Oil–source rock correlation and quantitative assessment of Ordovician mixed oils in the Tazhong Uplift, Tarim Basin

The origin of the marine oils in the Tarim Basin has long been a disputed topic. A total of 58 DST (drill stem test) crude oil and 8 rock samples were investigated using a comprehensive geochemical method to characterize and identify the origin of the Ordovician oils in the Tazhong Uplift, Tarim Basin, northwest China. Detailed oil–oil and oil–source rock correlations show that the majority of the oils have typical biomarker characteristics of the Middle-Upper Ordovician (O2+3) source rock and the related c...     

Stability of vegetable based oils used in the formulation of ecofriendly lubricants – a review

Human need for energy is insatiable. ManBackspace use of conventional and unconventional hydrocarbon sources has served human energy requirements but not without associated challenges of renewability, toxicity, depletion, degradability, and environmental hazards. Since a complete substitute for fossilized-energy sources is yet to be realized, one viable options available to man is alternative, renewable, ecofriendly, and biodegradable energy sources – thus, minimizing complete reliance on mineral based energy sources. Lubricants are finding relevance in product processing, transportation, agriculture, and other key sectors of industrial developments as a result of use of machines to aid human operations. While more than 70% of commercially available lubricants are from crude oil/hydrocarbon, commercial formulation of lubricants using vegetable base oils are gaining global interests. Lubricants obtained from bio-based oils are eco-compatible but are widely reported to be thermally and oxidatively unstable, especially when such biolubricants are produced from crude form of vegetable oils. The aim of this review is to reappraise various scholarly works on thermal-oxidative stability of vegetable oils so as to validate their usefulness as potential alternative and renewable sources of energy used in the production of lubricants as against continuous usage of mineral based energy sources which is ecologically non benign.     

Sedimentary Characteristics and Evolution of Asri Basin,Indonesia,in Early Tertiary

1.Introduction The Asri basin is oval in shape,covering about2500km2from north to south.The maximum thickness at the depocenter is around18,000feet(5,500m).It is adjacent to the Hera basin in the west and to the Sunda basin in the southwest(Fig.1).Now it is under the Java sea.The basement consists of granites,granodiorites,marbles,schists and quartzites(Tonkin and Himawan,1999).In the early Tertiary,the eastern side of the basin was a steep slope controlled by syn-rifting,and the western s…     

Origin and controlling factors of chlorite coatings—an example from the reservoir of T3x Group of the Baojie area, Sichuan Basin, China

The study of the chlorite coatings always attracts scholars in China and other countries because the chlorite coatings play an important role in the preservation of residual primary pores in sandstone reservoirs.At present,the study of the origin and the controlling factors is relatively few.The occurrence,time of formation,genesis,controlling factors,and the mechanism of chlorite coatings inhibiting quartz overgrowths were studied in detail with thin section and SEM analysis.Samples were from the sandstone reservoirs of the T3x Group in the Baojie area,the transitional zone from the middle to the south of Sichuan Basin.The results indicate that the chlorite coatings on the walls of the pore spaces are oriented perpendicular to grain surfaces in the form of isopachous(even-thickness) grain-coating,while the chlorite coatings at the contacts between adjacent detrital grains are arranged with a preferred orientation tangential to the surface of detrital grains.The chlorite coatings were formed in the eogenetic stage.They were formed by recrystallization of Fe-rich clay films during the syndepositional period,and chlorite cements would be recrystallized after the coatings’ formation.The formation of chlorite coatings was mainly controlled by the depositional environment,provenance conditions,and diagenetic environment.The presence of chlorite coatings could result in the preservation of primary pores in deeply buried sandstone reservoirs by effectively inhibiting quartz overgrowths and the development of compaction and pressure solution.     

Diagenesis and Its Effect on Reservoir Quality of Silurian Sandstones,Tabei Area,Tarim Basin,China

The diagenetic processes of the Tabei sandstones in the Tarim Basin include compaction, cementation (quartz overgrowths, calcite, clay minerals and a minor amount of pyrite), and dissolution of the feldspar and calcite cement. Porosity was reduced by compaction from an assumed original 40% to about 22.1%. Cementation reduced porosity to 26.6%. The Tabei sandstones lost a little more porosity by compaction than by cementation. Quartz cementation, especially syntaxial quartz overgrowth, is a major cause of porosity-loss in many reservoirs in moderately to deeply buried sandstone. Calcite cementation played a key role in the porosity evolution of sandstones. At the early stage of burial, the early calcite cement occupied most of the pore spaces resulting in significant porosity. On the other hand, some primary porosity has been preserved due to incomplete filling or the presence of scattered patches of calcite cement. In addition to calcite, several clay minerals, including illite and chlorite occurred as pore-filling and pore-lining cements. The pore-lining chlorite may have helped in retaining the porosity by preventing the precipitation of syntaxial quartz overgrowths. Illite, which largely occurred as hair-like rims around the grains and bridges on the pore throats, caused a substantial deterioration of penetrability of the reservoir. Calcite cement dissolution was extensive and contributed significantly to the development of secondary porosity.     

