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(a) Geological map of Maharashtra showing the study area (after Deshpande, 1998). (b) Detailed sample locations plotted on the sediment thickness map of Deccan Syneclise (after DGH, 2006).
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The association of iodine with organic matter in sedimentary basins is well documented. High iodine concentration in soils overlying oil and gas fields and areas with hydrocarbon microseepage has been observed and used as a geochemical exploratory tool for hydrocarbons in a few studies. In this study, we measure iodine concentration in soil samples...
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... area of 273910 3 km 2 in the western and south central part of India. Most of the basin is covered under the lava flows of the Deccan basalts of late Cretaceous, below which substantial thickness of Gondwana-Mesozoic sediments exist (Infraline, 2002). The area undertaken for this study is in and around the Dhule district of northern Maharashtra (Fig. 1a). The tectonic map of Deccan Syneclise showing some of the major structural features, updip, pinchouts, and fault closures is illustrated in Figure 2. The basin is bounded to the north by the Narmada-Son rift and to the south and east by Precambrian sediments and Archaean metamorphic rock exposures. The western limit is defined by ...
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... Kaladgi and Bhima depressions and Pranhita-Godavari graben, both with exposures of Gondwana-Mesozoic sediments lie on its southern and eastern margins, respectively, and the Narmada graben with Mesozoic sediments lies on its northern side (DGH, 2006). The study area is demarcated on the geological map of Maharashtra in Figure 1a, and the detailed sample location is shown over the sediment thickness map in Figure 1b. ...
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... Kaladgi and Bhima depressions and Pranhita-Godavari graben, both with exposures of Gondwana-Mesozoic sediments lie on its southern and eastern margins, respectively, and the Narmada graben with Mesozoic sediments lies on its northern side (DGH, 2006). The study area is demarcated on the geological map of Maharashtra in Figure 1a, and the detailed sample location is shown over the sediment thickness map in Figure 1b. ...
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... geophysical studies have shown the presence of $2.5-km thick Mesozoic sediments concealed below 2-km-thick Deccan Trap (DGH, 2006;Rao and Reddy, 2005;Harinarayana, 2008). The map of the sediment thickness modified after DGH, 2006 is shown in Figure 1b. ...
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... and others, 1987;Goudge, 2007). The detailed sample collection points are shown on the sediment thickness map of the Deccan Syneclise basin in Figure 1b. A total of 72 samples were collected from a depth of top 2-6 in. of the soil, at an interval of 5 km using a shovel. ...
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... sediments are expected to form the main source and reservoir facies (DGH, 2006), investigations in the areas of thick sedimentary rocks of Deccan Syneclise may be helpful to prioritize the regions for further activities. The northern part of sampled area, which reflects a majority of high iodine values, has sediment thickness of about 2-2.25 km (Fig. 1b). The middle region or the basement high-separating two relatively thick sediment sections i.e., north of Shirpur and north of Sakri-shows the elevated concentration of iodine (Fig. 1b). The southern part of the study region does not show the basement high and has comparatively thin sedimentation with lower values of iodine (<5 ppm). ...
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... the regions for further activities. The northern part of sampled area, which reflects a majority of high iodine values, has sediment thickness of about 2-2.25 km (Fig. 1b). The middle region or the basement high-separating two relatively thick sediment sections i.e., north of Shirpur and north of Sakri-shows the elevated concentration of iodine (Fig. 1b). The southern part of the study region does not show the basement high and has comparatively thin sedimentation with lower values of iodine (<5 ppm). The iodine anomalies are associated with the fixing of iodine in soils because of the interaction with the seeping hydrocarbons, thus a more likely inference drawn from this concentration ...
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... higher concentrations ($80-300 ppm) of these hydrocarbons are seen around Dondaicha, Sindkheda, north-west of Shirpur, and to some extent around west of Dhule. The iodine concentrations, posted over the light hydrocarbons (RC 1-4 ), show the iodine highs (>5 ppm) overlying the high concentration of soil gases near Dondaicha, Sindkheda, and northwest of Shirpur (Fig. 6a). The iodine lows are observed north east of Sakri and north of Dhule and between Dondaicha and Shirpur, where the soil gases are also found in low concentration (<60 ppm; Kumar, 2009). ...
