See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/303045427 Palynofacies, organic geochemical analyses and hydrocarbon potential of the takoradi 11-1 well, saltpond basin, Ghana Article · January 2015 CITATION READS 1 224 3 authors: David Atta-Peters Christopher Achaegakwo University of Ghana University of Ghana 30 PUBLICATIONS   107 CITATIONS    5 PUBLICATIONS   4 CITATIONS    SEE PROFILE SEE PROFILE Patience Garrey University of Ghana 2 PUBLICATIONS   3 CITATIONS    SEE PROFILE All content following this page was uploaded by Christopher Achaegakwo on 24 January 2017. The user has requested enhancement of the downloaded file. Petroleum & Coal ISSN 1337-7027 Available online at www.vurup.sk/petroleum-coal Petroleum & Coal 57(5) 478-499, 2015 PALYNOFACIES, ORGANIC GEOCHEMICAL ANALYSES AND HYDROCARBON POTENTIAL OF THE TAKORADI 11-1 WELL, SALTPOND BASIN, GHANA *D. Atta-Peters1, C. A. Achaegakwo2, P. Garrey3 Department of Earth Science, University of Ghana, P. O. Box LG 58, Legon, Accra, Ghana *dattapeters@gmail.com1, chrisach007@yahoo.com2, pgarrey@yahoo.com3 Received July 13, 2015, Accepted No vember 23, 2015 Abstract Hydrocarbon potential of the rocks in Takoradi 11-1 well in the Saltpond Basin have been investigated. Palynological and organic geochemical analysis were carried out on 49 cutting samples and 18 core samples respectively. Palynofacies analysis of the Albian – Cenomanian sediments reveal three palynofacies associations: PA-1 reflects deposition in distal mud-dominated oxic shelf conditions, PA-2 and PA-3 depo- sition under distal dysoxic – anoxic outer and inner shelf respectively. Palynofloral association which is indicative of the Albian – Cenomanian elaterate province, has pteridophytic and xerophytic forms that reflect a palaeoenvironment which was moist and humid in a warm coastal plain under arid/semi-arid climatic condition. Geochemical analysis shows low to moderate total organic content (TOC). It varies between 0.53 - 2.73 (ave 0.83 wt% TOC) and S2 values 0.33 – 8.36 (ave. 1.32 mg HC/g rock) which implies a poor to fair source rock. Rock- Eval pyrolysis indicates mainly kerogen type III (gas prone) of hydrogen index (HI) values 53 – 387 (ave 135 mg HC/g TOC). The thermal maturation parameters, Tmax of values between 427 – 441 (ave 436.5 C) and production index (PI) 0.02 – 0.15 (ave 0.06 mg HC/g rock) indi- cate that the rocks in the well are at immature to early mature stage oil window. Keywords: Palynofacies; Kerogen; Palynomorphs; Hydrogen index; Thermal maturation; Production index. 1. Introduction The Saltpond Basin is a Palaeozoic wrench modified pull-apart basin centrally located between the Tano-Cape Three Points and Accra-Keta (Fig. 1). Its total size is approximately 12,294 km2 with 204km2 onshore and 12,089 km2 offshore. About 95% of the basin lies in shallow water. The Saltpond Basin is limited by the Precambrian basin at the north [31]. At the east, it is separated from the Benin embayment by a hinge line whereas at the western limit between Cote d’Ivoire and Saltpond basin, it appears to be an easterly/lateral sedimentary onlap. The Saltpond Basin is mainly characterized by sandstone and shale dominated formations with varied thicknesses. Structurally, the basin is quite complex, characterized by a network of faults which can ultimately displace individual units [22]. Gently rolling folds coupled with the faulted blocks provide the trapping conditions for the accumulation of expelled hydrocarbons into reservoir units. The only known and proven petroleum system in the basin is the lower Palaeozoic petroleum system. This system has Devonian source rocks (Takoradi shales) with Type II kerogen and moderate to good total organic carbon (TOC) and Hydrogen Index (HI). The Devonian to Carboniferous reservoir rocks are the Takoradi sandstone formations. Burial history construction and geochemical analysis indicate that the source rock was mature for hydrocarbon generation in the Middle Cretaceous [2,8,22].. 