Deposits of oil and natural gas in porous layers of rock and shale often occur alongside large quantities of saltwater. In order to bring these resources to the surface for further production, oil and gas companies must first remove the surrounding saltwater, which is also known as produced water or oilfield brine. This liquid contains high levels of salt as well as industrial compounds and hydrocarbons. While there are various ways to dispose of the saltwater and flowback fluid resulting from hydraulic fracturing, improper disposal may pose a threat to subterranean and aboveground fresh water.
Firms may choose to recycle the saltwater via evaporation or distillation. However, these processes often require a significant, consistent flow of water in order to serve as financially viable disposal strategies. While this is possible in regions with a large number of producing wells and an established saltwater pipeline infrastructure, recycling does not account for 100 percent of saltwater disposal, thus necessitating additional disposal methods.
Oil and gas companies may opt to use saltwater disposal wells, injecting the saltwater into non-producing underground formations of porous rock. This practice requires layers of impermeable strata both above and below the disposal well to protect shallow fresh water and is used extensively throughout Texas, where it falls under the jurisdiction of the Railroad Commission of Texas. The agency has mandated that saltwater disposal wells must contain several layers of cement and steel to protect usable fresh water at shallow depths, and it has outlined three distinct layers of well casing. The commission also restricts the establishment of saltwater disposal wells to locations that already contain naturally occurring saltwater.
Based in Addison, Texas, Sentry Energy specializes in extracting oil from wells previously thought to be dry through a combination of cutting-edge extraction techniques and prudent exploration choices. Geologists generally locate oil and natural gas while working for oil companies or exploration firms.
When looking for a likely reservoir, geologists take into account the necessary elements for oil or gas to form and accumulate. A viable deposit must have source rock from which the oil is produced, porous reservoir rock to hold the oil, and trap rock to prevent the oil from escaping and to collect it in an accessible deposit. Early oil prospectors looked for oil and gas using clues on the surface, including features of the land, the kind of rock and soil found on the surface, and core samples obtained through shallow drilling. With these pieces of information, they then worked to make an educated guess about where oil might be.
Today, scientists utilize a number of high tech tools to improve their accuracy, including satellite imagery to examine the terrain, gravity meters to measure changes in the Earth’s gravitational pull due to oil, and magnetometers to examine the Earth’s magnetic field. Geologists also employ very sensitive detectors called sniffers to find hydrocarbons that suggest the presence of oil.
Finally, they use the science of seismology, in which they produce shock waves or vibrations that pass through the layers of the earth and reflect back, revealing the composition of the Earth’s crust much as a bat’s sonar reveals the objects ahead. Seismic surveys use a number of sources of vibration, including compressed air guns, thumper trucks, and explosives. The rate at which the vibrations travel through the ground varies depending on the density of the layers of rock. With sensitive microphones, geologists pick up the reflections of these shock waves and through interpretations they discover trapped oil or gas.
In the world of oil and natural gas extraction, setting up new drill sites on areas of land that have produced consistently high quantities of oil in the past is an innovative and low-risk way to ensure quality oil production. Sentry Energy Production LLC, a privately held oil and natural gas company based in Addison, Texas, draws upon this very method throughout all aspects of its operations. In addition to located new pay zones in productive areas, Sentry Energy Production also applies some of the latest advances in technology to extract additional oil from existing wells.
Like many oil companies, Sentry Energy Production makes heavy use of the pumpjack, one of the most ubiquitous pieces of oil drilling equipment in the history of the industry. Commonly referred to as a horsehead pump or a beam pump, the pumpjack utilizes reciprocating piston pump to extract oil from an oil well. In general, pumpjacks are most effective when used on land in areas that produce little oil with bottom hole pressure alone. Pumpjacks also have the potential to vary greatly in size, ranging from 5 to 40 liters of oil production during each pump cycle, based on the depth and weight of the oil in question. In most cases, pumpjacks rely on energy from a rotational motor to produce the vertical reciprocating motion necessary to extract oil.
Before the development of sophisticated electric motors, pumpjacks often relied on a network of rod lines that were connected to a wheel mechanism known as a Central Power. The Central Power system was highly inefficient, however, as it relied on combustion engines and required a high level of maintenance to operate at maximum production levels. Today, pumpjacks derive the majority of their energy from a device known as a prime mover. Although most prime movers currently take the form of an electric motor, many make use of unorthodox engine types such as propane systems and casing gas from the well itself. Deep in the well hole, pumpjacks contain a feature called a down-hole pump, composed of two ball check valves. As the pump descends into the well, oil enters the formation through a series of perforations in the casing and cement. As the pump lifts out of the well, the traveling valve closes, allowing the formation to safely transport the oil to the surface before depositing it in the pump barrel.