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... Surface geochemical surveys allow rapid and low-cost preliminary identification of hydrocarbon-bearing regions from hydrocarbon microseepages [18][19][20][21] . The underlying concept of surface geochemical prospecting is that faults and fractures provide pathways for light gaseous hydrocarbon migration from subsurface geological formations to the surface or shallow environment by diffusion and effusion, resulting in anomalies of surface hydrocarbon gases 22,23 . The existence of all hydrocarbon gas components, such as methane, ethane, propane, butane, and pentane, in the surface soils indicates the possibility of the presence of an active petroleum system in the subsurface 24 . ...
Discoveries of heavy crude oil in the Neoproterozoic rocks (Infracambrian rock sequence) from the Bikaner-Nagaur Basin of India emphasize the significance of studying and exploring the Neoproterozoic source rock potential in the southeastern part of Pakistan. This study evaluates the potential of the source rock in the Infracambrian rock sequence (Salt Range Formation) based on surface geochemical surveys, Rock–Eval pyrolysis, source biomarkers, geophysical characterization, and seismic inversion using machine learning for maturity index estimation. Core samples of Infracambrian rock were extracted for Rock–Eval pyrolysis and biomarker characterization. Additionally, 81 geomicrobial soil and gas samples were collected from the surface to explore the petroleum system and potential source rocks in the subsurface. Advanced interpretation techniques were used to investigate the origin and concentration of hydrocarbon gases at the surface, including Rock–Eval pyrolysis, thermal maturity, source biomarkers, and the environment of deposition of organic matter. The results show that the investigated samples are characterized by restricted marine clay devoid of sedimentary carbonate facies with thermal maturity in the early stage of the oil generation window. The seismic inverted maturity index profile demonstrates a reasonable correlation of thermal maturity with the biomarkers and Rock–Eval pyrolysis. Further scrutiny of the surface geochemical samples confirms the presence of higher concentrations of thermogenic C2–C4 hydrocarbons in the vicinity of anticlinal structures, suggesting the existence of an effective migration path along deep-seated faults to the surface. This study concludes that the Infracambrian rocks on the eastern flank of Pakistan are thicker, thermally mature, and have deep-seated structural closures, indicating a greater probability of heavy and light oil in this area than in the Bikaner–Nagaur Basin, India.
... Generally, these trace elements are found in higher concentrations around the periphery of hydrocarbon anomalies 8 . Previous studies reported the trace elements as useful indicator for hydrocarbon microseepage identification 1,7,13,20,22 . Most of these studies correlated the trace elements concentrations with adsorbed soil gas results and demonstrated that how the trace elements concentrations vary near hydrocarbon anomalies. ...
Active macro seepages of methane that occur in between the north bank of the Brahmaputra river and Himalayan foothill region of Assam Arakan Basin, India, indicate the presence of hydrocarbon accumulation in the subsurface, but the hydrocarbon prospects in this region are not well studied. We carried out an extensive field sampling, which included a total of 58 sediment core collections from an active gas seepage location and nearby areas at a depth of 2–2.5 m. Our sample locations are placed at 1 km intervals laterally. We performed laboratory investigations and mapped near-surface chemical alterations associated with active macro seepages and microseepages. The analysis of geochemical composition of hydrocarbon gases in the sediment indicates both the biogenic and thermogenic origins of seeped hydrocarbons. The stable isotope analysis of methane suggests the presence of thermogenic as well as mixed biogenic-thermogenic gases. The presence of such mixing of gases is caused by the secondary alteration processes during their migration through potential faults and fractures. The trace elements of the sediments show anomalous concentrations at different parts of the study area, with a wide range of concentrations for Ba (54 to 492 ppm), Cu (1–25 ppm), Cr (61–329 ppm), Ni (1–42 ppm), Pb (2–48 ppm), Th (2–32 ppm), U (4–39 ppm), V (19–133 ppm) and U (0.87–6.5 ppm). There are higher concentrations of adsorbed gases, trace elements, and microbes along the identified lineaments. Such higher concentration can be triggered by high hydrocarbon-oxidizing bacteria count, which is greater than 104 cfu/gm of soil of bacterial growth around the lineaments. We identified potential hydrocarbon prospects based on the macro and micro seepage analysis using integrated geological, geochemical and microbial techniques in the study area.