Characteristics of Guang’an Xu6 Tight Gas Reservoir in the Middle of Sichuan Basin,China

Tight gas reservoirs have been researched nearly 50 years and become more and more important in the future with the increasing consumption of nature gas. In this study, the characteristics of Guang’an tight gas reservoir, which lies in the middle of Sichuan Basin, China, was analyzed. This reservoir is a typical tight gas reservoir. First, the porosity and permeability of it are low. Second, it has high water saturation and diffused boundaries. Third, it does not have an obvious seal. Fourth, it does not have a clear gas-water contact. Fifth, it has geologic “sweet spots,” close to source rock. Sixth, it has normal reservoir pressure. According to the actual conditions of Guang’an tight gas reservoir, a new reservoir accumulation model is established, which integrates the knowledge of conventional and unconventional reservoir, and which can explain the special phenomenon that tight gas reservoir can produce water and have normal pressure.     

Source and Reservoir Rock Potential of Tertiary Units in the Kozaklı Basin,Central Anatolia,Turkey

The authors present the hydrocarbon source rock potential and reservoir properties of the Eocene Formations in the Central Anatolian Kozakl? Basin. Potential source and reservoir rocks in the Kozakl? basin include transgressive-regressive bank carbonates, fore-bank, deep-marine shales and sandstones, and coal and bituminous facies. The organic geochemical data of the Middle Eocene shales (Sar?lar Formation) show that inadequate to marginal source rock qualities, and marginally mature to overmature characteristics, resulting from heat flow regime of the studied area. Alemli Member of the ?ncik Formation is good to excellent according to TOC wt% and immature to mature source rock from T_max values. Sedimentological features and age data indicate that the Uzunlu Formation was deposited under the control of antecedent topography. Reservoir properties of the Uzunlu Formation and Keklicek member indicate that the carbonate unit is not adequate for reservoir rock. However, siliciclastics of the Sar?lar Formation could be reservoir potential due to its high porosity and permeability values.     

Characteristics of Oil and Gas Accumulation in Yong’an-Meitai Area of the Fushan Depression, Beibuwan Basin, South China Sea

The Yong’an-Meitai area is the focus of the present exploration in the Fushan Depression, Beibuwan Basin, South China Sea. All oils from this area are geochemically characterized by higher Pr/Ph ratio, higher proportion of heavy molecular weight hydrocarbons, and higher proportion of C29 regular steranes, which indicate that the organic matter of source rocks might have been deposited in an oxidizing palaeoenvironment and be dominated by higher plant organic matter input. The oil from E3w2 (the second member of Weizhou Fm. of the Oligocene) has a much higher density, relatively higher Pr/nC17 and Ph/nC18 ratios, and a “UCM—unresolved complex mixture” on gas chromatograms, which indicate that it has been slightly biodegraded. CPI and other terpane and sterane isomer ratios suggest they are all mature oils. The timing of oil charging in E3w2 and E2l1 (the first member of the Liushagang Fm. of the Eocene) determined by the homogenization temperatures of fluid inclusions and thermal evolution history are from 9-3 Ma and 8-3 Ma, respectively. Thus, the interpretation of E3w2 as a secondary reservoir is unlikely. The timing of oil charging is later than that of hydrocarbon generating and expulsion of Liushagang Fm. source rocks and trap formation, which is favorable for oil accumulation in this area. All molecular parameters that are used for tracing oil filling direction decrease with shallower burial depth, which suggests vertical oil migration. The widely occurring faults that penetrate through the source rocks of the Liushagang Fm. may serve as a fine oil charging conduit.     

