Fracture Analysis in the Outcrops of the Qara Chauq Anticlines, Zagros Fold and Thrust Belt of Kurdistan Region in Northern Iraq

  • Abdullah Awdal Department of Natural Resources Engineering and Management, School of Science and Engineering, University of Kurdistan Hewlêr, Erbil, Kurdistan Region, Iraq
Keywords: Fracture, Fault, Qara Chauq, Zagros, Kurdistan, Iraq


The Zagros Fold and Thrust belt is one of the world's most prolific petroleum provinces. Most hydrocarbon reserves are stored in naturally fractured reservoirs and such fracture systems can therefore have a significant impact on reservoir performance. Fractures are one of the most important paths for fluid flow in carbonate reservoirs. Fracture data were collected in the outcrops of the Kirkuk Group of Oligocene age around Qara Chauq South and Qara Chauq North anticlines located near the Kirkuk Oil Field. The studied formations outcropping in the Qara Chauq are the main reservoir units in the Kirkuk and Bai Hassan fields. In Kirkuk and surrounding fields, hydrocarbon production comes mainly from primary porosity with assistance from secondary porosity created by dolomitization, karstification, dissolution, vugs and fractures. Fracture attributes collected from outcrops are fracture orientation, density and length. The results show that fractures in the studied reservoir formation are not uniformly distributed due to massive lithologic nature and lack of well bedding. Furthermore, fracture orientations show a clear relationship to the local fold axis in the outcrops. NW-SE fracture set is perpendicular to the NW-SE fold axis. However, some fractures do not show any relation to the local folding. These fractures may have formed in a pre-folding or post folding stage. Other fracture orientations exhibit a symmetrical relation to the maximum horizontal stress direction. The comparative analysis of outcrop data underlines the importance of representative analogue data for reservoir modelling and production strategies.


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Author Biography

Abdullah Awdal, Department of Natural Resources Engineering and Management, School of Science and Engineering, University of Kurdistan Hewlêr, Erbil, Kurdistan Region, Iraq

Dr Abdullah Awdal received his PhD degree in Geology from the University of Aberdeen in the United Kingdom. He also holds a MSc in Petroleum Geoscience from the University of Bergen in Norway, and a BSc in Geology from Salahaddin University-Erbil.

Dr Awdal is a Petroleum Geologist with over 17 years of experience in the oil and gas industry and academia. He has been actively involved in a variety of exploration projects both onshore and offshore in the Middle East, Europe and North America. His research in the field of Petroleum Geoscience has resulted in a number of published articles in peer-reviewed journals.


