Productivity Index for a Gas Well
Productivity index for a gas well, abbreviated as \(J\), is a measure of the well's ability to produce gas relative to the pressure drawdown (the difference between the reservoir pressure and the flowing bottom-hole pressure). It is an important in reservoir engineering, used to evaluate the performance and efficiency of a gas well.
Key Points about Productivity Index
- Gas Flow Rate - This is the rate at which gas is being produced from the well.
- Reservoir Pressure - This is the pressure within the reservoir.
- Flowing Bottom-Hole Pressure - This is the pressure at the bottom of the well when gas is flowing.
Productivity Index Usage
- Evaluating Well Performance - A higher \(J\) indicates a more productive well for a given pressure drawdown.
- Well Comparison - \(J\) allows for the comparison of different wells within the same reservoir or across different reservoirs.
- Reservoir Management - Helps in planning the development and production strategies for a gas field.
Productivity Index for a Gas Well formula |
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| \( J \;=\; \mu \; h \;/\; 1422 \; T \; [\; 0.5 \; ln \; ( 4 \; A \;/\; 1.781 \; k \; WB_r^2 ) + S \;] \) | ||
| Symbol | English | Metric |
| \( J \) = productivity index for a gas well | \(MSCF/day/psi^2/cP\) | - |
| \( \mu \) (Greek symbol mu) = permability | \(mD\) | - |
| \( h \) = thickness | \(ft\) | - |
| \( T \) = temperature | \(R\) | - |
| \( ln \) = natural logarithm | \(dimensionless\) | - |
| \( A \) = drainage area | \(ft^2\) | - |
| \( k \) = shape factor | \(dimensionless\) | - |
| \( WB_r \) = wellbore radius | \(ft\) | |
| \( S \) = skin | \(dimensionless\) | |