... Surface geochemical surveys allow rapid and low-cost preliminary identi cation of hydrocarbon-bearing regions from hydrocarbon microseepages 23,53−55 . The underlying concept of surface geochemical prospecting is that faults and fractures provide pathways for light gaseous hydrocarbon migration from subsurface geological formations to the surface or shallow environment by diffusion and effusion, resulting in anomalies of surface hydrocarbon gases56,57 . The surface geochemistry shows anomalous concentrations of thermogenic C2-C4 hydrocarbons gases in surface soils above anticlinal structures that con rm the occurrence of mature source rock in the basin as well as an active migration. ...
Discoveries of heavy crude oil in the Neoproterozoic rocks (Infracambrian rock sequence) from the Bikaner-Nagaur Basin of India emphasizes the significance to study and explore the Neoproterozoic source rocks potential in the southeastern part of Pakistan. This study evaluates the potential of the source rock in the Infracambrian rock sequence (Salt Range Formation) based on surface geochemical surveys, Rock-Eval pyrolysis, source biomarkers, geophysical characterization, and seismic inversion using machine learning for maturity index estimation. Core samples of Infracambrian rock were extracted for Rock-Eval pyrolysis and biomarker characterization. Also, 81 geo-microbial soil and gas samples were collected from the surface to explore the petroleum system and potential source rocks in the subsurface. We followed the standard laboratory procedures to investigate the origin and concentration of hydrocarbons gases at the surface, thermal maturity, the source facies, and the environment of deposition of organic matter. The results show that the investigated samples are characterized by restricted marine clay devoid of carbonate source facies with thermal maturity in the early-stage of the oil generation window. Surface geochemical samples also confirm higher concentrations of thermogenic C2-C4 hydrocarbons over the vicinity of anticlinal structures proving the existence of an effective migration path along deep-seated faults to the surface. The inverted maturity index profile demonstrates a reasonable correlation of thermal maturity with the surface geochemical survey, source biomarkers, and Rock-Eval pyrolysis. It validates the reliability of multilayer linear calculator and particle swarm optimization algorithms for inverting seismic reflection data into a maturity index profile. The obtained results indicate a higher probability of heavy and light oil along the eastern flank of Pakistan, where Infracambrian rocks are thicker and more thermally mature, and deep-seated pledged structural closures occur, in comparison to the Bikaner-Nagaur Basin, India.
... Iodine concentrations show good relations with changes in organic matter amounts in marine sediments [70]. The source of iodine in sedimentary basin brines, which are large amounts of hydrocarbon accumulation, is organic-rich dehydrated sediments in the buried basin [8,10,30,68,71]. It is known that oilfield waters contain iodine with higher concentrations compared to seawater [7]. ...
All of the waters of the oil and gas production basins of the world are not saline, but all of them are rich in iodine. Hydrocarbons and iodine-rich waters may be derived from the oil or gas reservoirs in the subsurface to surface by geological events. Surface hydrocarbons seeps, which are direct indicators of an petroleum system in the subsurface may be degraded or volatilizable by atmospheric effects. But iodine is a stable biophilic element and does not volatilize. It is the main reason why iodine is an excellent surface exploration material. Iodine-rich waters provide proving from the surface or near-surface levels of the presence of oil or gas deposits in the subsurface. Iodine-rich waters are rich in mature petroleum hydrocarbons at the same time. Therefore, all organic geochemical analyses performed on rock and gas samples can be applied to these hydrocarbons-rich waters. Iodine-rich waters are an especially unique geochemical tool for petroleum exploration in basins/regions, where source rocks are not exposed at surface as outcrops (covered basins) or have been exhausted (depleted). Thus, it is a more suitable integrated usage of reservoir-targeted iodine geochemistry (water and soil) and oil in water analysis than the source rock-targeted organic rock and gas geochemistry for oil and gas exploration in active tectonic and geologically complex basins. Also, the integrated method has another significant advantage in the sampling richness for exploration in the basin/regions where a large number of water resources are available. Furthermore, the method identifies the presence of oil and gas deposits from a large number of samples. Through this feature of iodine-rich waters, the chances of discovering commercial hydrocarbon accumulations are increased. By performing iodine analysis on mud samples during drilling, it may be possible to determination whether there is commercial oil or gas in the well. Moreover, the zone(s) perforated in the well and the prediction of the volume of oil produced from it may also be determined. Iodine contents of reservoir waters (petroleum saturation, oil/water ratio) are high in petroliferous basins where source rocks are found containing high organic matter. In this case, the water saturation (water% ratio) of production wells will decrease. Reserves of oilfields increase as the iodine contents of reservoir waters increase. In this chapter, we focused the relationships between iodine and petroleum systems, the usage of iodine hydrogeochemical and pedogeochemical methods in petroleum exploration and production, case studies and recent advances.