2. Geology and tectonic setting Offshore, Ghana is situated to the eastward extension of the Romanche and St Paul fracture zones which can be traced to the offset portion of the Mid-Atlantic Ridge. The Saltpond Basin is located on the northwest-southeast trending horst block which is characterized by numerous local faults [22]. These faults subdivide the horst into minor blocks. The horsts together with the grabens form a complex network of faults related to intercontinental rifting associated with transform marginal basins. The basin can be divided into five main genetic units based on age and associated geological events. (Table 1). Fig. 1. Map of Saltpond basin showing Takoradi 11-1 well Structurally, the Saltpond basin is located within the Takoradi Arch, one of the three provinces of Ghana’s coastal basin [14]. According to [14], the arch on which the basin is located is represented by a series of tilted fault blocks striking north-northeast – south- southwest. This observation has been drawn from seismic sections of the basin derived from reflection seismic exploration. The stratigraphic sequence in the Saltpond basin spans the ages of late Ordovician to early Cretaceous as typified by the rocks of the Sekondian Group (Fig. 2), with the oldest formation, Ajua Shales resting unconformably on the crystalline basement rock and the youngest being the Essikado sandstone. Table 1 Genetic units of the Central basin (modified after [22]) Genetic unit Age Remarks (million years) Basement 4000Ma-570Ma Precambrian igneous and metamorphic rocks form the basement on which the Central basin is located. Intra- 463.9Ma-208Ma This unit is characterized by deposits thought to be in cratonic unit an intra-cratonic tectonic regime at the time when the African and South American continental plates were still joined. Formations within this unit are as follows;  Ajua formation  Elmina formation  Takoradi formation  Sekondi formation  Efia Nkwanta formation The sequence is mainly composed of clastic rocks depo- sited in shallow marine to brackish water environments. Pre-rift and 178-167.1Ma A minor clockwise rotation of the South American plate initial rift in relation to the African plate may have occurred as the South Atlantic ocean opened, instigating a dominantly extensional tectonic regime. The initial rifting of the plate began with the emplacement over a widespread area of volcanoclastics and doleritic sills and dikes. In Ghana, the age of these volcanics is dated between 162 Ma and 172 Ma [37]. Syn-rift and 145.6Ma-97Ma Major east-northeast - west-northwest trending fracture wrench unit zones, such as the Romanche and Chain fracture zones were formed as a result of the rifting of Africa and South America plate. In the Saltpond Basin, the Lower Cretaceous is charac- terized by thick, sandstone dominant formation deposi- ted under continental environment. Drift and 97Ma-0Ma Continental drifting began in Early Cenomanian and is passive identified by marine transgression deposits. Based on margin seismic and well data, the two most prominent uncon- formities are of Late Cretaceous and Eocene to Oligo- cene in age [37]. The Upper Cretaceous to Tertiary se- quence is composed mainly of marine shales with sub- ordinate sandstones [35]. 