Hydrochemical Assessment of The Francisco Castrillon-Munoz, MSc., P.Geol. Senior Hydrogeologist Worley Parsons

“Thinks are not always what they seem…” MACBETH W. Shakespeare

12 April 2012 Background and Objectives

Regional Hydrochemistry Overview

Local Devonian Hydrochemistry

Hydrochemical Conceptual and Numerical Model

Conclusions

2 17-Apr-12 Background

Devonian Keg River Formation:

proposed as disposal zone for process wastewater originating from in- situ project

historically used as a wastewater disposal zone

regional chemistry indicates water saline (>4000 mg/L)

local water samples (i.e., swabbed or pumped) returned TDS less than 4000mg/L TDS (DW13-04, 16-21, DW 09-03, DW 04-22)

3 17-Apr-12 Objectives

Review existing data & reliability (i.e., geology, hydrogeology and hydrochemistry regional and local)

Determine natural salinity of Keg River Formation beneath the Lease

Provide an explanation for the presence of water in the Keg River Formation that does not appear to be native

4 17-Apr-12 Local Stratigraphic Sequence

Quaternary S&G Channels Clearwater Fm

Cretaceous McMurray Fm.

McMurray Basal Sands

Upper Devonian Waterways Fm.

Watt Mountain Fm. Slave Point Middle and Fort Vermillion Lower Devonian Keg River Fm. Target Zone

Contact Rapids Fm. Point Elk

Paleozoic Granite Wash Fm. Precambrian Granite Paleogeography of the Keg River Formation

• Interpretation based on Keg River isochore, well logs, cores, and seismic data • Present day depositional thicknesses affected post-depositional dissolution/brecciation • Laterally equivalent carbonate build up and progressive/intermittent evaporite basin/sub-basins • Dissolution of laterally equivalent evaporites possibly encouraged late stage brecciation and significant thickness reduction

6 17-Apr-12 Source: Client Geoscience Group Regional Hydrochemistry Overview

River

Athabasca River

``

River N

GRAPH SCALE 1.0 TOWNSHIP

Fort McMurray Regional Hydrochemistry Overview

HYDROCHEMICAL 8 17-Apr-12 SEPARATION Local Hydrochemistry Overview

Groundwater Chemistry Data

Wastewater Pilot Injection

RAMP Database Local Sampling Events

• Three Quaternary Wells • Three McMurray Basal Wells • 13 Devonian Wells standing • Eight Devonian Wells sampled

Note: Some Devonian wells not sampled due to reduced formation flows Devonian Intervals Sampled and Wastewater Disposal Wells

Total Injection = 1.7 Mm3 (1983 to 1992)

Interpreted zones of injection influence

Pilot injection well Hydrochemical Groups of Local Devonian Water

Pilot Devonian Wells

Quaternary, McMurray Basal wells HYDROCHEMICAL and RAMP SEPARATION Surface water Hydrochemical Groups of the Lease

TDS<4000

Native Devonian Formation Water

Pilot

HYDROCHEMICAL SEPARATION Mixing of waters Mineralogy of Devonian Formations* Represented predominantly by:

•Calcite •Dolomite •Halite

Devonian formations deposited in meso-saline (calcite / dolomite) to hypersaline (halite) environment

Gypsum (possibly anhydrite) were also precipitated

Presence of trace bitumen staining within vugs noted in some cores

Authigenic source of organics suspected

*Source: Client Geoscience Group

14 17-Apr-12 Water Speciation Saturation Indices Calcite 2 Aragonite 1 Dolomite

0 Strontianite

-1 Gypsum

-2 Anhydrite

-3 Aqueous Silica Halite

Saturation Index Saturation -4

-5

-6 0 1000 2000 3000 4000 5000 Saturation Indices Total Dissolved Solids (mg/L) Calcite 2 Aragonite 1 Dolomite

