The tank material balance method is often quite adequate for analysing gas reservoirs. In such cases, it is possible to treat the reservoir as a huge "tank" of constant volume, for which a plot of P/Z versus cumulative gas produced (Gp) is a straight line intersecting the axes at the initial pressure and GIIP respectively. This allows accurate predictions, for example average reservoir pressure, to be made.
Unfortunately, there are a number of reservoir features which will cause the P/Z plot to depart from a straight line, for example aquifer influx or gas influx from un-represented sources such as poor quality rock or unmapped gas pockets. However, it is possible to take such features into account by making modifications to the basic material balance equation. Hence, when modelling complex gas reservoirs, GASMAN uses a modified material balance approach. This approach takes into consideration aquifer influx, multi-tank gas transmissibility and condensate/water production.
In practice, producing gas fields often consist of a number of isolated reservoirs with different characteristics. Moreover, each reservoir will be linked to a pipeline network through a number of wells connected at the surface through gathering centres. This network takes the gas to a central processing facility. To model such complex systems, MSE has extended the basic gas material balance method to a multi-tank, multi-well configuration.
For further information on how GASMAN can help optimise your gas production, please call +44 (0)20 8773 4500 or info@mse.co.uk.
GASMAN Screen Shot
Gasman screen: Tanks