Tag Archives: Material

Material Balance for a Water Drive Mechanism

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This article will demonstrate a material balance equation in a natural water drive mechanism.  A full material balance equation is shown below:

Figure 1 - Full Material Balance Equation

Figure 1 – Full Material Balance Equation

Assumptions

  • Reservoir pressure above the bubble point (Pb). Above a bubble point, Rs = Rsi.
  • No water injection
  • No gas injection
  • No gas cap
  • Neglect formation and connate water compressibility (Cf and Cw have little effect for a gas cap drive mechanism.)
Figure 2 - Material Balance Equation with Assumption for a Natural Water Drive Mechanism

Figure 2 – Material Balance Equation with Assumption for a Natural Water Drive Mechanism

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Material Balance for Gas Cap Drive Mechanism

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This article will demonstrate a material balance equation in gas cap drive mechanism.  First, we start with a full material balance equation.

Figure 1 - Full Material Balance Equation

Figure 1 – Full Material Balance Equation

Assumptions

  • No water production
  • No water injection
  • No gas injection
  • No water influx
  • Neglect formation and connate water compressibility (Cf and Cw have little effect for a gas cap drive mechanism.)

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Solution Gas Drive Mechanism Explained in Material Balance Equation

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Material balance equation can be applied for any drive mechanism and this article demonstrates how to apply the material balance equation in a solution drive mechanism. For a solution drive mechanism, there are 2 cases. The first case is when reservoir pressure is above a bubble point and the second case is when reservoir pressure is below a bubble point.

Solution Gas above Bubble Point

Start with a full material balance equation.

Figure 1 - Full Material Balance Equation

Figure 1 – Full Material Balance Equation

Assumptions Continue reading →

Material Balance Equation in Reservoir Engineering

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Material balance is a mathematic way to express mass conservation in a reservoir and a simple key principle is “what reservoir is produced must be replaced by other mass.”

Volume Produced = Volume Replaced

Volume Produced comes from Gas Production, Oil Production, and Water Production.

Volume Replaced comes from volume expansion, water in flux and water/gas injection.

Figure 1 shows the relationship of the material balance.

Figure-1---Concept-of-Material-Balance

Figure 1 – Concept of Material Balance

Let’s take a look at each component of equation. Continue reading →