rservoir engineering exam 1

Kriging

Geostatisitcal interpolation using known values to estimate unknown values

N=7758AhP(1-Swi)/Bo

What is the volumetric equation

Isopach map

How is area found?

Well logger

How is h found?

Well logger

How is Phi found?

Well logger

How is Swi found?

PVT study

How do we estimate Bo?

Initial gas cap vol/ initial oil zone vol

Define m

Cumulative production GOR scf/STB

Rp

Cumulative water production STB

Wp

Cumulative water influx rb

We

Initial oil formation factor rb/STB

Boi

Volume of oil in place STB

N

Will experience retrograde condensation, falls into phase envelop

Wet gas

Will remain gas, stays outside phase envelop

Dry gas

Reservoirs with higher crit T, close to cricondentherm

Rich Gas Condensate

Reservoirs with lower critical T, further from cricondentherm

Lean Gas Condensate

Steeply dipping, segregation of fluids, high permeability

What are the conditions required for gravity drainage drive?

Oil reservoir has contact with an aquifer, results in low decline of pressure, stable GOR

What’re conditions of water drive?

Larger gas cap causes slow pressure decline, GOR increases until gas depleated

Waht’re conditions of gas cap drive

Undersaturated reservoir, sources energy from gas expansion, pressure declines fast

Solution gas drive

Deterministic method

Single value based on data that is certain, does not provide insight into potential risk

Probablistic method

Uses monte carlo simulation in combination with volumetric estimation to provide insight into potential amounts of fluid within a reservoir

Bo

What relationship is modeled

Rs

What relationship is modeled?

Z

What relationship is modeled?

Cg

What relationship is modeled?

Mo

What relationship is modeled

depletion drive index

DDI

segregation drive index

SDI

water drive index

WDI

expansion drive index

EDI

injected water index

WII

injected gas index

GII

1

summation of all drives

A

Np[Bo+(Rp-Rs)Bg]

DDI

N[(bo-Boi)+(Rsi-Rs)Bg]/A

SDI

mNBoi[Bg/Bgi-1]/A

EDI

NBoi(1+m)[CwSwi+Cf/1-Swi]dP/A

WDI

(We-WpBw)/A

GII

GinjBginj/A

WII

WinjBwinj/A

N=F/Eo+mEg+Ef,w

N in terms of Havlena Odeh without injection terms

Np[Bo+(Rp-Rs)Bg]+WpBw

F=

(Bo-Boi)+(Rsi-Rs)Bg

Eo=

Boi(1+m)[CwSwi+Cf/1-Swi]dP

Ef,w=

Boi[Bg/Bgi-1]

Eg=