Petroleum Habitat of the Onshore and Offshore Ceara Basin based on Geological, Geochemical, and 2D Petroleum System Modeling
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The area covered by this project involves 2D seismic interpretation of a dense grid located in the Piauí-Camocim and Acaraú sub-basins. Coverage of the Icaraí sub-basin involves regional 2D seismic lines. No seismic data from the Mundaú sub-basin was used in this project. The seismic dataset consists of 6,153 km of 2D PSDM extending over an area of 20,260 km² that encompasses shelf, slope and deep-water domains. The interpretation of 2D seismic data allowed regional mapping of many horizons and focused on searching for leads and on defining a sequence stratigraphic framework for a complete 2D basin modeling evaluation. The work involved an integration of seismic and geological data from different petroleum systems that were investigated from a large data base of rocks from wells, oils, condensates and gas geochemical analyses. In some sub-basins exploratory risks might exist in relation to source rocks deposition, whereas in others sub-basins higher exploration risks are related to hydrocarbon charge. Although some oil accumulations have been found in the Mundaú sub-basin, most of the Ceará Basin remains as a “frontier basin”. A thorough risk assessment is provided for all compartments of the Ceará Basin.
Full references of all images are listed in the reports
Table of Contents
Introduction
Regional Geology
Tectonic Evolution of the Equatorial Margin
Ceará Structural and Stratigraphic Framework
Exploratory History
Petroleum System Overview through Geochemistry of Oils from Ceará Basin
Characterization of the Oil Systems
Biodegradation and Oil Quality
Carbon Isotopic Signatures and n-Alkanes Distribution of the Oils
Assignment of Oil Origin through Biomarkers Distribution
Maturity Parameters and Oil Cracking
Seismic Interpretation and Geological Characteristics of the Area
Seismic Data Quality Control
Navigation and Positioning
Polarity and Phase
Mis-Tie Analysis
Diverse Processing Problems
Well TyPing
Regional Mapping
Economic Basement
Middle Aptian Sequence (Mundaú Fm)
SAG Sequence (Trairi Mb)
Alagoas Sequence (Paracurú Fm top)
Albian-Cenomanian Sequence
Turonian/Santonian Sequence
Campanian/Maastrichtian Sequence
Oligocene Sequence
Tertiary/Quaternary Sequence
Leads Definition
Stratigraphic Modeling
Quality Control of Well Data (Conversion and Standardization of Log Files)
Characterization of Potential Reservoirs
Maastrichtian Sandstones
Albian Cenomanian
Alagoas Sandstones (Paracurú Formation and Trairi Member)
Mundaú Sandstones
Regional Correlations
Correlated Sequences
A-A’ Strike Oriented Section
B-B’ Dip Oriented Section
Play Fairway Mapping
Source Rocks and Charge
Reservoirs and Seals
Play Fairway Map
2D Petroleum Systems Modeling
Model Input
Geometries
Layering / age assignment
Lithologies / facies assignment
Boundary conditions
Petroleum systems elements
Fault properties
Erosion
Special modeling
1D Modeling
Calibration
P/T Modeling Results
Dip Line Temperature
Dip Line Maturity
Dip Line Transformation Ratio
Dip Line Time Extractions
Dip Line Pressure
Strike Line Temperature
Strike Line Maturity
Strike Line Transformation Ratio
Strike Line Time Extractions
Strike Line Pressure
Migration Modeling Results
Dip Line
Strike Line
Lead Evaluation (Dip Line)
Lead Evaluation (Strike Line)
Modeling Conclusions
Overall Conclusions
References
List of Figures
Location map of the Equatorial Brazilian basins. Note that the basins comprised in this project (Pará-Maranhão, Barreirinhas and Ceará) had its exploratory efforts limited to the shallow portion, as can be verified through the wells distribution. Note also, that the width of the platform increases towards the west.
Schematic Cretaceous stages of the breakup between Africa and South America, and the tectonic evolution of the Equatorial Atlantic. The scheme shows the approximate location of the Bové, Benin, Ivory Coast, Keta, Senegal, Volta Basins, the Benue Trough of Africa and the Para-Maranhão Basin in Brazil during the (A) Hauterivian, 125 Ma; (B) early Albian, 110 Ma; (C) late Albian, 100 Ma; (D) Santonian, 85 Ma. Modified from Marinho and Mascle (1987).
Tectonic evolution model for Gondwana supercontinent according Alkmin, 2001.
Relative movements of the cratons of the Gondwana supercontinent (Veevers, 2004).
Bathymetric map showing the fracture zones in the oceanic crust (lineaments in the sea floor topography displayed in white) of the Equatorial Margin and its correspondence with the gulf of Guinea in the African Counterpart elucidating the lateral movement between Africa and South America. These fracture zones also tend to offset sub-basins and affect sedimentation.
Gravimetric map of the Equatorial Margin of Brazil displaying the location of major transform zones.
Regional Map of the Equatorial and Northeastern Brazilian area displaying the magnetic data over the oceanic area and the geological information over the continental area. Note the interaction between the NE-SW and E-W lineaments. Note also that the E-W lineaments present in the Northeastern Brazil (Borborema province, e.g. Patos and Pernambuco Lineaments) is parallel to the oceanic fractures indicated in the Equatorial area, pointing to a common origin for both tectonic features.
