Anticline trap

Anticlinal traps which are the result of ductile crustal deformations... 

Fig. I. Types of natural gas reservoirs and entrapments (a) anticlinal trap (b) coral reef trap (c) stratigraphic trap (d) fault trap and (e) unconformity...

Fig. 2. Examples of anticline structural traps (a) Oil accumulates in a dome-shaped structure, The dome is circular in outline, (b) Anticlinal trap that is long and narrow, differing from the dome configuration...

In many oil and gas fields throughout the world hydrocarbons are found in fault bound anticlinal structures. This type of trapping mechanism is called a combination trap. 

A secondary feature is the development of rollover anticlines which form as a result of the downward movement close to the fault plane which decreases with increasing distance from the plane. Rollover anticlines may trap considerable amounts of hydrocarbons. 

A common structural trap, the anticline, is an upward bulge in the rock layers which forms an arch capable of holding oil under its apex. The buoyancy of oil and gas carries them upward through porous rock layers into the apex until they are trapped by an impermeable layer. Anticlinal type of folded structure is shown in Fig. 2. Reservoirs formed by folding of the rock layers or strata usually have the shapes shown in Fig. 2(a) and (b). These traps were filled by upward migration of oil and/or gas through the porous strata or beds to the location of Ihe trap. Further movement was arrested by a combination of the forms of the structure and the seal or cap rock provided by the formation covering the structure. 

Reservoir rocks and seals work together to form a trap for petroleum. Typical traps for petroleum include hills shaped like upside-down bowls below the surface of the earth, known as anticlines, or traps formed by faults. Abrupt changes in rock type can form good traps, such as sandstone deposits next to shale deposits, especially if a sand deposit is encased in a rock that is sufficiently rich in organic matter to act as a petroleum source and endowed with the properties of a good seal. 

Geophysicists examine seismic data, data derived from recording waves of energy introduced into the rock layers of the earth through dynamite explosions or other means, to determine the shape of the rock layers beneath the surface and whether or not traps such as faults or anticlines exist. 

Trap—A structure in which petroleum can accumulate and be stored. Anticlines (dome shaped structures below the surface of Earth) can form good traps. Traps can also form along faults and in areas where rock types change rapidly. 

Figure 5.4 Cross-section of a structural trap (Forties field. North Sea) a compactional anticline draped over an old basement high (from Elements of Petroleum Geology, by Robert C. Selley. Copyright ( ) 1985 by W.H. Freeman and Company. Reprinted by permission).

Filo Morado is an anticlinal oil field producing from the Agrio Formation at a depth of 3000 m (10,000 feet). Loma de La Lata consists of two stratigraphically-trapped... 

Traps associated with salt intrusions are of many types (example Fig. 1.2 -1.3) limestone reefs (Fig. 1.4) can also serve as reservoir rocks and give rise to overlying traps of anticlinal form as a result of different compaction. Examples are also known in which the reservoir rock extends to the surface of the earth but oil and gas are sealed in it by clogging of the pores by bitumen or by natural cements [3], Many reservoirs can display more than one of the factors that contribute to the entrapment of hydrocarbons. 

We have tried to delineate the main zones of formation of non-structural traps which are promising, as undrUled promising anticlinal structures become rare. 

Anticline Upfold of strata, a common form of petroleum trap. 

TVap Configuration of strata, such as an anticline, capable of trapping petroleum. 

Structural tr s Anticlines Fault traps Diapiric trq)s Salt diapirs Mud diapirs Stratigraphic traps... 

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