CHARACTERIZATION OF LAKHRA COAL BY TG/DTG

Non-isothermal thermogravimetry (Tg) and derivative thermogravimetry (DTG) studies are reported on a Pakistan lignite and Pakistan subbituminous coal. The burning profiles of the samples shows multi-peak configuration which is indicative of the heterogeneity of organic matter. The volatile matter profiles of these samples are characterized by rate of weight loss.     

Applications of Polycyclic Aromatic Hydrocarbons to Assess the Source and Thermal Maturity of the Crude Oils from the Lower Indus Basin,Pakistan

Abstract

A suite of six crude oils from Lower Indus Basin, Pakistan, were analyzed for geochemical characterization of source organic matter (OM) and thermal maturity. Distribution of polycyclic aromatic hydrocarbons (PAHs), alkylnaphthalenes, alkylphenanthrenes, alkyldibenzothiophenes, and aromatic biomarkers were reported from aromatic fractions of the crude oils. The aromatic hydrocarbons parameters revealed a higher thermal maturity of OM of source rock-generated Lower Indus Basin oils. Calculated vitrinite reflectance values from the methylphenanthrenes index 1 (MPI-1) and methyldibenzothiophene ratio (MDR) indicate that most of the oils reached a late oil generation window of thermal maturity. PAH distributions revealed the oils of two different origins are present in the Lower Indus Basin; two oil samples indicate aquatic source of OM and the aromatic biomarker distributions of retene, 1-MP, and 1,7-DMP indicate a significant contribution of land plant OM in the other four oils. This is the first study to report the distribution of aromatic hydrocarbons from Lower Indus Basin crude oils.     

SOLVENT EXTRACTION OF PAKISTAN COALS (III) EXTRACTION AND CHARACTERIZATION OF THE EXTRACTS BY SPECTROSCOPIC TECHNIQUES

Abstract

The Makerwal coal of Pakistan gives higher extractibi1ity with Tetrahydrofuran ( THF ) as compared to Sharigh, Sor-Range and Lakhra coals. The structural characterization of Pakistan coal extracts by FT-IR spectroscopy indicates that all the extracts contained less condensed aromatic rings in comparision to their original coal.     

Hydrocarbon Source Rock Assessments of the Late Jurassic Black Shales (Tokmar Formation) in the Central Taurus Region of Turkey

Abstract

The hydrocarbon source rock potential and the thermal maturity of the Late Jurassic Tokmar Formation in the Bo?untu area of the central Taurus region have been investigated. Tokmar Formation includes organic matter–rich dark grey shales alternating with carbonates that were deposited under dysoxic to anoxic marine conditions prevailed in the Late Jurassic. A total of 14 samples have been analyzed by Leco and Rock-Eval pyrolysis for determination of their hydrocarbon source rock characteristics and organic maturity. The total organic carbon content of the samples range from 0.26 to 1.53 wt%. The actual Rock-Eval pyrolytic yields (S₁ + S₂ peak values) are between 0.25 and 3.63 mg HC/g rock. The calculated hydrogen index and oxygen index values imply that the main organic matter types are Type II and Type III kerogens. T_max versus hydrogen index values indicate that the Bo?untu samples are thermally mature and took place in the oil generation window.     

Pyrolysis Kinetics of Asphaltite by Thermal Analysis

Abstract

Pyrolysis properties and kinetic analysis of asphaltite were investigated by means of thermogravimetry (TG) and derivative thermogravimetry (DTG). Thermal experiments were carried out from ambient temperatures to 1000°C in nitrogen atmosphere at different heating rates. TG/DTG curves showed that the decomposition proceeds through two steps with DTG peaks corresponding to the weight loss obtained. Kinetic analysis of the asphaltite decomposition steps was carried out under non-isothermal conditions. Coats-Redfern method was used to analyze the TG data for determination of kinetic parameters. Activation energies (E _a ) and pre-exponential factors (k _o ) were calculated for different heating rates and compared.     