Keywords: iodine, advanced materials, oil and gas exploration, organic geochemistry, reservoir performance, resource/reserve estimation
... The detection of iodine can be useful for two main types of applications; the first, measurements of the concentration and distribution of iodine in soils [362,424,425], and the transference of iodine in different forms between soils and plants, [426][427][428][429][430][431] as well as foods, [357,432] have been combined with characterization by inductively coupled plasma mass spectrometry (ICP-MS). The second main application is to detect the concentration of iodine and related compounds in a contaminated environment [363,[433][434][435]. ...
Searching for life biosignatures on Mars has been a very popular topic in the world. The Mars Organic Molecule Analyzer (MOMA) and Sample Analysis at Mars (SAM) instruments onboard the Exomars 2022 and Mars Science Laboratory rovers, respectively, are capable of organic matter detection and differentiating potentially biogenic from abiotic organics in Martian samples. To identify organics, these instruments both utilize Pyrolysis-Gas Chromatography coupled to Mass Spectrometry (Pyr-GC/MS), and thermochemolysis using the reagent tetramethylammonium hydroxide (TMAH) and derivatization using a mixture of N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA) and N,N-dimethylformamide (DMF). Both thermochemolysis and derivatization help to increase organic volatility of labile and refractory compounds. However, with the detection of chloride-bearing compounds on Mars, MTBSTFA/DMF, which is leaking on SAM, was considered as a possible carbon source of some organics that have been detected on Mars. Therefore, the reagent byproducts following degradation, both in the presence of and the absence of perchlorates, are proposed as a data reference, as well as possible routes of reagent degradation.In addition to MTBSTFA, TMAH is also used to search for organic compounds that could possibly be bioindicators and biosignatures in Martian samples. Deoxyribonucleic acids (DNA) as an information carrier and ribonucleic acid (RNA) form the basis for life on Earth. However, the optimal experimental conditions for the detection of DNA or RNA fragments and other organic compounds important to Earth life were poorly understood. Therefore, in this thesis, the building blocks of nucleic acids, such as nucleobases, nucleosides, nucleotides, PolyA, andbacteria were analyzed by Pyrolysis-GC/MS with TMAH thermochemolysis using a SAM-like ramp and flash pyrolysis at different temperatures (from 100 to 600 °C). The methylated nucleobases, ribose, and phosphate were detected at the highest intensities at 200 and 300 °C, respectively. Methylated adenine and adenosine are the main thermochemolysis products of Poly A. In addition, bacteria such as E. coli were also analyzed with TMAH thermochemolysis. Results demonstrated that TMAH thermochemolysis is able to characterize the fragments of DNA and RNA even at high temperatures with a limit of detection lower than 104 cells of E.coli.TMAH thermochemolysis was also applied to analyze the organic compounds from natural samples such as bacterial cells. The important organic compounds of extremophile bacteria have been studied and the thermochemolysis temperatures were optimized. The extremophile bacteria include cyanobacteria (Chroococcidiopsis cubana), anctinobacteria (Rubrobacter radiotolerans), and halophilic Archaea (Halobacterium salinarum). DNA or RNA fragments could be detected, with Adenine-derivatives being the easiest to detect and with the highest abundance compared with other nucleobases. However, the main compounds and the most detectable organic compounds from these natural samples are fatty acids. Glucopyranoside is one of the most important target compounds from the three extremophile bacteria used herein. Results demonstrated that TMAH thermochemolysis could be an efficient chemical method to detect life signatures on other planets for future missions.