Main transform zones at the moment of the Gondwana breakup in the region of Equatorial Margin. Modified from Rabinowitz and LaBrecque (1979).
Morphologic pattern of a transformant continental Margin (Oliveira, 2004.
Geological scheme showing the stages related to the Aptian Rift II phase.
Geological Scheme exemplifying the effects of the transform tectonics during the Albian Rift III phase.
Tectonic-stratigraphic evolution of the Rift and transitional phases of the Equatorial margin. From the Middle Aptian age, the transcurrent faults delimitated the uplifted sites with predominance of continental sedimentation varying laterally to subsiding sites with transitional sedimentation containing evaporites. During the Lower Albian, the transcurrent tectonic got more intense, followed by the appearing of oceanic crust resulting in a reticulated outline typical of transform margins.
Simplified geological map of the Brazilian Northeast (Brito Neves, 2000).
Structural map of the platform area of the Ceará basin displaying main tectonic features and the location of the Piauí-Camocim, Acaraú, Icaraí and Mundaú sub-basins (modified from Zalán, 1985).
Gravimetric map of Ceará basin displaying the Atlantic High and the Ceará High that separates the nearshore portion of Piauí-Camocim and Acaraú sub-basins.
Tectonic domains of the Equatorial Brazilian Margin and its African Counterparts according the Atlantic opening proposed by Matos (2000).
Sea bottom structural map of the study area showing the evidences of the oblique rifting.
Preferential area of transpressional and transtensional efforts. In the western area it is possible to observe a greater influence of the transpression efforts compared to transtension. In the eastern area it is the contrary.
Stratigraphic chart of Ceará basin (Condé, 2007).
Stratigraphic chart of the Ceará sub-basins: Piauí-Camocim, Acaraú-Icaraí and Mundaú. Note that large volumes of Upper Cretaceous and tertiary sediments are absent of Piauí-Camocim, Acaraú and Icaraí sub-basins.
Drilled wells through time in the Ceará Basin (Mundaú; Icaraí, Acaraú and Piauí-Camocim sub-basins).
Location map of the public time seismic lines of the Ceará basin and the nearshore wells. Note that most of the exploration efforts concentrated in the Mundaú sub-basin.
Oil types and reservoir intervals around the Mundaú sub-basin of the Ceará Basin.
API gravity map of the analyzed oils from the Mundaú sub-basin in the Ceará Basin. Note that the lacustrine oils sourced by the Mundaú shales display the highest API values. In contrast, low API values are linked to more paleo biodegradation and recent biodegradation in marine hypersaline oils (see 25-norhopane/hopane ratio map in Figure 29 and the recent biodegradation map in the Figure 30).
Sulfur content of the analyzed oils from the Mundaú sub-basin in the Ceará Basin. Low sulfur contents characterize most of the analyzed oils.
API gravity versus depth for the Ceará Basin oils. It seems that, in Mundaú sub-basin of Ceará Basin, the oil quality is not directly linked to the reservoir depth although it is strictly associated to the oil origin and recent biodegradation represented by the ratio Pri/nC17 (compare the values for well 1CES 0061D CE displayed in this diagram with its values in Figure 32).
Sulfur content versus depth of the Ceará Basin oils. It seems that in Mundaú sub-basin of Ceará basin, oil quality is not directly linked to reservoir depth.
Oil quality diagram for the Ceará oil samples. The oils recovered in the Mundaú sub-basin of the Ceará basin, have good quality, especially the lacustrine oils that have high API and low sulfur content.
Paleobiodegradation map of the Mundaú sub-basin at the Ceará Basin (measured by the ratio 25norhopane/hopane). Note the relation between the biodegradation and the oil quality maps shown the Figure 24.
Recent biodegradation map of the Mundaú sub-basin at the Ceará Basin (based on the pristane over nC17 ratio). Note the relation between the biodegradation and the oil quality maps shown in Figure 24.
Degree of paleobiodegradation based on 25-norhopane/hopane versus the reservoir depth. There is a slight tendency of increased paleobiodegradation with the decreased reservoir depth. Note that the lacustrine oils, although showing a wide vertical distribution, are non-biodegraded or mildly biodegraded.
Degree of recent biodegradation versus reservoir depth. Most of the analyzed oil samples (including all lacustrine samples) show a predominance of nC17 over pristane, the absence of recent biodegradation.
Biodegradation assessment diagram of the Ceará (Mundaú sub-basin) oil samples. Note that some the hypersaline oils have high ratios of 25-norhopane/hopane (>1) indicating paleobiodegradation (as in wells 3CES 0063D CE and 4 CES 0143 CE).
Whole oil and terpane traces (m/z 191) for the well 4CES 0143CE exemplifying a marine hypersaline oil from the Mundaú sub-basin that is composed of a mixture of oils from different generation pulses. This is indicated by the preservation of n-alkane, very high UCM compounds, and abundant nuclear demethylated hopanes (25-norhopanes).
Whole oil and terpane traces (m/z 191) of Mundaú sourced oils exposed to different biodegradation. The oil sample recovered from well 1CES 0008 CE is most biodegraded. The oil samples recovered from the wells 3CES 0061D CE and 4CES 0014 CE have experienced light biodegradation. Finally, the oil from well 1CES 0066 CE correspond a mixture of different charging pulse from the same source rock.
