Exploration and production are included in the “upstream” section of the oil and gas business. Geological surveys and land purchases are considered exploratory activities, whereas onshore and offshore drilling are production operations.
Different types of crude oil are classified according to their varied densities and sulfur levels. While sour foods have a high amount of sulfur, sweet foods do not (high sulfur content). Due to the relative ease with which they may be converted into gasoline, light and sweet crude oil often cost more than its heavier and sour cousins.
A barrel is the standard unit of volume measurement for oil; it is equivalent to 42 US gallons. Both associated and unassociated reservoirs include natural gas. Associated reservoirs were identified, developed, and produced alongside oil-containing pools. Typically, reservoirs are accompanied by related formations.
Every component of dry gas is methane. However, wet gas also contains water vapor (which exists with other hydrocarbons like butane). Transporting wet gas necessitates treating it to remove undesirable hydrocarbons and condensates; nonetheless, this process may increase producers’ profits through the sale of the treated gas’s byproducts.
In the lengthy and illustrious history of the energy industry, the discovery of shale gas in the United States represents a turning point. Experts foresaw decades in advance that the United States would become increasingly dependent on natural gas imported from other nations.
However, due to its shale gas industry, the United States is today the most significant natural gas producer in the world and the fastest-growing exporter of the commodity. In shale and other tight formations, technological improvements such as horizontal drilling and hydraulic fracturing have enabled production on a commercial scale.
Exploration
Oil and gas exploration services refer to the methods and techniques used to identify prospective drilling and extraction sites. Both exploration techniques are required for oil and gas exploration. Once upon a time, scientists and engineers had to rely on crude oil leaks and other surface indicators to find oil and gas resources.
Subsoil testing for onshore exploration and seismic imaging for offshore exploration techniques are merely two of the numerous techniques utilized in geological surveys. Governments provide mineral rights, which creates rivalry between energy companies. This can be accomplished via a concession agreement or a production-sharing arrangement. In the first scenario, producers would control any newly discovered oil or gas. Still, in the second scenario, the government would maintain ownership and participation rights.
Exploration services are dangerous and costly, with most funds coming from companies. Even failed exploration services efforts might cost between $5 million and $20 million per site. Seismic exploration techniques and good dry drilling are more instances of the missions we’re referring to.
If oil and gas are successfully extracted from an exploration location, the expenses of exploration can be recouped, and they are far less than the costs of alternative production approaches. A company’s confidence in its capacity to extract commercially viable amounts of oil and gas from a recognized resource using existing technology is the definition of proven reserves.
Periodic reevaluations guarantee that proven reserve projections stay current during the duration of a lease. There are several ways in which technological advancements might affect future forecasts.
Due to breakthroughs in hydraulic fracturing and horizontal drilling, the United States Geological Survey was able to increase its estimate of proven reserves for the Marcellus Shale by a factor of forty. Reserve estimations are impacted not just by technology advancements but also by market pricing and existing infrastructure.
Techniques
The process of determining where to drill might involve elements of both art and science. Observation of the topography of the search area is typically the first step in the main search for hydrocarbons. The location of surface faults is essential.
The presence of anticlines, a different kind of structural trap, is another sign that there are possible traps at depth. The Earth is discolored by naturally occurring crude oil leaks, and rainbow coatings form on the surface of streams.
Such firsthand proof is helpful, but most locations like these have been found and investigated a long time ago.
1. Geophysical Surveys
In petroleum research using geophysical methods, measuring equipment that can measure things like electrical currents, gravitational and magnetic anomalies, heat movement, geochemical relationships, and density changes from deep below the Earth’s surface can be exploited. These qualities can be used to narrow down the location of the hydrocarbons.
By employing vibration (which can be created by an explosive charge or sound-generating equipment), seismic surveys provide a picture of underground rock formations at depth. These surveys can sometimes go as deep as 30,000 feet below ground level.
Seismic surveys mainly offer a vision of underground rock formations at depth (BGL). The mechanism employed to accomplish this objective is the creation of sound waves down into the Earth’s crust.
These sound waves reflect off multiple boundaries between diverse rock strata in order to accomplish this purpose. On land, sound waves can be generated in one of two ways: either by inserting minuscule explosive charges into the ground or by utilizing vibrator trucks, which shake the ground using metallic pads that are propelled hydraulically.
The frequency formed may be felt far below the surface of the ground, even though the thud is hardly audible to the human ear. Electronic equipment that can receive the reflected sound waves, which are known as geophones, are used to pick up the echoes that are produced.
Surveys conducted at sea are carried out in a very different manner compared to those carried out on land. The cables for hydrophones are towed behind boats in the same way as geophone cables are towed behind ships on land.
