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Hydrocarbon accumulation: the seven critical elements (view source)
Revision as of 19:32, 21 January 2014
, 19:32, 21 January 2014Initial import
{{publication
| image = exploring-for-oil-and-gas-traps.png
| width = 120px
| series = Treatise in Petroleum Geology
| title = Exploring for Oil and Gas Traps
| part = Predicting the occurrence of oil and gas traps
| chapter = Value of geological fieldwork
| frompg = 19-1
| topg = 19-42
| author = Denise M. Stone
| link = http://archives.datapages.com/data/specpubs/beaumont/ch19/ch19.htm
| pdf =
| store = http://store.aapg.org/detail.aspx?id=545
| isbn = 0-89181-602-X
}}
Seven critical elements are necessary for subsurface hydrocarbon accumulations to occur:
* Reservoir rock
* Source rock
* Seal
* Thermal history
* Migration and trapping of hydrocarbons
* Geologic history of the basin
* Structural history and style
==Criticality==
Exploration risk is best understood by studying historically what has and has not been successful in a basin. In other words, what combination of the seven critical elements occurred to form existing fields and, conversely, what are the main reasons for the dry holes in that same basin? Is a common element responsible for the dry holes?
The goal of an exploration effort is to use all the data available to identify fully the technical risks and recommend the best course of action and investment. Action following a field project might range from no action, to acquiring more data in key areas, to drilling a well.
==Critical element checklist==
The following checklist summarizes key [[attributes]] of the seven critical elements. The working explorer should have a general understanding of these attributes in the basin studied.
===Reservoir rock===
General 3-D definition
* Sedimentary rock type(s)
* Gross thickness range
* Lateral continuity (faulted?)
* Mappability
* Depth of burial: structural relief of reservoir top
* Outcrop occurrences
Character of upper and lower boundaries
* Origin: erosional vs. depositional
* Nature: abrupt vs. gradational
* Seismic reflectivity
* Conformability
Diagnostic features
* Depositional environment
* Facies distribution
* Provenance
* Internal stratigraphic subdivisions
* Age diagnostic criteria: fossils, intrusives, marker horizons
* Electric log responses
* Pay distribution: vertical, lateral
* Sedimentary structures
Petrographic characteristics
* Composition: framework grain mineralogy, crystallinity
* Texture: grain size, sorting, roundness, crystallinity
* Degree of cementation
* Diagenetic alteration
* Microfossils
* Fractures
* [[Porosity]]
* [[Permeability]]
===Source rock===
* Age
* Thickness
* Lateral continuity
* Organic richness
* Thermal maturity
* Kerogen type
* Depositional environment
* Facies
* Mappability
* Carbonate vs. clastic
* Depth of burial
===Seal===
* Vertical seals
* Lateral seals
* Lithology of potential seals
* [[Capillary pressure]]
* Lateral continuity of sealing formations
* Presence of evaporates
* Fracture systems
===Thermal history===
* Rates of deposition
* Rates of burial
* Paleogeothermal gradient
* Tectonic history
* Location of kitchen areas
===Migration and trapping===
* Fault juxtaposition
* Fractures
* Lateral [[permeability]] and [[porosity]]
* Controls on migration
===Geologic history===
* Main tectonic events: compressional, tensional, wrench
* Structural overprinting
* Depositional history: continental, marine
* Episodes of subsidence: regional, local
* Controls on subsidence
* Unconformities
* Significant episodes of volcanism, subsidence, uplift, erosion
* Rates of deposition
* Paleotopography
* Paleoshoreline
* Paleoclimate
* Chronostratigraphy
===Structural history and style===
* Compressional vs. tensional basin
* Main structural elements
* Tectonic development
* Sequence of events
* Structural overprinting
* Fault trends: major and minor
* Basin boundary faults
* Major faults vs. minor faults
* Zones of weakness
* Dip domains
* Outcrop patterns
* Dip and strike trends
* Average throw on faults
==See also==
* [[Fieldwork and your exploration program]]
* [[Applying the seven critical elements]]
* [[Assessing risk]]
* [[How geological fieldwork fits in]]
==External links==
{{search}}
* [http://archives.datapages.com/data/specpubs/beaumont/ch19/ch19.htm Original content in Datapages]
* [http://store.aapg.org/detail.aspx?id=545 Find the book in the AAPG Store]
[[Category:Predicting the occurrence of oil and gas traps]]
[[Category:Value of geological fieldwork]]
| image = exploring-for-oil-and-gas-traps.png
| width = 120px
| series = Treatise in Petroleum Geology
| title = Exploring for Oil and Gas Traps
| part = Predicting the occurrence of oil and gas traps
| chapter = Value of geological fieldwork
| frompg = 19-1
| topg = 19-42
| author = Denise M. Stone
| link = http://archives.datapages.com/data/specpubs/beaumont/ch19/ch19.htm
| pdf =
| store = http://store.aapg.org/detail.aspx?id=545
| isbn = 0-89181-602-X
}}
Seven critical elements are necessary for subsurface hydrocarbon accumulations to occur:
* Reservoir rock
* Source rock
* Seal
* Thermal history
* Migration and trapping of hydrocarbons
* Geologic history of the basin
* Structural history and style
==Criticality==
Exploration risk is best understood by studying historically what has and has not been successful in a basin. In other words, what combination of the seven critical elements occurred to form existing fields and, conversely, what are the main reasons for the dry holes in that same basin? Is a common element responsible for the dry holes?
