Formation temperature T_i before the well was put on stream: T_i = T_e(t < 0)
See also
Natural Science / Geoscience / Geology / Rock
Petroleum Industry / Upstream / Subsurface E&P Disciplines / Petroleum Geology / http://nafta.wiki/x/LYBPB
[Reservoir pressure] [Formation pressure, Pe] [Drilled formation pressure, Pd] [Startup formation pressure, P0]