Transcript Basics of Geothermal Reservoir Engineering for New Zealand Tyler Kent University of Nevada, Reno.

Basics of Geothermal Reservoir Engineering
for New Zealand
Tyler Kent
University of Nevada, Reno
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Thanks to contributors
Sadiq Zarrouk (University of Auckland)
John Louie (UNR)
Dick Benoit (Alterra Power Corp)
Jim Echols (Magma Energy)
Alison Dorsey (UNR)
Holly McLachlan (UNR)
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Geothermal in New Zealand
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Geothermal in New Zealand
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Reservoir Engineer Needs to Know
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Temperature profile
Pressure distribution
Flow rate and specific enthalpy
Depth of fluids (produced and reinjected)
Permeability
Chemistry of the fluid
Tools
• Go Devil/ Caliper
• Pressure
Temperature Spinner
• Pressure Tranducer
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Measurements
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Casing condition
Wireline temperature
Wireline pressure
Flow rate (spinner)
Cementing job quality
Water sampling
Check for Blockage
(Zarrouk, 2012)
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Pressure
Temperature
Spinner (PTS)
Run
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(Zarrouk, 2012)
(Zarrouk, 2012)
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PTS Tool
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(Zarrouk, 2012)
High Temperature Casing Caliper
(HTCC) Tool
(Zarrouk, 2012)
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Measurements During Drilling
• Static Formation Temperature Test (SFTT)
– Measure the reservoir temperature while the rig is
on the well to estimate formation temperature
and make a decision on the well completion
(expensive but common)
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Static Formations Temperature Test
(Zarrouk, 2012)
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Pressure and Temperature vs. Depth
(Zarrouk, 2012)
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Completion Testing
• Water loss surveys
• Injection/falloff test (measure injectivity and
permeability thickness ratio)
• Shut in PT surveys (pressure and temperature
warm up curves)
• Discharge test (output test)
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Casing Caliper
Metal loss in 13 3/8” anchor casing
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(Zarrouk, 2012)
Split collar in 9 5/8” production casing
Determine Feed Zones
• Evaluate shut well for a month on a log scale
– 1,2,4,7,14,28 days
• Pivot Point is where pressure is entering
well bore and stays constant
(Zarrouk, 2012)
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Spinner
(Zarrouk, 2012)
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Injectivity Test at Depth of 1000m
followed by Pressure Falloff Test
(Zarrouk, 2012)
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Injectivity
• Constant injectivity
usually quoted with flow
range.
• Injectivity can change
– Fracturing
– Thermal
expansion/constractio
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– Solid
deposition/dissolutio
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(Zarrouk, 2012)
Estimate Production Capacity
• Measure injectivity
• Variation of pressure with changing injection
rate
• J<5
Useless
• J 10-20 Small
• J > 50 Excellent
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Example Fall-off Test
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Example Build-up Test
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Vertical Discharge Test
(Zarrouk, 2012)
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Russell James Formula
m= Mass flow rate (kg/s)
h = Specific enthalpy of the discharged fluid (kJ/kg)
A = Lip pressure pipe cross sectional area (m2)
Pc= Lip pressure (kPa abs)
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Energy Output
Take it to the Bank
(Zarrouk, 2012)
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What We Know Now
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Feed Zones
Reservoir Temperatures
Injectivity
Production Capacity
Proven Energy Reserves
Questions?
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