Worldwide Classification & Reporting Requirements for Geothermal Resources (after paper SPE 146435) Prof. Dr. Gioia Falcone Institute of Petroleum Engineering Department of Geothermal Engineering 03 May 2012
Outline Need for Geothermal Reporting Standards. Review of Key Definition Attempts. Analogy with the Oil & Gas Sector. Risk Assessment. Need for an Integrated Subsurface/Surface Approach. Challenges Ahead & Conclusions.
Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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The Goal
Standards? Rules? Guidelines? Codes?
Flexibility increases uncertainty Greater uncertainty = greater risk to investor Less confidence in geothermal development Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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What is the Target? Source? Reservoir? Fluids? Stored heat? Recoverable volume? Recoverable heat? Recoverable power? ….or simply the net $$$? Prof. Dr. G. Falcone Institute of Petroleum Engineering
(SPE et al, 2007)
Worldwide Classification & Reporting Requirements for Geothermal Resources
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Example: Geopressured Resources - 1 Highly pressurised hot brine (water trapped during burial process). Often saturated with methane. Found in large, deep aquifers. Wells flow pressurised to the surface. Water temperature is 90-200°C. (Texas Renewable Energy Resource Assessment, 2009)
Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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Example: Geopressured Resources -2 3 forms of energy can be exploited:
1.Thermal from the high temperatures. 2.Hydraulic from the high fluid flow pressure. 3.Chemical from the dissolved methane. (Texas Renewable Energy Resource Assessment, 2009)
Which one is the target resource?
Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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Definition - by Temperature & Use
(5 – 25 oC)
(20 – 75 oC)
(75 – 150 oC)
(> 150 oC) (after Texas Renewable Energy Resource Assessment, 2009) Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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Calculation of Temperature at Depth
(MIT, 2006) Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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By Temperature, Use, Type & Status
Prof. Dr. G. Falcone Institute of Petroleum Engineering
(after Bromley, 2009)
Worldwide Classification & Reporting Requirements for Geothermal Resources
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By “Potential” Potential”
(Piot, 2006; Rybach, 2009) Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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By “HeatHeat-inin-Place” Place” – Stored Heat
Sw Φ
= water saturation = porosity
Prof. Dr. G. Falcone Institute of Petroleum Engineering
(AGCC, 2010) Worldwide Classification & Reporting Requirements for Geothermal Resources
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By “HeatHeat-inin-Place” Place” – Power Potential
(AGCC, 2010)
Rf = QWH / QR
for liquid-dominated systems
QWH = heat at wellhead QR = heat in the reservoir Prof. Dr. G. Falcone Institute of Petroleum Engineering
(Muffler, 1979)
Worldwide Classification & Reporting Requirements for Geothermal Resources
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Key Oil & Gas Reporting Documents Guidelines for the Evaluation of Petroleum Reserves & Resources (SPE/WPC, 2001). Petroleum Resources Management System (PRMS) (SPE, WPC, AAPG, SPEE 2007). SEC Regulation S-K, Regulation S-X under the Securities Act of 1933, Securities Exchange Act of 1934 & Industry Guide 2. Modernization of Oil and Gas Reserves Reporting Requirements (SEC, 2010). Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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Differences with Oil & Gas Sector - 1 Commodity to be extracted is heat. heat Commodity (heat) is stored in both rock & fluid. fluid For some hydrothermal systems, a recharge may take place on a human time scale vs. a geological one. Natural geothermal fluids contain dissolved solids and gas that can be regarded as byby-products. products Geothermal energy can be used both for electrical generation & direct use. use Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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Differences with Oil & Gas Sector - 2 According to the SEC, “proved undeveloped reserves” only applies to projects to be developed within 5 years (too restrictive for geothermal electric power generation projects). Geothermal energy markets are site specific and cannot be compared to global hydrocarbons market. Geothermal energy cannot be easily transported from its site of production (or stored), hence it is deemed to stay a local energy, energy contrary to oil & gas.
Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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Resources & Reserves – Oil & Gas
(PRMS, 2007)
Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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Resources & Reserves - Geothermal
(AGCC, 2010) Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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Quantifying Total Project Risk Risking the geothermal value starts by identifying the in situ raw resource, and ends with the assessment of current & future market scenarios. 1. 2. 3. 4. 5. 6.
Exploration Drilling Well MW capacity Reserves estimate Geopolitical environment Energy markets
Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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Risk on Recovery Factor Representative historic database for conventional (i.e. hydrothermal) available for making estimates for new analogue geothermal occurrences. …not true for the new generation of exploitation concepts (e.g. EGS, low T binary/organic Rankine cycle power).
Example: the overall risk of an EGS project is strongly related to the success of the formation stimulation measures adopted. Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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Risk on Overall Plant Efficiency Energy conversion efficiency Power plant capacity factor Power plant downtime & life Example of cycle thermal efficiencies for energy conversion
(MIT, 2006)
Risk related to technology, fluid chemistry, maintenance plan, etc. Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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Need for Integrated Subsurface/Surface Approach 1. Identify possible resource. 2. Calculate heat in place. 3.
4. 5.
-A, h, depth, T (with corresponding uncertainty) Calculate heat arriving at surface. • -K, Q -Dynamic flow models (reservoir & wells) -Geo-mechanical models -Fluid & heat recharge Calculate recoverable energy. -Efficiency of heat use & energy conversion Apply cutcut-offs as/when appropriate.
Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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Geothermal Exploitation Components Geology & Geophysics
Flow in Porous Media
Prof. Dr. G. Falcone Institute of Petroleum Engineering
Drilling, Completions, Fracturing & Production Ops., Plants
(after Enel, 2005)
Field Performance Worldwide Classification & Reporting Requirements for Geothermal Resources
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Need for an Integrated Approach Forward cascade of calculations, or simultaneous solution of reservoir, wellbore & plant, or iterative procedure? What cut-offs and where? What models/packages? Deterministic & statistical approach (including Monte Carlo & Experimental Design). Integrated subsurface/surface modelling. Predictions of cum. heat/energy recovery vs. time. time Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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Challenges Posed by Standardisation Different types of resources & plants. Different uses & economics. Technology advancements. Impact of technology & economics on cut-offs. Naturally permeable aquifers vs. EGS. Varying environmental, policy & regulatory constraints. Standardising a workflow! Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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Conclusions Geothermal reporting standards needed to reduce risk to investor & increase confidence in geothermal development. Difficult to generalise procedures to quantify recoverable heat/power and associated project risk. Lessons learnt from oil & gas sector. Need for systematic subsurface/surface workflows. Prof. Dr. G. Falcone Institute of Petroleum Engineering
Worldwide Classification & Reporting Requirements for Geothermal Resources
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Worldwide Classification & Reporting Requirements for Geothermal Resources (after paper SPE 146435) Prof. Dr. Gioia Falcone Institute of Petroleum Engineering Department of Geothermal Engineering 03 May 2012
