The Utica Shale and Gas Play in Southern Quebec: Geological and Hydrogeological Syntheses and Methodological Approaches to Groundwater Risk Evaluation

COGEL-02221; No of Pages 15 International Journal of Coal Geology xxx (2013) xxx–xxx

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International Journal of Coal Geology

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The Utica Shale and gas play in southern Quebec: Geological and hydrogeological syntheses and methodological approaches to groundwater risk evaluation

D. Lavoie a,⁎,C.Rivarda, R. Lefebvre b, S. Séjourné c,R.Thériaultd, M.J. Duchesne a, J.M.E. Ahad a,B.Wange, N. Benoit a, C. Lamontagne f a Natural Resources Canada, Geological Survey of Canada—Quebec Division, 490 de la Couronne, Quebec City, QC G1K 9A9, Canada b Institut National de la Recherche Scientiﬁque — Centre Eau Terre Environnement (INRS-ETE), 490 de la Couronne, Quebec City, QC G1K 9A9, Canada c Consulting Geologist, Montreal, QC, Canada d Géologie Quebec, Ministère des Ressources naturelles du Quebec (MRN), 880 Chemin Ste-Foy, Quebec City, QC G1S 4X4, Canada e Natural Resources Canada, Geological Survey of Canada—Northern Canada Division, 601 Booth Street, Ottawa, ON, Canada f Ministère du Développement durable, de l'Environnement, de la Faune et des Parc du Quebec (MDDEFP), 675 boulevard René Lévesque Est, Quebec, QC G1R 5V7, Canada article info abstract

Article history: The risk of groundwater contamination from shale gas exploration and development is a major societal concern, Received 11 June 2013 especially in populated areas where groundwater is an essential source of drinking water and for agricultural or Received in revised form 22 October 2013 industrial use. Since groundwater decontamination is difficult, or nearly impossible, it is essential to evaluate ex- Accepted 23 October 2013 ploration and production conditions that would prevent or at least minimize risks of groundwater contamina- Available online xxxx tion. The current consensus in recent literature is that these risks are primarily related to engineering issues, including casing integrity and surface activities, such as truck traffic(equipmentandfluid haulage), waste man- Keywords: Utica Shale agement (mainly drill cuttings), and water storage and treatment when hydraulic fracturing is utilized. Concerns Geology have also been raised with respect to groundwater contamination that could result from potential fracture or Geochemistry fault interconnections between the shale unit and surficial aquifers, which would allow fracturing fluids and Hydrogeology methane to reach the surface away from the wellbore. Despite the fact that groundwater resources are relatively Environmental study well characterized in some regions, there is currently no recognized method to evaluate the vulnerability or risks to aquifers resulting from hydrocarbon industry operations carried out at great depths. This paper focuses on the Utica Shale of the St. Lawrence Platform (Quebec), where an environmental study aiming to evaluate potential risks for aquifers related to shale gas development has been initiated. To provide the context of these research efforts, this paper describes the regional tectono-stratigraphic evolution and current stress regime of the Cambrian–Ordovician St. Lawrence Platform, as well as the Utica Shale internal stratigraphy, mineralogy and thermal maturation. Then, the hydrogeological context of the St. Lawrence Platform is discussed. Finally, the methodology for this environmental study, based on geological, geophysical, geomechanical, hydrogeological and geochemical data, is presented. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.

1. Introduction In areas where water is relatively abundant, such as in Quebec and many regions of Canada and the U.S., groundwater quality is probably Improved production techniques are unlocking huge volumes of one of the highest concerns related to shale gas development. Contam- natural gas from shale in North America. In 2000, shale gas represented ination risks, mainly linked to engineering issues, are primarily related only 2% of U.S. natural gas production; by 2012 it was over 40% and this to the casing integrity and surface activities (e.g. truck traffic, water percentage is expected to increase in the near future (Hughes, 2013). In storage) (Jackson et al., 2013; MIT, 2011; Osborn et al., 2011; The Canada, production is increasing rapidly in British Columbia and almost Royal Society, 2012; US EPA, 2011, 2012). Concerns have also been all provincial jurisdictions have shale targets currently being explored raised with respect to groundwater contamination that could result and evaluated with highly variable technical successes and issues. from potential fracture or fault interconnections between the frac- From multiple independent government and society estimates, Canada stimulated shale unit and surficial aquifers, which would allow fracking has an endowment of close to 5000 Tcf of in-place natural gas in shale and/or flowback fluids and methane to reach the surface away from the (ERCB/AGS, 2012; Hayes and Ferri, 2013; Heffernan and Dawson, 2010). wellbore. Although groundwater resources are relatively well characterized in a few regions (see Rivard et al., 2013,thisissue),thereis currently no recognized method to evaluate the vulnerability or risks ⁎ Corresponding author. +1 418 654 2571. to aquifers resulting from hydrocarbon exploration/exploitation activi- E-mail address: [email protected] (D. Lavoie). ties carried out at great depths. There are also worries about long-

Fig. 1. Simpliﬁed geological map of southern Quebec with the Cambrian–Ordovician St. Lawrence Platform between the Precambrian Grenville basement and the Cambrian–Devonian Appalachians. Logan's Line marks the limit between the platform and the Appalachians whereas the platform is either in fault contact or unconformably overlying the Grenvillian basement. The map shows the location of oil and gas wells drilled in southern Quebec. The cross-section is on Fig. 3. Stratigraphic legend is for St. Lawrence Platform units. Modiﬁed from Thériault (2012a).

