Changes

:<math>% \text{ of reactive carbon} = \text{HI}_{\text{o}} / 1177 </math>

:<math>% \text{ of reactive carbon} = \text{HI}_{\text{o}} / 1177 </math>

For example, if the HI_o of Barnett Shale is estimated to be 434 mg HC/g TOC,<ref name=Jrv2007 /> then dividing by 1177 mg/g yields the percentage of reactive carbon in the immature shale; that is, 37% of the TOCo could be converted to petroleum. As substantiation for this calculation, immature Barnett Shale outcrops from Lampasas County, Texas, average 36% reactive carbon, although the range of values is 29 to 43%. Similarly, data from Montgomery et al. (2005) suggest a 36% loss in TOCo on laboratory maturation of low-maturity Barnett Shale cuttings from Brown County, Texas. Likewise, immature Bakken Shale contains 60% GOC as carbon in Rock-Eval measured oil contents (S1) and measured kerogen yields (S2), which is consistent with an HI_o of 700 (59.5%).

For example, if the HI_o of Barnett Shale is estimated to be 434 mg HC/g TOC,<ref name=Jrv2007 /> then dividing by 1177 mg/g yields the percentage of reactive carbon in the immature shale; that is, 37% of the TOCo could be converted to petroleum. As substantiation for this calculation, immature Barnett Shale outcrops from Lampasas County, Texas, average 36% reactive carbon, although the range of values is 29 to 43%. Similarly, data from Montgomery et al.<ref>Montgomery, S. L., D. M. Jarvie, K. A. Bowker, and R. M. Pollastro, 2005, [http://archives.datapages.com/data/bulletns/2005/02feb/0155/0155.HTM Mississippian Barnett Shale, Forth Worth Basin, north-central Texas: Gas-shale play with multi-tcf potential]: AAPG Bulletin, v. 89, no. 2, p. 155–175.</ref> suggest a 36% loss in TOCo on laboratory maturation of low-maturity Barnett Shale cuttings from Brown County, Texas. Likewise, immature Bakken Shale contains 60% GOC as carbon in Rock-Eval measured oil contents (S1) and measured kerogen yields (S2), which is consistent with an HI_o of 700 (59.5%).

This relationship for calculating the amount of GOC is true for any immature source rock once HI_o is determined or estimated. Using this relationship with HI_o probabilities, the range of original GOC and NGOC percentages for any HI_o can be determined. The values for GOC and NGOC for P90, P50, and P10 are also shown in Table 1. These values should not be considered mutually exclusive for a single source rock. Subdividing various organofacies within a source rock, if any, should be a common practice for calculating volumes of hydrocarbon generated with each organofacies having its own thickness, HI_o, and TOCo. Ideally, these organofacies differences should be mappable in an area of study.

This relationship for calculating the amount of GOC is true for any immature source rock once HI_o is determined or estimated. Using this relationship with HI_o probabilities, the range of original GOC and NGOC percentages for any HI_o can be determined. The values for GOC and NGOC for P90, P50, and P10 are also shown in Table 1. These values should not be considered mutually exclusive for a single source rock. Subdividing various organofacies within a source rock, if any, should be a common practice for calculating volumes of hydrocarbon generated with each organofacies having its own thickness, HI_o, and TOCo. Ideally, these organofacies differences should be mappable in an area of study.

Several companies including BP, Shell, ConocoPhillips, Newfield, and EOG Resources have signed deals to explore for shale resource systems in China, covering five different basins. In the Sichuan Basin, Late Ordovician and Early Silurian marine shales are being evaluated for their shale resource potential.<ref name=Li2010b /> The Upper Ordovician Wufeng and Lower Silurian Longmaxi shales average about 3.0% TOC, with thermal maturities from about 2.3 to 3.4% Ro being targeted.<ref name=Li2010b>Li, X., et al., 2010b, Upper Ordovician–Lower Silurian shale gas reservoirs in southern Sichuan Basin, China (abs.): Hedberg Research Conference on Shale Resource Plays, Austin, Texas, December 5–9, 2010, Book of Abstracts, p. 177–179.</ref> In the Junggar Basin, the Jurassic Badaowan Shale has TOC values from 2 to 8%, with thermal maturities from 0.60 to 2.0% Roe and is 50 to 80 m (164–262 ft) thick.<ref>Liu, H., H. Wang, R. Liu, Zhaoqun, and Y. Lin, 2009, Shale gas in China: New important role of energy in the 21st century: 2009 International Coalbed and Shale Gas Symposium, Tuscaloosa, Alabama, Paper 0922, 7 p.</ref> An excellent source potential also exists in the Upper Permian Lacaogou Formation (M. Burnaman, 2010, personal communication). The Triassic shales of the Ordos Basin and Jurassic shales of the Sichuan Basin are speculated to be shale-oil resource plays.<ref>Zou, C.-n., S.-z. Tao, X.-h. Gao, Y. Li, Z. Yang, Y.-j. Gong, D.-z. Dong, X.-j. Le, et al., 2010, [http://www.searchanddiscovery.net/abstracts/pdf/2010/annual/abstracts/ndx_caineng.pdf Basic contents, geological features and evaluation methods of continuous oil/gas plays in China]: AAPG Search and Discovery Article 90104, 7 p.</ref>

