Changes

  | part    = Traps, trap types, and the petroleum system

  | part    = Traps, trap types, and the petroleum system

  | chapter = Petroleum systems

  | chapter = Petroleum systems

  | frompg  = 3-1

  | frompg  = 3-27

  | topg    = 3-34

  | topg    = 3-30

  | author  = Leslie B. Magoon, Edward A. Beaumont

  | author  = Leslie B. Magoon, Edward A. Beaumont

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch03/ch03.htm

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch03/ch03.htm

  | isbn    = 0-89181-602-X

  | isbn    = 0-89181-602-X

}}

}}

In exploration, the general question is ''Where can we find substantial quantities of hydrocarbons that are economical to produce?'' To solve this problem, exploration geologists find and evaluate a prospect. In addition to helping evaluate petroleum charge, trap, and timing, the [[petroleum system]] concept can help in the exploration process by determining exploration intensity and assessing risk.

In exploration, the general question is ''Where can we find substantial quantities of hydrocarbons that are economical to produce?'' To solve this problem, exploration geologists find and evaluate a prospect. In addition to helping evaluate [[Calculating charge volume|petroleum charge]], trap, and timing, the [[petroleum system]] concept can help in the exploration process by determining exploration intensity and assessing risk.

==Play==

==Play==

A play is one or more prospects that may define a profitable accumulation of undiscovered petroleum. Traditionally, a play is developed and evaluated without any particular petroleum system in mind. For example, if a prospect (play) is identified near a series of oil fields in anticlinal traps, it could be argued—using geophysics and geochemistry—that the prospect is an anticlinal trap charged with the same oil.

A play is one or more prospects that may define a profitable accumulation of undiscovered petroleum. Traditionally, a play is developed and evaluated without any particular petroleum system in mind. For example, if a prospect (play) is identified near a series of oil fields in anticlinal traps, it could be argued—using geophysics and geochemistry—that the prospect is an anticlinal trap charged with the same oil.

Three independent variables—petroleum charge (fluids), trap (sedimentary rocks), and timing (time)—are usually evaluated. '''Petroleum charge''' is the volume and characteristics of the oil and gas available to the trap, if it exists. The '''trap''' includes the reservoir and seal rocks and the trapping geometry formed by the reservoir–seal interface. '''Timing''' is whether the trap formed before the petroleum charge entered the trap.

Three independent variables—petroleum charge (fluids), trap (sedimentary rocks), and timing (time)—are usually evaluated. '''[[Calculating charge volume|Petroleum charge]]''' is the volume and characteristics of the oil and gas available to the trap, if it exists. The '''trap''' includes the reservoir and seal rocks and the trapping geometry formed by the reservoir–seal interface. '''Timing''' is whether the trap formed before the petroleum charge entered the trap.

Each independent variable has equal weight because if any variable is absent (0), the prospect is a failure; if all variables are present (1.0), the prospect is a commercial success. Therefore, each independent variable can be evaluated on a scale of zero to one (0–1.0). Exploration risk is determined by multiplying the three variables: charge, trap, and timing.

Each independent variable has equal weight because if any variable is absent (0), the prospect is a failure; if all variables are present (1.0), the prospect is a commercial success. Therefore, each independent variable can be evaluated on a scale of zero to one (0–1.0). Exploration risk is determined by multiplying the three variables: charge, trap, and timing.

==Least to most risk==

==Least to most risk==

[[file:petroleum-systems_fig3-19.png|400px|thumb|{{figure number|2}}Example system for evaluating risk. From Magoon, 1995; courtesy AAPG.]]

[[file:petroleum-systems_fig3-19.png|400px|thumb|{{figure number|2}}Example system for evaluating risk. From Magoon;<ref name=Magoon1995 /> courtesy AAPG.]]

Using [[:file:petroleum-systems_fig3-19.png|Figure 2]] and stipulating that the complementary play is on the migration path for this petroleum system, a play located within or outside the geographic extent of the system has the following level of risk:

Using [[:file:petroleum-systems_fig3-19.png|Figure 2]] and stipulating that the complementary play is on the migration path for this petroleum system, a play located within or outside the geographic extent of the system has the following level of risk:

==Exploration intensity==

==Exploration intensity==

[[file:petroleum-systems_fig3-20.png|400px|thumb|{{figure number|3}}]]

[[file:petroleum-systems_fig3-20.png|400px|thumb|{{figure number|3}}Graphs conceptually summarizing the exploration process relative to time.]]

In a petroleum province, drilling density usually indicates how intensively an area has been explored. Though this is a relative measure, a petroleum province having one exploratory well every square kilometer is well explored compared with a province that has one well every 100 km². Exploration intensity by province ranges from lightly to moderately to heavily explored. However, in a petroleum province with overlapping [[petroleum systems]], the shallowest petroleum system may be heavily explored compared with the deeper petroleum systems. To determine level of exploration, each petroleum system in the province of interest should be mapped and the size and location of the commercial accumulations compared with the [[Dry hole|dry exploratory wells]]. The dry-hole ratio or success ratio determines exploration intensity and success.

In a petroleum province, drilling density usually indicates how intensively an area has been explored. Though this is a relative measure, a petroleum province having one exploratory well every square kilometer is well explored compared with a province that has one well every 100 km². Exploration intensity by province ranges from lightly to moderately to heavily explored. However, in a petroleum province with overlapping [[petroleum systems]], the shallowest petroleum system may be heavily explored compared with the deeper petroleum systems. To determine level of exploration, each petroleum system in the province of interest should be mapped and the size and location of the commercial accumulations compared with the [[Dry hole|dry exploratory wells]]. The dry-hole ratio or success ratio determines exploration intensity and success.

[[Category:Traps, trap types, and the petroleum system]]  

[[Category:Traps, trap types, and the petroleum system]]  

[[Category:Petroleum systems]]

[[Category:Petroleum systems]]