Tag Archives: natural gas

The Basics of Finding Oil and Natural Gas Presented by Sentry Energy

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.


What is Fracking?

Presented by Sentry Energy

In recent years, there has been a lot of interest in the process of hydraulic fracturing in the extraction of natural gas. Here, Sentry Energy explains how fracking works and why gas companies so frequently use the technique.

Also known as hydraulic fracturing, fracing, and hydrofracking, fracking is the process by which a rock layer can be cracked using fluid pressure. The process is usually used to increase the extraction rates and ultimate recovery of oil and natural gas. By opening up cracks in reservoir rock formations, energy professionals can greatly expand the yield of a given well or reservoir. Companies utilize the technique in around 90 percent of natural gas wells in the United States.

When fracking a well, gas companies inject a pressurized mixture of water, chemicals, and a proppant, such as sand, to hold the fractures open after ending the injection, so gas can travel to the surface. Hydraulic fracturing requires a very specific variety of sand. With very small, round particles of nearly pure quartz, the sand contains few impurities and does not disintegrate when pumped underground and put under the pressure inherent in the process. Companies conduct most fracking in horizontally drilled wells through shale reservoirs. Shale is particularly impermeable deep in the earth and the stimulating effects of fracking enable gas extraction. Companies create some reservoirs, such as the Bakken, Barnett Shale, Haynesville Shale, and Montney, almost exclusively through fracking and multistage completion systems.

While professionals engage in fracking in this country mostly to stimulate production in oil and gas wells, others employ the technique to stimulate groundwater wells, precondition rock for caving, enhance waste cleanup processes, dispose of waste, or measure the stress in the earth.