Planning a Section 4.3 application for Underground Gas Storage? Maximum bottomhole injection pressure and maximum average reservoir pressure data are required to define the upper limit to the operating pressures of the scheme (i.e. maximum wellhead injection pressure). A complete tabulated pressure history of the pool (date, well, type of test, stabilized pressure) is also required, with a P/Z versus cumulative gas production plot (if the pool is non-associated gas), or material balance calculations (if storage is into a gas cap in communication with an oil leg). This history indicates pressure support from the aquifer and how the reservoir may react to storage. Plan ahead, additional pool #welltesting may be required to support your application.