Plots of δ13C of the whole oil versus the Pristane/Phytane ratio. The lacustrine freshwater oils sourced by Mundaú Fm. can readily be identified by light δ13C values and the dominance of pristane over phytane compared to marine hypersaline oils in which δ13C values are above -28‰ and the phytane predominates over the pristane.
Whole oil traces as distinctive geochemical features of Lacustrine and marine oils from Mundaú sub basin.
Plots of hopane/ sterane versus pristane/phytane ratios for oils from the Ceará basin. Note that the lacustrine oils, as reported by Mello, 1988, have a higher pristane/phytane and hopane/sterane ratios when than the marine oils. The high pristane/phytane ratio for the oil sample from well 1CES 0079 CE is linked to the high thermal maturity, since the pristane is more resistant to thermal alteration than phytane.
m/z 259 Fragmentograms of a marine (upper fragmentogram – well 1CES 0079 CE) and a lacustrine ( well 3CES 0061D CE) oils from Ceará Basin showing the high abundance of lacustrine biomarker TPP relative to the C27 diasteranes in lacustrine freshwater and brackish water oils. In the marine oils the C27 diasteranes predominates over TPP.
Gammacerane index (GAM/H30 stands for Gammacerane over 30-Hopanes) versus hopane/sterane ratio for the samples from Mundaú sub-basin in the Ceará Basin. These ratios have been used to differentiate lacustrine fresh from saline and also from marine hypersaline and siliciclastic oils in the Brazilian marginal basins (Mello, 1988 and Mello et al., 1988). High values for hopane/ sterane (>10), and low values of gammacerane/ hopane ratios (<4), indicate lacustrine fresh to brackish to saline water source rock environments.
Plot of gammacerane index (GAM/H30 stands for Gammacerane over 30-Hopanes) versus diasteranes/TPP for oils from Mundaú sub-basin in the Ceará basin. The Diasterane/TPP ratio is very effective in differentiating marine oils (a predominance of diasterane over TPP) from lacustrine oils (TPP prevails over the diasteranes).
Gammacerane index versus C35/C34 hopanes for the oils from the Mundaú sub-basin in the Ceará Basin. The gammacerane index indicates the salinity of the source rock when deposited. This diagram allows a good separation of all oil types. There is a tendency of the lacustrine sourced oils fall in the C35/C34 range of 0.2 to 0.6, whereas the marine hypersaline oils have C35/C34 >1.
δ13C of the whole oil versus the Ts/Tm ratio of the Ceará oil samples. Both parameters are suitable to asses oil origin. In lacustrine oils, the C27 17α-trisnorhopane (Tm) dominates over the C27 18α-trisnorneohopane (Ts) present light values of δ13C, unlike the marine (hypersaline) oils.
Diasteranes/ TPP versus 3Me/ 4Me triaromatics for oils from the Ceará Basin. The Aptian marine hypersaline oils, as reported by Mello, 1988, have the highest 3Me/ 4Me triaromatics ratios compared to the other oil types.
C24 tetracyclic/ C26 tricyclic terpanes versus hopane/sterane ratio for Mundaú oil samples. The C24 tetracyclic/C26 tricyclic terpanes suitable to distinguish the marine oils, since most of them have high ratio values compared to lacustrine and mixed oils. In addition, very low values for hop/sterane are diagnostic of the marine oils.
Hopane/sterane ratio versus C27/C29 sterane diagram for the oil samples from the Mundaú sub-basin in the Ceará Basin. This diagram allows a good separation of the oil families, since the C29 sterane is more abundant than C27 sterane in marine oils. Conversely, high values of the hopane/sterane ratio are linked to the lacustrine oils.
m/z 191 Fragmentograms of oils from the Mundaú sub-basin. Note the differences in the Ts/Tm ratio, gammacerane abundance, tricyclic relative abundance between the lacustrine fresh water and marine hypersaline sourced oils.
m/z 217 Fragmentograms of oils from the Mundaú sub-basin. Note the differences in the carbon distributions of C27 versus C29 steranes for the lacustrine and the marine oils.
m/z 231 Fragmentograms of oils from the Mundaú sub-basin. Note the differences in the abundance of C29 and 3-methyl/4-methyl triaromatic steroid between the lacustrine and marine oils. The lacustrine oils have higher concentrations of C29 and 4-methyl triaromatic steroids.
m/z 245 Fragmentograms of oils from the Mundaú sub-basin. Note the increase of the relative abundance of the C29 3-methy aromatic steroids over the C29 4-methy aromatic steroids in the Marine oils compared to the lacustrine oils.
. Mass chromatograms from metastable ion monitoring of C27 to C30 steranes in a hypersaline Paracurú (!) sourced oil recovered from well 4CES 0012A CE.
Mass chromatograms from metastable ion monitoring of C27 to C30 steranes in a Mundaú (!) sourced oil recovered from well 3CES 0061D CE.
Plot of C29 αββ/(αββ + ααα) steranes versus Ts/Tm for oils from the Mundaú sub-basin in the Ceará Basin.
Plot of C29 αββ/(αββ + ααα) steranes versus S/(S+R).
. Map of TS/TS+TM for oils from the Mundaú sub-basin in the Ceará Basin.