of foreland basin limestone and argillaceous limestone comprises the Chazy, Black River and Trenton groups. The Trenton Group is overlain by the calcareous black mudstone of the Utica Shale. The Utica Shale is a diachronous unit, older approaching the Appalachian front, as in the Quebec City vicinity (Corynoides americanus–Orthogratus ruedemanni to the Climacograptus spiniferus graptolite zones) and younger to the southwest on the Laurentian platform, as in the Montreal region (Climacograptus pygmaeus graptolite zone). Diachronous east to west progression of subsidence was coincident with the progressive westward change from carbonate to siliciclastic sedimentation within the foreland basin, also documented elsewhere along the Appalachian Orogen (Ettensohn, 2008). The thickness of the Utica Shale ranges between 30 and 300 m, while the facies- and time-equivalent Stony Point Formation in southernmost Quebec can be as thick as 750 m. The Utica Shale unit is distinguished from younger siliciclastic facies by its higher calcite content, fine-grained limestone beds and lack of siltstone and sandstone suggesting that it was deposited prior to the influx of coarser sediments coming from the erosion of the advancing Appalachian thrust sheets. The uppermost preserved succession consists of Upper Ordovician sediments that accumulated during and after the overthrusting of the external Taconian thrust sheets. The flysch unit is dominated by thick successions of mudstones with subordinate alternating sandstone and siltstone of the Lorraine Group that consists of two formations: the Pontgravé Formation is coarser grained and more calcareous compared to the underlying Nicolet Formation. The Lorraine Group is the thickest (up to 3800 m; Globensky et al., 1993) and the most exposed unit of the St. Lawrence Platform. The Lorraine Group generally lies conformably over the Utica Shale (Globensky, 1987). The Queenston Group is found at the top of the preserved sedimentary pile. It comprises one formation (Bécancour Formation) that consists of post-orogenic shale, sandstone and conglomerate (Globensky, 1987). The only occurrence of post- Ordovician sediments deposited on the St. Lawrence Platform is found in the Montreal area where a small outcrop of a diatreme breccia exposes fragments of the entire Cambrian–Ordovician succession with the addition of Middle Devonian limestones (Globensky, 1987). Fi- nally, in Cretaceous times, silica-depleted–nepheline-rich plutons and lamprophyre dykes intruded the St. Lawrence Platform (Globensky, 1987; Rocher et al., 2003). Differential erosion has brought these intrusions at surface, which now form the Monteregian Hills of southern Quebec.

Fig. 2. Stratigraphic framework of the St. Lawrence Platform in southern Quebec. Upper 2.2.2. Structural framework Cambrian to Upper Ordovician clastics and carbonates were deposited under evolving In southern Quebec, most exposed strata of the St. Lawrence Plat- tectonic scenarios. The Upper Ordovician Utica Shale was deposited during the Taconian form are sub-horizontal, but are locally affected by mesoscopic open foreland shelf episode. No vertical scale. Modified from Lavoie (2008). folding or locally by drag folds neighboring faults. Major structural features include regional low angle thrust faults as well as normal faults bounding half grabens, and broad open folds related to the Chambly- subarkose gradually passing upward to nearshore shallow marine Fortierville Syncline (Fig. 1), the latter having been traditionally associ- quartz arenite (Lavoie, 2008). ated with the last increments of the Taconian Orogeny. Reprocessing A significant unconformity developed at the Cambrian–Ordovician and reinterpretation of regional deep seismic lines in southern Quebec boundary and was followed, in Early Ordovician times, by a eustatic have documented compressive deformation, including triangle zones sea level rise leading to the formation of a continental passive margin and blind thrusts, west of the previously assumed Appalachian structur- (Lavoie et al., 2012). In southern Quebec, the passive margin succession al front (Logan's Line, Figs. 8 and 10; Castonguay et al., 2006, 2010). is recorded by intertidal to shallow subtidal limestones and dolostones Other recent studies also advocate for a more complex structural evolu- of the Beekmantown Group, deposited in response to high-frequency tion than previously thought, including: 1) Middle Ordovician normal sea level fluctuations (Salad Hersi, 2012). The Lower Ordovician faulting that results in the formation of sags affecting the foreland Beekmantown Group is truncated by an unconformity, documented in basin carbonates prior to the deposition of the fine-grained, organic- many parts of North America (Jacobi, 1981; Lavoie et al., 2012). This un- rich Utica Shale on top of the foundering carbonate platform conformity marks the onset of the foreland basin along the Laurentian (Thériault, 2007); 2) Late Ordovician compressive deformation associ- margin. ated with the Taconian Orogeny; 3) post-Ordovician (probably ‘Acadi- Along the active foreland margin, the Lower Ordovician carbonate an’) folding (Pinet et al., 2008) and faulting (Sasseville et al., 2008). platform succession was covered by an initially slow to ultimately The Yamaska Fault is one of the many basin-parallel extensional rapid deepening-upward succession of limestone to argillaceous lime- faults that cuts through the basement–platform succession and, based stone to black organic-rich mudstone and capped by shallowing- on available seismic data, seems to die out in the overlying flysch upward flysch and post-orogenic molasse (Lavoie, 2008). The succession (Castonguay et al., 2010; Séjourné et al., 2013). This fault was active in

Fig. 3. Structural cross-section based on limited field outcrops, oil and gas well data and MRN deep seismic line M-2002 (modified from Castonguay et al, 2006, 2010). The Utica Shale is progressively thicker and deeper from NW to SE and is also remobilized and imbricated in thrust stacks beneath the St. Lawrence Platform and the Appalachians. Location of cross-section on Fig. 1. Cross-section modified from Séjourné et al. (2013).

Table 1 Average mineralogical composition of the Trenton Group, Utica Shale (lower and upper units, sensu Thériault, 2012b) and Lorraine Group. Feldspars are total potassic and sodic feldspars and clays are total illite, chlorite and kaolinite. Modiﬁed from Thériault (2012b).

Unit Quartz % Feldspars % Calcite % Dolomite % Clays %

Lorraine 27.1 10.1 8.0 6.5 46.4 Upper Utica 13.8 4.9 53.4 6.4 20.2 Lower Utica 11.3 4.4 52.5 4.7 25.8 Trenton 7.4 2.3 71.3 4.1 13.6

St. Lawrence Platform. Both wells show an upward decrease in calcite content coupled with an upward increase in clay content, from the top of the Trenton to the top of the lower unit of the Utica Shale. From the base to the middle part of the Utica Shale upper unit, the trend is inverted with a gradual increase in calcite and a decrease in clay. Finally, the initial trend of decreasing calcite with increasing clay contents characterizes the uppermost Utica succession to the lower part of the Lorraine Group (Thériault, 2012b).