The Sedimentary System and Evolution of the Early Tertiary in the Sunda Basin, Indonesia

1.Introduction The Sunda basin covers about7,000km2.Its maximum thickness at the depocenter is around16,000feet(5,000m).It has a north-south direction strike(Fig.1).The basement rock is believed to be Cretaceous granodiorite,metabasalt,mica schist and limestone(Tonkin and Himawan,1999).The basin began to take the shape at the Paleocene-early Oligocene,due to the collision of the Indian plate with the Eurasian plate(Hall,1997;Howells,1997).This collision produced the major NW-SE stress s…     

Existence and implications of hop-17（21）-enes in the lower Cretaceous of the Saihantala Sag, Erlian Basin, China

C31- to C35-hop-17(21)-enes are identified by gas chromatography-mass spectrometry (GC-MS) analysis to exist as double isomers in most samples of the Aershan Formation and members 1 and 2 of the Tenggeer Formation from well SH3. Comprehensive organic geochemistry and organic petrology study indicates that algae and bacteria are the main biological source of lower Cretaceous sediments in the Saihantala Sag, and this is in accordance with the existence of hop-17(21)-enes. The similar distributions of hop-17(21)-enes and hopanes of these samples indicate that hop-17(21)-enes were transformed into hopanes through hydrogenation during diagenesis processes. The existence of hop-17(21)-enes means that not only the formation of organic matter is related to an anoxic environment and a biological source of algae and bacteria, but also hop-17(21)-enes are direct indicators of hydrocarbon rock at an immature to low-maturity stage. High hydrocarbon conversion ratio, algae and bacteria source and a high abundance of organic matter suggest that the Saihantala Sag has the potential to generate immature to low-maturity oil, which may be of great significance for oil exploration in the Erlian Basin.     

Reservoir characterization of the Odovician oil and gas pools in the Tahe Oilfield, Tarim Basin, Northwest China

About 88. 1% of the proven reserves in the Tahe Oilfield in the Tarim Basin of Northwest China are trapped in Ordovician carbonate reservoirs. These reservoirs are formed by unconnected and interconnected networks of karstic porosity forming a heterogeneous and complex reservoir system. Oil, water and gas characteristics vary significantly in different portions of the Ordovician reservoir. There is no uniform oil/water contact in the field, adding to its complexity.An acid fracture treatment is beneficial in 76% of the wells, stimulating nonproductive wells and enhancing production in other wells by fracturing into unconnected reservoirs and enhancing flow pathways with acid. Acid fracture treatments should be a standard procedure for developing this and similar oil fields.     

Water Quality Monitoring of the Bezerra River （Cascavel,Brazil） Using SR-TXRF Technique

The present study aims to monitor and assess the water quality of the Bezerra River located in the Western Brazilian Parana state. For the monitoring of river waters, six samplings were established per month during one year. As indicators of the water quality, physico-chemical parameters such as water temperature, pH, turbidity, dissolved oxygen and COD （chemical oxygen demand） were chosen, as well as trace and majority element concentrations. It is noteworthy that the mean annual values of conductivity, turbidity and COD have progressively increased along the river with maximum values after the Cascavel western sewage treatment plant. Only 13 elements were found in the six collection points, but the metallic elements Cr, Mn, Fe, Cu and Zn have shown concentrations above the maximum limits recommended by Brazilian environmental legislation, suggesting the presence of highly polluting anthropogenic sources. Correlation analyses were used to determine the spatio-variability of water quality variables. The six collection sites were grouped into two clusters, with the element composition in the first cluster （sites 1, 2 and 6） being due to strong anthropogenic activities. The study of the Bezerra River water quality could help to develop municipal environmental policies and help with the management of water conservation in the Bezerra River basin.     

Controls of Tectonics on both Sedimentary Sequences and Petroleum Systems in Tarim Basin, Northwest China

Various orders of sequences were recognized in the Tarim Basin from unconformities. Three mega-sequence groups, six mega-sequences, sixteen super-sequences and forty-two sequences were determined from the Sinian to the Quaternary. The mega-sequences and super-sequences were in accordance with the locally tectonic events occurring in both the north and the south margins of the Tarim plate. The global sea level changes only worked to control formations in the tectonically stable periods or in the low order sequences. The sequences had close relationship to the source rocks, reservoirs and cap rocks, and the tectonic events determined the migration, accumulation, and preservation of the hydrocarbon. The three mega-sequence group cycles, including the early cycle-the Sinian-middle Devonian, the middle cycle-the upper Devonian-Triassic, and the late cycle-the Jurassic-Quaternary, corresponded to three reservoir formation cycles. So, it can be concluded that the local tectonic events controlled both the sequences and the distribution of oil and gas in the Tarim Basin.     