The goal of an exploration effort is to use all the data available to identify fully the technical risks and recommend the best course of action and investment. Action following a field project might range from no action, to acquiring more data in key areas, to drilling a well.
==Critical element checklist==
The following checklist summarizes key [[attributes]] of the seven critical elements. The working explorer should have a general understanding of these attributes in the basin studied.
===Reservoir rock===
General 3-D definition
* Sedimentary rock type(s)
* Gross thickness range
* Lateral continuity (faulted?)
* Mappability
* Depth of burial: structural relief of reservoir top
* Outcrop occurrences
Character of upper and lower boundaries
* Origin: erosional vs. depositional
* Nature: abrupt vs. gradational
* Seismic reflectivity
* Conformability
Diagnostic features
* Depositional environment
* Facies distribution
* Provenance
* Internal stratigraphic subdivisions
* Age diagnostic criteria: fossils, intrusives, marker horizons
* Electric log responses
* Pay distribution: vertical, lateral
* Sedimentary structures
Petrographic characteristics
* Composition: framework grain mineralogy, crystallinity
* Texture: grain size, sorting, roundness, crystallinity
* Degree of cementation
* Diagenetic alteration
* Microfossils
* Fractures
* [[Porosity]]
* [[Permeability]]
===Source rock===
* Age
* Thickness
* Lateral continuity
* Organic richness
* Thermal maturity
* Kerogen type
* Depositional environment
* Facies
* Mappability
* Carbonate vs. clastic
* Depth of burial
===Seal===
* Vertical seals
* Lateral seals
* Lithology of potential seals
* [[Capillary pressure]]
* Lateral continuity of sealing formations
* Presence of evaporates
* Fracture systems
===Thermal history===
* Rates of deposition
* Rates of burial
* Paleogeothermal gradient
* Tectonic history
* Location of kitchen areas
===Migration and trapping===
* Fault juxtaposition
* Fractures
* Lateral [[permeability]] and [[porosity]]
* Controls on migration
===Geologic history===
* Main tectonic events: compressional, tensional, wrench
* Structural overprinting
* Depositional history: continental, marine
* Episodes of subsidence: regional, local
* Controls on subsidence
* Unconformities
* Significant episodes of volcanism, subsidence, uplift, erosion
* Rates of deposition
* Paleotopography
* Paleoshoreline
* Paleoclimate
* Chronostratigraphy
===Structural history and style===
* Compressional vs. tensional basin
* Main structural elements
* Tectonic development
* Sequence of events
* Structural overprinting
* Fault trends: major and minor
* Basin boundary faults
* Major faults vs. minor faults
* Zones of weakness
* Dip domains
* Outcrop patterns
* Dip and strike trends
* Average throw on faults
==See also==
* [[Fieldwork and your exploration program]]
* [[Applying the seven critical elements]]
* [[Assessing risk]]
* [[How geological fieldwork fits in]]
==External links==
{{search}}
* [http://archives.datapages.com/data/specpubs/beaumont/ch19/ch19.htm Original content in Datapages]
* [http://store.aapg.org/detail.aspx?id=545 Find the book in the AAPG Store]
[[Category:Predicting the occurrence of oil and gas traps]]
[[Category:Value of geological fieldwork]]