dirk kassenaar earthfx watertech 2016

Assessing Cumulative Effects of SAGD Operations in the Mackay Watershed

Dirk Kassenaar, E.J. Wexler, P.J. Thompson, M. Takeda Earthfx Inc. Watertech 2016 April 7, 2015

Review of Cumulative Impacts – MacKay River Watershed

Introduction

In-situ Steam Assisted Gravity Drainage (SAGD) oil sand operations require a source of fresh water for steam injection.

Groundwater supply wells, generally drawing from aquifers above the oil production zone, are a preferred source.

2 - Introduction

From MEG Energy Corp.


Study Objectives

In 2014, Earthfx Inc. was hired by the Cumulative Environmental Management Association (CEMA) to answer the following question:

▪ Is there enough water in the Mackay watershed to sustain a responsible level of development

Cumulative effects analysis requires the integrated assessment of:

▪ Multiple anthropogenic stresses:

• Numerous spatially distributed SW and GW diversions

• Land use change (land clearing, drill pads, roads, etc.)

▪ Intersecting effects on surface and groundwater systems:

• Changes in groundwater levels (drawdowns) in all aquifer systems

• Changes to frequency, duration and severity of low flow conditions

3 - Introduction


Study Area

MacKay River Watershed is located immediately north-west of Fort McMurrray, AB ▪ Includes Syncrude Mine site and

numerous SAGD operations

Watershed Area: 5,600 km2

Model Area: 7,900 km2

4 - Summary of Model Development

Legend Lake

Namur Lake


Study Approach

Step 1: Integrated Model Development and Calibration ▪ Model Development: Compile Geology, Hydrogeology, Climate, Hydrology, Hydraulics

▪ Model Calibration:

• Build and pre-calibrate the SW and GW submodels

• Complete the fully integrated model calibration: Full reconciliation of entire hydrologic cycle water budget

Step 2: Sustainability Assessment ▪ Define Assessment Criteria and Climate Period

• Define aquifer drawdown and streamflow impact sustainability thresholds

• Select a representative “surrogate” climate assessment period (25 years)

▪ Simulate Pre-development (Baseline), Current and Full Build conditions over the climate period

▪ Compare, on a daily basis, Current and Full-build conditions against Baseline

• Evaluate GW drawdowns and streamflow changes against Assessment Criteria

5 - Introduction



MODELLING APPROACH

6 - Modelling Approach


Integrated Modelling Approach: Advantages

Study Approach: Fully integrated surface water and groundwater model

Better representation of: ▪ Groundwater recharge and

Dunnian GW feedback

▪ Streamflow and induced leakage

▪ SW/GW storage

▪ Cumulative effects of all SW and GW diversions

Flux inputs and calibration targets ▪ Measured precipitation as input

▪ Calibration to total streamflow and measured GW levels



Selected Model: USGS GSFLOW

USGS integrated GW/SW model ▪ Based on MODFLOW-NWT and PRMS (Precipitation-Runoff Modelling System)

▪ Open-source, proven and very well documented

▪ Fully-distributed: Cell-based representation

▪ Excellent balance of hydrology, hydraulics and GW




SUMMARY OF MACKAY MODEL DEVELOPMENT



Study Area Features

Topography (600 m of relief) ▪ Birch Mountains

▪ Thickwood Hills

Incised river and stream network ▪ MacKay River – main channel

▪ Dover and Dunkirk Tributaries

▪ Athabasca River: South and eastern boundary

Legend and Namur Lakes ▪ Plus over 100 other lakes in study area

Extensive muskeg and wetlands

Bedrock Channel Aquifers ▪ Key GW supply source for multiple projects

Anthropogenic Stresses ▪ Syncrude Mine

▪ SW and GW Diversions


AMBI, 2013)


GSFLOW: Multi-Resolution

GSFLOW is unique in that the resolution of the model can be adjusted to match key features

11

Climate inputs ( 2.5 km cells)

Surface Hydrology/Soil Zone ( 200x200 m cells)

Sub-surface Hydrogeologic Layers ( 13 layers of 400x400 m cells)

Stream Network Linear 1-D Channel segments (4000 km of streams represented, independent of grid resolution)

- Summary of Model Development


Model Grid

Fully distributed model: Every cell has unique properties

GW grid: 400 m by 400 m cells ▪ Selected to match assessment

averaging criteria (impact at 150 m from a well) but avoid focus on specific water users.

