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Utica shale gas-yulini

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  • 1. Shale Gas Resource Evaluation and Its Geochemistry Application Daniel Acker/GettyImage A Case Study of Utica Gas Shale in Quebec, Canada By : Yulini Arediningsih www.cleanBizAsia.com 1
  • 2. OutlineFast factsCharacteristics of gas shalesChallengesApplication of GeochemistryUtica Shale Gas System, Quebec, CanadaConclusions 2
  • 3. Fast Facts Due to its huge volume and very lowShale is the most common sedimentary rocks permeability, shale gas extraction processeshaving very low permeability. become complex requiring enormousGas shale plays triple functions as gas self- advanced stimulation techniques such asproducer, trap and storage, with lack of migration hydrofracturing, steam injection and etc. toShale gas becomes an alternative gas supply to improve their fracture system so they cansubstitute conventional gas whose production has flow at commercial rate.recently declined.Currently, Montney Fm. and Horn River Basin inWestern Canada have produced 1 Bcf of theirtotal 240 Tcf recoverable resource. Otherpotential gas shale plays i.e. Colorado Group(AB, SK), Utica Group (QC) and Horton BluffGroup (NB). 3 Source www.bbc.co.uk
  • 4. Characteristics of Gas ShalesLow matrix permeability < 0.01md, low matrix porosity<9%. To enable shale producing gas, favorable conditionsTypes of gas produced can be biogenic, thermogenic needed are :gas and mixed gas. High gas generation that are governed by : geochemical characteristics of the shale such asGas generated in shale is stored as : maturity, organic content, predominantly sorbed gas in organic fraction or kerogen; High gas preservation, that are controlled by free gas within micro (<2nm) to meso-sized(2- rock properties of the shale such as 50nm) pore spaces and shale fractures; large volume with sufficient thickness; and dissolved gas in formation water natural extensive natural or induced fracture pores and fractures of shale. permeability and porosity with sufficient gas saturation; lithological heterogeneity within the shale interval providing internal source – storage rock with good sealing Source : Bustin and Clarkson, 1998 4
  • 5. Application of GeochemistryWhat can be solved by applying Geochemistry studies : Characterization of shale source rocks including thermal maturity, source rock richnessand kerogen typing based on plots of TOC and data from Rock-Eval Pyrolysis analysis direct visual kerogen characterization vitrinite reflectance Sorption/desorption characteristics Geochemical modeling of hydrocarbon generation and preservation Gas play type (biogenic, thermogenic or mixed) Carbon isotopes analysis for maturity and gas potential 5
  • 6. ChallengesGIP estimation of shale gas resources is difficult mainly because of complex nature of gas storagebetween free gas and sorbed gas in nano to micro scale shale porosityMass balance calculation to estimate GIP needs careful considerationUnderstanding the geochemistry of stored gas will make better approach in estimating economic ofshale gas potentialPoor understanding on how organic geochemical characteristics (such as TOC, organic material,vitrinite content) controls gas adsorption/sorption capacity in the shale kerogenHowever we have better knowledge on vitrinite content and methane adsorption capacity showing positive correlation (Bustin and Clarkson, 1998) methane adsorption capacity can be controlled by increase in micro porosity due to thermal maturity (Levy et al, 2007) Shales with higher maturity, their maceral compositions tend to give a significant impact on methane adsorption capacity (Chalmers and Bustin, 2007). 6
  • 7. Utica Shale Gas Play, Quebec, CanadaSTATUS UPDATE :(Summarized from Lavoie et al (2011)) : Located in St. Lawrence Lowlands, southern of Quebec Exploration started in April 2008 so far 30 (Lavoie et al, 2011) wells have been drilled The main target : interval depth 1000-2000m of medium to deep thermogenic shale gas play (zone #2) calcareous and organic-rich Middle Ordovician Utica shale OGIP estimates : 120 -160 Bcf/section, overall giving significant Tcf amount of its total GIP accumulation. Factors of gas quality, the shale fracture network that can be hydrofractured, its strategic location and high gas demand have elevated the prospective status play to contingent resources/reserves. 7
  • 8. Utica Shale Gas Play, Quebec, CanadaGEOLOGY AND STRATIGRAPHY The Utica shales is typically calcareous and rich in organic materials deposited inmarine environment overlying the massive Trenton limestone during the Taconic Orogeny. Complex monoclinal and SW/NE trending normal fault system surrounding the potentialarea appears to have created favorable fracture network to ease hydro-fracturing process. 8
