Services - Reservoir Engineering
P/Z Analysis
P/Z versus cumulative production plot is the well known classic material balance analysis procedure for gas wells. The P/Z plot is a helpful complement to rate versus cumulative production analysis because it yields the gas-in-place, not just the recoverable reserves.
CalScan engineers use a custom built P/Z analysis program in which a straight-line is fitted through the plot of p/z versus Gp, via the least-squares technique. The P/Z plot can be generated directly from the bottom hole pressures data or computed from wellhead pressure data. Z-values are determined from correlations based on measured gas gravity, temperature and pressure. The recoverable reserves are calculated by specifying the provided abandonment pressure or a recovery factor.
