By definition, during Nolte Flow, pressure versus G-time has a constant slope and Nolte Flow is a sign of an open fracture. The departure from this constant slope is evidence of closure. Everyone would typically agree on this closure pick. Height Recession, Transverse Storage, Pressure Dependent Leak-off and Tip Extension however appear to be the more common signatures reported in well reports highlighting a) more complex reservoirs, b) problematic data sets, c) incorrect use of the G-function plot, d) misunderstanding of the fluid leak-off dynamics, or all of the above.
Welltest solutions developed in the late eighties and early nineties are shown to be very beneficial for closure identification and after-closure analysis in shale plays and requires a second look. In this presentation, a look back at some of the welltesting communities “trade secrets” will be reviewed and will show how they can be easily used in today’s complex reservoirs.