Oil and gas exploration
Oil and gas exploration is the search by geologists and others for deposits of hydrocarbons beneath the surface of the earth. Originally oil and gas exploration was a simple matter of looking for areas where the oil had risen to the surface of the earth or top of the water and digging or drilling below for the crude oil. Western Pennsylvania where the first successful oil well was drilled by Drake has areas of natural oil springs.
An example of a discovery of this sort to be publicized was at Oil Creek Pennsylvania in 1859. The river itself runs over a very shallow reservoir of oil. Beside the creek are hundreds of shallow pits four to six feet deep which fill with water and oil after a heavy rain. The oil can be skimmed from the top. The Seneca Indians in the area used the oil as a salve among other things. A historic advertisement for Seneca Oil dating from 1792 claims the oil is a panacea for everything from consumption to venereal disease.
Oil and gas exploration soon led to the discovery of oil fields in Texas and Oklahoma and later in California. Small individuals or partnerships moved across the landscape, putting money, effort and faith in drilling hole after hole, hoping against hope for the gusher to come in. These small operations were called wildcatters.
The larger companies preferred to use the services of a petroleum geologist in their efforts at oil and gas exploration. The geologist's duty was to study various surface features of the earth such as oil seeps, natural gas seeps, and pockmarks in order to determine where the reservoirs of hydrocarbons might lie beneath the earth's surface. Once such areas are located, more sophisticated techniques come into play. Magnetic surveys or gravity surveys are used to define large-scale characteristics of the subsurface geology, followed by further studies similar to radar, which map the underground in more detail. When these results meet the criteria of the company, a test or exploration well will be drilled for ultimate proof of the presence of oil and gas.
Oil and gas exploration is an expensive business. A shallow off-shore well can cost between 10 and 30 million dollars, while a well in deep water might run as high as $100 million. The companies cannot afford to be wrong often, or they will no longer be in business.
Successful oil and gas exploration requires five elements. If any one of the elements is missing, there is no chance of hydrocarbons forming. These elements include: 1. source rock such as shale or coal which is rich in organic matter; 2. Migration of hydrocarbons from the source rock under pressure in order to move toward the surface; 3. A trap which captures the buoyant hydrocarbons; 4. A seal which prevents the hydrocarbons from escaping all the way to the surface and dissipating into the air or ground; 5. a reservoir of porous limestone or sandstone.
Additional oil and gas exploration continues, but the expectation is that most of the accessible sites have already been found by petroleum geologists.
An example of a discovery of this sort to be publicized was at Oil Creek Pennsylvania in 1859. The river itself runs over a very shallow reservoir of oil. Beside the creek are hundreds of shallow pits four to six feet deep which fill with water and oil after a heavy rain. The oil can be skimmed from the top. The Seneca Indians in the area used the oil as a salve among other things. A historic advertisement for Seneca Oil dating from 1792 claims the oil is a panacea for everything from consumption to venereal disease.
Oil and gas exploration soon led to the discovery of oil fields in Texas and Oklahoma and later in California. Small individuals or partnerships moved across the landscape, putting money, effort and faith in drilling hole after hole, hoping against hope for the gusher to come in. These small operations were called wildcatters.
The larger companies preferred to use the services of a petroleum geologist in their efforts at oil and gas exploration. The geologist's duty was to study various surface features of the earth such as oil seeps, natural gas seeps, and pockmarks in order to determine where the reservoirs of hydrocarbons might lie beneath the earth's surface. Once such areas are located, more sophisticated techniques come into play. Magnetic surveys or gravity surveys are used to define large-scale characteristics of the subsurface geology, followed by further studies similar to radar, which map the underground in more detail. When these results meet the criteria of the company, a test or exploration well will be drilled for ultimate proof of the presence of oil and gas.
Oil and gas exploration is an expensive business. A shallow off-shore well can cost between 10 and 30 million dollars, while a well in deep water might run as high as $100 million. The companies cannot afford to be wrong often, or they will no longer be in business.
Successful oil and gas exploration requires five elements. If any one of the elements is missing, there is no chance of hydrocarbons forming. These elements include: 1. source rock such as shale or coal which is rich in organic matter; 2. Migration of hydrocarbons from the source rock under pressure in order to move toward the surface; 3. A trap which captures the buoyant hydrocarbons; 4. A seal which prevents the hydrocarbons from escaping all the way to the surface and dissipating into the air or ground; 5. a reservoir of porous limestone or sandstone.
Additional oil and gas exploration continues, but the expectation is that most of the accessible sites have already been found by petroleum geologists.