3.4. Organic geochemistry

The Utica Shale has been considered as an excellent source rock for conventional hydrocarbon exploration in southern Quebec (Lavoie et al., 2009). Lavoie et al. (2011) and Thériault (2012b) have released over 2300 Rock-Eval (II and VI) analyses from 88 wells and few outcrops of Utica Shale and Lorraine Group. The data are presented on maps for the lower and upper informal units of the Utica Shale, as well as for theLorraineGroupinThériault (2012b); most pertinent information is presented below. Fig. 4. A) The Utica Shale along the Jacques Cartier River, 50 km southwest of Quebec City on the north shore of the St. Lawrence River. B) Close-up view of the river cliff showing prominent limy mudstone beds forming a 3 m thick thickening upward interval. Exposed 3.4.1. Thermal maturation vertical view is 7 m. Various thermal maturation indicators (Tmax, organic matter reflec- tance, transformation ratio or production index) indicate that the Utica Shale is a mature succession with a southwesterly maturation increase from oil window–condensate zone in the Quebec City area to the 3.2. Structural framework of the Utica Shale in Quebec dry gas zone (Fig. 7). A southeasterly trend is also documented with an increase of thermal conditions from condensate and dry gas north of the There are few structural studies specific to the Utica Shale. From a St. Lawrence River towards dry gas and overmature to the southeast. detailed high resolution satellite (QuickBird) images and field surveys, Pinet (2011) documented a complex fracture framework along the 3.4.2. Total organic carbon (TOC) low-tide north shore of the St. Lawrence River southwest of Quebec Based on TOC values from Rock-Eval analyses, the two units of the City. Two generations of folds, superimposed over the regional Utica Shale may be recognized with the upper Utica having a general Chambly-Fortierville syncline, are recognized. Faults trend N100°– higher mean TOC value (Thériault, 2012b). However, for both units, N120° or N30°–N60°; however their precise kinematic is unknown. Fracture orientations are fairly scattered, but NE and WNW sets dominate.

3.3. Mineralogy

The ﬁrst systematic work on the mineralogical composition of the Utica Shale is from Thériault (2012b). Nearly 300 X-ray diffraction analyses were carried out on Trenton Group, Utica Shale and lower Lorraine Group cuttings from 18 wells. The average mineralogical values of the Trenton, Utica (lower and upper), and Lorraine groups are shown in Table 1 (Thériault, 2012b). The Utica Shale samples are rich in calcite whereas the Lorraine shales are calcite-poor, clay-rich with higher percentages of quartz and feld- spar compared to the Utica Shale. Fig. 5 shows the progressive mineralogical transitions between the Trenton Group and the lower Utica Shale and between the upper Utica Shale and the overlying Lorraine Group. The progressive upsection changes in the mineralogical composition of the Trenton–Utica–Lorrainesuccessionareshownfortwowells Fig. 5. Evolution of calcite versus clays ratios for the Trenton Group to the Lorraine Group. (Fig. 6): the A069 well is located west of the Yamaska Fault, whereas A general trend of progressively decreasing calcite content with associated increasing the A162 well is situated east of the latter (Thériault, 2012b). The min- clays content is noted. eralogical trends shown here are almost ubiquitous for all wells in the Modiﬁed from Thériault (2012a).

Fig. 6. Detailed vertical mineral trends for the Trenton (TR) to the Lorraine (LO) groups for two wells. Calcite content decreases from the Trenton Group to a minimum near the top of the lower Utica Shale (LOW UT), calcite content rapidly increases up to the middle part of the upper Utica Shale (UP UT) and then decreases significantly to minimal values at the base of the Lorraine Group. Clays as well as quartz + feldspars content trends inversely to that of the calcite. Modified from Thériault (2012a). the highest TOC values (about 1% and 2% for the lower and upper altered domains, the Utica Shale consists of Type II organic matter units, respectively) are commonly located in the northeast area (vicinity (Thériault, 2012b), an interpretation supported by organic petrography of Quebec City) with some high values in the north–central zone (Trois- (Bertrand, 1991). Rivières area) (Fig. 8). This pattern is compatible with the thermal zona- tion of the Utica, with higher thermal conditions associated with lower 3.5. Exploration focus residual organic matter in the rock. Higher TOC values (2.0%) are located west of the Yamaska fault and correlate with lower thermal maturation Thériault (2012a) has proposed three exploration fairways for the (Fig. 7). Utica Shale in southern Quebec (Fig. 9). These fairways, which are based on the depth of the Utica Shale as well as on structural domains, 3.4.3. Hydrogen index (HI) and oxygen index (OI) were proposed following detailed re-examination and reinterpretation HI and OI values are commonly used as a proxy for the nature of the of well logs, drilling reports and seismic lines (Thériault, 2012a). The organic matter: hydrogen-rich/oxygen-poor organic matter (e.g., algal- first fairway consists of the shallow domain of the Utica Shale and and bacteria-derived lipids) is identified as Type I organic matter and occurs north and northwest of the Yamaska Fault, where the Utica is hydrogen-poor/oxygen-rich organic matter (e.g., plant-derived lignin) found between 0 and 800 m in depth. The second exploration fairway is designated as Type III organic matter. Type II is an intermediate type occurs between the Yamaska Fault to the northwest and Logan's Line commonly associated with marine microorganisms. All three types of to the southwest; in this area, the Utica Shale is between 1200 and organic matter have different potentials to release oil or natural gas. 2500 m in depth. Finally, the third fairway is located east of Logan's Similar to TOC content, increases in thermal conditions will affect the Line where the Utica Shale occurs in thrust slices and also most likely HI value, as hydrogen is rapidly consumed by the production of hydro- deeper in the autochthonous platform. Geoscientific knowledge on the carbons. Based on residual HI and OI values in the least thermally Utica Shale is highly variable with the shallow and central fairways

Fig. 7. Map of the production index (PI) for the upper Utica Shale. Production index is a proxy for thermal maturation as it indicates the degree of transformation of organic matter into hydrocarbons. PI lower than 0.4 indicates liquids window. Increases of PI from NE to SW and from NW to SE are noted. The area west of the Yamaska Fault is the thermally least mature domain. The NW to SE increase is related to deeper burial of the Utica. Modified from Thériault (2012a). having a significantly better well coverage compared to the easternmost, Elevation of the St. Lawrence Lowlands is generally below 60 m a.s.l. thrust-dominated fairway (Séjourné et al., 2013; Thériault, 2012a,b). in this area (except for the Monteregian Hills) and the topography is Shale gas exploration in the Utica Shale began in 2006 in southern relatively flat. There are several important rivers, such as (from west Quebec. A total of 18 vertical wells and 11 horizontal wells have been to east, on the south shore of the St. Lawrence River) the Richelieu, drilled (Fig. 9), and 18 hydraulic fracturations have been performed Yamaska, St-François, Nicolet, Bécancour, and Chaudière that are all until 2010. So far, most of the exploration has focused primarily on tributaries of the St. Lawrence River. Twenty-two watersheds are totally the central fairway, where 24 of the 29 shale gas wells have been or partly included within the zone of shale gas potential (the main ones drilled; the shallow and thrust fairways have been little explored are presented in Fig. 10). The climate of this region is humid continental (3 and 1 wells, respectively). Based on a limited number of hydraulic with mean annual precipitation ranging from 950 to 1150 mm/y, of fracturations, initial production (IP) values were highly variable, as which ~20% falls as snow. Mean annual temperatures vary between one would expect in a new basin. The best IP value for a horizontal 4.4 °C and 6.8 °C and the coldest (January) and warmest (July) months well was 11 mmscf/d of natural gas (in the northeastern area of the have mean temperatures of −9to−12 °C and 19 to 21 °C, respectively central fairway), whereas in the less mature domain (in the immediate (Carrier et al., 2013; Environment Canada, 2013). In the area covered by vicinity of Quebec City), limited production of light oil and condensates theMontérégieEstproject(Carrier et al., 2013), it was estimated that were encountered during testing of a vertical well. about 20% of the population is supplied by groundwater, but that 58% of municipalities with a population lower than 5000 use groundwater. Furthermore, groundwater supplies all residential needs outside of 4. Hydrogeological context of the St. Lawrence Platform areas covered by water supply systems.