3. Materials and method Forty-nine (49) samples between intervals (5430-9750ft) from the Takoradi 11-1 well was obtained from Ghana National Petroleum Corporation (GNPC) core lab. They were prepared for palynomorphs following standard maceration techniques, using (35%) HCl and (40%) HF to digest the carbonates and silica contents of the samples. The residue was cleaned and centrifuged in ZnBr2 (S.G. 2.0).The floating organic matter was sieved through 10μ and 20μ sieves. Permanent slides were prepared using glycerol gelatin as the mounting medium. All sample slides were studied using the Lecia DMEP 750 microscope. Quantitative analysis of the overall kerogen composition was carried out by counting 400 particulate organic matter and palynomorphs to determine relative abundances in percen- tage of kerogen (Appendix 1, 2). These were then subjected to cluster analysis (Q-mode) using the computer programme SPSS (version 20). This cluster analysis forms discrete groupings that are based on the percentages of kerogens and are thus displayed in a dendro- gram (Fig. 3). TOC and Rock Eval pyrolysis data from 18 core samples was provided by GNPC using Rock Eval II Pyrolyzer. All geochemical results used for the interpretation are listed in Appendix 3 Figure 2 Stratigraphic sequence in the Saltpond Basin (modified after [5]) 4. Results and discussion 4.1 Palynofacies analysis and palaeoenvironment Palynofacies analyses is widely used for studying and explaining organic facies patterns. They permit recognition of sedimentary organic matter (SOM) and in addition describing processes that are contemporaneous or later to formation of the SOM which assists in hydro- carbon source rock evaluation [10,11,55] identified four main constituents of SOM; palyno- morphs, phytoclasts, opaques, and amorphous organic matter (AOM). Palynofacies analyses involves the identification of these groups, their absolute and relative proportions, sizes and preservation rates [54,55]. Being based on optical observation of organic particles present in sedimentary rocks, it provides more variables upon which to base determinations of sedimentary environments [10,55]. Cluster analysis (Q-mode), discriminated three discrete groupings (paly- nofacies type) based on the percentages of kerogens (Fig. 3; Table 2; 3). The AOM-Palyno- morphs-Phytoclasts (APP) ternary plot [55] (Fig. 4) was used to identify depositional environ- ment. Palynomorphs have environmental connotation and can thus be used to infer palaeo- climatic and palaeoenvironmental characteristics [55]. 4.1.1. Palynofacies assemblage 1 (PA-1). Relatively equal dominance of Palynomorphs and AOM. Plate III Fig. A, B PA-1occurs at sample depths (ft) 7860, 8310, 7770, 9390, 9210, 8670, 8760, 8400, 8580, 8490, 6150, 8220, 6060, 9300, 5880, 8040, 8130, 5970, 5430, 5700, 8940, 9030, 7950, 7230, 7320, 5610, 9120, 5520 and 6240. It is made up of relatively equal dominance of AOM (30%) and palynomorphs (32%) with phytoclasts (26%). Opaques have relative abundance of 12%. The palynomorph group is characterized solely by terrestrial palynomorphs. On the APP ternary diagram of [55], PA-1 plots in field V which reflects distal mud-dominated oxic shelf conditions. This facies is attributed to shallow marine – nearshore environment. The fact that terrestrial elements are abundant with the presence of almost structureless woody particles, and the absence of marine palynomorphs, it is likely that the AOM from PA-1 is from terrestrial origin. The absence of marine microplanktons might imply terrestrial con- ditions, but could equally reflect a strong dilution of marine elements by terrestrial organic input [21]. The opaques are most likely derived by the oxidation of translucent phytoclast materials during transport. 4.1.2. Palynofacies assemblage 2 (PA-2). AOM dominant. Plate III, Fig. C, D PA-2 is concentrated at sample depths (ft) 9480, 9570, 9660 and 9750. AOM dominates the total organic matter composition of this palynofacies (up to 45% of total organic matter). The high abundance of AOM is the result from the combination of environments with high preservation rates and low energies in reducing basins, with increased water column resul- ting in dysoxic or anoxic bottom condition. [12, 30, 36, 54, 55]. Phytoclasts (28%) also support the suggested offshore setting, where irrelevantly low concentrations were equated to weak terrestrial influx and deposition in distal settings located far from land vegetation [4]. The presence of terrestrial palynomorphs (14.5%) indicates input from a river or transport from a nearshore environment. Marine microplanktons (0.5%) are rare, this reflects a relatively nearshore marine influence. This palynofacies association (PA-2) plots in the field VII of the APP diagram thus supporting deposition in a distal dysoxic – anoxic shelf environment, located relatively far from high terrestrial organic matter input. 