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the source rock. Vitrinite reflectance can determine if oil and gas have been generated. If all the
source rock samples from an unexplored basin show that hydrocarbons were never generated in
that basin, further exploration would be discouraged.
Geochemistry can also be used to identify the source rock for a specific crude oil. The
crude oils in traps can then be correlated with source rocks to determine the migration path for
the petroleum. The migration path would be an excellent area for future exploration for
undiscovered oil and gas fields.

Text 2
Plays and Trends
A play is a combination of trap, reservoir rock, and seal that has been shown by
previously discovered fields to contain commercial petroleum deposits in an area.
A trend or fairway is the area along which the play has been proven and more fields
could be found.
A prospect is the exact location where the geological and economic conditions are
favorable for drilling an exploratory well. A prospect can be presented by using prospect maps
that illustrate the reasoning for selecting that drilling location. The maps include at least a
structure and isopach map of the drilling target and a map of test results and fluid recoveries
from wells in the area. An economic analysis of the prospect should include reserves and risk
calculations.
There are four major geological factors in the success of a particular prospect. First, there
must have been a source rock that generated petroleum. Second, there must be a reservoir rock to
hold the petroleum. Third, there must be a trap. This includes a reservoir rock configuration that
has four-sided closure, a seal on the reservoir rock, and no breach of the trap. Fourth, the timing
must be right. The trap had to be in position before the petroleum migrated through the area.
Geologists have put together petroleum systems for all petroleum producing areas of the
world. A petroleum system is a volume of sedimentary rocks that includes a source rock that is or
has generated oil and gas and all the seeps and accumulations of that oil and gas. It can be an
entire basin or part of a basin. The essential elements that include source rock, reservoir rock,
seal, and overlying sediments in that petroleum system are identified. The timing of processes
that include trap formation and petroleum generation, migration, and accumulation for that
petroleum system are determined.

Task 3. Answer the following questions, using the vocabulary from Task 1.
1. What does Geochemistry study?
2. What are often good indications of the proximity of a petroleum trap?
3. In what way are surface samples of waters and soils examined to find out if there
is oil or gas in the area?
4. What could indicate the presence of a petroleum reservoir in the area?
5. What method is used to determine the maturity of a source rock?
6. What is vitrinite?
7. Can geochemistry be used to identify the source rock for a specific crude oil?
8. What is a play?
9. What is the difference between a trend or fairway and a prospect?
10. How many major geological factors are there in the success of a particular
prospect? Characterize them.
11. What is a petroleum system?
12. What are the essential elements of the petroleum system?

Task 4. Choose the correct definition:
1 A prospect a is a volume of sedimentary