Petroleum Exploration — An Introduction
Objective: After reading this unit you would be able to understand: What are hydrocarbons? What are their properties? What are the main products derived from crude oil and their uses Exploration milestone-an overview. INTRODUCTION: By definition petroleum is a generic name for hydrocarbons, including crude oil, natural gas liquids, natural gas and their products. Petroleum comes from the Latin petra meaning rock or stone & oleum meaning oil. Petroleum occurs in the earth in combination of any of the four states: gas, liquid, semisolid, and solid. Chemically, petroleum is a mixture of carbon, hydrogen and oxygen (called hydrocarbons) with minor amounts of nitrogen, oxygen, and sulfur as impurities along with heavy metals. Petroleum is organic; it contains complex carbon, hydrogen molecular structures (CH4) called chains that are linked together to form long-chains of more complex molecules. TYPES OF PETROLEUM: There are three general types of petroleum: 1. Crude oil, 2. Natural gas, and 3. Semi-solid and Solid forms. 1. Crude oil refers to liquid petroleum as opposed to refined oil. These are liquid hydrocarbons that contain varying amounts of dissolved gases, bitumens, and other impurities. In the raw state, crude oil resembles ordinary lubricating oil. It is immiscible with water and has a density less than that of sea water -- thus, crude oil floats on water. Crude oil is however, soluble in naphtha, carbon disulfide, ether, and benzene.
Thick crude oil.
Lighter crude oil
Very light crude oil.
Petroleum in solid state at room temperature Figure 1
2. Natural gas is petroleum gas as distinguished from manufactured gas. Natural gas consists of lighter paraffin hydrocarbons (hydrocarbons of the methane series), the most abundant being methane gas (CH4). 3. Semi, and solid forms are called heavy hydrocarbons and bitumens. They comprise materials such as asphalt, tar, pitch, albertite, or any number