Agosta, F. (2008). Fluid flow properties of basin-bounding normal faults in platform carbonates, Fucino Basin, central Italy. In: Wibberley, C.A.J., Kurz, W., Imber, J., Holdsworth, R.E., Collettini, C. (Eds.). The Internal Structure of Fault Zones: Implications for Mechanical and Fluid-flow Properties, 299, 277-291.
Ahmadhadi, F., Daniel, J.-M., Azzizadeh, M. & Lacombe, O. (2008). Evidence for prefolding vein development in the oligo-miocene asmari formation in the Central zagros fold Belt, Iran. Tectonics, 27(1). DOI:
Antonellini, M. & Mollema, P.N. (2000). A natural Analog for a fractured and Faulted reservoir in dolomite: triassic Sella group, northern Italy. AAPG Bull, 84, 314-344.
Awdal, A.H., Braathen, A., Wennberg, O.P. & Sherwani, G.H. (2013). The characteristics of fracture networks in the Shiranish formation of the Bina Bawi Anticline; comparison with the Taq Taq Field, Zagros, Kurdistan, NE Iraq. Petroleum Geoscience, 19, 139-155.
Awdal, A.H., Healy, D. & Alsop, G.I. (2016). Fracture patterns and petrophysical properties of carbonates undergoing regional folding: a case study from Kurdistan, N Iraq. Marine and Petroleum Geology, 71, 149-167.
Aydin, A. (2000). Fractures, faults, and hydrocarbon entrapment, migration and flow. Mar. Petrol. Geol., 17, 797-814.
Barr, D., Savory, K.E., Fowler, S.R., Arman, K. & Mcgarrity, J.P. (2007). Pre-development fracture modelling in the Claire field, west of Shetland, 270. Geological Society, London, Special Publications, 205-225. DOI:
Bourne, S.J., Brauckmann, F., Rijkels, L., Stephenson, B.J., Weber, A. & Willemse, E.J.M. (2000). Predictive Modelling of Naturally Fractured Reservoirs Using Geomechanics and Flow Simulation. Paper ADIPEC 0911 presented at the 9th Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, U.A.E., 10.
Burberry, C.M. (2015). The Effect of Basement Fault Reactivation on the Triassic-Recent Geology of Kurdistan, North Iraq. Journal of Petroleum Geology, 38(1), 37-58.
Casini, G., Gillespie, P.A., Verges, J., Romaire, I., Fernandez, N., Casciello, E., Saura, E., et al. (2011). Sub-seismic fractures in foreland fold and thrust belts: insight from the Lurestan Province, Zagros Mountains, Iran. Pet. Geosci., 17, 263-282.
Dunnington, H.V. (1958). Generation, migration, accumulation and dissipation of oil in northern Iraq. In: Weeks, L.G. (ed.) Habitat of Oil. American Association of Petroleum Geologists, Special Publications, 18, 1194–1251.
Environmental Systems Research Institute (ESRI) (2015). ArcGIS 10.4 for Desktop.
Fouad, S.F.A. (1983). Geology and structure of Qara Chouq folds. M.Sc. Thesis, Baghdad University, Iraq.
Fouad, S.F. (2012). Western Zagros Fold – Thrust Belt, Part I: The Low Folded Zone. Iraqi Bulletin of Geological Mining, Special Issue, 5, 39-62.
Fouad, S.F. (2015). Tectonic Map of Iraq. Scale 1: 1000 000, 3rd Edition, 2012. Iraqi Bulletin of Geology and Mining, 11(1), 1-7.
GeoDesign (2015). Makhmur Area Mapping Report Kurdistan. Commercial report, unpublished. 65 pages.
Grasemann, B. & Schmalholz, S.M. (2012). Lateral fold growth and fold linkage. Geology, 40, 1039-1042.
Heidbach, O., Rajabi, M., Reiter, K. & Ziegler, M. (2016): World Stress Map 2016. GFZ Data Services. URL:
Huang, Q. & Angelier, J. (1989). Fracture spacing and its relation to bed thickness. Geol. Mag., 126, 355-362.
Jassim, S.Z. & Goff, J.C. (2006). The Geology of Iraq. Dolin, Prague, p. 341.
Jonoud, S., Wennberg, O.P, Larsen, J.A. & Casini G. (2013). Capturing the Effect of Fracture Heterogeneity on Multiphase Flow During Fluid Injection. SPE Reservoir Evaluation & Engineering, 16(2), 194-208. SPE Paper 147834-PA.
Lacombe, O., Bellahsen, N. & Mouthereau, F. (2011). Fracture patterns in the Zagros Simply Folded Belt (Fars, Iran): constraints on early collisional tectonic history and role of basement faults. Geol. Mag., 148, 940-963.
Lapponi, F., Casini, G., Sharp, I., Blendinger, W., Fernandez, N., Romaire, I. & Hunt, D. (2011). From outcrop to 3D modelling: a case study of a dolomitized carbonate reservoir, Zagros Mountains, Iran. Pet. Geosci., 17, 283-307.
