Recovery is the process of extracting, or "recovering" oil and gas from a reservoir. When a well is drilled, natural pressures within the reservoir often cause the well to flow on its own. This is called Primary Recovery. However, when the pressure drops and the well stops flowing, about two-thirds of the original oil in place is still underground. To extract the oil and/or gas after initial pressures have dropped off, companies use Secondary Recovery processes. Secondary oil recovery techniques increase pressure in depleted or low-pressure reservoirs. A variety of techniques are utilized, such as installing pump jacks, waterflooding, gas and steam injection.
In formations characterized by low porosity and permeability, newly drilled wells are often unable to flow on their own. The oil or natural gas is trapped in the rock. Well stimulation techniques such as fracing, or frac jobs, are used to initiate production. Frac jobs open up channels within the reservoir rock so the oil or gas can flow. This is accomplished by injecting fluid at very high-pressures that cause the rock to crack, or fracture.
Fracture fluid can be oil-based, water-based, acid-based or foam. Continued fluid injection increases the fracture's length and width. This allows more reservoir fluid to drain into the wellbore along the new fractures once the well is put back into production. Hydraulic fracturing and acidizing are two of the most common frac treatments used. Hydraulic fracturing injects fresh or salt water. Acidizing enlarges the flow channels by dissolving the rock, which is usually limestone.
Enhanced Oil Recovery (EOR) techniques are becoming increasingly important in making drilling projects economically attractive. Sometimes referred to as Secondary or Tertiary Recovery, EOR is essential to the economic viability of exploration and development. in both conventional and unconventional settings. Learn more about gas injection, hydraulic injection, acidizing.
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