TERTIARY OIL-PRONE COALS AND CARBONACEOUS SHALES IDENTIFIED AS POTENTIAL SOURCE ROCK OF THE CARACARA SUR OIL FIELD IN THE LLANOS BASIN, COLOMBIA García -Mayoral, M. Flor ; Grimmer, J., Medina, A., Cuñado, E., Navarro, J., Rodríguez -Pardo, R. 3 rd -6 th April 2016 mariaflor.garcia@cepsa.com
Tertiary oil-prone coals and carbonaceous shales as potential source rock of the Caracara Sur oil field Geological setting of Caracara Sur oil field (the Llanos basin, Colombia) PERIOD EPOCH Neogene Miocene CENOZOIC/TERTIARY Oligocene Paleogene Sandstones, Caracara Concession Eocene shales, and coals in deltaic environment Paleo cene Upper Cretaceous MESOZOIC Marine shales Lower Generalized lithostratigraphic column of the Llanos Basin AAPG|SEG|ICE Barcelona| 3 rd- 6 th April 2016 2
Tertiary oil-prone coals and carbonaceous shales as potential source rock of the Caracara Sur oil field Carbonera C7 logs and samples analyzed Organic-rich coal and Samples carbonaceous shale beds Wireline gamma of Carbonera C7 section Formation evaluation log Oils Rocks ray log CCS-C17 C6 C7-A Carbonera C7 section: ~300 ft C7-B C7-1 C7-2 C7-3 C7-M Multiple pay zones ~2-10 ft each Average ~20-25%; Average S w ~40-60% AAPG|SEG|ICE Barcelona| 3 rd- 6 th April 2016 3
Tertiary oil-prone coals and carbonaceous shales as potential source rock of the Caracara Sur oil field Carbonera C7 logs and samples analyzed Samples Samples Wireline gamma Wireline gamma ray log ray log CCS-C17 C6 C7-A Carbonera C7 section: ~300 ft C7-B C7-1 C7-2 C7-3 C7-M AAPG|SEG|ICE Barcelona| 3rd-6 th April 2016 4
Guideline 1. Oil characterization GC-FID (whole oil) o GC-MS (biomarkers) o 2. Rock characterization: cuttings & conventional core plugs Rock-Eval pyrolysis (organic matter quantity, kerogen o quality, maturity) and TOC (Total Organic Carbon) GC-FID (whole extracts) o GC-MS (biomarkers) o 3. Kinetic analysis of rocks Non-isothermal open-system pyrolysis (bulk kinetics) o Closed-system MSSV pyrolysis (compositional information) o 4. Oil-source rock correlation AAPG|SEG|ICE Barcelona| 3 rd- 6 th April 2016 5
OIL CHARACTERIZATION AAPG|SEG|ICE Barcelona| 3 rd- 6 th April 2016 6
Tertiary oil-prone coals and carbonaceous shales as potential source rock of the Caracara Sur oil field The GC- FID “fingerprint” profile of Caracara Sur oils reveals a mixture of different organic matter sources Marine source FID1 A, FID1A, Front Signal (CCS-C17\CRUDOS\COLUMNA 60M\CCSC17 5054,5-5055 SLUGS.D) Oil 5054.5-5055 Contaminants nC28 pA (Algal/microbial input) from sandstone 70 nC13 nC14 TAR ~ 0.60-0.75 preservation nC12 nC15 foams Pr/Ph ~2.0 60 nC16 nC17 nC11 nC18 nC19 nC20 Terrestrial source nC21 50 nC22 nC23 nC24 (Land plant input) nC25 nC26 nC27 nC29 nC10 40 IP14 IP16 nC30 IP13 nC31 PHYTANE nC32 IP18 nC33 30 nC34 PRISTANE nC35 nC36 nC37 nC38 nC39 nC40 20 IP11 IP15 Unresolved complex mixture (UCM) IP10 TAR = Terrigenous Aquatic Ratio (nC 27 +nC 29 +nC 31 )/(nC 15 +nC 17 +nC 19 ) 10 m in 40 60 80 100 120 Bimodal distribution (organic matter mixture: marine and terrigenous sources) Light, volatile hydrocarbons evaporated Biodegradation (baseline hump of UCM) TAR < 1.0 suggest predominance of marine organic matter AAPG|SEG|ICE Barcelona| 3 rd- 6 th April 2016 7
Tertiary oil-prone coals and carbonaceous shales as potential source rock of the Caracara Sur oil field Source and environmental-related biomarkers suggest a predominant marine component in Caracara Sur oils Sterane ternary diagram Homohopane distribution Crude oils 40 C28 R 4867-4867,5 35 0,00 1,0 4883-4886 Lacustrine 30 4886,8-4887,15 0,8 4886-4889 25 0,25 H31-H35 % 5003-5006 20 0,6 5018-5021 0,50 15 5054,5-5055 0,4 5058-5059 10 0,75 5061-5064 0,2 5 5064-5067 Marine Terrestrial 0 5112,6-5115 H31 H32 H33 H34 H35 1,00 0,0 1 2 3 4 5 5115 0,00 0,25 0,50 0,75 1,00 H31-H35 (22R+22S) C27 R C29 R Homohopane distribution with H 35 /H 34 >1.0, Algal-type kerogen (marine organic matter) typical of marine anoxic sedimentary Presence of C 30 steranes (marine origin) environments associated with high availability of reduced S. AAPG|SEG|ICE Barcelona| 3 rd- 6 th April 2016 8
