May 2013 - Rocky Mountain Association of Geologists

More documents

Recommendations

Info

Lead StoryContinued from page 13Front Range between Loveland, CO and the Wyomingborder were plotted (Fig. 3a). To more clearly portraythe difference between thrust- and strike-slip-dominatedlocalities, bubble maps of percent strike-slip faults wereplotted (Fig. 3b), with low % strike slip fault localities(high % thrust faults) shown asgreen bubbles, high % strike-slipfault localities as red bubbles,and more equal proportions ofstrike-slip and thrust faulting asyellow bubbles. This bubble mapclearly defines 2 wide strike-slipcorridors. One is centered on theLivermore embayment, whoseNE-striking high-angle faultswere proposed to have dextralstrike-slip motion by Erslev andHoldaway (1999), Larson (2008)and Tetreault (2008) on the basisof fracture orientation deflections,paleomagnetic pole rotations, and3D structural restorations. Still,until this GIS analysis, we did notsuspect that the zone of pervasivestrike-slip shear extended beyondthe exposures of the major strikeslipfaults. In addition, this analysisalso shows that the area around theplunging Milner Mountain anticlinewest of Loveland is also a shear zone of dominantlystrike-slip minor faulting.The existence of strike-slip corridors and transferzones in the Rockies, long advocated by Stone (1969)and others, may have important implications to naturalfractures in resource plays. For instance, areas dominatedby low-angle thrust faulting may lack large subverticalminor faults that create permeability conduits betweenunits. This can be a good thing if bounding units containwater, but it can be a bad thing when well economics andfracture stimulation require communication betweenvertically-adjacent units.The existence ofstrike-slip corridorsand transfer zonesin the Rockies,long advocated byStone (1969) andothers, may haveimportant implicationsto natural fracturesin resource plays.ConclusionsThe NioFracture compilation unifies diverse publicdomain fracture data into one comprehensive database,aiding predictions of unconventional reservoir fracturepermeability. Initial results show a remarkable uniformityof Laramide fractures indicatingENE-WSW compression despitemajor differences in the trendsof major structures. Zones wheremajor structures are oblique toregional compression typicallyare dominated by strike-slip minorfaults and ENE-striking joints.Post-Laramide E-W to NE-SWextension has locally createdoverprinting fracture sets roughlyorthogonal to Laramide fractures.Thus, if an exploration effortwants to drill perpendicular tothe major open fracture set, itis critically important to knowthe age of the area’s dominantfractures. Based on the regionalpatterns shown by the NioFractureGIS initiative, horizontal drillingtargeting Laramide joints andminor strike-slip faults legs shouldbe roughly NNW-SSE. If mostreservoir permeability is createdby NW-SE post-Laramide jointing and normal faulting,NE-SW horizontal drilling may be more ideal. Theseregional patterns are complicated by local fracturemechanisms, which the NioFracture initiative is currentlyinvestigating.For information on access to the NioFracturedatabase, please contact Eric Erslev at eerslev@uwyo.edu.ReferencesErslev, E.A., and Holdaway, S.M., 1999, Laramide faulting andtectonics of the northeastern Front Range of Colorado, inLageson, D.R., Lester, A.P., and Trudgill, B.D., eds., Coloradoand adjacent areas: Boulder, Colorado, Geological Society ofVol. 62, No. 514May 2013
Lead StoryAmerica Field Guide 1, p. 41-49.Erslev, E.A., and Koenig, N.B., 2009, 3D kinematicsof Laramide, basement-involved Rocky Mountaindeformation, U.S.A.: Insights from minor faults andGIS-enhanced structure maps, in Kay, S., Ramos, V.,and Dickinson, W.R., eds., Backbone of the Americas:Shallow Subduction, Plateau Uplift and Ridge andTerrane Collision: GSA Memoir 204, p. 125-150.Holdaway, S.M., 1998, Laramide deformation of thenortheastern Front Range, Colorado: evidence fordeep crustal wedging during horizontal compression:Unpublished M.S. thesis: Fort Collins, Colorado StateUniversity, 146 p.Kennedy, L.E., 2011, Laramide transpression and blockrotation followed by northeast-southwest extension,southeast Wind River Basin area: Unpublished M.S.thesis, Laramie, University of Wyoming, 98 p.Kennedy, L., Erslev, E., and Aydinian, K., 2012, Mapping RockyMountain fractures: GIS methods for resource plays: AAPGAbstracts with Programs, 2012 Rocky Mountain SectionMeeting, Grand Junction, CO.Larson, S., 2008, Laramide transpression and oblique thrusting inthe northeastern Front Range, Colorado: 3D kinematics of theConnect with RMAG Online!You can nowconnect tothe RMAGon Linkedin,Twitter, andFacebook.AVAILABLE:Access to extensive geological/geophysical data filesaccumulated over 50 years of oil and gas exploration in theRocky Mountain province and containing numerousundeveloped and/or untested prospects is available undernegotiated consultation and assistance agreement. Call oremail for particulars.CONTACT: 303-797-6308 don@dsstone.comLivermore Embayment: Unpublished M.S. thesis, Fort Collins,Colorado State University, 420 p.Stone, D.S., 1969, Wrench faulting and Rocky Mountain tectonics:Mountain Geologist, v. 6, p. 67-79.Tetreault, J., Jones, C.H., Erslev, E., Hudson, M., and Larson, S., 2008,Paleomagnetic and structural evidence for oblique slip folding,Grayback Monocline, Colorado: Geological Society of AmericaBulletin, v. 120, p. 877-892.»CONNECT WITH US ON LINKEDIN!LIKE US ON FACEBOOK!FOLLOW US ON TWITTER!OUTCROP15www.rmag.org
Page 1 and 2: OUTCROPNewsletter of the Rocky Moun
Page 3 and 4: OUTCROPThe Rocky Mountain Associati
Page 7 and 8: 12-14 AUGUST 2013COLORADO CONVENTIO
Page 9: LEAD STORYNioFracture Initiative at
Page 17: RMAG and PTTCPresentJune Short Cour
Page 20 and 21: THANK YOU TO 2012 RMAGFOUNDATION DO
Page 22 and 23: PetroFecta ® from Fluid Inclusion
Page 24 and 25: New MembersWelcome to New RMAG Memb
Page 26 and 27: QualityMulti-client DataVol. 62, No
Page 28 and 29: GetMorefromyourCoreWith reservoirs
Page 30 and 31: Petroleum Systems Modeling —State
Page 32 and 33: RMAG Monthly Luncheon Program - May
Page 34 and 35: Dinosaur Ridge Boy Scout DayBy Greg
Page 36 and 37: THANK YOU to Vince MatthewsBy Laura
Page 38 and 39: Submit a Manuscript to The Mountain
Page 40 and 41: ALLOutcrop Adsare in Color atNo Ext
Page 42 and 43: August58,2013attheCSM:Risk,Uncertai
Page 44: Advertisers IndexAAPG..............

May 2013 - Rocky Mountain Association of Geologists

Create successful ePaper yourself

Delete template?

Save as template?