0 Strontianite

-1 Gypsum

-2 Anhydrite Aqueous -3 Silica Saturation Index Saturation Halite -4

-5 4000 5000 6000 7000 8000 Total Dissolved Solids (mg/L) Hydrochemical Processes

Pilot

Mixing

Calcite dissolution or precipitation: 2+ - CaCO3 + CO2 + H2O ↔ Ca + 2HCO3

Dolomite dissolution or precipitation: 2 2+ 2+ 2- CaMg(CO3) ↔ Ca + Mg + 2CO3 Hydrochemical Processes Gypsum dissolution: 2+ 2- CaSO4(2H2O) + H2O↔ Ca + SO4 + 3H2O

Sulphate reduction: 2- - 2CH2O + SO4 → 2HCO3 + H2S

Pilot

Mixing Hydrochemical Processes

Sulphate reduction: 2- - 2CH2O + SO4 → 2HCO3 + H2S

Pilot Hydrochemical Processes

Strontianite dissolution: 2+ 2- SrCO3 → Sr + CO3

Pilot

Mixing Hydrochemical Processes

Pilot

Mixing Halite dissolution: NaCl → Na+ + Cl- Hydrochemical Conceptual Model

2+ - Calcite dissolution and precipitation: CaCO3 + CO2 + H2O ↔ Ca + 2HCO3

2 2+ 2+ 2- Dolomite dissolution and precipitation: CaMg(CO3) ↔ Ca + Mg + 2CO3

2- Main Hydrochemical Gypsum dissolution: CaSO4(2H2O) + H2O↔ Ca2+ + SO4 + 3H2O

Sulphate reduction: 2CH O + SO 2- → 2HCO - + H S Processes 2 4 3 2

2+ 2- Strontianite dissolution: SrCO3 → Sr + CO3

Halite dissolution: NaCl → Na+ + Cl-

Wastewater Injection well Sampling wells

Quaternary Deposits Ca-Mg-HCO3 Type Shallower System Clearwater Fm. Aquitard

McMurray Fm. Aquitard

Waterways Fm. Hydraulic Barrier

Mixing Na-HCO 3 water Middle and Lower Devonian Type Na-Cl Formations (Mainly Lower System Keg River) Type Hydrochemical Numerical Model

Initial water (2 samples) + “Reactant Phases”  Final water (target well) + “Product Phases” NETPATH Hydrochemical Modelling (Plummer et al 1994)

Table A Chemical Input for NETPATH Model 1 and 2

Well Wastewater Model 1 Model 2 Well name –TDS/pH (NETPATH Database No.) DW 1-16- (19) 3245-(81) Well 16-21- (82) Well 13-4 (17)

Initial water Water Initial water 1 2 Final water 1 Final water 2

Temp (oC) 7 7 7 7

pH 7.72 8.1 7.54 8.05

Ca 407 10 333 102

Mg 196 1 144 45.5

Na 2320 80 694 488

K 16 6 14 13.9

Cl 4060 23 1520 759

SO4 as SO4 580 20 235 26.6

Alk/TDIC 342+ 181* 708* 479*

Fe 0.22 0.2 0.71 0.1

F 1.92 ND 1.78 2.35

Sr 8.96 ND (0.18)** 3.77 2.86

H2S(aq) as S 0.0 ND ND 74

+ - : Field Alk as CaCO3; * : Field Alk as HCO3 ; ** only considered in Model 2 . Concentration as milligrams per litre. NETPATH Hydrochemical Modelling Results

Model 1 (Devonian Native Water + Wastewater = Well 16-21)

NETPATH Hydrochemical Modeling Results

Model 2 (Devonian Native Water + Wastewater = Well 13-4)

Conclusions

• Two distinctive hydrochemical groups observed in the Keg River Formation

• Chemical equilibrium models and mixing models indicate:

• Higher TDS water observed beneath the Lease represents natural Keg River Formation

• Lower TDS water observed beneath the Lease represents mixing with previously injected wastewater