Reservoir drive mechanism

Reservoir drive mechanism

Is a source of energy for driving the fluids out through the wellbore

Primary recovery

Primary recovery refers to the production of oil and gas from a reservoir without the use of any process such as fluid injection to supplement the natural energy of the reservoir

 Primary recovery mechanism 

There are six driving mechanisms for oil recovery

Reservoir drive mechanism

Rock and fluid expansion drive mechanism

Reservoir drive mechanism

 Can be defined as the mechanism wherein the displacement of oil from the formation to the 
production wells are accomplished by rock and fluid expansion

Characteristics of rock and fluid expansion drive mechanism

A very rapid decline in pressure 

  Constant gas oil ratio that is equal to the gas solubility at the bubble point pressure

Nil water production

Ultimate recovery factor is less than 5%

The Depletion Drive Mechanism

Reservoir drive mechanism


Can be defined as the mechanism wherein the displacement of oil from the formation to the 
production wells are accomplished by expansion of solution gas

Characteristics of  Depletion Drive Mechanism

 A rapid decline in pressure

because there is no extraneous fluid or gas caps are available to provide a replacement of the gas and oil withdrawals


Increasing GOR

Water- free oil production

%Ultimate recovery factor may be average from 15 to 25 

Well behavior requires pumping at an early stage


Gas-Cap drive mechanism

Reservoir drive mechanism

can be defined as the mechanism wherein the displacement of oil from the formation to the 
production wells are accomplished by expansion of the original free gas cap


and can be defined as the presence of agas cap with little or no water drive 

Characteristics of  Gas-Cap drive mechanism

Reservoir drive mechanism

A slow decline in pressure

 due to pressure tends to be maintained at a higher level in a depletion drive reservoir 

Increasing GOR

Nil water production

Well behavior long life well

Water-drive mechanism

Reservoir drive mechanism

can be defined as the mechanism wherein the displacement of oil from the formation to the 
production wells are accomplished by water influx from the aquifer into the reservoir

Characteristics of  water drive mechanism

a very gradual decline in the pressure 

due to the oil and gas withdrawals from the reservoir are replaced almost volume for volume by water encroaching into the oil zone


More or less constant GOR


Early increasing water production

Ultimate recovery factor ranges from 35% to 75% of the original oil in place


The Gravity drainage drive mechanism

Reservoir drive mechanism

Can be defined as the mechanism wherein the displacement of oil from the formation to the producing wells is accomplished as a result of differences in densities of the reservoir fluids

Characteristics of  The Gravity drainage drive mechanism


Variable rates of pressure decline depending principally upon the amount of gas conservation


Low gas-oil ratio
due to a migration of the evolved gas up structure due to gravitational segregation of the fluids



Formation of a secondary gas cap in reservoirs those initially was undersaturated

Little or no water production

ultimate recovery factor up to 80% of the original oil in place

The Combination driving mechanism

Reservoir drive mechanism

can be defined as the mechanism by which both water and free gas are available in some degree to displace the oil toward the producing wells


Characteristics of The Combination driving mechanism

Relatively rapid pressure decline


Ultimate recovery from combination drive reservoirs is usually greater than recovery from depletion drive reservoir but less than recovery from water drive reservoir

Gas-Cap drive mechanism



 Gravity drainage drive mechanism




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