... Recently, potassium has been used to detect traces of primordial life in rocks (Aubineau et al., 2019). Iodine will be a practical and useful element to identify petroleum deposits and also to reduce the hydrocarbon exploration risk to a minimum and to discover new deposits suitable for commercial exploitation (Mani et al., 2011;Özdemir, 2019). Continental, regional, and local large-scale geochemical projects such as 'International Geochemical Mapping' (Darnley, 1995), demand special requirements for geochemical analysis. ...
Progress in both basic and applied geochemical studies highly depend on the progress of the analytical instrumentation in general. In recent times, there have been spectacular developments in different instrumental analytical techniques used for accurate determinations of elemental/isotopic abundances from per cent levels to pg/g levels in a variety of geological materials. Some of the important instrumental analytical techniques which are currently in use for geochemical studies include atomic absorption spectrometry (AAS), inductively coupled plasma atomic emission spectrometry (ICP‐AES), recently introduced microwave plasma‐atomic emission spectroscopy (MP‐AES), X‐ray fluorescence spectrometry (XRF), instrumental neutron activation analysis (INAA), inductively coupled plasma mass spectrometry (ICP‐MS), ICP‐time of flight mass spectrometry (ICP‐TOF‐MS), high resolution inductively coupled plasma mass spectrometry (HR‐ICP‐MS), and multi‐collector‐ICP‐MS (MC‐ICP‐MS), with each one having its own merits and the limitations. Developments in sensitive high‐resolution ion microprobe (SHRIMP) opened up zircon geochronology and has revolutionized age dating of rocks by in‐situ isotopic analysis on single mineral grains such as zircons. Recently emerged MC‐ICP‐MS in combination with collision/reaction cell is allowing detection of small variations in natural isotopic compositions of non‐traditional stable isotopes. Advancements in other microanalytical techniques such as laser ablation‐ICP‐MS (LA‐ICP‐MS), electron probe micro‐analyser (EPMA), scanning electron microscopy and energy dispersive X‐ray spectroscopy (SEM‐EDS), laser‐induced breakdown spectroscopy (LIBS), have markedly improved direct solid analysis, in‐situ probing of individual minerals, fluids, and melt inclusions. Raman spectroscopy is currently emerging as a powerful geochemical analytical tool. Some interesting combination instruments such as ICP‐MS/AES showed synergic benefits when used in geochemical studies. There is also substantial progress in other critical areas such as sample preparation, sample decomposition, development of geochemical reference materials, and quality issues in general. Miniaturization is perhaps the most notable current trend in analytical techniques, and their use in exploration studies provide near‐real time sampling guidance in the field. In this review, all these aspects are updated, summarized and discussed at depth with practical examples. However, most of these instruments are expensive and complex and future developments may focus on some of the drawbacks of the current systems to realize their full potential for geochemical/geochronological studies. In recent times, there have been spectacular developments in different instrumental analytical techniques such as atomic absorption spectrometry (AAS), inductively coupled plasma atomic emission spectrometry (ICP‐AES), microwave plasma‐atomic emission spectroscopy (MP‐AES), x‐ray fluorescence spectrometry (XRF), instrumental neutron activation analysis (INAA), inductively coupled plasma mass spectrometry (ICP‐MS), ICP‐time of flight mass spectrometry (ICP‐TOF‐MS), high resolution inductively coupled plasma mass spectrometry (HR‐ICP‐MS), multi‐collector‐ICP‐MS, (MC‐ICP‐MS), and sensitive high‐resolution ion microprobe (SHRIMP), which are used for accurate determinations of elemental/isotopic abundances in geological materials, for both basic and applied geochemical studies. Advancements in other microanalytical techniques such as laser ablation‐ICP‐MS (LA‐ICP‐MS), electron probe micro‐analyser (EPMA), scanning electron microscopy and energy dispersive x‐ray spectroscopy (SEM‐EDS), laser‐induced breakdown spectroscopy (LIBS), have markedly improved direct solid analysis, in‐situ probing of individual minerals, fluids, and melt inclusions. There is also substantial progress in other critical areas such as sample preparation, sample decomposition, development of geochemical reference materials, and quality issues in general.