Massaro, L., Corradetti, A., Tramparulo, F. d’Assisi, Vitale, S., Prinzi, E.P., Iannace, A., Parente, M., et al. (2019). Discrete Fracture Network Modelling in Triassic–Jurassic Carbonates of NW Lurestan, Zagros Fold-and-Thrust Belt, Iran. Geosciences, 9, 496.
McQuillan, H. (1973). Small-scale fracture density in Asmari Formation of Southwest Iran and its relation to bed thickness and Structural setting. AAPG Bull., 57, 2367-2385.
Narr, W., Schechter, D.W. & Thompson, L.B. (2006). Naturally Fractured Reservoir Characterization. Society of Petroleum Engineers, Richardson, TX.
Nemati, M. & Pezeshk, H. (2005). Spatial distribution of fractures in the Asmari Formation of Iran in subsurface environment: effect of lithology and petrophysical properties. Nat. Resour. Res., 14, 305-316.
Nelson, R.A. (2001). Geological Analysis of Naturally Fractured Reservoirs (2nd ed.). Gulf Professional Publishing, Houston, p. 332.
Rashid, F., Hussein, D., Lawrence, J. & Khanaqa, P. (2020). Characterization and impact on reservoir quality of fractures in the Cretaceous Qamchuqa Formation, Zagros folded belt. Mar. Petrol. Geol., 113, 104–117.
Rashid, F., Hussein, D., Lawrence, J.A. & Ahmed, Z. (2021). Fluid flow and permeability analysis of tight gas carbonate reservoir rocks using fractures and dynamic data. Journal of Natural Gas Science and Engineering, 90, 103894.
Reif, D., Decker, K., Grasemann, B. & Peresson, H. (2012). Fracture patterns in the Zagros fold-and-thrust belt, Kurdistan region of Iraq. Tectonophysics, 576-577, 46-62.
Sadeq, Q.M., Bhattacharya, S.K. & Ismail, W. (2016). Conceptual Fracture Modelling For Carbonate Reservoir in Bai Hassan Oil Field Northern Iraq. Journal of Aquaculture Research & Development, 7(2), 1000397.
Sahib, L.Y., Marandi, A. & Schüth, C. (2016). Strontiumisotopes as an indicator for groundwater salinity sources in the Kirkuk region, Iraq. Science of the Total Environment, 562, 935–945.
Sharp, I., Gillespie, P., Lønøy, A., Horn, S. & Morsalnezhad, D. (2006). Outcrop Characterization of Fractured Cretaceous Carbonate Reservoirs, Zagros Mts, Iran (SPE Paper).
Sharp, I., Gillespie, P., Morsalnezhad, D., Taberner, C., Karpuz, R., Vergés, J., Horbury, A., et al. (2010). Stratigraphic architecture and fracture-controlled dolomitization of the Cretaceous Khami and Bangestangroups: an outcrop case study, Zagros Mountains, Iran. In: vanBuchem, F.S.P., Gerdes, K.D. & Esteban, M. (eds) Mesozoic and Cenozoic Carbonate Systems of the Mediterranean and the Middle East: Stratigraphic and Diagenetic Reference Models. Geological Society,London, Special Publications, 329, 343–396. DOI:
Stephenson, B.J., Koopman, A., Hillgartner, H., Mcquillan, H., Bourne, S., Noad, J.J. & Rawnsley, K. (2007). Structural and stratigraphic controls on fold-related fracturing in the Zagros Mountains, Iran: implications for reservoir development. In: Lonergan, L., Jolly, R.J.H., Rawnsley, K., Sanderson, D.J. (Eds.), Fractured Reservoirs, vol. 270. Geological Society, London, Special Publications, 1-21.
Tavani, S., Storti, F., Soleimany, B., Fallah, M., Mu~noz, J.P. & Gambini, R. (2011). Geometry, kinematics and fracture pattern of the Bangestan anticline, Zagros, SW Iran. Geol. Mag., 148, 964-979.
Underwood, C.A., Cooke, M.L., Simo, J.A. & Muldoon, M.A. (2003). Stratigraphic controls on vertical fracture pattern I Silurian dolomite, northeasten Wisconsin. AAPG Bull, 87, 121-141.
Wennberg, O.P., Svånå, T., Azizzadeh, M., Aqrawi, A.M.M., Brockbank, P., Lyslo, K.B. & Ogilvie, S. (2006). Fracture intensity vs. mechanical stratigraphy in platform top carbonates: the Aquitanian of the Asmari Formation, Khaviz Anticline, Zagros, SW Iran. Pet. Geosci., 12, 235-245.
How to Cite
Awdal, A. (2022, December 27). Fracture Analysis in the Outcrops of the Qara Chauq Anticlines, Zagros Fold and Thrust Belt of Kurdistan Region in Northern Iraq. UKH Journal of Science and Engineering, 6(2), 26-37.
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