4.1.3 Palynofacies assemblage 3 (PA-3). Palynomorphs dominant with phytoclasts and AOM. Plate III, Fig. E, F. PA-3 occurs at sample depths (ft) 6960, 7050, 6510, 7410, 7140, 6330, 6600, 6690, 7500, 5790, 6780, 6870, 6420, 8850, 7590 and 7680. It is characterized by high percen- tage of palynomorphs (44%) mainly spores and pollen and phytoclast (27%). This palyno- facies is dominated by terrestrial elements with no marine palynomorphs. The dominance of miospores (terrestrial palynomorphs) may suggest that deposition might have taken place in the vicinity of an active fluvio-deltaic environment with proximity to source or nearshore [16, 21]. AOM (23%) is moderately preserved with opaques making up 6% of total organic matter. The low amounts of opaques in PA-3 suggest low salinity due to close proximity to fluvio- deltaic sources [36]. It is also characterized by nearly equal percentages of phytoclast and AOM (27% and 23% respectively) which is indicative of shallow marine to nearshore environ- ment [3]. On the APP ternary diagram, PA-3 plots in field VII which is interpreted to indicate deposition in distal dysoxic – anoxic shelf condition [55]. The higher occurrences of terrestrial palynomorphs and lower abundance of AOM present in PA-3 relative to that in PA-2 indicate deposition in shallower (inner shelf) marine conditions close to land vegetation. Fig. 3 Dendrogram by Q-mode of Takoradi 11-1 well shows the grouping of samples Table 2 Palynofacies associations identified after cluster analysis Palynofacies Types Description Cluster PA-1 Relatively equal dominance of palynomorphs A and AOM PA-2 AOM dominant B PA-3 Palynomorphs dominant with phytoclast and C AOM Table 3 Palynofacies types and their percentages relative abundance of total kerogen. Palynofacies type AOM Phytoclasts Opaques Palynomorphs PA-1 30 26 12 32 PA-2 45 28 12 15 PA-3 23 27 6 44 Palynofacies fields Environment of deposition I Highly proximal shelf or basin II Marginal dysoxic-anoxic basin III Heterolithic oxic shelf (‘proximal shelf’) IV Shelf to basin transition V Mud-dominated oxic shelf (‘distal shelf’) VI Proximal suboxic-anoxic shelf VII Distal dysoxic-anoxic ‘shelf’ VIII Distal dysoxic-oxic shelf IX Distal suboxic-anoxic basin Fig. 4 A ternary APP palynofacies diagram with lower box showing key to palynofacies fields indicated on in the original diagram. (after [54]) 5. Palaeoclimate and palynofloral province The interval under study (5430-9750ft) is characterized by elater-bearing forms which are stratigraphically restricted to the Albian – Cenomanian Elaterate Province in the Africa- South America (ASA) region [1, 6, 13, 23-24, 26-27, 29, 33-34, 39, 44, 46, 51]. This province is characterised by the absence of bi- and trisaccate pollen, low abundances of fern spores, the presence of ephedroid complexes, Classopollis in association with Afropollis and frequent elater-bearing pollen and high percentages of angiosperm pollen. A. jardinus, R. polymorphus and Classo- pollis classoides which are associated with the elater forms in this interval have been reported from Aptian – Cenomanian age and are not found in sediments younger that the Cenomanian. The distribution of these characteristic elements paralleled the palaeolatitude and the axis of the Elaterate Province approximates the