4.1. Physiography and climate 4.2. Distribution and nature of unconsolidated sediments The area of prospective shale gas resources extends on both sides of the St. Lawrence River, from Quebec City to Montreal. The main region The stratigraphy and architecture of the unconsolidated sedimenta- of interest, the central fairway (#2, see Fig. 9), lies on the south shore, ry cover of the St. Lawrence Platform are complex, mainly due to in the St. Lawrence Lowlands overlying the deep (1200 to 2500 m) multiple glaciation/deglaciation cycles (Lamothe, 1989; Occhietti et al., St. Lawrence Platform successions. The area of the fairway is widest 1996). While a nearly continuous till sheet covers most of the lowlands, (about 150 km) in the southwest part and becomes much narrower it is the marine and lacustrine units respectively overlying and underly- northeastward near Quebec City. ing this till that complicate the regional stratigraphic framework.

Fig. 8. Map of the total organic carbon (TOC) content for the upper Utica Shale. Higher TOC values (around 2%) are found in the area west of the Yamaska Fault and correlate with lower thermal maturation. The lowest TOC values are found in the relatively low thermal maturity Montreal area, which suggests lower level of original organic matter content for that speciﬁc part of the depositional basin. Modiﬁed from Thériault (2012a).

Champlain Sea (11 200 to 9800 years BP) sediments are ubiquitous in of these projects were completed in 2013: the Montérégie Est the lowlands; the silt and clay cover being particularly thick (N15 m) (~9000 km2) and Bécancour (~3000 km2) projects, overlying the west- and continuous in a central triangular zone extending north of the ern and central parts of the shale gas potential area. Fieldwork in PACES Monteregian Hills with its apex near Trois-Rivières. Elsewhere, the projects typically includes: geophysical surveys, drilling and soundings, fine-grained marine unit is generally discontinuous and significantly groundwater sampling, hydraulic testing, and implementation of mon- thinner. To the west, near the Canadian Shield, the marine sediment itoring wells that are later integrated into the provincial monitoring net- cover also includes large and thick sandy deltaic bodies deposited at work, after the project's completion. Project deliverables include: the mouth of rivers entering the Champlain Sea as well as discontinuous bedrock and surficial geology maps, surficial sediment thickness, piezo- patches of offlap sands deposited during marine regression. In the metric and vulnerability maps (DRASTIC index), description and charac- central triangular region, the total mean thickness of unconsolidated teristics of hydrogeological contexts, recharge and groundwater quality sediments is about 30 m but observed thickness locally exceeds 80 m. assessments, and conceptual models (Carrier et al., 2013; Larocque The regional till is locally underlain by discontinuous remnant bod- et al., 2013). From these studies, valuable information about hydraulic ies of mainly glaciolacustrine silty clay sediments and alluvial sands. properties and the hydrodynamics within the St. Lawrence Platform Buried peat, a potential biogenic source of methane, can also be locally area was obtained. observed under the marine sediments. These were emplaced during The regional aquifer consists of fractured rock of low to moderate glacial–deglacial events that predate the last (Late Wisconsinan) (~10−5–10−6 m/s) hydraulic conductivity. Characteristically, wells in regional glacial cycle and occur mainly in the Trois-Rivières region. A the rock aquifer yield enough water to supply single family dwellings 1:100 000 scale map of the surficial geology of the St. Lawrence and, in a few areas, small- to medium-size municipalities. According Lowlands is currently in preparation (Parent and Rivard, 2013). to Carrier et al. (2013), residential wells in fractured rock are typically 15 cm in diameter (6 in), cased through surficial sediments and open 4.3. Bedrock hydraulic properties, fracturing and hydrodynamics in the section drilled through fractured rock, with a total depth less than 50 m for 75% of such wells. Municipal wells in fractured rock typ- Séjourné et al. (2013) described hydrogeological work that has been ically are 15 to 20 cm in diameter and drilled at depths of 70 to 100 m carried out in the St. Lawrence Platform since the 60s. Several water- (Carrier et al., 2013). The limited depth of wells in fractured rock reflects sheds overlying the Utica Shale are currently being studied within the the rapidly decreasing density of fractures (and hydraulic conductivity) framework of the Programme d'Acquisition de Connaissances sur les with depth below the fractured rock aquifer subcrop (Ladeveze et al., Eaux Souterraines (PACES Program) in Quebec (#1 to 5 in Fig. 10)and 2013). Bedrock aquifers are under either confined or semi-confined this hydrogeological characterization will be completed in 2015. Two conditions. Medium- to high-yield aquifers are mainly found in

