Reservoir drive mechanism

Reservoir drive mechanism

Is asource of energy for driving the fluids out through the wellbore

Primary recovery

Primary recovery refer to the production of oil and gas from areservoir without 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 difined as the mechanism wherein the displacement of oil from the formation to the
production wells is accomplished by rock and fluid expansion

Characteristics of rock and fluid expansion drive mechanism

Very rapid decline in pressure

 Constant gas oil ratio that is equal 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 difind as the mechanism wherein the displacement of oil from the formation to the
production wells is accomplished by expansion of solution gas

Characteristics of  Depletion Drive Mechanism

Rapid decline in pressure

becouse there is no extraneous fluid or gas caps are available to provide areplacement of the gas and oil withdrawals


Increasing GOR

Water- free oil production

%Ultimate recovery factor my be average from 15 to 25

Well behavior requires pumping at early stage


Gas-Cap drive mechanism



Reservoir drive mechanism

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


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

Characteristics of  Gas-Cap drive mechanism

Reservoir drive mechanism

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 difind as the mechanism wherein the displacement of oil from the formation to the
production wells is accomplished by water influx from aquifer into the reservoir


Characteristics of  water drive mechanism

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 difinea as the mechanism wherein the displacement of oil from the formation to the producting wells is accomplished as aresult of differences in densities of the reservoir fluids

Characteristics of  The Gravity drainage drive mechanism


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


Low gas-oil ratio
due to migration of the evolved gas upstructure due to gravitational segregation of the fluids



Formation of secondary gas cap in reservoirs those initially were 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 difinea as the mechanism in 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

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