palaeoequator [25]. The abundance of the pteridophytic spores (eg. Cicatricosisporites, Deltoidspora, Cyathidites, Concavisporites) in most of the samples is attributable to vegetation growing on wetland such as riversides and coastal areas under fairly humid conditions [43, 45, 49]. These conditions are important for the production and transportation of resinous material (SOM) of high hydrogen index which is essential for hydrocarbon production. The equally high percentage of elater pollen and Afropollis is an indication of their parent plants inhabiting humid coastal plains [15, 38, 47]. The elaterates and associated xerophytes (Classopollis and Ephedripites) have been correlated with warmth and aridity [26, 27, 48, 50, 58]. These sediments were thus deposited in a palaeoenvironment which was moist and humid in a warm coastal plain under arid/semi-arid climate condition. 6. Source rock evaluation Evaluation of source rocks for their hydrocarbon potential is essential in exploration processes. To evaluate the hydrocarbon source potential of the Takoradi 11-1 well, samples were sub- jected to Rock Eval pyrolysis. Four parameters were acquired. These are S1, free hydrocarbons; S2, pyrolyzed hydrocarbons from the cracking of kerogen; S3, quantity of CO2 released and Tmax, the temperature at which most of the hydrocarbons were produced. These parameters were used to calculate the following: Oxygen Index [OI = (S3/TOC) x 100], Hydrogen index [HI = (S2/TOC) x 100], Production index [PI = S1 / [S1 + S2]. The three main factors for evaluating the potential of a rock to produce petroleum are:  Potential quantity of produced hydrocarbon which is based on S1, S2, and TOC.  Hydrogen type index which is based on HI, and S2/S3 ratio.  Thermal maturity for petroleum generation which is based on PI and Tmax [42]. Table 4 below shows the standard guidelines for interpreting source rock quantity, quality and maturation, and commonly used Rock-Eval parameters. Table 4 Guidelines for interpreting source rock quantity, quality and maturation, and commonly used Rock-Eval parameters [17-18, 20, 41, 42, 56] Quantity TOC S (mg HC/g rock) S (mg HC/g rock) 1 2 Poor <0.5 <0.5 <2.5 Fair 0.5-1 0.5-1 2.5-5.0 Good 1-2 1-2 5-10 Very Good 2-4 2-4 10-20 Excellent >4 >4 >20 Quality HI (mg HC/g TOC) S2/S3 Kerogen Type None <50 <1 IV Gas 50-200 1-5 III Gas and Oil 200-300 5-10 II/III Oil 300-600 10-15 II Oil >600 >15 I 0 Maturation Ro (%) Tmax ( C) TAI Immature 0.2-0.6 <435 1.5-2.6 Early Mature 0.6-0.65 435-445 2.6-2.6 Peak Mature 0.65-0.9 445-450 2.7-2.9 Late Mature 0.9-1.35 450-470 2.9-3.3 Post Mature >1.35 >470 >3.3 6.1 Organic richness and hydrocarbon generation potential The organic richness and potential of a rock sample is evaluated by measuring the amount of total organic carbon TOC in the whole rock and pyrolysis derived S [57]2 of the rock samples . Carbonates and shales are considered hydrocarbon source if TOC exceeds 0.3 and 0.5%, respectively [41, 52]. The source rock potential has been identified according to the classification scheme of [9] shown below in Table 5. Table 5 Classification of organic matter quantity and source rock potential Quantity TOC wt% S 2 Poor 0 – 0.5 0 – 1 Fair 0.5 – 1 1 – 5 Good 1 – 2 5 - 10 Very Good 2 – 4 10 - 20 Excellent >4 >20 Samples from the Takoradi 11-1 well have an average TOC of 0.83 wt% and S2 of 1.32 mg/g which indicate fair source rocks (Table 5, Fig. 5). Figure 5 Plot of S2 versus TOC indicating hydro- Fig. 6. Plot of S2 versus TOC indicating the kerogen carbon potential and source rock efficiency types of the studied samples. The plot of S2 versus TOC and determining the regression equation is the best method for analyzing the true average HI and measuring the adsorption of hydrocarbons by the rock matrix [40]. The analyzed samples from the well gave an average HI of 134 mg HC/ g TOC, thus falling