GNS Science Consultancy Report 2006/0XX

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APPENDIX 1 NOTES ON THE GEOTHERMAL ENERGY GENERATION IN OIL AND GAS SETTINGS CONFERENCE The conference was held in March 2006 at the Southern Methodist University (SMU) in Texas, organised by D. Blackwell. The main point of the conference is the enormous potential of oil and gas settings in providing geothermal power. What oil and gas operators view as the death of a fossil fuel system is viewed as the source of another energy by the geothermal industry that also has the blessings of the environmentally conscious population. Talks were about 75% technical, 25% laws and regulations affecting geothermal and oil and gas systems in the USA (main points of talks are in Table 4). The most interesting talks and posters were centred on the heat flow map of the USA that SMU had published at the AAPG. The map making was led by David Blackwell of SMU. One of the main offshoots of this map is the reestimation of the geothermal potential of the USA using oil and gas wells and EGS technology (EGS= Enhanced or Engineered Geothermal Systems). The total conservative geothermal potential of the USA is 43,617,976 MWe. At present geothermal provides 8900 MWe of power to 24 countries world-wide. The oil and gas operators view water flooding as the end of the field whereas geothermal operators see this phenomenon as the start of a new source of energy. Some of the problems in harnessing geothermal energy from oil and gas wells are not technical but include the lack of communication between people in the oil and gas and geothermal industries and the lack of overt support from the federal government. During the meeting the discussion panel decided to write a one-page white paper report on “Geothermal Energy Generation in Oil and gas Settings”, to be submitted to the government and oil and gas operators. Interestingly, the convenors sent nearly 15,000 invitations to oil and gas operators and technical people, government officials and the media to attend this conference (which is the first in the world and quite important for the future energy outlook of the USA, at least) but there were only 90 attendees,
Table 5. Main points of presentations during the Oil and Gas conference held in March 2006. Speaker Company/Agency Topic Main Points of Talk Ray LaSala Susan Petty Dub Taylor Louis Capuano Paul Thomsen David Blackwell Will Gosnold US DOE Geothermal Technologies Black Mountain Technology State Energy Conservation Office (SECO)- Texas Renewable Program ThermaSource, Inc ORMAT Southern Methodist University University of North Dakota, Dept of Geol & Geol. Engg Dept. of Energy Geothermal Focus US 2006 Enhanced Geothermal System Resource Evaluation Texas Renewable Program and Demonstration Sites Comparison between geothermal and oil & gas drilling Modular binary power generators Geothermal resources in sedimentary basins Northern Great Plains geothermal resources Berni Karl Chena Hot Springs Resort Geothermal electrical application in Alaska Dick Benoit Mike Shook Prentice Creel Sustainable Solutions Chevron-Texaco Halliburton Scaling and corrosion abatement Heat extraction from sedimentary formations Well integrity to extend a well’s life DOE’s geothermal budget for 2007: $0.00 yet they plan to have 40,000 MWe from geothermal by 2040 at 80 o C including overpressured systems: 43,617,976 MWe @20% recovery, using ORC and conventional steam turbines (lots of very conservative assumptions in calculations) Texas is the 5 th largest energy user in the world and most of the energy sources are from fossil fuels. Major differences: temperature, production pressures, rock formation characteristics, production rates and types of discharge fluids; tubings used in oil & gas, slotted liners in geothermal Binary and flash steam turbines, modular (mainly an advertising spiel- presentation on ORMAT data most people in the geothermal industry already know). Turbine efficiency is now 88%. Discussed what factors SMU considered in making heat flow map of USA (AAPG publication) e.g., used several correction factors to estimate BHT’s at various depths. Scenarios for development of sedimentary basins: co-production of fluids, geopressured fluids, sedimentary EGS (enhanced geothermal systems) Anomalously high temperatures in this region partly due to blanketing effect of shales and heat advection in regional groundwater flow system. 74 o C waters from well used to provide electricity for resort using ORC system of United Technologies where Carrier air conditioners are reengineered as reverse chillers (smallest module is 200kw). Used thermal waters are cascaded for use in greenhouse, space heating and an ice house (Kalina cycle) Main problems in oil & gas wells that would be used as geothermal wells would be carbonate scaling and corrosion due to hyper saline fluids Modelled several scenarios on how heat can be extracted from oil & gas wells: best case is a vertical well dual doublet with a circulation rate of 6.31 kg/s. Inlet T (T of water being fed into well)= 27 o C, fed water heated to 203 o C. There is a need to balance circulation rate and temperatures for optimum energy efficiency- best model is use of horizontal wells but modelling study still ongoing. Geothermal production from mature watered-out oil & gas fields and from fields with on-going water-flooding Use of zoned seal foam cement extolled because of its high strength, high viscosity and excellent displacement properties, resulting to better cementing jobs- the key to long lives of wells GNS Science Report 2007/23 29
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Page 4 and 5: CONTENTS ABSTRACT..................
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Page 8 and 9: Figure 1. Temperature, depth and pe
Page 10 and 11: 2.0 ABANDONED OIL AND GAS WELLS IN
Page 12 and 13: Figure 5. Map showing the distribut
Page 14 and 15: Figure 6. Drilled vertical depths o
Page 16 and 17: Figure 8. Temperatures ranges of on
Page 18 and 19: Table 1. Number of wells within a r
Page 20 and 21: 3.3 REASONS FOR ABANDONING WELLS Mo
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Page 24 and 25: 5.0 CURRENT GEOTHERMAL USE OF ABAND
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Page 30 and 31: 10. Determine how geothermal produc
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Page 38 and 39: Table 6. Basic well data for onshor
Page 40 and 41: Well Name NORTH ISLAND TARANAKI Dat
Page 42 and 43: Well Name SOUTH ISLAND WEST COAST D

GNS Science Consultancy Report 2006/0XX

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