Several companies including BP, Shell, ConocoPhillips, Newfield, and EOG Resources have signed deals to explore for shale resource systems in China, covering five different basins. In the Sichuan Basin, Late Ordovician and Early Silurian marine shales are being evaluated for their shale resource potential.<ref name=Li2010b /> The Upper Ordovician Wufeng and Lower Silurian Longmaxi shales average about 3.0% TOC, with thermal maturities from about 2.3 to 3.4% Ro being targeted.<ref name=Li2010b>Li, X., et al., 2010b, Upper Ordovician–Lower Silurian shale gas reservoirs in southern Sichuan Basin, China (abs.): Hedberg Research Conference on Shale Resource Plays, Austin, Texas, December 5–9, 2010, Book of Abstracts, p. 177–179.</ref> In the Junggar Basin, the Jurassic Badaowan Shale has TOC values from 2 to 8%, with thermal maturities from 0.60 to 2.0% Roe and is 50 to 80 m (164–262 ft) thick.<ref>Liu, H., H. Wang, R. Liu, Zhaoqun, and Y. Lin, 2009, Shale gas in China: New important role of energy in the 21st century: 2009 International Coalbed and Shale Gas Symposium, Tuscaloosa, Alabama, Paper 0922, 7 p.</ref> An excellent source potential also exists in the Upper Permian Lacaogou Formation (M. Burnaman, 2010, personal communication). The Triassic shales of the Ordos Basin and Jurassic shales of the Sichuan Basin are speculated to be shale-oil resource plays.<ref>Zou, C.-n., S.-z. Tao, X.-h. Gao, Y. Li, Z. Yang, Y.-j. Gong, D.-z. Dong, X.-j. Le, et al., 2010, [http://www.searchanddiscovery.net/abstracts/pdf/2010/annual/abstracts/ndx_caineng.pdf Basic contents, geological features and evaluation methods of continuous oil/gas plays in China]: AAPG Search and Discovery Article 90104, 7 p.</ref>

The Oil and Natural Gas Corp. of India (ONGC) is drilling its first shale resource system in the Damodar Basin, with an objective of a Permian shale with a thickness of about 700 m (sim2300 ft) (Natural Gas for Europe, 2010).

The Oil and Natural Gas Corp. of India (ONGC) is drilling its first shale resource system in the Damodar Basin, with an objective of a Permian shale with a thickness of about 700 m (sim2300 ft).<ref>Natural Gas for Europe, 2010, [http://naturalgasforeurope.com/category/news-by-country/other-countries/india First shale gas well in India spudded].</ref>

In Australia, Beach Energy has announced plans to test the Permian section of the Cooper Basin for shale gas. This is likely the Permian Roseneath Shale, which is highly mature in the basin (see [[:File:M97FG8.jpg|Figure 8]]).

In Australia, Beach Energy has announced plans to test the Permian section of the Cooper Basin for shale gas. This is likely the Permian Roseneath Shale, which is highly mature in the basin (see [[:File:M97FG8.jpg|Figure 8]]).

Of course, nearby the United States, activity has been high in Canada, whereas only recently has activity been under way in Mexico's Burgos Basin.

Of course, nearby the United States, activity has been high in Canada, whereas only recently has activity been under way in Mexico's Burgos Basin.

The worldwide exploration effort for shale-gas resource plays will continue for years to come and will likely impact global energy resources in a very positive way. Although recent concerns over groundwater contamination are of extreme importance to all of us both outside and within industry, it should be noted that more than 40,000 shale-gas wells have been hydraulically stimulated and more than one million conventional wells (Montgomery and Smith, 2010). Hype often takes precedence over facts as indicated, for example, by recent cases involving groundwater wells in the Fort Worth Basin. The United States Environmetal Protection Agency cited recent drilling operations in the Barnett Shale as the cause of these groundwater wells, but this was not substantiated. Geochemical data conclusively proved that although gas existed in these water wells, the gas migrated from shallow gas-bearing reservoirs in the basin and not from drilling operations in the Barnett Shale itself (Railroad Commission of Texas, 2011). Although there is and should be concern over any groundwater contamination issues, most of which are the result of ongoing geologic processes, the track record from drilling all the shale-gas wells and such evidence as cited in the Railroad Commission of Texas (2011) hearing provide support for the safe drilling record of industry. Accidents will occur in all industries, and human endeavors and regulations assist in minimizing such unwanted results by all parties, including companies doing the exploration and production, because their livelihoods also depend on positive impact. Perhaps the biggest concern should be the rapid expansion of shale-gas drilling that has stressed the need for availability of a qualified and knowledgeable workforce. As such, management and the supervision of work and drilling crews become perhaps of equal importance as regulatory efforts to improve environmental safety based on new geologic and chemical information.