in the range of gas prone kerogen (Fig. 6) The plot of HI versus TOC (Fig. 7) presents the relationship between generation potential and the kerogen types present. The TOC results show that most of the samples from the well generally have a fair generative potential and supports the presence of a dominant type III kerogens (gas - prone). Tissot et al. [52] proposed a genetic potential (GP = S1 + S2) for the classification of source rocks. According to their classification scheme, rocks having GP of less than 2 mg HC/ g rock correspond to gas-prone rocks or non-generative ones, 2 - 6 mg HC/ g rock are moderate source rocks with fair gas/oil potential, and GP greater than 6 mg HC/ g rock are good source rocks. The samples in well Takoradi 11 – 1 have poor to fair organic carbon content and poor to fair genetic potential (0.36 – 8.55; ave 1.37) (Fig. 8) and thus the rocks can be described as predominantly gas - prone source rocks. Fig. 7. Plot of Hydrogen index versus TOC indicating Fig. 8. Plot of S1+S2 versus TOC showing the amount of kerogen types and generation potential. Genetic potential of rocks. 6.2 Kerogen type and maturity Kerogen types can be identified by optical methods and by organic geochemical methods where values of elemental analysis of C, O, and H are plotted on a Van Krevelen diagram which defines four types of kerogen [32, 42, 53]. The organic matter type is an important parameter in evaluating source rock potential and has a first order control on the nature of the hydro- carbon products. Kerogen types can also be distinguished by plotting HI versus OI from Rock-Eval pyrolysis on a modified Van Krevelen diagram [18]. The kerogen designation is based entirely on HI [28] but the kerogen quality and maturity are determined by plotting HI versus Tmax rather than HI versus OI (Fig. 9). This eliminates the use of OI as a kerogen type indicator. Fig. 9 shows that the samples are predominantly Type III kerogens (gas prone). The HI values (53 – 142; and 353 and 387 for two samples) for the samples with average HI of 135 HC/g TOC also suggests predominant kerogen Type III. The plot of HI versus Tmax is routinely used to depict both the type of kerogen present in a source rock, in order to avoid the influence of OI for determining kerogen type [28]. Fig.10 shows that the samples from Takoradi well 11-1 contain mainly gas-prone Type III kerogens. The inferred vitrinite reflectance (0.52 – 0.77; ave 0.65) data in Appendix 1 indicates that most of the samples are within the early mature zone. Thermal maturity is influenced by source rock organic matter type and the presence of excess free hydrocarbon together with the other factors like mineral matter, content, depth of burial and age [56]. Data indicators for maturity includes Tmax, Production Index (PI) and Vitrinite Reflectance. The increase of maturity level of organic matter corresponds to an increase in Tmax particularly for immature samples. PI = {S1 / [S1 + S2]} is a valuable method for indicating the thermal maturity of organic matter. The following relations between Tmax and PI are observed:  Immature organic matter has Tmax and PI values less than 430°C and 0.10, respectively;  Mature organic matter has a range of 0.1– 0.4 PI. At the top of oil window, Tmax and PI reach 460°C and 0.4, respectively;  Mature organic matter within the wet gas-zone has PI values greater than 0.4; and  Post-mature organic matter usually has a high PI value and may reach 1.0 by the end of the dry-gas zone [7, 41, 42]. Most of the samples from the well have Tmax > 4350C and <0.1 PI thereby making them early mature and indigenous samples, yet to enter the hydrocarbon generation zone (Fig. 11). Fig. 9 Modified Van Krevelen diagram indica- Fig. 10 Plot of Hydrogen Index versus Tmax ting the Kerogen types of the studied samples. showing the relationship between kerogen types and maturity levels. Fig. 11 Plot of Tmax versus Production Index Fig.12 Plot of Production Index versus Tmax showing the hydrocarbon-generation zone. showing levels of kerogen conversion and maturity. Plot of production index versus Tmax (Fig. 12) indicate that rock samples from Takoradi 11-1 well has a poor to fair source rock quality of early maturity with low level of conversion and no contaminated or migrated hydrocarbons. 