▪ Can be refined for future studies

SW Grid: 200x200 m cells ▪ Improved representation of overland

flow, wetlands, interflow and soil zone processes and properties

Stream routing: ▪ All streams and rivers simulated


400x400 m GW grid


Geologic Setting


Surficial Geology Bedrock Geology

Predominantly tills and glaciolacustrine deposits

Subcrop of units that dip to the southwest


Geologic Information


Primary sources for geologic borehole data:

25,000 - Alberta Geological Survey

255 - Atlas (Western Canada Sedimentary Basin)

Limited geologic data in Birch Mountains and central portion of study area


Conceptual Stratigraphic Model


After AGS Source: Andriashek and Atkinson, 2007

Empress Channel Sands: Key water supply aquifer


Hydrostrat. Layers


19 layer strat. model used to produce 17 layer hydrostrat. model. ▪ Some units of similar hydraulic

properties were combined.

▪ McMurray Basal Sands added as separate aquifer unit.

Model does not extend below Prairie Fm. Aquiclude ▪ Assumed minimal communication

due to low vertical K of unit.

▪ Simulating higher salinities (>50,000 mg/L TDS) would require density dependent groundwater flow.

Period Unit Stratigraphic

Model Unit

Hydrostratigraphic Model

Quaternary

1 Late Lacustrine 1 Aquitard

2 Surface Sand 2 Aquifer

3 Grand Centre Till 3 Aquitard

4 Middle Sands 4 Aquifer

5 Intermediate Till 5 Aquitard

6 Empress Channel Sands 6 Aquifer

Cretaceous

7 Labiche Formation 7 Aquitard

8 Pelican/Viking Formation 8 Aquifer

9 Joli Fou Formation 9 Aquitard

10 Grand Rapids Formation 10 Aquifer

11 Clearwater Formation 11 Aquitard

12 Wabiskaw Formation

13 McMurray Formation

(includes Basal Sands)

12 Aquitard

13 Basal Sand Aquifer

Devonian

14 Winterburn Formation (not included)

15 Grosmont Formation 14 Aquifer

16 Lower Ireton Formation 15 Aquitard

17 Cooking Lake Formation 16 Aquifer

18 Beaverhill Lake Group 17 Aquitard

19 Watt Mountain Formation (Top of Elk Point Group)

Base of Model

Prairie Formation

(not included) Keg River Formation

Contact Rapids Formation

Laloche Formation

Precambrian


GW Level Data

803 wells with water level data

Well assigned to hydrostrat. units based on screened intervals.

Limited long term temporal monitoring data (GOWN)



Groundwater Submodel Calibration


Unit Number of

Wells (n)

ME (m)

MAE (m)

RMSE (m)

Range in Observations

(m)

RMSE as Percent of

Range (%)

Overburden 236 -1.36 4.40 7.18 509.4 1.4%

Empress 58 -7.01 8.33 2.89 189.5 1.5%

Labiche 4 24.50 25.53 32.78 176.3 18.6%

Viking 42 -9.04 10.67 12.65 38.9 32.5%

Joli Fou 10 -5.24 9.44 10.46 28.5 36.8%

Grand Rapids 53 -8.45 8.58 11.58 94.7 12.2%

Clearwater 114 -5.55 8.97 12.06 188.6 6.4%

McMurray 71 0.56 11.47 19.50 279.7 7.0%

Cooking Lake 2 62.09 89.00 108.52 198.3 54.7%

Overall 590 -3.35 7.86 13.55 524.6 2.6%

200

300

400

500

600

700

800

200 300 400 500 600 700 800

Sim

ula

ted

(m

asl)

Observed (masl)

Overburden

Empress Fm.

