WP 5: Assessment of Groundwater Chemistry

Transcription

1 SHale gas Exploration and Exploitation induced Risks Thisproject hasreceivedfundingfrom the EuropeanUnion s Horizon2020 research and innovation programme under grant agreement No WP 5: Assessment of Groundwater Chemistry Andrew Gunning, RSKW Stirling Nelly Montcoudiol, University of Glasgow Catherine Isherwood, RSKW Stirling First Annual Meeting Napoli -June7-9, 2016 Hotel Palazzo Esedra, Piazzale Tecchio,

2 Assessment of Groundwater Chemistry 15:30 15:40 Overview of WP5 objectives for groundwater, progress on deliverables, context and forward plan (A. Gunning, RSKW) 15:40 15:55 The Development of Conceptual models and hydrogeological risk assessment for shale oil & gas basins in Europe WP 5.1 (C. Isherwood, RSKW; N. Montcoudiol, GLA; A. Gunning, RSKW ) 15:55 16:05 Initial results from the processing and analysis of baseline hydrogeological and hydrochemicaldata, WP 5.2 (N. Montcoudiol, GLA; C. Isherwood, RSKW) 16:05 16:15 Discussion points, Q& A, planned publications (A. Gunning, RSKW; N. Montcoudiol, GLA; C. Isherwood, RSKW) 2 A. XXXX, Gunning, dhgffhdgfjhgdsjfhgdfhdg Overview of Groundwater Chemistry

3 Overall Objectives for Groundwater WP 5.1 EU AUS USA Review of literature, global risks and EU Basins Assess Shale Basins in EU and develop Generic Risk Settings Canada WPs 3.1, 3.3 & 5.2 WP 5.3 Data collection, modelling and assessment of the Wysin site in the Baltic Basin Develop Recommendations For Best Practice 3 A. Gunning, Overview of Groundwater Chemistry

4 Detail on WP 5 and Timelines 5.1 The development of conceptual hydrogeological models across the main shale oil and gas plays within the EU. Competed Jan Detailed hydrogeological modelling and interpretation of the groundwater monitoring network at the Wysin site. Underway: Due Month Developing recommendations for best practice in risk assessment relating to drinking water aquifers. Underway: Due Month 36 4 A. Gunning, Overview of Groundwater Chemistry

5 Main Objectives A method to assess potential impacts and risks to drinking water aquifers during the operational phases of shale oil & gas exploitation Objective assessment of risks posed by shale oil & gas exploitation: developed around long term monitoring of the Wysin site including baseline information (which is a critical omission in shale developments in North America) Improved understanding of risks and a method to assess them will yield benefits for regulators and promote a better understanding of the issues around the development of shale oil and gas. 5 A. Gunning, Overview of Groundwater Chemistry

6 Groundwater Risk Assessment The objective: an assessment of potential impacts of shale oil & gas exploration and development on groundwater resources, in terms of possible pollution or resource impairment. Three possible scenarios in which groundwater could be impacted: Around the well-bore as a result of failure in well integrity -drilling fluids or flowback fluid allowed to escape into surrounding strata; Groundwater flow arising from fracture stimulation eg pathways created by frac process including leakage to abandoned wells or zones of enhanced permeability Risks associated with the transfer of contaminants through surface activity such as spills of contaminants are not included within the research proposal. 6 A. Gunning, Overview of Groundwater Chemistry

7 Generic Settings & Conceptual Models Assessment of potential risks to the groundwater resource from exploitation of shale oil and gas resources. Data gathered from published and publicly available sources. Three main parts to the assessment: 1. Review & assessment of shale oil and gas resource and development potential; 2. Hydrogeological resource classification; 3. Development of high-level screening method to inform an initial groundwater risk assessment process. 7` C. Isherwood, Generic Settings & Conceptual Models

8 Shale Oil & Gas Assessment 25 basins identified within the EU, of which nine are cross-border basins 8 C. Isherwood, Generic Settings & Conceptual Models

9 Data Sources A number of data sources provided key information: USGS National & Global Assessment Project US EIA/ARI reports Lyell Collection online library OnePetro online library State oil & gas regulators National oil companies Exploration & production companies Quality and quantity of data are very variable between different EU member states. 9 C. Isherwood, Generic Settings & Conceptual Models

10 PESL Analysis Other factors of importance to a developing shale oil and gas industry include: Political climate Economics Social Licence/acceptance The factors vary widely and are subject to change Analysis gives a snapshot of current status Analysis requires regular reviews and updates Example: Yorkshire planning consent 10 C. Isherwood, Generic Settings & Conceptual Models

11 Hydrogeological Resource Classification Undertaken for shale basins with potential activity within the next five years. Primary focus on groundwater used as a drinking water resource. Data largely derived from state water & environmental regulators. Assessment collated information on: Geology & structure Hydrogeology resources, abstraction, quality Resource classification o Sensitivity to change o Status as a drinking water resource 11 C. Isherwood, Generic Settings & Conceptual Models