6.3 Expulsion ability S1 represents the free hydrocarbons already present in the sample, and S2 represents the hydrocarbons generated during pyrolysis. Free hydrocarbons are those already produced from organic material and will be proportional to the Total Organic Carbon (TOC) of any given source rock. The Ocean Drilling Program uses S1/TOC of 1.5, to determine the presence of indigenous versus migrated or non-indigenous hydrocarbon levels [28]. The plot of S1 versus TOC (Figure 13) shows that all source rocks contain an expected level of S1 hydrocarbons for their given TOC, and are hence predominantly indigenous. Fig. 13 S1 versus TOC as an indicator of indigenous and non-indigenous hydrocarbons 7. Conclusion The organic geochemical analysis of the studied samples show a fair to moderate organic matter (0.53 – 2.37 wt% TOC) which is gas prone. Palynofacies analyses reflect kerogen type III which were deposited in three palynofacies associations: PA-1 which is deposition in distal mud-dominated oxic shelf conditions; PA-2 deposition in a distal dysoxic – anoxic (outer) shelf condition and PA-3 distal dysoxic – anoxic (inner) shelf environment. Deductions from palynomorph assemblages which are characteristic of the Albian – Cenomanian elaterate province, reveal deposition in a moist, humid coastal plain under warm arid/semiarid tropical condition. Organic geochemical analysis indicate mainly type III kerogen, immature to early mature source rock with fair hydrocarbon generation potential to generate gas. Acknowledgement The authors acknowledge GNPC for providing data for the study. Our special thanks goes to Mr. Ebenezer Apesegah, Manager in charge of Geology, GNPC for being supportive during the study. References [1] Abubakar MB, Luterbacher HP, Ashra, AR, Ziedner R, Maigari AS. 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Appendicisporites jansonii Pocock, 1962 B. Triplanosporites sp. C. Gnetaceaepollenites ?irregularis D. Retimonocolpites variplicatus Schrank and Mahmoud, 1998 E. Gleicheniidites senonicus Ross, 1949 F. Galaeocornea causea Stover, 1963 G. Cyberosporites pannaceus (Brenner) Srivastava, 1977 H. Cyathidites australis Couper, 1953 I. Elaterosporites africanensis Herngreen, 1973 J. Cretacaeisporites polygonalis (Jardiné et Magloire) Herngreen, 1973 K. Chomotriletes minor (Kedves) Pocock 1970 L. Elateropollenites jardinei Herngreen, 1973 PLATE II All Figures х 800 Fig. A. Classopollis torsus (Ressinger) Couper, 1958 B. Elaterosporites klaszii (Jardiné et Magloire) Jardine, 1967 C. Reyrea polymorphus Herngreen, 1973 D. Ephedripites irregularis Herngreen, 1973 E. Multiplicisphaeridium ramusculosum (Deflandre) lister, 1970 F. Appendicisporites bilateralis C. Singh, 1971 G. Ephedripirtes sp H. Afropollis jardinus Doyle et al., 1982 I. Sofrepites legouxiae Jardine, 1967 J. Veryhachium lairdi (deflandre) Deunff, 1958 K. Elaterosporites protensus (Stover) Jardine, 1967 L. Cicatricosisporites hallei Delcourt and Sprumont, 1955 PLATE III All Figures х 200 Fig. A, B. Palynofacies Assemblage 1 (PA-1). Relatively equal dominance of AOM and palynomorphs with phytoclasts. C, D. Palynofacies Assemblage 2 (PA-2). AOM dominant E, F. Palynofacies Assemblage 3 (PA-3). Palynomorphs dominant with phytoclast and AOM. PLATE I PLATE II PLATE III Appendix 1 Relative Percentage Abundance of SOM and Palynomorphs DEPTH/FT AOM PHYTOCLASTS OPAQUES PALYNOMORPHS 5430 40.29 14.29 10.00 35.43 5520 34.29 