Labiche Aquitard

Viking Aquifer

Joli Fou Aquitard

Grand Rapids Aquifer

Clearwater Aquitard

McMurray Aquifer/Aquitard

Cooking Lake Aquifer

1:1

Error Intervals (±10 m)

Steady-state submodel calibration.

Better calibration in aquifers where data more plentiful.


Hydrologic Submodel Development (PRMS)

Based on the USGS Precipitation-Runoff Modeling System (PRMS) code

Fully distributed implementation

200m x 200m cells (196,832 unique cell HRUs)


In each unique cell:


Climate Inputs

Precipitation and temperature interpolated on a daily basis over a 2.5km x 2.5km grid ▪ Inverse distance squared weighting

25 year daily climate time series input for each grid cell



Vegetative Cover Classes

26 wetland and vegetative cover classes ▪ 17 types of wetlands

Model parameters assigned by class: ▪ Seasonal Cover density

▪ Vegetation indices

▪ Soil zone properties

▪ Overland flow and shallow interflow parameters



Overland Flow

Overland flow and interflow simulated with a topographically defined cascade network

200x200m cell representation



Lateral Flow Processes


PRMS Soil Zone

MODFLOW Layer 1

MODFLOW Layer 2

• Head Dependant • Saturation Dependant


Dunnian Flow Processes: SW/GW Feedback


Groundwater feedback dominates in discharge areas, wetlands and shallow aquifers

▪ GW feedback in up to 60% of the watershed

Complex transient runoff and rejected recharge

▪ Occurs when the water table is at or near surface

▪ Spatially controlled: Tends to occur in stream valley areas

▪ Seasonally controlled: Tends to occur in spring when WT is high

GW discharge to the soil zone can become interflow or overland flow

Overland flow can re-infiltrate downslope: “3D recharge”

U n s a t u r a t e d z o n e

S t r e a m S t r e a m

G r a v i t y d r a i n a g e

R e c h a r g e

G r o u n d - w a t e r f l o w


Frozen Ground

New frozen ground module developed for this study ▪ GSFLOW is Open Source!

Based on a modified form of the Stefan Equation ▪ Derived by the U.S. Army Corps of Engineers

Model code follows Emerson (1994)


𝑋𝑓 =86,400𝐾𝑓𝐼𝑓

𝐿 + 𝐶 𝑇𝑎 +𝐼𝑓

2𝑡

0.5

𝑋𝑓 = 𝑑𝑒𝑝𝑡ℎ 𝑜𝑓 𝑓𝑟𝑜𝑠𝑡 𝐾𝑓 = 𝑡ℎ𝑒𝑟𝑚𝑎𝑙 𝑐𝑜𝑛𝑑𝑢𝑐𝑡𝑖𝑣𝑖𝑡𝑦

𝐼𝑓 = 𝑓𝑟𝑜𝑠𝑡 𝑖𝑛𝑑𝑒𝑥 𝑑𝑒𝑔𝑟𝑒𝑒 𝑑𝑎𝑦𝑠

𝐿 = 𝑙𝑎𝑡𝑒𝑛𝑡 ℎ𝑒𝑎𝑡 𝐶 = 𝑣𝑜𝑙𝑢𝑚𝑒𝑡𝑟𝑖𝑐 ℎ𝑒𝑎𝑡 𝑐𝑎𝑝𝑐𝑖𝑡𝑦 𝑇𝑎 = 𝑚𝑒𝑎𝑛 𝑎𝑛𝑛𝑢𝑎𝑙 𝑠𝑜𝑖𝑙 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑡 = 𝑑𝑢𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑡ℎ𝑒 𝑓𝑟𝑒𝑒𝑧𝑖𝑛𝑔 𝑝𝑒𝑟𝑖𝑜𝑑

𝑤ℎ𝑒𝑟𝑒


Frozen Ground Response

Frozen soil dynamics affect both surface and subsurface processes: ▪ SW Runoff and Recharge: Enhanced runoff during spring freshet, no winter recharge