12 HRC Matrix Nineteen of the 25 basins required an HRC. STATUS SENSITIVITY Low Moderate High Very High Low Low Low Moderate Moderate Moderate Low Moderate Moderate High High Moderate Moderate High High Very High Moderate High High Very High 11 show a high resource classification 7 show a moderate resource classification 1 shows a low resource classification. Moderate and Low classifications usually reflect a moderate or low dependence on groundwater for drinking, or a level of protection from contamination by the basin geology. In some cases the groundwater is not suitable for drinking owing to its geological situation and history. 12 C. Isherwood, Generic Settings & Conceptual Models

13 Conceptual Models Four categories: 1. Depth to target shale 2. Depth of water 3. Tectonic setting 4. Anthropogenic activity 13 C. Isherwood, Generic Settings & Conceptual Models

14 Conceptual Models 1-Depthtotargetshale Influence on likelihood of a connection between the frack zone and key receptors. Shallow frack zones have a greater possibility of influencing nearsurface activities. 2-Depthtowater Depth of drinking water abstraction influences the likelihood of any connection between the frack zone and the drinking water resource. 3- Tectonic setting Influence on transport pathways for contaminants. 4- Anthropogenic activity Creation of new and preferential flow pathways, connections between previously distinct catchments. 14 C. Isherwood, Generic Settings & Conceptual Models

15 Risk Screening Matrix Basin Shale-Water Separation Tectonic Setting Human Activity Receptor: Value Sensitivity 15 C. Isherwood, Generic Settings & Conceptual Models Further Investigation Requirement Confidence Level Comments Alum Shale Wide L Extensive H Moderate M High High H High Good Groundwater provides entire water supply Aquitaine Narrow H Extensive H Extensive H High High H Very High Good Groundwater provides much of water supply; tectonic situation complex Baltic Wide L Limited L Extensive H High High H Moderate Good Groundwater provides all/much of water supply Basque-Cantabrian Wide L Extensive H Extensive H Moderate Very High H High Good Groundwater provides limited public supply; tectonic situation complex Clare Moderate M Limited L Limited L Moderate High M Moderate Moderate No local groundwater information.. Ebro Wide L Limited L Moderate M Low High M Moderate Moderate Limited detail Fore-Sudetic Monocline Moderate M Moderate M Limited L High Moderate M Moderate Poor Limited basin-specific information in various areas. Lower Saxony Wide L Extensive H Extensive H High High H High Good Lublin Wide L Extensive M* Extensive H Moderate High M High Moderate Midland Valley of Scotland Narrow H Extensive L* Extensive H Low Moderate L Low Good Molasse Moderate M Extensive H Extensive H High High H Very High Good Northern England Narrow H Extensive M* Extensive H Moderate High M Moderate Good Groundwater provides much of water supply; tectonic situation complex Groundwater provides limited public supply but also spa waters; relatively complex tectonics. Groundwater not much used for drinking; much of area affected by mine water drainage and natural poor water quality Situation varies between countries; tectonic situation complex; depth of water used for drinking varies widely. Variable hydrogeology across region, some areas have higher resource value than others. Pannonian Moderate M Extensive H Extensive H High High H Very High Poor Limited data for several countries Paris Moderate M Limited L Extensive H Moderate Very High H High Good Groundwater provides some public supply and abstraction pressure is high. Podlasie Wide L Moderate L* Moderate M High Moderate M Moderate Poor Limited basin-specific information in various areas. SE France Moderate M Extensive H Moderate M Moderate High M Moderate Moderate Vienna Narrow H Extensive H Extensive H High High H Very High Good Wessex & Weald Narrow H Extensive M* Extensive H High Very High H Very High Good West Netherlands Wide L Extensive H Extensive H High High H High Good Variable hydrogeology across region, some areas have higher resource value than others. Limited information available. Situation varies between countries; tectonic situation complex; depth of water used for drinking varies widely. Considerable water stress in the area; some uncertainty over depth of active abstractions. Groundwater provides most of the public supply; some water stress noted.

16 Risk Screening: Baltic Basin Parameter Value Risk Depth to Target Shale ~ 3000 m anddeeper Depth of Drinking Water To 800 m Shale-Water Separation 2200 m or greater: Wide LOW Tectonic Setting Limited LOW Anthropogenic Activity Conventional Oil & Gas, extensive HIGH Groundwater Value High Groundwater Sensitivity High HIGH Further Investigation MODERATE Confidence Level Good 16 C. Isherwood, Generic Settings & Conceptual Models

17 Data Collection in the Field Continuous data Barometric probe: P atm & T air Downhole probes: P abs, T GW & Spec. Cond. Intermittent data One-time GWL measurements Groundwater samples: Set-up for purging and sampling GW3 o Purging of well & record of physico-chemical parameters o Collection of samples / QA / alkalinity test o Samples stored at 4 C Recording physico-chemical parameters during purging of GW4 o Accredited lab: cations, anions, trace elements & dissolved gases; SUERC for isotopes 17 N. Montcoudiol, Groundwater Baseline Monitoring

