Difference between revisions of "Trap classification levels"
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==Basis for each level== | ==Basis for each level== | ||
| − | A fairly flexible classification scheme has been devised in which each of the three trap systems is divided into three trap regimes, based primarily on the processes that control trap formation in the systems. The trap regimes can be divided into geometric classes and the classes into genetic families. Classifying traps using levels and the same basis at each level brings more consistency and value to classification. The table below shows the basis for each classification level and its definition. | + | A fairly flexible classification scheme has been devised in which each of the three [[trap]] systems is divided into three trap regimes, based primarily on the processes that control trap formation in the systems. The trap regimes can be divided into geometric classes and the classes into genetic families. Classifying traps using levels and the same basis at each level brings more consistency and value to classification. The table below shows the basis for each classification level and its definition. |
{| class = "wikitable" | {| class = "wikitable" | ||
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| Regime | | Regime | ||
| Process | | Process | ||
| − | | The dominant way of forming part or all of the trap closure. If the trap is structural, was the closure formed by folding, faulting, or fracturing? If the trap is stratigraphic, was the closure formed by depositional, erosional, or diagenetic processes? If the trap is fluidic, was closure formed by pressure, temperature, or chemical processes? | + | | The dominant way of forming part or all of the trap [http://www.glossary.oilfield.slb.com/en/Terms.aspx?LookIn=term%20name&filter=closure closure]. If the trap is structural, was the closure formed by folding, faulting, or fracturing? If the trap is stratigraphic, was the closure formed by depositional, erosional, or diagenetic processes? If the trap is fluidic, was closure formed by pressure, temperature, or chemical processes? |
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| Class | | Class | ||
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* Geometry—the external shape and size of the trap; may also include geometry of internal trap elements. | * Geometry—the external shape and size of the trap; may also include geometry of internal trap elements. | ||
| − | * Composition—the makeup of the reservoir, seal, or fluid that creates or defines the trap boundaries. | + | * Composition—the makeup of the [[reservoir]], [[seal]], or fluid that creates or defines the trap boundaries. |
|- | |- | ||
| Family | | Family | ||
| Genesis | | Genesis | ||
| − | | The way all or part of the trap closure came into being. For example, for an isolated marine carbonate trap, was the closure formed because of the reservoir | + | | The way all or part of the trap closure came into being. For example, for an isolated marine carbonate trap, was the closure formed because of the reservoir and seal facies relationships of a reef, an oolite bar, or a tidal channel? |
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| − | + | ||
==Sublevels== | ==Sublevels== | ||
Using one term to classify traps geometrically, compositionally, or genetically is not always adequate. To solve this problem, intermediate groupings such as superfamilies or superclasses can be added where necessary. Trap classes can be subdivided into subclasses and styles if needed, and trap families can be subdivided into subfamilies and varieties. These extra levels allow a fuller description of traps. | Using one term to classify traps geometrically, compositionally, or genetically is not always adequate. To solve this problem, intermediate groupings such as superfamilies or superclasses can be added where necessary. Trap classes can be subdivided into subclasses and styles if needed, and trap families can be subdivided into subfamilies and varieties. These extra levels allow a fuller description of traps. | ||
Revision as of 13:36, 28 October 2014
| Exploring for Oil and Gas Traps | |
| |
| Series | Treatise in Petroleum Geology |
|---|---|
| Part | Traps, trap types, and the petroleum system |
| Chapter | Classification of exploration traps |
| Author | Richard R. Vincelette, Edward A. Beaumont, Norman H. Foster |
| Link | Web page |
| Store | AAPG Store |
Basis for each level
A fairly flexible classification scheme has been devised in which each of the three trap systems is divided into three trap regimes, based primarily on the processes that control trap formation in the systems. The trap regimes can be divided into geometric classes and the classes into genetic families. Classifying traps using levels and the same basis at each level brings more consistency and value to classification. The table below shows the basis for each classification level and its definition.
| Classification level | Basis | Function/Definition |
|---|---|---|
| System | Controlling geologic element | Dominant control of the trap—structural, stratigraphic, or fluidic. |
| Regime | Process | The dominant way of forming part or all of the trap closure. If the trap is structural, was the closure formed by folding, faulting, or fracturing? If the trap is stratigraphic, was the closure formed by depositional, erosional, or diagenetic processes? If the trap is fluidic, was closure formed by pressure, temperature, or chemical processes? |
| Class | Geometry and/or composition | |
| Family | Genesis | The way all or part of the trap closure came into being. For example, for an isolated marine carbonate trap, was the closure formed because of the reservoir and seal facies relationships of a reef, an oolite bar, or a tidal channel? |
Sublevels
Using one term to classify traps geometrically, compositionally, or genetically is not always adequate. To solve this problem, intermediate groupings such as superfamilies or superclasses can be added where necessary. Trap classes can be subdivided into subclasses and styles if needed, and trap families can be subdivided into subfamilies and varieties. These extra levels allow a fuller description of traps.
Degree of interpretation at different levels
Classification requires different degrees of interpretation at different levels of the proposed scheme. The highest levels require presumably less interpretation than do the lower levels. The higher levels are broader generalizations and reveal broader relationships. Classification at lower levels is more interpretive and therefore more open to disagreement. For example, trap geometries, which establish trap classes, are typically well understood; whereas trap genesis, used to establish trap families, relies on interpretation, is often the subject of considerable disagreement and debate, and may be the last trap element fully understood.
Trap systems & corresponding regimes
The proposed classification scheme divides traps into the following systems and their corresponding regimes.
Trap classes and families
As mentioned previously, the various trap regimes can be subdivided into trap classes and trap families, based on geometry, composition, and genesis. Ultimately, every oil accumulation can hopefully be classified correctly at the class and family levels.
See also
- Classification philosophy
- Trap
- Classification basis
- Classifying traps
- Trap systems: structural, stratigraphic, and fluidic
External links
| find literature about Trap classification levels |
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