Map of C29 αββ/ (αββ + ααα) steranes for oils from the Mundaú sub-basin of Ceará Basin.
Oil cracking diagram of the Ceará oil samples. Note that the lacustrine oils are highly cracked compared to the marine oils.
Oil cracking map of the Mundaú sub-basin in the Ceará Basin.
Ceará location map displaying the 2D depth seismic lines interpreted in this work, the drilled wells and the exploration blocks. Note that only ten wells can be tied to the received seismic lines.
Regional map of Ceará Basin showing the distribution of the seismic lines analyzed in this study (in green) together with additional public seismic lines in time required to ANP (in red).
Regional map of Ceará Basin showing the distribution of the seismic lines analyzed in this study (in green) together with additional public seismic lines in time delivered by ANP (in red).
SEG-Y files stored on network drives. Ceará basi.
Example of a Ceará seismic line loaded in software Petrel 2009 1..
Evaluation of the acquisition parameters of the seismic data from the Ceará basin.
Reference Map illustrating the regions of datum and fuses from Brazil.
Base Map displaying the location of the seismic grid loaded in software Petrel 2009 1.1. and the cultural data. Note that the seismic lines presented a problem in the datum.
Interpretation project of the Ceará Basin with seismic data, well data, cultural data in coordinate reference system WGS84, UTM, Zone 24 South.
Petrel’ Settings Window showing the geodetics parameters used for Ceará basin.
SEG-Y’ header of the line 136-BBR_PSDM_WHITH_POSTP_GAIN_DEPTH displaying the datum 23 south (display from the software SeiSee). Take look in the X, Y lines (bytes X=73-76; Y=77-80; CDP=21-24). The wrong coordinates are the same for all bins.
SEG-Y’ header of the line 136-BBR_PSDM_WHITH_POSTP_GAIN_DEPTH displaying the datum 24 south (display from the software SeiSee). Take look in the X, Y lines (bytes X=73-76; Y=77-80; CDP=21-24). The wrong coordinates are the same for all bins.
Petrel display showing a positive number as a peak and a negative number as a trough.
Polarity and color convention and definition of American and European Polarity. Brown et al, 2003.
Subsurface features which can generate sufficiently high amplitude reflections to be useful for interpretative assessment of phase and polarity. Probable impedance profiles are drawn. Brown et al, 2003.
Phase and Polarity circles presented diagrammatically for an impedance increase. Brown et al, 2003.
Initial color scheme pattern.
Seabed reflection in deep water displaying zero – phaseness and American Polarity. Line 7125_BBR_PSDM_WITH_POSTP_GAIN_DEPTH.
Composite line showing Dip and strike line. Note the symmetry between line.
Seismic line from the Ceará Basin with the occurrence of smiles depending on the velocity model used during migration.
Seismic line from the Ceará basin with the occurrence of seismic multiples.
Seismic noise, with the occurrence of artifacts created in the processin.
Seismic line 148 exemplifying the well tying performed in the Ceará basin. Note that all of the wells are projected.
Stratigraphic chart of the Ceará Basin with the identification of the eight horizons mapped (plus the sea bed) in this work.
Screenshot of the seismic line 6961 displaying the eight seismic horizons (plus the seabed) mapped in this work. Note that the basement proposed in the current interpretation do not refers to the crystalline basement, but to the economic basement as discussed along the text of this report.
Structural map in depth of the economic basement of the Ceará basin. The Economic basement corresponds to the base of the Mundaú Formation.
Seismic grid used in the Ceará interpretation project displaying the area in which the oceanic/transitional crust was identified (in dark blue). The black dashed line represent the location of the Romanche shear zone.
Seismic Line 6961_BBR_PSDM exemplifying the interpretation of the strong reflector ‘intra economic basement’ mapped in distal parts of the Ceará basin. As this reflector represents a thinning of the crust as a whole, it can be interpreted as the Transitional Crust limit. This theory fully agrees with the model established by IPEX team in the Barreirinhas basin.
Strike oriented seismic line exemplifying the behavior of the Paleozoic sequence along the Ceará basin. Note that this sequence occurs predominantly in the platform domain, being thicker in the area where transpressive events have acted with major expression..
Structural map in depth of the Mundaú F.
Isopach map of the Mundaú Formation.
Seismic line 6955_BBR_PSDM exemplifying the seismostratigraphic pattern of the Mundaú Fm. in the Ceará basin. The well displayed is the 1CES 0052 CE.
Structural map of the SAG sequence. Note that the NNE-SSW trend in the Eastern area is inherit from the rift phase (compare with Figure 88).
Isopach map of the SAG sequence.
DIP oriented seismic line exemplifying the seismofacies of the SAG Sequence. Note the development of salt layers in deep water.
Seismic line 7021_BBR_PSDM showing the Lower Albian sequence crossed by the well 1CES 0050 CE.
Structural Map in depth of the Alagoas Top.
Isopach map in meters of the Alagoas Sequence.
Structural Map in depth of the Albian-Cenomanian sequence.
Isopach map in meters of the Albian-Cenomanian Sequence.
Structural Map in depth of the Turonian/Santonian. The non interpolated areas indicate the presence of volcanic rocks.
Isopach map in meters of the Turonian/Santonian Sequence.
