSML Mud-Log

• Primary and secondary lithologies• Use of the following characteristics as

Qualifiers

•Mineral content

•Fossil content

•Cement

•Grain size

•Sorting

•…~ 10 others

Lithology types in WITSML v1.3used by Mudlog and Core - 1

Andesite

Anhydrite

Arkose

Basalt

Breccia

Calcarenite

Calcilutite

Calcisiltite

Chalk

Chert

Clay

Claystone

Coal

Conglomerate

Diabase

Diorite

Dolerite

Dolomite

Dolomite, Calcareous

Extrusive Rock (Volcanic)

Feldspar

Gabbro

Glauconite

Gneiss

Granite

Gravel

Greenstones

Greywacke

Gumbo

Gypsum

Halite

Igneous

Intrusvie Rock (Plutonic)

Lignite

Limestone

Limestone, Argillaceous

Qualifiers in WITSML v1.3used by Mudlog and Core - 1

Anhydrite

Argillaceous

Barite

Belemnitic

Bioturbated

Bituminous

Bryozoans

Burrowed

Calcareous

Calcite concr

Calcitic

Carbonaceous

Chalky

Chamosite

Chert

Chlorite

Concretions

Conglomeratic

Coral

Crinoids

Diatoms

Dolomite concr

Dolomite Stringer

Dolomitic

Feldspar

Ferruginous

Fissile

Forams gen

Fossil Frags

Fossils gen

Glauconite

Glauconitic

Gravelly

Gypsiferous

Halite

Outline

• Introduction• Business Objectives, Motivation and

Work flows• Resources• Lithology in WITSML 1.3• Enhanced Lithological Classification• Conclusions

Enhanced Lithological Classification

• Current approaches – Base on Shell ’95 standard legend– Add sedimentary rock types with names,

descriptions, abbreviations and adjectives– Add mineral types, names, abbreviations and

adjectives– Possibly provide images of rocks as go-bys– Avoid over-complication

• Produce draft classification and taxonomy from available resources

• Validation by practising geologists

Material Classification

Material Composition

FluidRockMineral

MetamorphicIgneousSedimentary

Fossil

Property

Property and Composition are attribute sets inherited by Minerals and Rocks etc, but the sets have additional attributes in, and appropriate to, each sub-class

Common attributes of Sedimentary Rocks - 1

• Textural & Compositional– Grain size– Sorting– Roundness– Sphericity– Compaction– Non-skeletal particles

(lithic fragments)– Pellets and grains

• Porosity & Permeability– Qualitative and

quantitative– Fabric and non-fabric

selective– Archie classification

and types

• Color – Names, abbreviations

& qualifiers

Examples

• Sorting– unsorted [((srt))]– very poorly sorted [((srt))]– poorly sorted [(srt)]– poorly to moderately well

sorted [(srt)-srt]– moderately well sorted [srt]– well sorted [srt]– very well sorted [srt]– unimodally sorted

[unimod srt]

– bimodally sorted [bimod

srt]

• Compaction– not compacted [not cmp]– slightly compacted [(cmp)]– compacted [ cmp ]– strongly compacted cmp– friable [ fri ]– indurated [ ind ]– hard [ hd ]

• Color– green [ gn ], dark [ dk ]

[Note: Entire abbreviations, including parentheses, are in Square Brackets]

Common attributes of Sedimentary Rocks - 2

• Accessory Minerals– References extensible list and abbreviations of

mineral class names– e.g.: Feldspar (Fld)

• Fossil content– References extensible list and abbreviations of

fossil class names– e.g.: Bryozoa (Bry)

Common attributes of Sedimentary Rocks - 3

• Stratification and Sedimentary Features– Bedding thickness and appearance– Character of base of bed– Large non-bedded features: lens, bioherm etc– Cross bedding and lamination– Ripplemarks– Planar laminations– Graded bedding– Soft sediment deformation– Syn-depositional features

Common attributes of Sedimentary Rocks - 4

• Post-depositional features– Consolidation, cementation, weathering– Diagenetic structures– Nodules and concretions

Igneous and Metamorphic Rocks

• Minimal treatment given that these are not often of primary interest in E&P

• Names, descriptions, abbreviations and adjectival forms of ~12 types in each category– Examples– Granite, (Gr), granitic– Schist, (Sch or sch???), schistose

Next steps

• Collect feedback from April informal SIGs – Requirements, use cases, and availability of

specialists

• Review meetings with SIG member specialists in May

• Revise and publish Standard by end June• Promote and assist pilot implementations

in 2H2005

Conclusions

• XML based Lithologic vocabulary is under development and will be partially implemented for Mud logging part of WITSML 1.3

• Design is for usage in wider rock description and analysis, including wellsite and laboratory work

• Draft specification will be posted in 2Q2005, reviewed by SIG Member geological experts, then revised and published by POSC

Thank you for your attention

More information fromPaul Maton maton@posc.org +44 1932 828794Alan Doniger doniger@posc.org +1 713 267 5124Gary Masters masters@posc.org +1 713 267 5111