Tertiary oil-prone coals and carbonaceous shales as potential source rock of the Caracara Sur oil field Presence of oleanane suggests terrigenous organic matter input from angiosperms and constrains the source rock age to Late Cretaceous or younger Oleanane and gammacerane distributions 4867-4867,5 C7-A5 35 5121-5124 C7-M 4883-4886 C7-A3 30 25 4886,8-4887,15 C7- 5115-5118 C7-M A3 20 15 10 5115 C7-M 4886-4889 C7-A3 5 0 5112,6-5115 C7-M 5003-5006 C7-1.1 5064-5067 C7- 5018-5021 C7-1.1 2.1B.2 5061-5064 C7- 5054,5-5055 C7- %Ol((Ol+H30) 2.1B.2 2.1A %Gamm/(Gamm+H30) 5058-5059 C7- 2.1B.1 Oleanane index ~ 25-30% suggests terrestrial organic matter input from angiosperms (flowering land plants), and this range of values is compatible with a possible Tertiary source rock (Moldowan et al., Science (1994), 265: 768-771) Gammacerane index ~ 15% (water column stratification) AAPG|SEG|ICE Barcelona| 3 rd- 6 th April 2016 9
Tertiary oil-prone coals and carbonaceous shales as potential source rock of the Caracara Sur oil field Abundant 25-norhopanes indicate severely biodegraded oils and the presence of at least two charge pulses 25-norhopane distribution 25-norhopane series 4867-4867,5 25-norH C7-A5 5121-5124 C7- 4883-4886 C7- 2,50 M A3 H 29 H 30 2,00 5115-5118 C7- 4886,8-4887,15 Ol 1,50 M C7-A3 1,00 4886-4889 C7- 5115 C7-M 0,50 A3 0,00 5112,6-5115 5003-5006 C7- C7-M 1.1 5064-5067 C7- 5018-5021 C7- 2.1B.2 1.1 5061-5064 C7- 5054,5-5055 2.1B.2 C7-2.1A 5058-5059 C7- 25-norhopane 2.1B.1 Abundant 25-norhopanes coexisting with n-alkanes are indicative of: Severe biodegradation o Oil mixtures from different charges: (i) a first severely biodegraded charge, and o (ii) a second fresh and non-biodegraded charge 25-norHop/H 30 >> 1.0, suggesting that the first biodegraded charge is predominant AAPG|SEG|ICE Barcelona| 3 rd- 6 th April 2016 10
Tertiary oil-prone coals and carbonaceous shales as potential source rock of the Caracara Sur oil field Caracara Sur oils have similar maturity levels and each pulse might have been generated at different stages of source rock maturity % R eq based on PAHs % R eq based on C 29 sterane biomarkers 4867-4867,5 C7-A5 4867-4867,5 C7-A5 1,2 5121-5124 C7-M 4883-4886 C7-A3 1,2 5121-5124 C7-M 4883-4886 C7-A3 1 1,0 0,8 5115-5118 C7-M 4886,8-4887,15 C7-A3 0,8 5115-5118 C7-M 4886,8-4887,15 C7-A3 0,6 0,6 0,4 0,4 5115 C7-M 4886-4889 C7-A3 5115 C7-M 4886-4889 C7-A3 0,2 0,2 0 0,0 5112.6-5115 C7-M 5003-5006 C7-1.1 5112.5-5115 C7-M 5003-5006 C7-1.1 5064-5067 C7-2.1B.2 5018-5021 C7-1.1 5064-5067 C7-2.1B.2 5018-5021 C7-1.1 5061-5064 C7-2.1B.2 5054,5-5055 C7-2.1A 5061-5064 C7-2.1B.2 5054.5-5055 C7-2.1A 5058-5059 C7-2.1B.1 5058-5059 C7-2.1B.1 % R eq (MDR) % R eq (C 29 S/(S+R)) % R eq (MPI-1) % R eq (C 29 bb S/( bb S+ R)) % R eq (DNR-1) % R eq ~ 0.7 based on C 29 sterane isomers (recalcitrant biomarkers) could be more related to the maturity of the first predominant biodegraded charge % R eq ~ 1.0 based on PAHs (weathering-prone compounds) could be more related to the maturity of the fresh, non-biodegraded second charge AAPG|SEG|ICE Barcelona| 3 rd- 6 th April 2016 11
ROCK CHARACTERIZATION AAPG|SEG|ICE Barcelona| 3 rd- 6 th April 2016 12
Tertiary oil-prone coals and carbonaceous shales as potential source rock of the Caracara Sur oil field Rocks with high organic richness have hydrocarbon generation potentials typical of type II and II/III kerogens, but are immature Hydrocarbon Organic richness Organic matter type Maturity Maturity potential TOC, wt % HI, mg HC/g TOC T max , ºC % R o (exp) S 2 , mg HC/g rock 0 20 40 60 0 100 200 300 0 200 400 600 400 420 440 460 0,4 0,5 0,6 0,7 4700 4700 4700 4700 4700 III II & Immature Mature Excellent (>4) Excellent (>20) Immature Mature II/III <435 ºC >435 ºC 4750 4750 4750 4750 4750 4800 4800 4800 4800 4800 4850 4850 4850 4850 4850 4900 4900 4900 4900 4900 4950 4950 4950 4950 4950 5000 5000 5000 5000 5000 5050 5050 5050 5050 5050 5100 5100 5100 5100 5100 5150 5150 5150 5150 5150 5200 5200 5200 5200 5200 Cutting <2% TOC Core <2% TOC AAPG|SEG|ICE Barcelona| 3 rd- 6 th April 2016 13 Cutting >2% TOC Core >2% TOC
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