Mechanism of diagenetic trap formation in nearshore subaqueous fans on steep rift lacustrine basin slopes—A case study from the Shahejie Formation on the north slope of the Minfeng Subsag,Bohai Basin,China

Diagenetic traps in conglomerate in nearshore subaqueous fans in the steep slope zones of rift basins have been important exploration targets for subtle reservoirs in eastern China. However, the mechanism of how those traps were formed is not clear, which inhibits further exploration for this type of reservoir. In order to solve the problem, we take as an example nearshore subaqueous fans in the upper part of the fourth member of the Shahejie Formation(Es4s) on the north slope of the Minfeng Subsag in the Dongying Sag. Combining different research methods, such as core observation, thin section examination, scanning electron microscope(SEM) observation, fluid-inclusion analysis, carbon and oxygen isotope analysis of carbonate cements, and analysis of core properties, we studied the genetic mechanisms of diagenetic traps on the basis of diagenetic environment evolution and diagenetic evolution sequence in different sub/micro-facies. Conglomerate in Es4 s in the north Minfeng Subsag experienced several periods of transition between alkaline and acidic environments as "alkaline–acidic–alkaline–acidic–weak alkaline". As a result, dissolution and cementation are also very complex, and the sequence is "early pyrite cementation / siderite cementation / gypsum cementation / calcite and dolomite cementation——feldspar dissolution / quartz overgrowth——quartz dissolution / ferroan calcite cementation / ankerite cementation / lime-mud matrix recrystallization / feldspar overgrowth——carbonate dissolution / feldspar dissolution / quartz overgrowth / pyrite cementation". The difference in sedimentary characteristics between different sub/micro-facies of nearshore subaqueous fans controls diagenetic characteristics. Inner fan conglomerates mainly experienced compaction and lime-mud matrix recrystallization, with weak dissolution, which led to a reduction in the porosity and permeability crucial to reservoir formation. Lime-mud matrix recrystallization results in a rapid decrease in porosity and permeability in inner fan conglomerates in middle-to-deep layers. Because acid dissolution reworks reservoirs and hydrocarbon filling inhibits cementation, reservoirs far from mudstone layers in middle fan braided channels develop a great number of primary pores and secondary pores, and are good enough to be effective reservoirs of hydrocarbon. With the increase of burial depth, both the decrease of porosity and permeability of inner fan conglomerates and the increase of the physical property difference between inner fans and middle fans enhance the quality of seals in middle-to-deep layers. As a result, inner fan conglomerates can be sealing layers in middle-to-deep buried layers. Reservoirs adjacent to mudstones in middle fan braided channels and reservoirs in middle fan interdistributaries experienced extensive cementation, and tight cemented crusts formed at both the top and bottom of conglomerates, which can then act as cap rocks. In conclusion, diagenetic traps in conglomerates of nearshore subaqueous fans could be developed with inner fan conglomerates as lateral or vertical sealing layers, tight carbonate crusts near mudstone layers in middle fan braided channels as well as lacustrine mudstones as cap rocks, and conglomerates far from mudstone layers in middle fan braided channels as reservoirs. Lime-mud matrix recrystallization of inner fan conglomerates and carbonate cementation of conglomerates adjacent to mudstone layers in middle fan braided channels took place from 32 Ma B.P. to 24.6 Ma B.P., thus the formation of diagenetic traps was from 32 Ma B.P. to 24.6 Ma B.P. and diagenetic traps have a better hydrocarbon sealing ability from 24 Ma B.P.. The sealing ability of inner fans gradually increases with the increase of burial depth and diagenetic traps buried more than 3,200 m have better seals.     

Preparation,Characterization, and Properties of 7-Nitrotetrazolo[1,5-f ]furazano[4,5-b]pyridine 1-Oxide

ABSTRACT

The synthesis, characterization, and properties of 7-nitro-tetrazolo[1,5-f]furazano[4,5-b]pyridine 1-oxide (NFP) are reported. NFP is prepared by the diazotization of 3,6-di(hydrazino)-3,5-di(nitro)pyridine followed by the extrusion of molecular dinitrogen and ring closure.     