The worldwide exploration effort for shale-gas resource plays will continue for years to come and will likely impact global energy resources in a very positive way. Although recent concerns over groundwater contamination are of extreme importance to all of us both outside and within industry, it should be noted that more than 40,000 shale-gas wells have been hydraulically stimulated and more than one million conventional wells.<ref>Montgomery, C. T., and M. B. Smith, 2010, [http://www.jptonline.org/index.php?id=481 Hydraulic fracturing: History of an enduring technology].</ref> Hype often takes precedence over facts as indicated, for example, by recent cases involving groundwater wells in the Fort Worth Basin. The United States Environmetal Protection Agency cited recent drilling operations in the Barnett Shale as the cause of these groundwater wells, but this was not substantiated. Geochemical data conclusively proved that although gas existed in these water wells, the gas migrated from shallow gas-bearing reservoirs in the basin and not from drilling operations in the Barnett Shale itself (Railroad Commission of Texas, 2011). Although there is and should be concern over any groundwater contamination issues, most of which are the result of ongoing geologic processes, the track record from drilling all the shale-gas wells and such evidence as cited in the Railroad Commission of Texas (2011) hearing provide support for the safe drilling record of industry. Accidents will occur in all industries, and human endeavors and regulations assist in minimizing such unwanted results by all parties, including companies doing the exploration and production, because their livelihoods also depend on positive impact. Perhaps the biggest concern should be the rapid expansion of shale-gas drilling that has stressed the need for availability of a qualified and knowledgeable workforce. As such, management and the supervision of work and drilling crews become perhaps of equal importance as regulatory efforts to improve environmental safety based on new geologic and chemical information.

==Conclusions==

==Conclusions==

* Jones, R. W., 1984, Comparison of carbonate and shale source rocks, in J. Palacas, ed., Petroleum geochemistry and source rock potential of carbonate rocks: AAPG Studies in Geology 18, p. 163–180.

* Jones, R. W., 1984, Comparison of carbonate and shale source rocks, in J. Palacas, ed., Petroleum geochemistry and source rock potential of carbonate rocks: AAPG Studies in Geology 18, p. 163–180.

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* Peters, K. E., and M. R. Caasa, 1994, Applied source rock geochemistry, in L. B. Magoon and W. G. Dow, eds., The petroleum system: From source to trap: AAPG Memoir 60, p. 93–117.

* Peters, K. E., and M. R. Caasa, 1994, Applied source rock geochemistry, in L. B. Magoon and W. G. Dow, eds., The petroleum system: From source to trap: AAPG Memoir 60, p. 93–117.

* Railroad Commission of Texas, 2011, [http://www.rrc.state.tx.us/meetings/ogpfd/RangePFD.PDF&sa=U&ei=WIAQT9DPA6Xu0gGBxlC_Aw&ved=0CAcQFjAB&client=internal-uds-cse&usg=AFQjCNHn-_WOT9BMMdwJJalA1JclwbfUfw Texas Railroad Commission hearing, 2011, Docket No. 7B-0268629] - Commission called hearing to consider whether operation of the Range Production Company Butler unit well no. 1H (RRC No. 253732) and the Teal unit well no. 1H (RRC No. 253779), Newark, East (Barnett Shale) Field, Hood County, Texas, are causing or contributing to contamination of certain domestic water wells in Parker County, Texas, v. 1, 123 p.

* Railroad Commission of Texas, 2011, [http://www.rrc.state.tx.us/meetings/ogpfd/RangePFD.PDF&sa=U&ei=WIAQT9DPA6Xu0gGBxlC_Aw&ved=0CAcQFjAB&client=internal-uds-cse&usg=AFQjCNHn-_WOT9BMMdwJJalA1JclwbfUfw Texas Railroad Commission hearing, 2011, Docket No. 7B-0268629] - Commission called hearing to consider whether operation of the Range Production Company Butler unit well no. 1H (RRC No. 253732) and the Teal unit well no. 1H (RRC No. 253779), Newark, East (Barnett Shale) Field, Hood County, Texas, are causing or contributing to contamination of certain domestic water wells in Parker County, Texas, v. 1, 123 p.