▪ GW Discharge: Significantly reduced winter discharge to streams and wetlands



Model Calibration and Validation

Calibrated then verified against over 38 year period

A range of hydroclimatic conditions simulated


Validation Calibration


Model Calibration and Validation

Hydrologic submodel and the final integrated model were calibrated against streamflow observations at 6 Water Survey (EC) and RAMP stations

Historical observations at discontinued stations were an important source of insight



Model Calibration and Validation Good match to streamflow

observations at study area gauges

Daily Nash-Sutcliffe 0.65

Monthly Nash-Sutcliffe 0.75

Good match to validation period: Model has adequate predictive power



Distributed Results



Distributed Results (GSFLOW)



GSFLOW GW/SW Outputs


April May


GW/SW Animation

Animation shows spring melt and changes in GW levels and streamflow

Click for Animation


https://youtu.be/raEm4Lk_vrI?t=5m21s


GSFLOW Outputs

Spring change in water levels and streamflow



GSFLOW Outputs

Spring change in water levels and streamflow

Click for Animation


https://youtu.be/raEm4Lk_vrI?t=5m44s


GSFLOW GW/SW Water Budgets

Significant inter-annual and seasonal storage effects.


-4

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1

2

3

4

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Avg

Flo

ws

(mm

/mo

nth

)

Monthly Average GW Inflows and Outflows - Pre-Development Conditions

Lake Seepage Stream Leakage Surf Leakage Recharge Wells Net Const. Head Net Storage

-20

-15

-10

-5

0

5

10

15

20

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Flo

ws

(mm

/yr)

Simulated Inflows and Outflows by Water Year - Pre-Development Conditions

Lake Seepage Stream Leakage Surface Leakage Recharge Wells Net Const. Head Net Storage


Model Development Conclusions

The Mackay GSFLOW model represents the complex transient surface and subsurface process and their interaction and feedback

Extensive submodel development and integrated model calibration was undertaken to all available data

Key aspect of the integrated model calibration: ▪ Directly measured flux input: Precipitation

▪ Directly observed calibration targets: Total measured streamflow and GW heads

▪ Overall water budget must balance – no water is gained or lost




ASSESSMENT SCENARIOS: CRITERIA AND RESULTS

38 - Assessment Scenarios


Diversion Scenarios

Baseline: No pumping

Current Conditions: ▪ 4 Operations including 11

pumped wells.

Full-Build Conditions: ▪ 14 Operations including 42

pumped wells.


Current Operations

Current Operations

Current Operations


Land Use Change

Processing facilities and well pads ▪ Assumed to be 100m by 100m gravel

pads spaced 500m on center

▪ Reduced ET, due to the loss of vegetation, increased runoff

Full Build Scenario: ▪ Drill pads are estimated to cover 6% of

the planned project areas;

▪ Roads, pipelines, and facilities cover another 4%.

40 - Recommendations for Phase 3


Assessment Climate Period

25 year period includes a range of hydroclimatic conditions

▪ Includes both wet years (1997) and drought years (1998-1999, 2009 and 2011).

▪ 5 year spin-up period before start of assessment

41

Surrogate Climate Period

- Assessment Scenarios


GW Sustainability Assessment Criteria

In summary, it was agreed that the sustainable drawdown is 50% of the available drawdown in a confined aquifer. ▪ Threshold selection based on the Alberta Environment Water Conservation and Allocation Guideline for Oilfield

Injection (AENV, 2006)

▪ For unconfined aquifers, 66% of the average saturated thickness was used.

▪ Available drawdown based on average water level determined by 20 year baseline simulation.

Assessment Process: all three scenarios run using the same climate inputs ▪ Only difference is diversions and land use change

▪ Daily outputs for every model cell and stream reach saved for comparison

• Drawdown calculation

• Alberta Desktop Assessment

If, under Current or Full-build development conditions, drawdowns exceeded this threshold on any particular day in a 20 year assessment simulation, the cumulative diversion was considered locally unsustainable.