Fig. 9. Simplified geological map of southern Quebec with the location of the 27 shale gas wells drilled between 2007 and 2012 (wells 1 and 2 have been drilled in 2006 and targeted conventional reservoirs beneath the shale). The map shows the three exploration fairways as proposed by Thériault (2012a). The fairways are limited by the Yamaska Fault and Logan's Line and are based on depth of the Utica and tectonic context. Legend as on Fig. 1. Modified from Thériault (2012a). coarse-grained surficial sediments, such as glaciofluvial or fluvial sedi- with depth, most fractures being encountered in the first 15 to 35 m. ments, which have limited lateral extents. Residential wells are rarely Most of the fractures and discontinuities observed through wellbore installed in surficial sediments, but municipal wells are. Again, accord- televiewer in wells transecting units of the St. Lawrence Platform ing to Carrier et al. (2013), municipal wells in granular aquifers typically were not water-bearing (Carrier et al., 2013; Crow et al., 2013). are 15 to 24 cm in diameter but have a limited saturated thickness be- In the Montérégie Est study, results of hydraulic properties have tween 15 and 20 m. The regional fractured rock aquifer recharge varies shown that spatial variations of hydraulic conductivities (K) of the var- between nearly zero (below the clay and silt units) to moderate ious geological formations are not statistically significant, but rather (through till), but can locally be quite high (through coarse-grained vary with depth within the fractured rock aquifer (Laurencelle et al., sediments). Discharge zones mainly correspond to streams, where the 2013). The interpretation of pumping tests also suggested equivalent clay is thin or absent, and along the Appalachian foothills (Carrier porous media behavior. Typical yields are b1L/s(Carrier et al., 2013; et al., 2013). Groundwater depth is very shallow, being typically in the McCormack and Therrien, in press) and large pumping rates can seldom order of 0–6m(3–4 m on average). be obtained. Municipal wells completed in the fractured rock aquifer of In the Montérégie Est project, bedrock wells were investigated with this area have an average yield of 3.8 L/s, with a maximum of 12.7 L/s, borehole geophysics, mainly using acoustic televiewer images (Crow while municipal wells completed within unconsolidated sediments et al., 2013). Studied wells penetrated bedrock from 14 to 135 m can reach 19.0 L/s (Carrier et al., 2013). below surface, but most penetrated bedrock units for less than 20 m. As the target area (fairway #2, Fig. 9) falls between the Logan Line This penetration corresponds to the average bedrock thickness of and the Yamaska Fault, some concerns exist about fluid migration wells available in the provincial database for the St. Lawrence Platform. paths along regional- and local-scale faults and associated fractures. Al- Twelve of the logged wells were located over the St. Lawrence Platform, though secondary calcareous and silica cements may have considerably the others were located in the Appalachians and Monteregian Hills. As a reduced their permeability, the existence of permeable pathways complement, outcrops were also studied, mainly in quarries. Results in these fractured zones cannot be disregarded. As concluded by showed that the orientation of surficial permeable fracture networks, Berkowitz (2012), groundwater flow can be controlled by only a few at least in the Montérégie Est area, is in agreement with brittle struc- deep fractures that may be difficult to identify. A concern thus arises tures that developed during the Taconian Orogeny (Lavoie et al., from the use of hydraulic fracturation techniques nearby to these 2009). In a limited number of shallow wells, two fracture sets were geological features, with a possible reactivation of these pre-existing identified: a dominant set of sub-horizontal fractures (dip varying be- discontinuities or connection with pre-existing fracture networks tween 0 and 22°) with a mean varying between NNE–SSW and N–S (Konstantinovskaya et al., 2012; Séjourné et al., 2013). Structural strike and a secondary, nearly orthogonal vertical set (Ladeveze et al., discontinuities in the St. Lawrence Platform essentially consist in 2013). Results also showed that fracture density decreases rapidly Lower Paleozoic normal faults, NE–SW fractures and fractures induced

Fig. 10. Location map of oil and gas shows in overburden and bedrock in the St. Lawrence Lowlands. Reported gas shows in water wells may come either from the overburden or the underlying bedrock aquifer. Delineations of completed and current hydrogeological characterization projects are also shown. Logan's Line separates the St. Lawrence Platform from the Appalachians. Modiﬁed from Séjourné et al., 2013.

from intrusions of Cretaceous mafic dykes (including Monteregian In the Montérégie Est area, groundwater quality varied from non- Hills). Both 2D and 3D deep seismic surveys, typically used by the indus- potable to fair and to acceptable, mainly due to its salinity (brackish try, allow the identification of major faults, but fail to identify conven- water) in the northwestern part, but also locally due to several other pa- tional sub-seismic resolution features, hence the need to combine the rameters and elements exceeding potable limits or esthetical criteria, seismic interpretation to other analytical techniques such as regional including Cl, Ba, F, Fe, Mn, hardness, sulfides, and total dissolved solids structural analysis and borehole imagery, in order to develop a robust (TDS) (Beaudry et al., 2011). In the Bécancour area, a 10 km wide structural model integrating data from different sources and scales zone along the St. Lawrence River also contains brackish water; (Séjourné et al., 2013). upstream from this area, groundwater is usually of good quality and only a few samples exceeded potable water limits for Ba and F. Similar 4.4. Groundwater quality to the Montérégie Est area, issues mainly concern esthetic criteria (namely Fe, Mn, hardness and TDS) (Larocque et al., 2013). Groundwater sampling for the Montérégie Est and Bécancour pro- The presence of dissolved gases in groundwater in the St. Lawrence jects allowed the collection of 237 and 112 well samples, respectively, Platform area has been reported since the 1950s (Séjourné et al., 2013), typically from 20 to 50 m deep (mainly residential wells). Both major most probably sourced from the underlying organic-matter rich rock and minor ions were analyzed, and isotopic analyses (δ2Handδ18O, intervals of the Utica Shale, thinner intervals of the Lorraine Group 3Hand14C) were performed on a subset. Dissolved gas was also and buried Quaternary peat. However, the nature and source of the sampled within the scope of a project funded by the Strategic Environ- gas (biogenic or thermogenic) were not investigated (Séjourné et al., mental Assessment (SEA) committee created by the Ministère du 2013). Clark (1955, 1964a,b,c) compiled nearly 600 occurrences of Développement Durable, de l'Environnement et des Parcs du Quebec dissolved gas in water wells of the western part of the St. Lawrence (MDDEFP) to assess environmental issues related to shale gas develop- Platform (5600 km2). Other data were compiled by the Ministère des ment. Pinti et al. (2013) sampled 130 wells for analyses of dissolved gas Ressources Naturelles du Quebec (water-well reports and database for in groundwater over a 14 000 km2 study area covering the St. Lawrence oil and gas wells, in Séjourné et al., 2013). Platform and the Appalachian foreland, south of the St. Lawrence River. The spatial distribution of known presence of dissolved gas in They concluded that the majority of the methane found in groundwater groundwater for parts of the St. Lawrence Lowlands is presented in had a biogenic origin. Only 18 wells (14%) had a methane concentration Fig. 10. There are no reported analyses characterizing the gas nature larger than 7 mg/L, which is considered an alert threshold by the or source in this database. In the absence of geochemical analyses, it is MDDEFP. not possible to constrain the actual depth from which thermogenic

