Petroleum System: From Source to Trap

I. Introduction 3

II. What is petroleum? 3-4

III. Source Rock: 4-7

a. Formation of Petroleum in the Source Rocks

b. Types of source rocks

c. Migration of petroleum

4. Reservoir: 7-11

1. Formation of the Reservoir

2. Types of Reservoir

3. Its main properties

4. The relation between reservoir and the other

Components of the petroleum system

5. Trap 11-16

1. The Definition of Trap and How the Trap Works

2. The Distribution of Petroleum in Trap

3. Structural Trap

4. Stratigraphic Trap

6. An Example of a Complete Petroleum System 16-20

VII. Recommendation and Conclusion 20-21

VIII. References 22-23

I. Introduction

This paper covers a very interesting topic for people who are keen on the geological concepts to the discovery of petroleum. The subject matter itself covers research findings on how related areas in petroleum discovery can be appreciated by students in this particular field; more so, by ordinary people who may or may not have a deeper level of understanding and appreciation about the wealth of the earth, particularly on petroleum.

The work required of this paper is not easy. It takes a lot of patience in finding the right mix of materials that would produce the kind of output the student wants to find out and to prove his thoughts about the subject matter. Considering that the subject matter is highly technical, one has to patiently go through the rigors of reading lots of materials, comparing and writing down notes and drawing conclusions for one self. How one appreciates the subject matter and his researched work truly reflects how this paper, as a whole, is well thought about, understood and presented. It is hoped that at the end of this paper, one is able to get the bigger picture about the processes involved in the petroleum system, from its source to trap, and that he can draw for himself, in layman's terms, how processes can be understood by ordinary people.

II. Petroleum

Petroleum "occurs in a liquid phase as crude oil and condensate and in a gaseous phase as natural gas" (Petroleum Geology, 2003). The development of petroleum in gaseous phase is largely dependent on the "kind of source rock from which the petroleum was formed and the physical and thermal environment in which it exists" (Petroleum Geology, 2003). Petroleum is commonly identified as the crude oil, in liquid form, which is found deep below the ground surface around less than 20,000 feet.

Petroleum is "found in sedimentary basins in sedimentary rocks" and for it to develop accumulations it has to meet several conditions, namely: "(1) There must be a source rock, usually high in organic matter, from which petroleum can be generated; (2) There must be a mechanism for the petroleum to move, or migrate; (3) A reservoir rock with voids to hold petroleum fluids must exist; (4) The reservoir must be in a configuration to constitute a trap and be covered by a seal--any kind of low-permeability or dense rock formation that prevents further migration" (Petroleum Geology, 2003). The accumulations of petroleum may also be determined when the source and reservoir rocks occur.

A petroleum geologist is a specialist who identifies possible areas where the accumulation of petroleum is. As he locates the traps, he keeps track of subsurface information and gathers data in the drilling exploratory wells. Petroleum geologists run geophysical surveys and interpret them in order to be used to "construct maps, cross sections, and models" to depict whether or not the subsurface has petroleum, which can be drilled for possible exploratory wells (Petroleum Geology, 2003).

III. Source Rocks

Source rocks are those rocks that are "rich in organic matter which, if heated sufficiently, will generate oil or gas" (Source Rock, 2007). They are "good storage containers for oil and gas" (Source Rocks as Reservoir, 2005). Examples of source rocks are shales or limestones however they only contain about 1% organic matter. Source rocks are rich with organic matter. Research studies show that it is necessary for source rocks to have a complete petroleum system where organic matter is preserved without degradation (Source Rock, 2007).

a. Formation of Petroleum in the Source Rocks

b. Types of source rocks

c. Migration of petroleum

IV. Reservoir: