Geothermal Drilling & Producing Well Integrity Challenges. Colin Stuart BEng FIMechE Ken Seymour BScPhD MBA CEng 22 September 2016

Transcription

1 Geothermal Drilling & Producing Well Integrity Challenges Colin Stuart BEng FIMechE Ken Seymour BScPhD MBA CEng 22 September 2016

2 Presentation outline 1. Introduction to Stuart Wright 2. Geothermal Energy Trends 3. Geothermal Drilling & Producing Well Integrity Challenges 4. Solutions to Geothermal Drilling & Producing Well Integrity Challenges 5. Summary 2

3 Introduction to Stuart Wright Safe and Reliable Wells Consulting Intelligent Risk Solutions Training 3

4 2. Geothermal Energy Trends 4

5 Geothermal basics where does the heat come from? Clean and sustainable heat from the Earth. It yields warmth and power that we can use without polluting the environment. Geothermal heat originates from Earth's fiery consolidation of dust and gas over 4 billion years ago. At earth's core, temperatures may reach over 9000 F. 8 x W 32.3 x W 1.7 x W 5

6 Geothermal has a long history The oldest known pool fed by a hot spring, built in theqin dynasty in the 3rd century BCE. PrincePieroGinoriContitested the first geothermal power generator on 4 July 1904, at the same Larderellodry steam field where geothermal acid extraction began. It successfully lit four light bulbs. In 1911, the world's first commercial geothermal power plant was built there. Geothermal power plants operating in 25 countries globally. 3 BCE 1904 Present Day 6

7 Installed geothermal electric capacity by country (2015) Indonesia Case Study United States Philippines Indonesia Mexico New Zealand Italy Iceland Kenya Japan Turkey Iran Costa Rica El Salvador Nicaragua Russia Guatemala Papua-New Guinea Portugal China Germany France Ethiopia Austria Australia Thailand Electric Capacity (MW) Electric Capacity (MW) 7

8 Types of geothermal systems HEATING & COOLING Ground-Source Heat Pumps Simple Wells POWER Conventional Geothermal Complex Wells Enhanced Geothermal Systems (EGS) - Summer: liquid moves heat from building into ground. - Winter:pre-warmed air & water heats the building. Extract hot water hosted in naturally permeable geological formations -Hydraulic fracturing. -Pump cold water from surface through fractures and heated water back to surface through a second well to drive turbines. 8

9 International Energy Agency (IEA) roadmap vision of geothermal power production by region thru 2050 By 2050, geothermal electricity generation could reach 1,400 TWh per year, i.e. around 3.5% of global electricity production, avoiding almost 800 mega tonnes of CO2 emissions per year. 9

10 IEA predicted growth of geothermal power capacities by technology By 2050, more than half of the projected increase comes from exploitation of ubiquitously available hot rock resources, mainly via enhanced geothermal systems (EGS). 10

11 3.Geothermal Drilling & Producing Well Integrity Challenges 11

12 What is a well? 1. Awellisapressurevessel 2. Itisapressurevesselthatiscreatedinapressureenvironment drilling 3. A completed well consists of a tubular pressure vessel (tubing and casing), an adapter (wellhead)andaseriesofvalves(bopstackorxmastree) production The challenge is maintaining wellbore integrity through both the drilling and production phases. DRILLING PHASE PRODUCTION PHASE BLOWOUT PREVENTER (BOP) WELLHEAD & XMAS TREE 12

13 Well complexity P 5000 psi T < 100 C HP / HT / HPHT XHP / XHT / XHPHT / UHPHT Geothermal Wells Onshore Onshore Offshore (Shallow Water) Offshore (Deepwater) Salt Dome PP> 10k psi BHT>300 F Onshore Offshore (Shallow Water) Offshore (Deepwater) Offshore (Ultra-Deepwater) Salt Domes PP>15 to 20K psi BHT>400F Rudimentary / Basic Well Design Approach Low Importance to Material and Connection Performances Industry standard well design software (StressCheck, TDAS) Engineered Well Design Approach Proper Material Selection Knowledge of suitable connection with reliable performances (ISO Cal I to IV) Industry standard Well Design Software (StressCheck, WellCat) Advanced Well Design with Life Cycle Well Integrity Approach Industry Standard Well Design Software with Thermal Simulation (WellCat) Proper Material Selection Knowledge of Full Service Connection Performances (ISO 13679) 13

14 Well integrity challenges in oil and gas wells In a completed oil and gas well the ISO standard recognises at least 26 possible leak paths i.e. loss of integrity, some of which could lead to an uncontrolled flow. The oil and gas industry has developed rigorous standards of best practice over the last 100 years. The geothermal industry has not developed to this level of maturity, and generally follow oil and gas well design principles. 14

15 Oil & Gas vs. Geothermal wells complexity Simple Wells Complex Wells Future Wells Prediction Oil & Gas Geothermal Oil & Gas Geothermal Oil & Gas Geothermal Max PP(psi) 5,000 5,000 20,000 10,000 20,000 15,000 Max BHT ( ⁰ F) ,500 Location Onshore Onshore On/Offshore Onshore On/Offshore On/Offshore Well Complexity Index Geothermal Oil & Gas

16 Example loss of control events at geothermal sites - Blowouts - H2s release - Seismicity events - Landslides - Pipe ruptures - Turbine failures New Zealand, 1980 Iceland, 1999 USA, 1998 Philippines, 2003 Australia, 2009 Japan,

17 Future challenges for the geothermal industry Future growth in deeper, hotter rocks (EGS) will need increasingly complex wells which could become even more challenging than oil and gas wells due to extreme high temperatures. More complex wells leads to increased blowout risk and potentially lethal risks with high pressure water or steam, which is compounded if H2s is involved. The Geothermal industry need to evolve more complex well skills and Risk Management to reduce risks of uncontrolled flow. We cannot afford the geothermal industry to become another fracking issue 17

18 4. Solutions to Geothermal Drilling & Producing Well Integrity Challenges 18

19 Solutions must suit stakeholders on all sides Rigorous implementation of standards Risk of losses reduction Appropriate risk ranking Better targeting of premiums Well drilling review Indication that risk is manageable Proper barrier rules implementation i.e. RTBC Assurance that risk is manageable 19

20 Appropriate risk ranking 1. To provide the Underwriter with a high level screening to enable an estimated loss of control insurance premium to be calculated. 2. The tool does not replace the Drilling Well Review in determining the final level of risk for the well. 3. The tool is designed to identify risk elements existing specifically for Geothermal projects. 20

21 Well complexity P 5000 psi T < 100 C HP / HT / HPHT XHP / XHT / XHPHT / UHPHT Geothermal Wells Onshore Onshore Offshore (Shallow Water) Offshore (Deepwater) Salt Dome PP> 10k psi BHT>300 F Onshore Offshore (Shallow Water) Offshore (Deepwater) Offshore (Ultra-Deepwater) Salt Domes PP>15 to 20K psi BHT>400F Rudimentary / Basic Well Design Approach Low Importance to Material and Connection Performances Industry standard well design software (StressCheck, TDAS) Engineered Well Design Approach Proper Material Selection Knowledge of suitable connection with reliable performances (ISO Cal I to IV) Industry standard Well Design Software (StressCheck, WellCat) Advanced Well Design with Life Cycle Well Integrity Approach Industry Standard Well Design Software with Thermal Simulation (WellCat) Proper Material Selection Knowledge of Full Service Connection Performances (ISO 13679) 21

22 Sample of high level risk ranking tool # Geothermal Well Key Elements Risk Ranking Well is tapping a hot water source at a depth where temperatures exceed the boiling point of water at ambient surface conditions Well is tapping a geothermal source rock where the water does not reach boiling point at ambient surface conditions Well is tapping Hot Rock(s) or Enhance Geothermal System (EGS) source reservoir for steam generation purposes 4 Geological Formations 5 Well Risk Management 6 Casing Design 7 New Technology 8 Multiple Targets/ Objectives 9 Change of Scope 10 Well Barrier Plan 11 Human Factors 22

23 Well drilling review Well Type People Process Well Control Preparedness Equipment SAFE OPERATION MAJOR INCIDENT Well Control Event Risk Rating 23

24 Proper barrier rules implementation i.e. RTBC RTBC is a unique CLOUD BASED well barrier validation and monitoring solution that helps to protect: People Assets Environment 24

25 RTBC software operating environment 25

26 RTBC Daily Integrity Report sample Wear bushing was found stuck across Blind RAMs, but was subsequently retrieved on Root cause investigation in progress. Kill line P-tested to 3000 psi for 15 mins Valve HCR P-tested to 2500 psi for 15 minson Manifold P-tested to 2500 psi for 15 minson Dies of spider slip fell while RIH scraper BHA. Dies subsequently recovered via pipe RAM bonnet after POOH BHA and closing Blind RAMs. Root cause of dies slip fall currently unknown.

27 Summary of Geothermal integrity issues Rapid growth of Geothermal power generation Geothermal wells becoming more complex Application of Intelligent Risk Solutions to assess and manage risk 27

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