Hydrocarbons are chemical compounds made of hydrogen and carbon, petroleum and natural gas are a part of this chemical group. Hydrocarbons can be simple molecules, such as methane (one carbon atom surrounded by four hydrogen atoms), or much complex compounds like asphalt and coal.
Earlier, people relied on hydrocarbons mainly as a fuel to speed up their lifestyle. Today, people are dependent on petroleum products in more extensive way. Plastics, commercial sprays, paints, medicinal oils, cosmetics and even chewing gum, all contain petroleum products.
Formation of Hydrocarbons
Hydrocarbons are formed and accumulated in the pores of sedimentary rocks. Millions of years ago, organic residue from dead plants and animals was deposited in sedimentary basins. The sediments are buried deeper by mechanism of subsidence, where they are exposed to high temperatures and pressures which transforms them into oil and gas through the thermal cracking of organic matter.
Oil and Gas Reservoir
The oil and gas generated are expelled from the source rock in which they are formed and being lighter than water they tend to rise towards the earth’s surface through the pores and spaces of permeable rock or along minor fractures and fault lines. In their path if they encounter impermeable layer, or seal, they cannot migrate further and deposits of hydrocarbons are formed under this seal accumulated in the pores and fissures of rock reservoir. If not stopped they escape and seep away at the surface or lose their volatile components and solidify as bitumen.
Exploration to production
Success in Oil exploration means finding the correct rock types and structures beneath the earth that have the potential to hold large quantities of oil that can be produced commercially. The days are gone when oil wells were drilled merely only the basis of surface characteristics of earth and production was obtained. These days the process of oil and natural gas exploration to production involves a series of advanced technological stages.
The time line of exploration to production
3) Open Hole Logging
4) Casing and Cementing
5) Cased Hole Logging
8) Production Logging
9) Primary Production
10) Secondary Production
11) Tertiary Production
12) Well abandonment
In the series of articles to follow each step in Exploration and Production (E&P) of Hydrocarbons will be dealt in detail.