Please cite this article as: Lavoie, D., et al., The Utica Shale and gas play in southern Quebec: Geological and hydrogeological syntheses and methodological approaches to groundwater risk evaluation, Int. J. Coal Geol. (2013), http://dx.doi.org/10.1016/j.coal.2013.10.011 D. Lavoie et al. / International Journal of Coal Geology xxx (2013) xxx–xxx 11 gas could originate. Although a migration from the Utica Shale through a understand the hydrogeological system behavior. This project also natural fracture network cannot be ruled out, the abundance of natural greatly benefits from the knowledge acquired on the St. Lawrence Plat- gas documented in all geological formations from the top of the Utica form of current and completed PACES and GSC projects (Rivard et al., Shale to the surface tends to suggest a shallow source for the gas accu- this issue). In order to collect additional information that will allow mulated at the bedrock/overburden contact (Séjourné et al., 2013). A the investigation of potential preferential pathways, four thematic similar situation is documented in Pennsylvania by Molofsky et al. studies were developed: geophysical, geomechanical, geochemical and (2013) where shallow gas bearing shale units are the source of dis- hydrogeological studies. A vulnerability assessment will ultimately solved thermogenic methane in groundwater. Based on the study of integrate all acquired information. St-Antoine and Héroux (1993) on isotopes (δ13Candδ2H) and nature Fig. 11 provides an overview of the work that will be carried out in of gas (presence or absence of C2+ compounds) in small gas accumula- each of the thematic studies. Work related to these studies is also indi- tions in unconsolidated sediments, it was concluded that, in the Trois- vidually presented in the following sections. It must be understood, Rivières area, both biogenic and thermogenic gases are present. Near- however, that they all interact between each other and benefitfrom surface seismic surveys in the Montérégie Est area have also provided one another. For example, near-surface seismic surveys will help identi- evidence of escaping fluids within surficial sediments (Pugin and fy structural discontinuities and potential fluid escape pathways, but Pullan, 2011; Pugin et al., 2013). also the selection of well locations to be drilled for soil and water A preliminary 2D groundwater flow and transport model of the bed- sampling. rock was also constructed for the Montérégie Est area, in which the model is based on a homogeneous horizontal, though anisotropic verti- 5.1. Geophysical study cal, hydraulic property and simplified boundary conditions (Carrier et al., 2013; Laurencelle et al., 2013). The modeled cross-section is The integration of a suite of new and existing geophysical data will 80 km long and 2000 m deep, extends from the Appalachian and ends provide accurate imaging of the geological structures at different scales in the St. Lawrence Platform. This aquifer system is not chemically in and depths. The dataset will include: 1) legacy petroleum exploration equilibrium with current conditions, as for example, the 2200 km2 seismic reflection data to image major structures such as faults and zone of brackish groundwater, downstream of the Richelieu and fold; 2) high-resolution shallow seismic reflection data to provide sub- Yamaska rivers (Beaudry et al., 2011). A modeling exercise was per- surface imaging of the upper 1000 m to complement deep hydrocarbon formed to explore the evolution of its dynamics since the last glacial exploration seismic data, in order to better image geometrical relation- maximum and better understand its actual state. This model and the ships between the different units and identify near-surface fault sys- geochemical results also suggest that discharging groundwater is usual- tems; 3) an airborne transient electromagnetic (TEM) survey to more ly a mixture of water from different ages and thus, of different geochem- accurately define the vertical extension of the faults in the shallow sub- ical evolutions (Carrier et al., 2013; Laurencelle et al., 2013). surface and map the depth to the top of the saline aquifer; 4) a shallow 3-component Vertical Seismic Profile (VSP) in a ~200 m-deep well to 5. Methodology for a local-scale study on potential upward determine the attenuation parameters of the near surface low-velocity fluid migration zone; 5) high-resolution cross-well seismic tomography in two ~200 m-deep wells to provide insights regarding the distribution Hydrogeological and geochemical properties of the Utica Shale and and orientation of fracture networks and the spatial relationships be- overlying Lower Paleozoic succession, as well as the extent, permeabil- tween different sets of fractures; and 6) interpretation of borehole geo- ity, and connectivity of discontinuities (faults, fractures, dykes) are physics data from both a deep (existing) petroleum well and shallow poorly known in the St. Lawrence Lowlands (Séjourné et al., 2013). water wells to characterize geological characteristics, such as informa- Knowledge of these characteristics is crucial to study potential upward tion on ductility, bedding and lithological characters, as well as fracture migration. To this end, the Geological Survey of Canada, in collaboration frequency, orientation and dip. with the Institut National de la Recherche Scientifique (INRS), the The integration of these geophysical tools, in particular deep and Ministère du Développement durable, de l'Environnement et des Parcs near-surface geophysical and borehole surveys, will provide informa- du Quebec, and Environment Canada has initiated in 2012, a 4-year tion on plausible open fracture pathways. High-resolution seismic project to assess the occurrence of preferential pathways (fractures or surveys may also provide fluid escape locations in surficial deposits. faults) that might link the deep-seated targeted shale to surficial aquifers. In this contribution, we describe the methodology used to evaluate 5.2. Geomechanical study geological and hydrogeological backgrounds as well as potential environmental impacts in the area surrounding a specificsitewhereahori- An increasing number of studies that address the geomechanical be- zontal shale gas well was completed and fracked. The selected drilling havior of a shale gas reservoir and its overlying layers (including cap- site for the study is the most productive well drilled for shale gas in rock and surficial aquifers) in the context of shale gas development southern Quebec (Talisman Energy, St-Édouard HZ No. 1a, Fig. 9). The are now available in the literature (Abousleiman et al., 2007; Britt and 30-day production testing resulted in a stabilized gas flow rate of circa Schoeffler, 2009; Brodylo et al., 2011; Du et al., 2009). Field observations 0.17 million m3/d (6 MMscf/d); such high volume indicates that the of ground deformation associated with fluid injection were reported at multistage fracking of the well was very successful. various sites, mainly for CO2 storage, oil sands and other fluid injection A400km2 study area was selected for this study because fluid applications (Goodarzi et al., 2012; Hawkes and McLellan, 2005; Khan migration must be studied at the local scale with detailed data, due to et al., 2011; Morris et al., 2011; Rutquist, 2012, 2011; Shukla et al., both specific pathways that water and gas may take and physical pro- 2010, 2011). Nonetheless, fluid injection for shale gas extraction is cesses that control fluxes. This area is small enough so that transport different from those other applications in terms of duration, intensity can be modeled and large enough to include major documented struc- and spatial extent. tural discontinuities. The current Quebec Government moratorium on The geomechanical study focuses on numerical modeling to investi- fracking offers an ideal opportunity to carry out such a project prior to gate ground deformation and stress changes in response to shale gas shale gas development. exploration/exploitation and hence, its effects on hydraulic conductivity The regional geological context is quite well known, from the recent and groundwater flow. Specifically, geomechanical models of the Utica syntheses of Lavoie et al. (2009), Konstantinovskaya et al. (2012), Shale will be constrained by major geological features, e.g., faults and Thériault (2012a,b) and Séjourné et al. (2013). Reports and databases major rock units. The model results will be further used to feed into for water wells and gas and oil wells are being examined to better the hydrological model for groundwater flow studies. Because of certain