Overburden Impacts


Overburden Aquifers

Layer 1 Drawdowns

Percent of Total Available Drawdown


Channel Aquifers


Empress Formation Aquifer

Layer 4 Drawdowns



Confined Aquifers


Viking/Pelican Aquifer

Layer 5 Drawdowns



Deep Aquifers


Grand Rapids Aquifer

Layer 8 Drawdowns



GW Sustainability Assessment

Cumulative GW drawdowns are significant, in particular in the lower highly confined aquifer units

▪ Offset by the fact that lower units have much greater available drawdown

On a watershed scale, GW drawdowns appear to broadly stabilize within the 20 year period, suggesting sustainable water use

Localized zones where drawdown exceed 50% of total available drawdown



SW Sustainability Assessment Criteria

Alberta Desktop Method: ▪ Simulated frequency-duration relationship is calculated for every reach under baseline conditions

▪ The discharge that is exceeded 80% of the time is the ecosystem baseflow (EBF) component.

ADM Criteria 1: ▪ No surface water diversions are allowed below the 80% EBF threshold

• No diversion allowed when flow is below the lowest flows that occur up to 20% of the time.

ADM Criteria 2: ▪ Above the 80% EBF threshold, up to 15% of the available flow can be diverted.

20 year Baseline simulation used to determine weekly EBF threshold in every stream reach



SW Sustainability Assessment Criteria

Frequency-duration relationship calculated in the watercourse in a natural state.

EBF Weekly Threshold for Mackay River at Fort McKay:



SW Sustainability Assessment

Threshold for Mackay River at Fort McKay shown ▪ ADM Criteria 1 - fails for select days, as shown in red

▪ ADM Criteria 2 - never more than 15% diverted

Numerous other stream locations also assessed



Local SW Effects

While the overall watershed passes the ADM criteria at the Mackay outfall point, local streams fail the 15% ADM criteria ▪ i.e. GW diversions locally induce

leakage that exceeds 15% of the EBF (ecological baseflow)



Sustainability Assessment Conclusions

In summary, the analysis indicates that projected water use in the study area is broadly sustainable, from both a groundwater and surface water aspect, on a watershed scale.

This conclusion is supported by two findings: ▪ Results indicate that drawdowns do not, on a watershed scale, appear to grow over time

▪ Accumulated streamflow losses do not exceed the 15% ADM threshold along the main channel of the Mackay and Dover Rivers.

The results do indicate, however, that under the full build scenario, cumulative groundwater diversions appeared to create unsustainable local impacts, as measured by both the groundwater drawdown and ADM thresholds.



Water Budget Comparisons


-20

-15

-10

-5

0

5

10

15

20

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Flo

ws

(mm

/yr)

Simulated Inflows and Outflows by Water Year - Pre-Development Conditions


-20

-15

-10

-5

0

5

10

15

20

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Flo

ws

(mm

/yr)

Simulated Inflows and Outflows by Water Year - Full Build Conditions


Pre-development shows how wet and dry years replenish and deplete storage (royal blue)

Full build scenario shows greater fluctuations in storage


Water Budget Comparisons Winter pumping depletes storage, replenished by April recharge.


Full-Build Conditions Baseline Conditions


Other Insights

Winter pumping under frozen ground conditions depletes shallow aquifer storage

Baseflow discharge in May is reduced by 50% due to freshet replenishment of shallow aquifer storage.

Understanding seasonal and inter-annual storage is essential


0.0

1.0

2.0

3.0

4.0

5.0

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7.0

8.0

9.0

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Av

era

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Mo

nth

ly G

rou

nd

wa

ter

Dis

ch

arg

e t

o

Str

ea

ms

(m

m/y

ea

r)

Pre-Development

Full Build

Average Monthly GW Discharge to Streams


Overall Conclusions

56 - Recommendations for Phase 3

Detailed, fully integrated SW/GW modelling can provide significant insight into both cumulative effects and watershed function.

Numerous applications – Local impact assessment, water budgeting, climate change, drought assessment, eco-hydrology and water management.