Basin framework

Exploring for Oil and Gas Traps
Series	Treatise in Petroleum Geology
Part	Critical elements of the petroleum system
Chapter	Sedimentary basin analysis
Author	John M. Armentrout
Link	Web page
Store	AAPG Store

The term “basin”

The term “basin” has different meanings in different disciplines. Stratigraphers refer to a basin as the location of sedimentary fill deposited in the geologic past. Structural geologists think of a basin as a container created by tectonic processes, such as rifting. Often the term is used to name and locate a geographic province, such as the Williston basin, which in turn is separate from the genetic use of basin to mean a sedimentary basin—the focus of this article.

Defining the basin framework

To define a basin, we follow the steps listed in the table below.

1. Define the outline of the basin and important regional structural features.
2. Map total sediment thickness.
3. Identify subbasins (depocenters and minibasins).
4. Map age and location of oil and gas fields.
5. Map age and location of source rocks.

Basin outline and structural features

The particular study area, whether only a part of a basin or an entire basin itself, should be identified on a large-scale geographic map using total sediment thickness as the primary control. We then map major regional structural features. If postdepositional deformation has resulted in erosion, we construct a paleogeographic restoration to approximate the original depositional basin outline (see Paleogeography).

Basins, depocenters, and minibasins

The interaction of the eustatic cycles of sediment accumulation within geographically shifting regional depocenters results in a complex stratigraphic architecture later deformed by tectonic movement. This deformation results in the formation of subbasins, depocenters, and minibasins. Minibasins in the GOM basin are relatively small areas of sedimentary thicks bounded by faults and salt-cored highs. We subdivide the basin into depocenters by identifying age-specific sediment thicks. We then subdivide depocenters into minibasins by identifying areas within the depocenter isolated by structure.

Subbasin sediment thickness, location

Each basin consists of a number of subbasin elements that have significant impact on exploration for hydrocarbons within each of these subbasins. We can prepare (or locate) a map showing total sediment thickness and the distribution of hydrocarbon occurrences within each subbasin element.

Source age, location

Hydrocarbon types reflect the composition of the kerogens from which they were generated and provide an estimate of the potential number of source-rock intervals or variations of kerogen facies within a source rock. We can prepare or locate a map showing the distribution of hydrocarbon types.

See also

• Example: defining a basin outline
• Example: mapping sediment thickness and field location
• Example: mapping hydrocarbon types

External links

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