More remarks on material balance

1
More remarks on material balance

• Wellbore storage
• During wellbore storage period the wellbore
  pressure increases (or decreases) linearly with
  time

2
Wellbore Storage Material Balance Equation
Drawdown tests
Buildup tests
3
More remarks on material balance

• During "late time" in a reservoir, material
  balance "dictates" the production

4
Material balance dictated PSS and BD

• Pseudo steady state
• Bounded reservoir with no-flow outer boundary
• Constant rate
• Long time
• Boundary dominated flow regime
• Bounded reservoir with no-flow outer boundary
• Constant flowing wellbore pressure
• Long time
• But before studying those flow regimes, let us
  revisit the DIFFUSIVITY EQUATION

5
DIFFUSIVITY EQUATION

• Analogies
• Derivation
• Boundary conditions
• Various coordinate systems
• Dimensionless variables
• Well Performance indicators
• Productivity Index
• Skin
• Flow regime

6
Analogies

• Heat flux (Fourier's law)
• Mass flux (Fick's law)
• Electric flux (Ohm's law)
• Fluid mechanics--flow in pipes (Poiseuille's law)

7
Continuity (mass conservation)
8
Other Ingredients

• Darcy's law
• Ñ p pressure gradient
• k effective permeability
• m fluid viscosity
• g acceleration due to gravity
• Equation of State
• slightly compressible liquid
• c is constant and small

(
Ñ
p

)
9
(No Transcript)