19.43 12.86 33.43 5610 32.86 20.00 10.00 37.15 5700 40.86 17.14 11.14 30.86 5790 23.43 18.29 15.43 42.86 5880 31.43 22.29 13.71 32.57 5970 25.71 25.43 15.71 33.14 6060 29.14 31.43 10.00 29.44 6150 26.57 29.14 12.00 32.29 6240 36.86 18.57 10.00 34.57 6330 21.43 27.14 8.860 42.57 6420 28.29 28.00 5.430 38.29 6510 20.00 32.29 8.570 39.07 6600 22.57 24.00 8.860 41.43 6690 21.71 23.43 7.710 47.14 6780 28.00 28.57 5.710 37.71 6870 28.00 28.29 6.290 37.43 6960 21.14 32.00 6.860 42.00 7050 19.43 29.14 7.430 42.00 7140 10.29 33.43 8.570 47.71 7230 37.43 22.29 7.710 32.57 7320 40.29 21.43 6.000 32.29 7410 17.43 34.29 8.290 40.00 7500 24.86 27.14 14.29 42.29 7590 29.14 25.14 5.140 40.57 7680 32.29 20.00 5.430 42.29 7770 33.71 26.57 8.860 30.86 7860 33.43 29.14 11.14 26.29 7950 31.71 25.71 8.290 34.29 8040 30.29 21.71 14.57 30.86 8130 34.29 21.71 14.57 29.44 8220 28.86 28.29 10.57 32.29 8310 33.43 28.57 11.43 26.57 8400 30.57 31.43 5.140 32.86 8490 28.00 30.57 7.140 34.29 8580 31.43 30.00 7.710 30.86 8670 26.00 33.71 9.430 30.86 8760 23.14 34.57 10.86 31.43 8850 26.29 26.86 8.570 38.29 8940 31.71 23.71 8.290 36.29 9030 32.86 22.86 8.570 35.71 9120 34.29 22.00 9.710 34.00 9210 36.57 26.29 7.430 29.71 9300 30.86 28.57 11.43 29.14 9390 33.71 27.43 10.29 28.57 9480 40.86 29.71 11.14 18.29 9570 40.86 28.29 9.710 21.14 9660 39.71 30.86 16.86 12.57 9750 49.70 25.40 13.40 11.50 Appendix 2 Relative Percentage Abundance of SOM and Palynomorphs used for Ternary Plot DEPTH/FT AOM PHYTOCLASTS PALYNOMORPHS 5430 40 25 35 5520 35 32 33 5610 33 30 37 5700 41 28 31 5790 23 34 43 5880 31 36 33 5970 26 41 33 6060 29 41 29 6150 27 41 32 6240 37 29 35 6330 21 36 43 6420 28 33 38 6510 20 41 39 6600 23 33 41 6690 22 31 47 6780 28 34 38 6870 28 35 37 6960 21 39 42 7050 19 37 42 7140 10 42 48 7230 37 30 33 7320 40 27 32 7410 17 43 40 7500 25 41 42 7590 29 30 41 7680 32 25 42 7770 34 35 31 7860 33 40 26 7950 32 34 34 8040 30 36 31 8130 34 36 29 8220 29 39 32 8310 33 40 27 8400 31 37 33 8490 28 38 34 8580 31 38 31 8670 26 43 31 8760 23 45 31 8850 26 35 38 8940 32 32 36 9030 33 31 36 9120 34 32 34 9210 37 34 30 9300 31 40 29 9390 34 38 29 9480 41 41 18 9570 41 38 21 9660 40 48 13 9750 50 39 12 Appendix 3 WELL: TAKORADI 11-1 Company: GNPC LOCATION: OFFSHORE GHANA S1 S 2 S3 Genetic Hydrogen Oxygen TOC S2/S3 (mg (mg (mg Potential Production Index Index Ro Tmax S1/ TOC Depth (ft) (wt % (mg HC/ HC/ g HC/ g CO2/ (mg HC/ Index (mg HC/ (mg CO2/ (%) (oC) (mg HC/ of rock) mg CO2) rock) rock) g rock) g rock) g rock) g rock) g rock) 4350-4440 2.37 0.19 8.36 0.6 13.93 8.55 0.02 353 25 0.53 427 0.08 5640-5730 0.67 0.01 0.2 30 0.01 6810-6900 0.69 0.03 0.98 0.19 5.16 1.01 0.03 142 28 0.69 436 0.04 6990-7080 0.53 0.03 0.33 0.24 1.38 0.36 0.08 62 45 0.67 435 0.06 7080-7170 0.63 0.04 0.88 0.18 4.89 0.92 0.04 140 29 0.71 437 0.06 7260-7320 0.72 0.04 0.85 0.15 5.67 0.89 0.04 118 21 0.74 439 0.06 7320-7410 0.82 0.03 1.51 0.18 8.39 1.54 0.02 184 22 0.78 441 0.04 7410-7500 0.71 0.04 0.57 0.29 1.97 0.61 0.07 80 41 0.69 436 0.06 7500-7590 0.63 0.02 0.66 0.17 3.88 0.68 0.03 105 27 0.74 439 0.03 7590-7680 0.68 0.02 0.93 0.18 5.17 0.95 0.02 137 26 0.71 437 0.03 7860-7950 0.98 0.04 1.02 0.29 3.52 1.06 0.04 104 30 0.65 434 0.04 7950-8040 1.44 0.05 0.76 0.36 2.11 0.81 0.06 53 25 0.72 438 0.03 8040-8130 0.66 0.05 0.78 0.44 1.77 0.83 0.06 118 67 0.69 436 0.08 8220-8310 0.8 0.07 0.47 0.18 2.61 0.54 0.13 59 23 0.71 437 0.09 8310-8400 0.77 0.02 0.46 0.16 2.88 0.48 0.04 60 21 0.78 441 0.03 8550-8610 0.67 0.12 0.7 0.3 2.33 0.82 0.15 104 45 0.67 435 0.18 8700-8790 0.57 0.03 0.48 0.14 3.43 0.51 0.06 84 25 0.69 436 0.05 9980-10020 0.68 0.17 2.63 3.97 0.66 2.8 0.06 387 584 0.25 Minimum 0.53 0.01 0.33 0.14 0.66 0.36 0.02 53 21 0.526 427 0.01 Average 0.83 0.06 1.32 0.46 4.10 1.37 0.06 134.70 61.89 0.70 436.5 0.07 Maximum 2.37 0.19 8.36 3.97 13.93 8.55 0.15 387 584 0.778 441 0.25 View publication stats