  • 9. Utica Shale Gas Play, Quebec, CanadaGEOCHEMISTRY STUDIES This good TR estimate may provide confidence in applying theSamples analysed are from low maturity Utica shales to provide mass-balance approach for the calculation of OGIP.an estimation of TOCoriginal for transformation ratio (TR) andkerogen type estimation (see next figure) Thermal maturity, measured in reflectometry-vitriniteequivalence (Ro eq.), varies between 1 and 4% from thenorthwest toward the southeast. TOCpresent day : 1 and 6% (samples from the south to northeastof the Utica shale play) suggesting a mature to dry natural gasand condensate type. Shales with TOC of 4 and 6% have a lower maturity level(between 0.5 to 1.0% Ro eq.) The Utica shales are type II based on data of maturity (%Ro)and HI TR is estimated to be 75% (1% TOCpresentday over 4% TOCoriginal) (Lavoie et al, 2011)signifying that large quantities of natural gas in the system havebeen generated from the kerogen. 9
  • 10. Utica Shale Gas Play, Quebec, CanadaGAS GEOCHEMISTRY Overall, gas type in the St. Lawrence Lowlands range fromlow maturity (wet) to high-maturity (dry) thermogenic gas. GC analysis of main target zone (medium to deepthermogenic play) contains gas with 95% methane. Towardshallower thermogenic zone located on the north shore of theSt. Lawrence River, the gas become less mature containinghigher ethane and propane. Data of ethane carbon isotopes and gas wetness from theUtica shale gas wells are plotted within a isotope rolloveranomaly zone as represented by data from the Barnett,Haynesville, and Marcellus prolific gas shales. This signifiespromising future potential of the Utica gas shale. The isotopic data from the Utica shale gas wells alsosuggest that : (Lavoie et al, 2011) all gas encountered is thermogenic generated from the same source rock, Indication of increasing maturity trend 10
  • 11. ConclusionsUnderstanding the geochemistry of stored gas will make better approach in estimating economicof shale gas potentialGIP estimation of shale gas resources is difficult mainly because of complex nature of gasstorage between free gas and sorbed gas in nano to micro scale shale porosityApplication of geochemical techniques and analyses such as kerogen typing (S2 vs TOC plot)and ethane isotopes, in the Utica Shale gas data provides positive contribution on understandingthe gas resources in the Utica Shale. The results suggest the shale contain a mature to drynatural gas and condensate type.More importantly, good estimate of TR value from TOCpresent day vs TOCoriginal data provideconfidence in applying the mass-balance approach for the calculation of OGIP. 11
  • 12. Cited ReferencesAllen, N., Aplin, A.C., Thomas, M., 2010, Organic geochemical controls on shale gas storage, a conference poster at www.ceg.ncl.ac.ukBustin, M. R., Bustin, A., Ross, D., Chalmers, G., Murthy, V., Laxmi, C., Cui, X., 2008. Shale Gas Opportunities and Challenges. Search and Discovery Articles #40382 (2009). Adapted from oral presentation at AAPG Annual Convention, San Antonio, Texas, April 20-23.Bustin, R.M. and Clarkson, C.R., 1998: "Geological Controls on Coalbed Methane Reservoir Capacity and Gas Content"; The International Journal of Coal Geology, V. 38, p.3-26.Bustin, A.M.M., Bustin, R.M. and Cui, X., 2008, Importance of fabric on the production of gas shales; Unconventional Gas Conference, Keystone, Colorado, February 10–12, 2008, Society of Petroleum Engineers, SPE 114167Bustin, R.M. 2005. Gas Shale Tapped for Big Pay. AAPG Explorer, February 2005Chalmers GLR and Bustin RM, 2007, The organic matter distribution and methane capacity of the Lower Cretaceous strata of Northeastern British Columbia, Canada, International Journal of Coal Geology, 70, 223-239 Shale Gas consortiumCurtis, J.B., 2002, Fractured shale-gas systems, AAPG Bulletin, v. 86, no. 11 (November 2002), pp. 1921–1938Kuuskraa V.A. and Stevens, S.H., 2009, Worldwide Gas Shales and Unconventional gas: A Status Report, Worldwide Gas Shales and Unconventional GasLavoie, J.Y. , Marcil, J.S., Dorrins, P.K., Lavoie, J., and Aguilera, R., 2011 Natural-Gas Potential in the St. Lawrence Lowlands of Québec: A Case Study, Journal of Canadian Petroleum Technology, p.72-82Levy JH., Day SJ., Killingley J.S, 1997, Methane capacities of Bowen Basin coals related to coal properties, Fuel, 76(9), 813- 819Passey, Q.R., Bohacs, K.M., Esch, W.L., Klimentidis, R., and Sinha, S, 2010, From Oil-Prone Source Rock to Gas-Producing Shale Reservoir – Geologic and PetrophysicalCharacterization of Unconventional Shale-Gas Reservoirs, SPE 131350Pittsburgh, C.B., Kieschnick, RSr., Lewis, R.E., Waters, G., 2006, Producing Gas from Its Source, Oilfield Review, Autumn, p.36-49http://www.neb.gc.ca/clf-nsi/rnrgynfmtn/nrgyrprt/ntrlgs/prmrndrstndngshlgs2009/prmrndrstndngshlgs2009nrgbrf-eng.htmlTalukdar, S.C, 2009, Application of Geochemistry for Shale Gas Assessment, Baseline Resolution, Weatherford 12