Use of dynamite
The usage of dynamite in the past resulted in the production of sound waves; however, this method proved hazardous to marine life and ultimately led to their extinction. The exploration technique that is now the one that is most frequently recognized to produce sound waves is to employ pulses of compressed air to generate large bubbles, which are then caused to burst below the surface of the water, which results in the production of sound.
After traveling to the ocean floor and being blocked by the rocks there, the sound waves are forced back up to the surface, where they are picked up by the hydrophones. The procedures involved in the processing and depicting the dry ground approach are the same as those in the wet ground technique.
Advanced Techniques
The most advanced technological feat in this field is currently 3D seismic imaging (3-D). The collected data is sent to a computer, generating a high-resolution, three-dimensional image of the subsurface structures and formations. It’s a pricey procedure, costing around $30,000 each mile (Satterwhite, pers comm).
An in-depth seismic survey can assist in finding opportunities and reduce the likelihood of drilling ineffective holes. Therefore, it may be worth the cost. This contrasts with the fact that, although it can cost millions of dollars to drill a well, it is necessary.
Seismic surveys, whether on land or in water, may typically be undertaken without negatively impacting residents’ quality of life or the surrounding environment. To find potential [hydrocarbon] deposit locations, exploratory geologists rely heavily on this technology.
Many more geophysical methods exist, such as magnetometers and gravimeters, in addition to the relatively new field of geochemical prospecting. Furthermore, geochemical prospecting has only been practiced for a brief period.
A magnetometer is an instrument that measures variations in the Earth’s magnetic field. It is attached to a long wire that is trailed behind an aircraft. The magnetometer follows the plane as it is towed. The slight variations in Earth’s gravitational force may be measured with a gravimeter.
Large amounts of dense subsurface rock are revealed as these shifts are mapped. This helps geologists better comprehend the underground structures that exist. Geochemical prospecting uses delicate machinery to detect trace amounts of gases released by petroleum sources. This method is new, yet it is gaining popularity quickly in many parts of the world.
2. Remote Sensing
“Remote sensing” describes analyzing and mapping surface features using aerial photographs (RS). The use of satellite imagery has increased recently because of the vast areas of the Earth’s surface that may be seen in such images.
Moreover, satellite imagery not only reveals what can be seen with the human eye, but it may also reveal minute variations in the distribution of minerals and plants, as well as the kind of soil, all of which are crucial pieces of the exploration jigsaw. For instance, the Ouachita Mountains in southeastern Oklahoma are depicted in detail, along with the rest of the region’s surface topography. NASA’s satellite, more than 500 miles from Earth, took this picture in November 1972.
The twisted and faulted rocks that make up these mountains were initially laid down during the Paleozoic. These mountains are made up of Paleozoic rocks that are now hidden by more recent deposits to the south. There are many distinct types of reservoirs for hydrocarbons in these mountains, and they are all made up of diverse geological characteristics.
In addition, there is a subset of remote sensing called Side Looking Airborne Radar, which makes use of pictures taken by a flying radar that was aimed at the ground (SLAR). As this region is frequently shrouded in clouds, detailed maps of the area did not exist before the development of this SLAR image. Nonetheless, this image has opened fresh possibilities.
These kinds of maps are helpful for geologists in identifying prospective hydrocarbon resources. Structural traps for hydrocarbons are uncommon in synclines but work well in anticlines.
3. Wild Cat
Wildcat wells have a success rate of around one in ten. Still, only about one in fifty discover quantities of oil or gas that are commercially significant. The drilling of many wildcat wells is based on hunches, intuition, or only a little knowledge of geology.
Most of the time, they are founded on photographic evidence and personal experience in a region. As mentioned before, one of the first exploration methods was known as Creekology. However, recent technological breakthroughs have led to the development of computer-enhanced capabilities that can be accessed via laptops.
As a result, a plethora of information tailored exclusively for hydrocarbon exploration has accumulated. The equipment used in the field is now more compact, lighter, accurate, and dependable, offering far more detailed data.
Conclusion
In a nutshell, these are all the main exploration techniques that are used by the gas and oil industries. The people experts in providing these services are hired by this sector to ensure the best services. The oil and gas sector provides a high number of exploration jobs to engineers and workers. People interested in exploration jobs can practically experiment with everything and learn a lot by being in this sector.
FAQs
What is meant by the term “oil and gas services”?
Oil and gas services are goods and procedures used to assist the oil and gas sector. Some examples of oil and gas services include energy exploration, the transportation of petroleum and gas to refineries, and the processing and delivery of energy assets to market.
What are the three different sub-industries that make up the oil and gas industry?
- Upstream
- Downstream
- Mainstream