18 GWL Some Theory Reference=probe:P abs =P w +P atm (pressureinmh 2 0) Reference = sea level: H = WL + P atm (m.a.s.l) Z L c P atm Conversion from pressure to water levels & heads P abs WL=Z L c +P w WL=Z L c +(P abs P atm ) P W H=Z L c +P abs H WL Heads flow direction Groundwater levels & heads behaviour of the aquifer 0 18 N. Montcoudiol, Groundwater Baseline Monitoring

19 GWL Raw Data P abs = P w + P atm Increase in GWL GWL ±stable 19 N. Montcoudiol, Groundwater Baseline Monitoring

20 GWL Water Pressure (P w ) P abs = P w + P atm Increase in the GWL GWL ±stable 20 N. Montcoudiol, Groundwater Baseline Monitoring

21 GWL Other Wells P abs = P w + P atm Although GW2 clearly confined, behaviour as unconfined or semi-confined Slight rise 21 N. Montcoudiol, Groundwater Baseline Monitoring

22 GWL Barometric Corrections GWL fluctuations resulting from a multitude of effects (natural or anthropogenic) P abs = P w + P atm Among them: barometric fluctuations and Earth tides noise Barometric response variable (Δt & ΔP) Software BETCO (Toll & Rasmussen, 2007) Δt = 4-9h Δt = 7-22h Δt = 2h Δt = 10-14h Example of step response for GW1 Reference:Toll, N. J. & T. C. Rasmussen, Removal of barometric pressure effects and earth tides from observed water levels. Ground Water. 45(1): DOI: /j x. 22 N. Montcoudiol, Groundwater Baseline Monitoring

23 GWL Corrected Results GW3: unconfined/low K Effect of pumping (10d) Effect of pumping (4d) GW1, GW2 and GW4 with similar behaviour (semi-confined) 23 N. Montcoudiol, Groundwater Baseline Monitoring

24 GW Chemistry T C Accuracy ± 0.1 C GW2: sampling brings warmer water GW4: no impact of sampling GW3: slight decrease / small oscillations GW1: sampling brings colder water 24 N. Montcoudiol, Groundwater Baseline Monitoring

25 GW Chemistry Spec. Cond. (25 C) GW4: increase during sampling Accuracy ±1% ms/cm GW3: no change GW1/GW2: decrease during sampling 25 N. Montcoudiol, Groundwater Baseline Monitoring

26 GW Chemistry Analysis Results Quality control: ion balance < 10% Similar chemistry for all boreholes: Major ions: o Ca-HCO 3 watertype typicalinquaternaryformations o Little temporal variations Minor traces: o Mn: µg/l(2-3x regulations) o Traces:As,Ba,Cr,F -,Ni&Sr(<regulations) o <DL:Al,B,Br -,Cd,Cu,Fe,Hg,Li,Pb,Sb&Se meq/l Ca 2+ HCO - 3 Mg 2+ SO 2-4 Na + + K + Cl meq/l Ca 2+ HCO - 3 Mg 2+ SO 2-4 Na + + K + Cl meq/l Ca 2+ HCO - 3 Mg 2+ SO 2-4 Na + + K + Cl - GW1 GW2 GW meq/l Ca 2+ HCO - 3 In red: early indicators/flow back Dissolvedgases:CH 4,C 2 H 6,C 3 H 8 andethylene<dl 26 N. Montcoudiol, Groundwater Baseline Monitoring Mg 2+ Na + + K + Cl - SO 4 2- GW4

27 Conclusions Although drilling logs suggested a rather confined aquifer(e.g. GW2): Data from pressure transducers semi-confined or unconfined aquifer Heterogeneous Quaternary sediments/ discontinuous clay layer Homogeneous chemistry same aquifer/ limited temporal variability Downholeprobesasearlywarningtoolforchemicalchanges abletopickup some tiny variations in temperature and specific conductivity following sampling events Follow-up issues: Sampling of dissolved gases Tracer tests Groundwater modelling 27 N. Montcoudiol, Groundwater Baseline Monitoring

28 Summary of WP 5 WP 5 will provide an objective risk assessment of the potential impacts of hydraulic fracturing on aquifers that are used as drinking water supplies. Wysin provides an optimum site to address these impacts: Task 5.1. Develop Generic Settings (Task Leader: Andrew Gunning RSKW; UGL) Task 5.2. Detailed Hydrogeological Modelling (Task Leader: Andrew Gunning RSKW; UGL) Task 5.3. Recommendation for Best Practice (Task Leader: Paul Younger UGL; RSKW). Key outcomes are the establishment of baseline conditions at Wysin and a comparison with post frac hydrogeology. 28 A. Gunning, Overview of Groundwater Chemistry