Fig. 11. Schematic chart of planned research activities for each sub-study. limitations of commercial software, our own methodologies for the un- results will also help us identify water types, recharge and discharge conventional shale gas applications are being developed. In particular, zones and estimate residence time. In addition to groundwater new numerical algorithms capable of simulating discontinuous rocks sampling, soil sampling is planned at several sites in order to better are being developed that overcome the shortcomings of commercial characterize subsurface gas dynamics and transport processes. For this computer codes. While the development is still at its early stage, en- purpose, methane, CO2 and radon concentrations will be measured. couraging results with 2D cross-section with a discrete element soft- Where possible, existing data from industry and consultants reports, ware have been obtained from preliminary modeling (Wang, 2013). as well as from provincial databases will be used in combination with Core samples will be tested for mechanical properties in a laboratory data collected during this study. for estimating their effective porosity, permeability and ductility (so as to validate the Poisson's ratio and Young's modulus estimated from 5.4. Hydrogeological study borehole geophysics) at a given confinement pressure provided by available data. Such parameters will help refining the geomechanical The hydrogeological study firstaimsatintegratingalltheinfor- models. mation and data generated from the first three studies. New hydrogeological data will also be acquired using the observation wells. 5.3. Geochemical study This will form the basis for the development of a numerical model used to assess the potential for fluid flow (gas and water) to migrate The groundwater chemical study aims to characterize sources of dis- from the targeted gas shale formation to surficial aquifers. The goal is solved natural gas components and other naturally occurring constitu- to verify if, from a groundwater resources protection point of view, a ents. This step is critical to understanding the potential risks to safe development of shale gas resources can be achieved. aquifers in areas that may undergo shale gas development. A baseline New observation wells will be drilled around the shale gas well and chemical study should be carried out prior to shale gas development where faults (or fractured zones) will have been identified using geo- so that aquifer background chemical “fingerprints” can be put in context physical surveys. The observation wells will be drilled at variable depths to any potential future disturbances caused by anthropogenic activities. (between 50 and 200 m or to the fresh/saline interface). Their location Concentrations of the principal natural gas constituents (methane, will be determined so as to obtain a uniform spatial distribution cover- ethane and propane) and volatile organic compounds (VOCs) in water ing various geological formations, considering existing sampled private samples will be determined. Natural abundance of stable carbon water wells. In each newly drilled observation well, borehole geophys- (δ13C) and hydrogen (δ2H) isotope ratios of methane will be used in ics will first be carried out. Then hydraulic testing (e.g. slug tests) and conjunction with concentration ratios of methane to higher-chain hy- sampling in different sections of the wells will be conducted, based on drocarbons to evaluate sources of methane in the subsurface. In order information obtained from geophysical logging (only the most perme- to discriminate recent from geologically older groundwater, natural able intervals will be tested and sampled). Core samples from newly abundance of radiocarbon (14C) and tritium will also be measured on drilled observation wells will undergo a suite of laboratory analyses, in- selected samples. The sources of extractable organic acids containing cluding uni- and tri-axial tests, and permeability tests as well as X-ray naphthenic acids in groundwater samples will also be evaluated fluorescence (XRF) analyses. Families of near-surface fractures at the (Ahad et al., 2012). Although the levels of these compounds in forma- local scale will be compared to the regional picture. This information tion and flowback waters may be low, their characterization could pro- on fracturing, in combination with lineament investigation using vide a unique tool to distinguish between natural background and Lidar, near-surface seismic surveys and spatial distribution of soil and anthropogenic contamination (Ahad et al., 2012, 2013). Complete water geochemical results, may provide indications of preferential geochemical analyses, including minor and major ions, physicochemical fluid migration pathways (e.g. along structural discontinuities). parameters, traces inorganic elements such as alkalinity, metals, nutri- A conceptual hydrogeological model will first be developed based on ents and sulfur, will also be carried out on all samples. available information and understanding of the system hydrodynamics. Both monitoring wells drilled for the project and residential wells Several conceptual models may have to be considered if not enough ev- will be sampled, likely 3–4 times annually for two years to evaluate idence of pathways can be found. Development of equiprobable fracture the impact of seasonal variation on groundwater geochemistry. These networks using a stochastic model is considered. However, a simpler

