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3.boundary Condition Section 3

This document discusses three types of boundary conditions for reservoir pressure analysis: 1. Infinite-acting reservoir assumes boundaries do not affect pressure response during testing and reservoirs are large. 2. Pseudo steady state occurs for finite reservoirs or closed systems, where prolonged production causes boundaries to impact pressure, which then declines at a constant rate reflecting reservoir size. 3. Steady state has constant pressure throughout production for finite reservoirs supported by a constant pressure boundary like an aquifer or gas cap.

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68 views5 pages

3.boundary Condition Section 3

This document discusses three types of boundary conditions for reservoir pressure analysis: 1. Infinite-acting reservoir assumes boundaries do not affect pressure response during testing and reservoirs are large. 2. Pseudo steady state occurs for finite reservoirs or closed systems, where prolonged production causes boundaries to impact pressure, which then declines at a constant rate reflecting reservoir size. 3. Steady state has constant pressure throughout production for finite reservoirs supported by a constant pressure boundary like an aquifer or gas cap.

Uploaded by

Bright Moon
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Boundary Conditions

Section # 3

Boundary Conditions
1.

Infinite-acting reservoir:

It is assumed that the reservoir has such a large areal extent that
none of the reservoir boundaries are felt by the pressure response
generated during the test.

2.

Pseudo Steady State (finite reservoir or closed system)

As production continues from a well with closed boundaries, all


the reservoir boundaries will eventually be felt indicating that
Pseudo Steady State (P.S.S.) is reached. The rate of the
reservoir pressure depletion (dP/dt) becomes constant and its
magnitude reflects the size of the reservoir.

3. Steady State (finite reservoir with constant press. boundary)


Under Steady Steady boundary conditions, the pressure
distribution in the reservoir remains constant throughout the
production life of the reservoir, at constant production rate.

Boundary Conditions
1. Infinite-acting:
Short tests - pressure wave does not reach any reservoir boundaries
Large reservoirs
r
inv

Pi
t1

t2

Pwf1

Pwf2

rinv
rinv: Radius of investigation

ft

kt
948 c t

Reservoir radius, r

Boundary Conditions
2. Pseudo-Steady-State (P.S.S.):
Long tests - pressure wave reaches all reservoir boundaries
Small reservoirs
Pi
t1
t2
Pwf1

Pwf2

Reservoir radius, r

Boundary Conditions
3. Steady State:
Reservoirs under pressure maintenance schemes
The presence of a large aquifer or gas cap
Pi
Pressure constant for t =

Pwf

Reservoir radius, r

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