Seismic line BA2_103801_PSDM exemplifying the seismic character of the Turonian/Santonian sequence. The well 1CES 0056 CE, used for the tying of the seismic interpretation, is displayed.
Structural map in depth of the Cretaceous top. The non interpolated areas indicate the presence of volcanic rocks.
Isopach map in meters of the Upper Cretaceous Sequence.
Seismic line 7017_BBR_PSDM exemplifying the seismic character of the Campanian Maastrichtian Sequence in the platform area. The well 1CES 005A CE is displayed.
Middle Oligocene structural map in depth.
Isopach map in meters of the Oligocene Sequence.
Seismic line 7013_BBR_PSDM exemplifying the seismic character of the Oligocene Sequence in the platform domain. The well 1CES 0005A CE is displayed.
Isopach map in meters of the Tertiary/Quaternary sequence.
Sea bottom structural map.
Recovered Oil Volume versus Play Type. Ceará Basin. Note that most of the oil is expected to occur in plays related to the Paracuru sandstones, what is extremely favorable because of the proximity between reservoirs and source rock levels.
Leads distribution according the reservoir.
Lead 01 Summary Chart.
Lead 02 Summary Chart.
Lead 03 Summary Chart.
Lead 04 Summary Chart.
Lead 05 Summary Chart.
Lead 06 Summary Chart.
Lead 07 Summary Chart.
Lead 08 Summary Chart.
Example of the conversion of .lis to .las files, by the Schlumberger software.
Example of the well 1CES 0001 CE. This well just presents the log curves Cali, GR and DT in a small stretch of the well.
1CES 0011 CE – Exemple of the GR in the .las file, but with nule values in the petrophysical software.
Stretch of the composite log from the well 1CES 0027 exemplifying the possible Upper Cretaceous turbidites of Maastrichtian age.
NPHI x Neutrao Crossplot (GR: 0 to 50°API) of the well 1MAS 0030 MA, from 3690 to 3705m. The data displayed ratify the lithologic composition of sandstones with high content of clay.
Petrophysical evaluation of the well 1MAS 0030 MA. Phie ranges from 10 to 20% and the Sw from 30 to 40%.
Stretch of the composite log from the well 1CES 0048 CE exemplifying the better characteristics of the Albian-Cenomanian reservoirs.
Stretch of the composite log from the well 1CES 0048 CE exemplifying the good characteristics of the Albian-Cenomanian reservoirs.
Stretch of the composite log from the well 1CES 0045 CE exemplifying the carbonatic reservoirs from Trairi Member.
Stretch of the composite log from the well 1CES 0054 CE exemplifying the siliciclastic reservoirs from Paracuru Member.
Stretch of the composite log from the well 1CES 0019 CE exemplifying the reservoirs from Mundaú Formation.
Stretch of the composite log from the well 1CES 0109 CE exemplifying the reservoirs from Mundaú Formation.
Stretch of the composite log from the well 1CES 0146 CE exemplifying the reservoirs from Mundaú Formation.
Location map of the regional geological well sections developed in the Ceará Basin. Since all the wells drilled so far were concentrated in the shelf region, the establishment of a geological model for deep basin areas have considered predominantly the information provided by the new acquired seismic data.
Composite logs of the wells 1CES 0002 CE and 1CES 0055 CE exemplifying the unconformity that separates the Rift III Sequence (represented by the Mundaú Formation) into two. Note the differences in the lithologic associations between the lower and upper sections.
Stretch of the composite log of the wells 2CES 0087 CE and 1CES 0048 CE exemplifying the base of the Transitional Sequence. Note that the well 2CES0087CE is located just beside a faulted block, representing the input of alluvial fans in the restricted environment.
Stretch of the composite log of the wells 1CES 0053B CE and 1CES 0056 CE exemplifying the intermediary part of the Transitional Sequence (Trairi Member). Note the incidence of carbonate layers interbedded with the continuous shales that represent a regional drowning in the eastern portion of the Ceará Basin.
Stretch of the composite log of the well 1CES 0046 CE exemplifying the halite occurrence in the Ceará basin.
Stretch of the composite log of the well 1CES 0048A CE exemplifying the high sandstone content of the Albian Sequence due to the proximity of a Transbrasilian faulting lineaments.
Stretch of the composite log of the well 1CES 0056 CE exemplifying the differences between the lithostratigraphic content of the Albian-Cenomanian and Turonian/Santonian sequences.
Stretch of the composite log of the well 1CES 0056 CE exemplifying the pelitic sedimentation associated to the Campanian/Maastrichtian sequence. Note the input of turbiditic sandstones that may represents important basin targets.
Stretch of the composite log of the well 1CES 0056 CE displaying the mixed platform established during the Paleocene/Eocene ages.
Stretch of the composite log of the well 2CES 0087A CE displaying the Oligocene sequence.
Stretch of the composite log of the well 1CES 0005A CE displaying the Oligocene sequenc.
Zoom-in of the Figure 12 displaying the schematic location of the A-A’ strike oriented well section in relation to the major basin structures and the respective sedimentological characteristics according the tectonic model used in this work.
A-A’ strike oriented well correlation developed by IPEX team using the Petrel Software. These tops were extracted from biostratigraphic zonations performed by Petrobrás (AGP Files). Further interpretations based on lithostratigraphy and seismic interpretations are presented in Figure 146.