Petroleum Source Rock Characteristics of the Lower Tertiary Formations in the Ereğli-Ulukışla Basin,Southern Central Anatolia,Turkey

Abstract

Potential source rocks in the Ere?li-Uluk??la basin include Campanian-Maastrichtian limestones and marls, Upper Paleocene-Lower Eocene deep-marine shales, and Middle-Upper Eocene continental slope deposits, including shales and sandstones. Organic geochemical analyses and palynofacies observations show that the organic components in Upper Paleocene-Upper Eocene sediments are mainly coaly and woody, with minor herbaceous and algal-amorphous-like organic matter, indicating that they are terrigenous (mainly Type III and Type IV kerogen). The organic carbon content of these rocks ranges from 0.04 to 0.73%, and they have marginal source rock quality for oil generation. A plot of HI versus T-max values implies that the Upper Paleocene-Lower Eocene samples are in the early stage of oil generation, while the Middle-Upper Eocene samples are thermally immature. The pristane/phytane ratio for Tertiary samples corresponds to a transition from anoxic to oxic depositional conditions.     

In situ Raman spectroscopic quantification of CH_4–CO_2 mixture: application to fluid inclusions hosted in quartz veins from the Longmaxi Formation shales in Sichuan Basin,southwestern China

We re-evaluate the Raman spectroscopic quantification of the molar ratio and pressure for CH_4–CO_2 mixtures. Firstly, the Raman quantification factors of CH_4 and CO_2 increase with rising pressure at room temperature, indicating that Raman quantification of CH_4/CO_2 molar ratio can be applied to those fluid inclusions(FIs) with high internal pressure(i.e., 15 MPa).Secondly, the v_1(CH_4) peak position shifts to lower wavenumber with increasing pressure at constant temperature, confirming that the v_1(CH_4) peak position can be used to calculate the fluid pressure. However, this method should be carefully calibrated before applying to FI analyses because large discrepancies exist among the reported v_1(CH_4)-P curves, especially in the highpressure range. These calibrations are applied to CH_4-rich FIs in quartz veins of the Silurian Longmaxi black shales in southern Sichuan Basin. The vapor phases of these FIs are mainly composed of CH_4 and minor CO_2,with CO_2 molar fractions from4.4% to 7.4%. The pressure of single-phase gas FI ranges from 103.65 to 128.35 MPa at room temperature, which is higher than previously reported. Thermodynamic calculations supported the presence of extremely high-pressure CH_4-saturated fluid(218.03–256.82 MPa at 200 °C), which may be responsible for the expulsion of CH_4 to adjacent reservoirs.     

Perceptions of hygiene training amongst food handlers,managers and training providers – A qualitative study

An important element in the effectiveness of food hygiene training is the support given by managers, both pre and post training, to motivate food handlers to enact the safe food handling practices learnt during training. This study explores the personal views of food handlers, their managers, and accredited training providers towards the provision and evaluation of food hygiene training in the South-West London region, exploring the pre and post training support given to food handlers, and its effects on the attitude and behaviour of food handlers to enact safe food handling practices in the workplace. In total seventy telephone interviews were conducted.Findings demonstrate that most food industry managers are aware of their responsibilities to train food handlers, but often do not provide adequate support to promote the enactment of safe food handling practices, or evaluate its effectiveness. Thus, any positive effects gained from food hygiene training programmes, are ephemeral.     

Joint geophysical and geochemical evaluation of source rocks – A case study in Sayun-Masila basin,Yemen

Integration of geophysical and geochemical approaches is used for qualitative and quantitative evaluation of source rocks. The Upper Jurassic rocks in the Sayun-Masila basin are used as a case study due to its high hydrocarbon potentiality. Stratigraphically, these rocks could be differentiated from base to top into: Shuqra, Madbi and Nayfa formations. The total organic carbon (TOC) values were determined in the shale and/or carbonate intervals of these formations from four studied wells by the ΔlogR method using sonic, resistivity and gamma-ray log data. Then the discriminant analysis was applied in differentiating source from non-source rocks. Also, the effect of the burial and thermal histories on the organic material maturation and the oil and/or gas generation was studied through the application of two analytical methods, namely, the level of organic metamorphism (LOM) and the time-temperature index (TTI), depending on the corrected temperature logs integrated with the time and depth data. The reliability of the obtained results has been confirmed and combined with the results supplied from geochemical analyses. The Upper Jurassic sediments are found to be oil–prone source rock in a mature stage. The Madbi Formation is considered as the most effective source rock. The burial and thermal histories of the basin in four modeled wells showed that mature oil generation window and hydrocarbon expulsion would have been initiated in the depocenters from Upper Jurassic Madbi Formation source rock during Late Cretaceous to Middle Miocene time.