دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

secondary recovery technique for oil. The carbon dioxide gas is injected and alternated with water. CO2 lowers the viscosity of most oils, but may trigger severe asphaltene and scale precipitates.

n: (EOR) 1. the introduction of artificial drive and displacement mechanisms into a reservoir to produce a portion of the oil unrecoverable by primary recovery methods. To restore formation pressure and fluid flow to a substantial portion of a reservoir, fluid or heat is introduced through injection wells located in rock that has fluid communication with production wells. See alkaline (caustic) flooding, gas injection, micellar-polymer flooding, primary recovery, secondary recovery, tertiary recovery, thermal recovery, waterflooding. 2. the use of certain recovery methods that not only restore formation pressure but also improve oil displacement or fluid flow in the reservoir. These methods may include chemical flooding, gas injection, and thermal recovery.

one or more of a variety of processes that seek to improve recovery of hydrocarbon from a reservoir after the primary production phase.

n: a method of improved oil recovery in which chemicals dissolved in water are pumped into a reservoir through injection wells to mobilise oil left behind after primary or secondary recovery and to move it toward production wells. The chemical solution includes surfactants or surfactant-forming chemicals that reduce the interfacial and capillary forces between oil and water. releasing the oil and carrying it out of the pores where it has been trapped. The solution may also contain cosurfactants to match the viscosity of the solution to that of the oil to stabilise the solution and to prevent its adsorption by reservoir rock. An electrolyte is often added to aid in adjusting viscosity. Injection of the chemical solution is followed by a slug of water thickened with a polymer. which pushes the released oil through the reservoir. decreases the effective permeability of established channels so that new channels are opened. and serves as a mobility buffer between the chemical solution and the final injection of water.

n: the use of waterflooding or gas injection to provide additional formation pressure to supplement and to conserve natural reservoir drives. Although commonly begun during primary production, pressure maintenance is a form of improved recovery. See improved recovery, secondary recovery.

n: 1. the use of waterflooding or gas injection to maintain formation pressure during primary production and to reduce the rate of decline of the original reservoir drive. 2. waterflooding of a depleted reservoir. 3. the first improved recovery method of any type applied to a reservoir to produce oil not recoverable by primary recovery methods. See pressure maintenance, primary recovery.

a recovery improvement process such as water flooding or gas flooding.

n: 1. the use of improved recovery methods that not only restore formation pressure but also improve oil displacement or fluid flow in the reservoir. 2. the use of any improved recovery method to remove additional oil after secondary recovery. Compare primary recovery, secondary recovery.

an enhanced recovery process that goes beyond water or gas flooding. It may involve steam, fire, chemicals, miscible gases, bacteria or other techniques.

n: the combining of leased tracts on a fieldwide or reservoirwide scale so that many tracts may be treated as one to facilitate operations like secondary recovery. Compare pooling.

purposely injecting water below and/or into the reservoir to drive the oil towards the producing wellbore. This is a secondary recovery mechanism.