A-A’ strike oriented geological section developed by IPEX team.
Zoom-in of the Figure 12 displaying the schematic location of the B-B’ strike oriented well section in relation to the major basin structures and the respective sedimentological characteristics according the geological model used in this work.
B-B’ strike oriented well correlation developed by IPEX team using the Petrel Software. These tops were extracted from biostratigraphic zonations performed by Petrobrás (AGP Files). Further interpretations based on lithostratigraphy and seismic interpretations are presented in Figure 149.
B-B’ strike oriented geological section developed by IPEX team.
Geochemical Log of the well 1CES 0015CE highlighting the source characteristics of the Mundaú Fm.
Speculative sites of generation windows for the Aptian Mundaú source rock in Ceará basin. Note that toward the west, the Mundaú source rocks are not expected. For further information, please check the text.
Geochemical Log of the 1CES 0008 CE well highlighting the source characteristics of the Paracurú Fm.
Speculative sites of generation windows for the Aptian Paracurú source rock in Ceará basin. Note that toward the west the Mundaú source rocks are not expected. For further information, please check the text.
Depositional Model of the Campanian/Maastrichtian Sequence (Upper Cretaceous). This model can be used as facies map input for a future 3D basin modeling in the area.
Stretch of the well 1CES 0002 CE exemplifying the ‘Siliciclastic Platform’ unity postulated for the Campanian/Maastrichtian sequence.
Stretch of the well 1CES 0052 CE exemplifying the ‘Slope Deposits’ postulated for the Campanian/ Maastrichtian sequence. Note the prominent intercalations of thin layers of sandstones, and the deepening conditions illustrated by the thinning upward of the whole sequence.
Stretch of the well 1CES 0056 CE exemplifying the ‘Deep Basin deposits’ unity postulated for the Maastrichtian/Campanian sequence.
Depositional Model of the Turonian/Santonian Sequence. This model can be used as facies map input for a future 3D basin modeling in the area.
Stretch of the well 1CES 0048A CE exemplifying the ‘Mixed Platform’ unity postulated for the Albian-Cenomanian sequence.
Stretch of the well 1CES 0053B CE exemplifying the ‘Deep Basin Deposits’ unity postulated for the Albian-Cenomanian sequence.
Lithofacies association of the Alagoas Sequence.
Lithofacies Map of the Alagoas Sequenc.
Play fairway Map of Ceará basin.
Base Map of the Ceará basin. Location of modeled seismic lines is displayed in red.
Input geometries and seismic image of the dip line (6961). The line runs approximately south-west (left) – north-east (right), and is approximately 87 km long. Location of geologic features such as leads, volcanics, and wells are indicated.
Gridded layer stack of the Dip line (6961) with seismic image (top), and without seismic image displayed (bottom).
Input geometries and seismic image of the strike line (148). The line runs approximately west-north-west (left) – east-south-east (right), and is approximately 251 km long. Wells are displaye.
Gridded layer stack of the Strike line (148) with seismic image (top), and without seismic image displayed (bottom).The color coding and stratigraphic subdivision of the two models (strike and dip) are largely consistent.
The two alternative schemes of Age Assignment. `Traditional` age estimations based on ANP data (left), and the Age Assignment done by IPEX for consistency with the other basins (right).
Final Age Assignment Tables using the `new` scheme, as used in both models. Dip line (left) and Strike line (right) Black rectangles highlight source layers, yellow rectangles highlight layers which comprise of dedicated leads. Note that ages of erosional events (see below) are also included in the table.
Fine layering of the dip line (top) and of the strike line (bottom), as used in the simulations. Note that black colors are used for source intervals. Yellow colors within the sequence indicate reservoir layers.
Exemplary section of facies / lithology distribution as used for the input data set of the Dip line model.
Exemplary section of facies / lithology distribution as used for the input data set of the strike line model.
Facies distribution as used in the Dip line model. Facies types are named by numbers according to the input displayed in Figure 172.
Facies distribution as used in the Strike line model. Facies types are named by numbers according to the input displayed in Figure 172.
Facies Definition Table as used in both models. Facies types are named by numbers according to the input exemplarily displayed in Figure 172.
Geometries of the Dip line model showing PWD at 66 Ma (top), and at 99 Ma (bottom). Gradual increase of water depth in the deep basin. Shallow water conditions in the Tertiary on the shelf.
Exemplary heat flow history as used in the model, shown for a location on the shelf in the dip line model.
Kinetic scheme of the IES_TII_Toarcian_Shale_4C kinetic.
Dip line model with unconformities (red meandering lines).
Map of Ceará basin with approximate location of modeled wells (1CES 0015 CE and 1CES 0078 CE). See Figure 164 to assess the location of the modeled lines.
Input data set for 1CES 0015 CE. Layering, Age Assignment, lithologies and potential source properties (top), and boundary conditions (bottom). Note heat flow peak around 110 Ma, and values of approximately50 mW/m2 at present day, used for temperature calibration.
Temperature Calibration of 1CES 0015 CE. Good fit with BHT data (left), but considerable over-calibration of maturity (VR) data (right).
VR Calibration of 1CES 0015 CE. The heat flow scenario (left) required for calibration is unrealistically cold.