Please cite this article as: Lavoie, D., et al., The Utica Shale and gas play in southern Quebec: Geological and hydrogeological syntheses and methodological approaches to groundwater risk evaluation, Int. J. Coal Geol. (2013), http://dx.doi.org/10.1016/j.coal.2013.10.011 D. Lavoie et al. / International Journal of Coal Geology xxx (2013) xxx–xxx 13 model using anisotropic hydraulic conductivities may also be consid- shale gas production and zones where it might be necessary to modify ered if not enough information is available on deep fracture networks. industry's current practices in order to minimize impacts or risks to Groundwater flow numerical simulations will then be carried out groundwater resources. This study will be carried out at the local using first a 2D model to simulate flow along a streamline from a topo- scale, at the location of an industry exploration site, so as to provide graphic high in the Appalachians towards the St. Lawrence River. If the an example of risk assessment related to the shale gas industry in regard 2D model shows that deep regional groundwater flow is significant, to real geological constraints of a given region. The developed method- simulations could also integrate results of a fracking operation, using ology could serve as a basis for the development of a regulatory frame- permeability changes provided by the geomechanical study, to investi- work for exploration permits within the context of responsible energy gate the impact of fracking on the groundwater flow regime, especially development and should be applicable to other sites in Canada and immediately after the hydraulic fracturing when new flow paths have elsewhere. been opened up and the formation is at the highest pressure. Reactiva- tion of existing structural discontinuities and connectivity with induced Acknowledgments fractures will be investigated, based on core analysis results and in conjunction with the geomechanical modeling study. Afterwards, a local 3D The first author is indebted to various colleagues who shared their numerical hydrogeological model comprising the study area and its knowledge on the Utica Shale over the years, in particular thanks to close surroundings will be developed, using results of the 2D model to Dr. Tony Hamblin (GSC—Calgary), Dr Langhorne “Taury” Smith and define boundary conditions. Groundwater flow and transport simula- Dr. John Martin both from the New York State Museum and Dr. Nicolas tions will be run using the different generated scenarios. Geochemical Pinet (GSC—Quebec). The authors would also like to thank Dr. Michel analyses from newly drilled and residential wells will help constrain Parent from the GSC—Quebec for his review of the Quaternary geology these scenarios using conventional groundwater geochemistry, ground- part and Dr. Sébastien Castonguay (GSC—Quebec) for his thorough water isotopic data (including residence time indicators) and concen- and careful review of the original manuscript. The manuscript benefited trations of light natural gases and their inferred origins based on their from suggestions and comments from an anonymous reviewer and isotopic signature. those of Dr. Daniel Soeder, co-editor of this special issue of the Interna- tional Journal of Coal Geology. 5.5. Vulnerability and risk assessment study References Finally, a vulnerability and risk assessment study will also be carried out, which will use the understanding acquired from the first four sub- Abousleiman, Y., Tran, M., Hoang, S., Bobko, C., Ortega, A., 2007. Geomechanics field and studies. Because shale gas development depends on many factors laboratory characterization of the Woodford Shale: the next gas play. SPE Annual Technical Conference and Exhibition, 11–14 November 2007, Anaheim, California, (mainly geological, economical, environmental and societal) and in- U.S.A. http://dx.doi.org/10.2118/110120-MS (14 pp.). volves several decision steps from governmental authorities, risk as- Ahad, J.M.E., Pakdel, H., Savard, M.M., Simard, M.-C., Smirnoff, A., 2012. Extraction, sepa- sessment models and uncertainty estimations represent very useful ration and intramolecular carbon isotope characterization of Athabasca oil sands acids in environmental samples. Anal. Chem. 84, 10419–10425. tools. Ahad, J.M.E., Pakdel, H., Savard, M.M., Calderhead, A.I., Gammon, P.R., Rivera, A., Headley, The current project will adapt the approach presented by Cushman J.V., Peru, K.M., 2013. Characterization and quantification of mining-related ‘naph- et al. (2001), on environmental risk assessment, to potential surficial thenic acids’ in groundwater near a major oil sands tailings pond. Environ. Sci. Technol. 47, 5023–5030. aquifers in relation to shale gas activities, as a tool for decision making. Allen, J.S., Thomas, T.A., Lavoie, D., 2009. Stratigraphy and structure of the Laurentian These decisions could include the site location according to the geolog- rifted margin in the northern Appalachians: a low-angle detachment rift system. Ge- ical context and surface activities, approvals for deep injection of ology 37, 335–338. fl fl Baird, G.C., Brett, C.E., 2002. Indian Castle Shale: late synorogenic siliciclastic succession in owback uids and enforcing the implementation of special measures an evolving Middle to Upper Ordovician foreland basin, eastern New York State. Phys. to avoid explosion risks if methane is found near the surface. This Chem. Earth 27, 203–230. approach will include 1) the identification of contaminants and risk Beaudry, C., Malet, X., Lefebvre, R., et Rivard, C., 2011. Délimitation des eaux souterraines of gas explosion, 2) the identification of preferential pathways from saumâtres en Montérégie Est, Québec, Canada. Commission géologique du Canada, Dossier public 6960. http://dx.doi.org/10.4095/289123 (26 pp.). the shale gas target to the surface (that will be available from Berkowitz, B., 2012. Characterizing flow and transport in fractured geological media: A re- the hydrogeological study), 3) probability assessment of future risks, view. Adv. Water Resour. 25 (8–12), 861–884. given that more work would be performed in the area, and 4) identifica- Bertrand, R., 1991. Maturation thermique des roches mères dans les bassins des basses- terres du Saint-Laurent et dans quelques buttes témoins au sud-est du Bouclier tion of areas and locations of most concerns. Results from this study will canadien. Int. J. Coal Geol. 19, 359–383. provide scientific information that will be useful for assessing the Britt, L.K., Schoeffler, J., 2009. The geomechanics of a shale play: what makes a shale pro- potential risks associated with shale gas extraction, and for developing spective. SPE Eastern Regional Meeting, 23–25 September 2009, Charleston, West Virginia, USA http://dx.doi.org/10.2118/125525-MS (9 pp.). robust environmental regulations to protect groundwater supplies. Brodylo, J., Chatelier, J.Y., Matton, G., Rheault, M., 2011. The stability of fault systems, in the south shore of the St. Lawrence Lowlands of Québec — implications for shale 6. Conclusion gas development. Proceedings of the Canadian Unconventional Resources Confer- ence, Calgary, 15–17 Nov. 2011, CSUG/SPE 149307 (19 pp.). Carrier, M.-A., Lefebvre, R., Rivard, C., Parent, M., Ballard, J.-M., Benoit, N., Vigneault, H., The currently publicly available compilation maps and cross- Beaudry, C., Malet, X., Laurencelle, M., Gosselin, J.-S., Ladevèze, P., Thériault, R., sections provide a modern understanding of geological parameters of Beaudin, I., Michaud, A., Pugin, A., Morin, R., Crow, H., Gloaguen, E., Bleser, J., Martin, A., Lavoie, D., 2013. Portrait des ressources en eau souterraine en Montérégie the Utica Shale and their regional variations, including stress regime Est, Québec, Canada. Final report INRS R-1412. and structural framework, regional thickness, depth, mineralogy, TOC, Castonguay, S., Dietrich, J., Shinduke, R., Laliberté, J.-Y., 2006. Nouveau regard sur HI and maturation variations (from condensate to dry gas zones) l'architecture de la plate-forme du Saint-Laurent et des Appalaches du sud du Québec fi fl upon which our detailed work will rely. A methodology has been de- par le retraitement des pro ls de sismique ré exion M-2001, M-2002 et M-2003. Geological Survey of Canada, Open File 5328. scribed, that is currently being developed to evaluate the presence or Castonguay, S., Dietrich, J., Lavoie, D., Laliberté, J.-Y., 2010. Structure and petroleum plays absence of preferential pathways (fractures or faults) linking the of the St. Lawrence Platform and Appalachians in southern Quebec: insights from in- fl – fracked shale interval and the surficial aquifer. This study will be carried terpretation of MRNQ seismic re ection data. Bull. Can. Petrol. Geol. 58, 219 234. Clark, T.H., 1955. Région de St-Jean-Beloeil. SIGEOM, Rapport RG, 66 (92 pp.). out using existing hydrogeological, geological, and industry data, Clark, T.H., 1964a. La région de Saint-Hyacinthe (moitié ouest). 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