... It was proved by Land (1991) that the fluids in sedimentary basins have a mechanism to flow from depths towards the Earth's surface. Harrison and Summa (1991) calculated the vertical velocities of the fluids in sedimentary basins and suggested iodine release from the thermal alteration of the organic matter in solution (Mani et al., 2011). Synder and Fabryka- Martin (2007) stated that the formation of water has the same 129 I/I age with the environment in which the water is produced and interacts with the organic matter. ...
Iodine concentration found in sedimentary rocks cannot be found in any rock-forming mineral and cannot be absorbed in clays. Shales generally contain high iodine concentrations like 1-20 ppm. High iodine concentrations have been measured in shales containing kerogen, the primary organic matter. As the iodine content increases in shales, the oil and organic carbon content also increases. Organic-rich sediments or their volatile derivatives (hydrocarbons) are the primary sources of iodine in sedimentary basins. Iodine enrichment in basin waters increases with the proximity to the petroleum reservoirs and the depth of burial. Iodine generally migrates together with organic matters due to its proximity to organic matters and is a good tracer for hydrocarbon migration and the movement history of the related waters. Biological connection between iodine and carbon systems are well established. There is a strong correlation between organic C and iodine concentrations in marine sediments. As the iodine preserves its close relation with organic C, the age of the iodine will be the age of the organic matter which the iodine is in relation with. Therefore, iodine has been used in many studies as a sensitive tracer to discover oil and/or gas field. It has been showed by the current studies that the geological and geophysical surveys supported by an iodine-129 isotope system could increase the efficiency of petroleum exploration. In this study, the applications of the 129I isotope system in petroleum geology are examined through the case studies.
Keywords: Iodine, 129I isotope, isotope geochemistry, petroleum geology, oil and gas exploration
... Iodine has been used to discover an oil and gasfi eld in the many studies (e.g. Ginis, 1966;Kudel'sky, 1977;Gallagher, 1984;Allexan et al., 1986;Singh et al., 1987;Tedesco et al., 1987;Gordon and Ikramuddin, 1988;Tedesco and Goudge, 1989;Leaver and Thomasson, 2002;Goudge, 2007Goudge, , 2009Mani et al., 2011;Hummel, 2011). Collins and Egleson (1967), Collins (1969Collins ( , 1975, Bojarsky (1970), Schoeneich (1971), Kudel'sky (1977) and Levinson (1980), in these studies, have proved the relationship between petroleum and iodine-rich waters in hydrocarbon production basins. ...
... Land (1991) and Stueber et al. (1993) studies have proved that to be a fl ow mechanism from depths towards Earth's surface of fl uids in sedimentary basins. Harrison and Summa (1991) has calculated vertical velocities of fl uids in sedimentary basins and suggested iodine releasing model from thermal alteration of organic matter in solution (Mani et al., 2011). Synder and Fabryka- Martin (2007) stated that formation water has same 129I/I age with on the environment it derives and organic matter it interacts. ...
... Potential contribution from preanthropogenic meteoric water is also shown in the diagram (Liu et al., 1997). 1989; Leaver and Thomasson, 2002;Mani et al., 2011) in the Southeastern Anatolia basin. Besides, the identifi cation of oil and gas potential of the basin in detail and the determination of new exploration areas and the selection of new well locations will be drilled in existing licenses of these analyses are expected to provide signifi cant contributions. ...
This study was made for investigating the relationship between iodine and hydrocarbon accumulations and to determine iodine contents of formation waters in the Southeastern Anatolia basin oilfields where have been produced almost all of the Turkey oils (more than 95%). Formation water samples have taken from 234 production wells in 49 oilfields which have different geological structures where oil and gas production has performed by the Turkish Petroleum Company (TPAO).