Input data set for 1CES 0078 CE. Layering, Age Assignment, lithologies and potential source properties (top), and boundary conditions (bottom). Note heat flow peak around 110 Ma, and values of approximately60 mW/m2 at present day, used for temperature calibration.
Temperature Calibration of 1CES 0078 CE. Good fit with BHT data (left), but considerable over-calibration of maturity (VR) data (right). Note impact of erosion (flat part of the curve in the right-hand graph).
VR Calibration of 1CES 0078 CE. The heat flow scenario (left) required for calibration is unrealistically cold.
Time extraction showing Transformation ratio of the hypothetic Mundaú source interval.
Dip line (top) and Strike line (bottom) with wells used for calibration (red).
Temperature calibration of the Dip line model, unchanged Crustal heat flow scenario. Over-calibration at the location of well 1CES 0052 CE.
Temperature calibration of the two models, calibrated and decreased heat flow scenario, additionally using decreased radioactive heat production in the basement. Dip line (top): 1CES 0052 CE (left) and 1CES 0055 CE (right). Strike line: 1CES 0048A CE (left), and 1CES 0005A CE (right). Good fit with present day temperature data.
Temperature calibration at 1CES 0050 CE (Strike line). The mentioned Base Case scenario yields over-calibration (left). In spite of decreased heat flow (additionally -5 mW/m2), the results of the separately calibrated scenario (right) show a similar over-calibration.
Heat flow history of a location roughly in the middle of the Strike line, Base Case scenario. Note the slow heat flow decline between approximately110 and 66 Ma.
Present day temperature of the base case scenario. Faults are not displayed in this chapter for better visibility of the results.
Temperature of pre-defined leads (base case scenario). Most leads show present day temperatures above 70° C. Location of time extractions (Figure 196) are indicated (red dots).
Time Extractions showing the temperature history of the lead in the SAG layer (left), and of the lead in the Paracurú Formation (right). Extraction locations are displayed in Figure 195. Red lines indicate 80°C.
Present day temperature of the `hottest` scenario. The isolines are elevated by approximately400 in the shallow part of the section. Compare with Figure 194.
Present day temperature of the `coldest` scenario. The isolines are depressed by approximately400 in the shallow part of the section. Compare with Figure 194.
Present day maturity (%Ro) of the Base Case scenario. The yellow area indicates overmaturity. It is elevated around the volcanic build-up due to the high temperatures during intrusion of volcanics.
Present day maturity (%Ro) of the Base Case scenario, shown for source rocks only. Location of time extractions shown in Figure 201 are indicated with red dots.
Maturation history of the two sources? Mundaú Fm. (left), and Paracurú Fm. (right). See Figure 200 for location of the extractions.
Comparison of the two alternative schemes of age assignment. `Official` ages (top) versus younger, IPEX age assignment (bottom). The differences are marginal.
Variability of present day maturity in dependency upon heat flow history. `Hot` scenario (top) versus `cold` scenario (bottom). The results are not dramatically changed.
Impact of erosion on present day maturity. Scenario with zero eroded thickness. The results are hardly modified (compare with Figure 200).
Impact of radioactive heat production in the Basement layer. Scenario with no heat production (top) versus scenario with default properties of a Precambrian granite (bottom). The impact is well visible. The Base Case scenario therefore uses only 50% of heat production of the mentioned lithology.
Maturity of the sources as calculated in the second, `coldest` Base case scenario. Slight differences when compared with the results displayed in Figure 200.
Transformation Ratio of the two source rocks as calculated in the Base Case scenario.
Transformation Ratio of the two source rocks as calculated in the `Really Cold` scenario (top), and in the `Zero Eroded Thickness` scenario (bottom).
Transformation Ratio in the `coldest` scenario (70-40).
Transformation Ratio in the scenario using the simpler kinetics by Pepper & Corvi.
Time extraction of the Mundaú source rock (base case). Location is displayed in the right-hand Figure (red dot). Left Figure: Black curve shows temperature through time. Red curve shows transformation ratio. Note impact of erosions in the temperature history (‘kinks’).
Time extraction of the Mundaú source rock (cold scenario 70-40). Location is displayed in the right-hand Figure (red dot).
Time extractions of the Paracurú source rock (base case). Locations are displayed in the right-hand Figure (red dots). Left Figure: All curves now show transformation ratio through time. Note partially ongoing transformation in the Tertiary.
Time extractions of the Paracurú source rock (very cold). Locations are displayed in the right-hand Figure. In the left graph, blue and purple curves show temperature, while black and red curves show transformation ratio.
Distribution of Pressure Excess Hydraulic. Overpressure is present in the deep part of the sequence inboard of the shelf slope. Note that the range of values is 0 -5 MPa in this Figure.
Modeled porosity distribution. The only lead which faces a risk of porosity / reservoir quality is the deepest one, located in the SAG sequence.
Present day temperature of the strike line, base case scenario. The lifted isolines at basement level are due to high conductivities of the volcanic rocks above.
Temperature of pre-defined leads (base case scenario). All shallow leads show present day temperatures below 70° C. Location of time extractions (Figure 219) are indicated (red dots).
Time extractions of selected leads (base case scenario). The extractions are shown from left to right according to their location indicated in Figure 218. Small risk of biodegradation (top and bottom), medium risk of secondary cracking in the deepest lead (middle).
