Petrophysical Signatures of the Liquid-Steam Phase Transition in - PowerPoint PPT Presentation

Petrophysical Signatures of the Liquid-Steam Phase Transition in Geothermal Reservoir Rocks BRUHN, David; MILSCH, Harald; SPANGENBERG, Erik GFZ Potsdam, Germany FLÓVENZ, Ólafur; KRISTINSDÓTTIR, Líney Halla; Icelandic Geosurvey (ÍSOR), Reykjavík, Iceland JAYA, Makky Freie Universität Berlin, Germany.

Sample characterisation Sample 3A 58 Ftbl Hyaloclastite Basalt Sandstone Rock type Ölkelduháls ÖJ-1 Krafla KH-1 Fontainebleau Origin/Well no. 795 187 -- Depth (m) 20.7 20 7.5 Porosity (%) Density (g/cm 3 ) 2.15 2.37 2.45 0.81 0.78 10.8 Fluid conductivity (mS/cm) 80 19 50 Pore pressure (bar) 175 50 100 Conf. Pressure (bar)

The apparatus 1 & 5: Downstream and upstream pumps (Pmax: 50 MPa, flow rate: <15 l/h) 2: Reservoir for chemical fluid analysis 3: Pressure vessel and heater (Pmax: 140 MPa, Tmax.: 250C) 4: Confining pressure pump (Pmax: 140 MPa oil) 6: Fluid reservoir (10 l)

The liquid-steam transition Release of pore fluid reduces Sample 58 pore pressure => vaporisation 20 20 pore pressure pump volume 15 17,5 Conductivity decreases gradually (bar) (cm 3 ) 10 15 5 12,5 0 10 Pore pressure cycling in sandstone 0 500 1000 1500 Sample 58 0,6 60 time (min.) 40 0,5 20 1 conductivity (mS/cm) Conductivity [mS/cm] Pore pressure [bar] 20 pore pressure (bar) 16 0,9 0,4 0 12 0,8 0,3 -20 8 0,7 0,2 -40 4 0,6 0,1 -60 0 0,5 0 -80 0 500 1000 1500 0 50 100 150 200 250 300 350 time (min.) Time [hours]