Also, the drilling mud samples from EBY-17 oilwell in Elbeyli (Adıyaman) field has collected, and their iodine analyses were carried out. Although the fields in the Southeastern Anatolia basin are
old and some fields the secondary production methods are used, the high relationship between the oil and gas deposits and iodine were proved. As well as in other oil and gas fields in the world, not
all reservoir waters in the Southeastern Anatolia basin are saline. However, all of them are rich in iodine. Therefore, the iodine-rich waters are a direct indicator for oil and gas producible reservoirs
(containing mature hydrocarbon). Reservoir-targeted iodine geology and hydrogeology methods have simple sampling process, and laboratory analyses can result in a short time. The results are
low cost, reliable and consistent. In the case when these data are utilized with other geological and geophysical methods, it is determined will be a practical and useful tool to reduce the hydrocarbon exploration risk to a minimum and to discover new deposits suitable for commercial production.
Keywords: Southeastern Anatolia basin, iodine, petroleum hydrogeology, oil and gas exploration, oilfield waters, formation waters
... Basically, geochemical techniques record and analyze the concentrations of gas on the surface area that have migrated from deep accumulations (Sechman et al., 2011). The gas has migrated upward, along the faults or fractures, from subsurface hydrocarbon accumulations to the near surface environment, by diffusion and effusion, which results in surface hydrocarbon anomalies (Mani et al., 2011). This paper presents the results of surface geochemical surveys conducted over the selected petroleum prospective structures at operated Block PM 322 located in the Melaka Straits on the Malay side of the Central Sumatra Basin. ...
The use of surface geochemical exploration methods is based on the concept that all petroleum accumulations suffer some leakage to shallower intervals and eventually to the surface. The objective of this study is to analyze geochemical properties such as moisture content, grain size, and mineral properties of the outcrop sample. Subsequently to relate these geochemical properties with petroleum parameters such as porosity, permeability, fluid flow, type of rock, minerology, and chemical composition. Three samples were collected within 100m x 100m parameters to provide an average value result. The samples were taken 20cm below surface and on the shoreline of Pantai Bagan Lalang. The moisture content and organic content of the sample can be known as a percentage of its oven dried weight with its wet sample. The mechanical sieve method was conducted in accordance with ASTM D 422 for the grain size distribution analysis. Lastly, X-ray diffraction analysis was conducted to identify mineral composition based on the peak from a graphical result computed from the XRD machine. Water content analysis results was then related with the fluid flow of the samples while soil organic content was studied to identify shale deposition. Besides, grain size distribution analysis provided porosity range value and permeability overview when correlated with grain size and sorting of the samples. XRD analysis provided graphical data of mineral composition that can be correlated with sample history. In conclusion, Pantai Bagan Lalang indicates a negative quantitative value of a potential reservoir would have.
... In fact, microbial prospecting method for hydrocarbon research and exploration is based on the premise that the light gaseous hydrocarbons migrate upward from subsurface petroleum accumulations by diffusion and effusion, and are utilized by a variety of microorganisms present in the subsoil biological community (Mani et al. 2011;Wu et al. 2014). The methane, ethane, propane, and butane-oxidizing micro-organisms exclusively utilize these gases as carbon source for their metabolic activities and development. ...
Microbial prospecting technique was applied in El Hajeb oilfield, Tunisia for potential hydrocarbon resource exploration by examining the anomalous abundance of hydrocarbon oxidizing bacteria. The method depends on the seepage of light gaseous hydrocarbons such as C1 – C5 from the petroleum pools to the shallow surface giving the reasonable conditions to the development of highly specialized bacterial population. A total of 51 soil samples were collected from 1.5 m depth. Bacterial counts for n-propane utilizing bacteria ranged between nil and 2.44 × 10⁵ cfu/gm. The light gaseous hydrocarbons analysis showed that their concentrations were 102, 55, 41, 20, 21, 19, 10 and 141 ppb for C1, C2, C3, iC4, nC4, iC5, nC5 and ΣC2⁺, respectively. The gas concentration maps showed the presence of dynamic hydrocarbons micro-seepage from petroleum systems. The integrated geomicrobial and adsorbed soil gas results demonstrated that the anomalous hydrocarbon zones spread in all territory which could presumably help to evaluate highpotentialareas. In conclusion, our study confirms that the use of microbial data and adsorbed gas analyses of soil samples is a low cost tool for hydrocarbon exploration. This technique has been confirmed and can be applied successfully in frontier basins.