Reservoir temperatures as a result of simulating the `coldest` end member scenario. Variability of reservoir temperatures is not dramatic.
Present day maturity of the strike line, base case scenario. Overlay is displayed for the whole section (top), and for the source intervals only (bottom). Blue color indicates immaturity, green colors show oil window maturity, red is for gas window. The Paracurú source is immature in the platform area, while the Mundaú source is largely in the gas window.
Present day maturity of the strike line, sensitivity testing. Hottest end member (top), and coldest end member (bottom). The general maturity profile is not modified by in large.
Transformation ratio of sources in the base case scenario. The Mundaú source is mostly completely transformed. The Paracurú source shows a similar range of maturity when compared to the results of the dip line.
Sensitivity testing of transformation ratio. Hottest end member scenario (top), and scenario with zero eroded thickness (bottom).
Time extractions of the Mundaú source rock (base case). Locations are displayed in the right Figure. In the left graph, all curves display history of transformation ratio.
Time extractions of the Paracurú source rock (base case). Locations are displayed in the right Figure. All curves display history of transformation ratio.
Distribution of Pressure Excess Hydraulic. No significant overpressures are present in the Strike line model. Note that the range of values is 0 -5 MPa in this Figure.
Modeled porosity distribution. The only lead which faces a risk of porosity / reservoir quality is the deepest one, located in the SAG sequence.
Migration history of the Dip line. Displayed time steps are 103 Ma, 99 Ma, 80 Ma, 66 Ma, 23 Ma and Present Day. The blue overlay colors indicate areas with petroleum saturation above zero. Green vectors depict liquid, red vectors vaporous hydrocarbons. Most expelled HCs (mostly gas from the Mundaú Formation) are lost through seepage until 23 Ma. The Paracurú source rock charges the system very late.
Migration simulation results of the base case scenario. The modeled accumulations are very small. The total amount of trapped liquids is only 12 MMbbls. See Figure 229 for further explanation.
Migration simulation results of the base case scenario, calculated in IP mode (default settings). The modeled accumulations are very small. Dark green and red dots indicate migration (percolation), light green and red dots indicate accumulated petroleum. See Figure 229 for further explanation.
Migration simulation results of the base case scenario, calculated in IP mode (default settings). Zoom-in into the platform area. No overlay is displayed in order to make the lead distribution visible (yellow). One accumulation is highlighted (red arrow).
Migration simulation results of the hottest scenario (`CrustHF`). Charge from the Paracurú is considerably increased.
Migration simulation results of the coldest scenario (`70-40`). All hydrocarbons are now sourced from the Mundaú sequence.
Migration simulation results of the colder Base Case scenario with dedicated seals above the defined leads. The amount of trapped petroleum is not significantly increased.
Migration simulation results of the colder Base Case scenario with dedicated seals above the defined leads, calculated in IP mode. The amount of trapped petroleum is now well increased. The accumulation in the Sag layer (red arrow) now contains approximately 97 MMbbls of oil in place. Two other accumulations are highlighted with red circles.
Migration simulation results of a `hotter` scenario (Crustal heat flow -10 mW/m2) with dedicated seals calculated in IP mode. A lead in the slope area in the Paracurú Formation is highlighted (red circle).
Migration history of the strike line. Displayed time steps are 103 Ma, 98 Ma, 80 Ma, 66 Ma, 23 Ma and Present Day. The blue overlay colors indicate areas with petroleum saturation above zero. Green vectors depict liquid, red vectors depict vaporous hydrocarbons. Most expelled HCs are lost through seepage until 23 Ma. Recent oil charge (green) occurs from the Paracurú source in the eastern part of the section.
Migration modeling result of the Strike line (base case scenario). Selected accumulations in defined leads are highlighted (red circles).
Migration modeling result of the Strike line (base case scenario). Zoom-in into the eastern area. No overlay is shown for visibility of leads (yellow). Accumulations in leads are highlighted (red circles). One accumulation is shown with composition (red arrow).
Migration modeling result of the Strike line (base case scenario), calculated in IP mode. Zoom-in into the eastern area. No overlay is shown for visibility of leads (yellow). Accumulations are generally similarly distributed, but mostly smaller. The same accumulation as in Figure 240 is highlighted (red arrow).
Migration modeling result of the Strike line (`hot` scenario with unchanged Crustal heat flow).
Migration modeling result of the Strike line (`cold` scenario, 70-40 mW/m2).
Migration simulation results of the scenario with special sealing lithologies above the leads. A much larger amount of Mundaú sourced hydrocarbons is trapped in this version of the model. One large accumulation occurs in the Mundaú Formatio.
Migration simulation results of the scenario with special sealing lithologies above the leads combined with higher heat flow.
Comparison of fault scenarios. The total amount of trapped petroleum and the filling of one selected accumulation (red arrow) are displayed. Closed faults (top), and open faults (bottom). Open properties for normal faults /closed properties for reverse faults (top), and no faults considered (bottom).
Dip line model with facies overlay, displaying the defined and numbered leads.
Strike line model with facies overlay, displaying the defined and numbered leads.
Event chart of Ceará Basin showing the main events during the evolution of the petroleum system of the basin.
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