Geochemical Characterization of Offshore Western Niger Delta Source Rock

Abstract

A geochemical characterization of rock samples obtained from three offshore fields, MJ, MF, and ML, was carried out. Offshore oil and onshore oil samples were also studied for correlation. The gas chromatographic data showed that the three offshore fields studied exhibited different and unique geochemical signatures. Most rock samples from the MJ field have moderate thermal maturity; n-alkane and their isoprenoid hydrocarbon distribution indicated predominant mixed organic matter with some terrestrial organic matter. The organic matters were deposited in alternating oxic and anoxic environments. In the MF field, sedimentation of the organic matter in the shallow depths was under reducing environments, whereas that of the deeper depth horizons was under oxidizing environments. The rock samples in the field had predominant input from marine organic matter with moderate thermal maturity. In the ML field, the geochemical data indicated that oxic conditions prevailed during sedimentation of the organic matter. About half of the rock samples from this field are thermally mature, with almost equal distribution of marine and terrestrial organic facies. Marine organic matter was prevalent in the shallow depth horizons, whereas terrestrial organic matter was prevalent in deeper depth horizons. The offshore oil samples and offshore rock extracts are also correlative. This study indicates that there are two petroleum systems in the offshore western Niger Delta—marine and terrigenous petroleum systems—though the terrigeonous system is more pervasive.     

Organic geochemistry of the Upper Triassic–Middle Jurassic Shemshak Group (Alborz Mountains,NE Iran)

Abstract

The organic geochemistry of shale samples of Shemshak Group at Dehmolla section in Eastern Alborz Mountains in the present study are discussed throughout the Rock-Eval pyrolysis. The results used to describe the quantity, type, maturity, and petroleum potentials of the Shemshak Group sediments. The pyrolysis data show that the total organic carbon values of the shale samples are between 0.08 and 20.98?wt% and the generation potential (S1+ S2) of the studied samples ranges from 0.02 to 9.47?mg HC/g rock revealing the organic richness of these samples varies from poor to good. The type of hydrocarbon products (S2/S3) ranging from 0.06 to 2.33 and the type of hydrocarbon determined from Tmax versus HI indicate mainly well for gas generation. Based on the HI versus OI plot diagram, the type III of kerogen is the main type of organic matter in studied samples. These data also show that most of the samples were deposited in oxic environments with low sedimentation rate and high amount of organic matter from the terrestrial source. “Tmax” values ranging from 416?°C to 602?°C in studied samples indicate that most of the samples are over mature and located in gas zone.     

The Geochemical Significance of Cambrian Organic Matter From Salt Range of Potwar Basin,Pakistan

Selected Cambrian sediments from Salt Range region of the Potwar Basin of Pakistan have been analyzed for saturated and aromatic hydrocarbons. Biomarker and nonbiomarker parameters are shown immature to marginally mature nature of marine organic matter deposited in suboxic depositional environment and carbonate settings. Interesting feature of straight chain hydrocarbons is the unusual abundance of even carbon numbered alkenes (C₁₆–C₂₈) that probably indicates the strong microbial activity/deposition or contamination by exposure of sediments to surface in younger times. Cambrian organic matter of Salt Range is not much affected and altered by subsurface temperature and pressure. Hence diagnostic molecular parameters are still showing distinction and valuable for interpretation of geochemical characteristics of Cambrian sedimentary organic matter.     

Petroleum Geochemistry of Lower Indus Basin,Pakistan: II. Oil-oil and Oil-source Rock Correlation

Nine crude oils and eight source rock samples from Cretaceous sequences, Lower Indus Basin have been characterized by means of diagnostic biomarker parameters in order to establish genetic liaison among them. The biomarker geochemistry indicators such as relative distribution of C₂₇-C₂₈-C₂₉ ααα-20R steranes, C₁₉ and C₂₃ tricyclic terpanes (TT), C₂₄ tetracyclic terpanes (TeT), hopanes distribution, steranes/hopanes ratio, presence of unidentified compound X (C₃₀ pentacyclic triterpane), and pristane (Pr) to phytane (Ph) ratio suggest that the crude oils contain predominantly terrigenous organic matter (OM). Based on these data, the analyzed crude oils from the Lower Indus Basin are genetically associated and could be classified into a single group. Geochemical correlation studies of crude oils and source rock sediments indicate that Lower Goru shales and Sembar could be the probable source rocks for the petroleum generated from Cretaceous strata, Lower Indus Basin, Pakistan.     

EXTRACTION OF LIGNITE WITH TOLUENE IN SUB- AND SUPERCRITICAL STATES

Abstract

Nine Chinese lignite samples were extracted with toluene using a nonisothermal experimental technique at sub- and supercritical conditions in a semi-continuous apparatus. The effects of lignite properties, pressure, and H-donor solvent on the yields were investigated.

The results show that the oil yield is about 1.8 to 2.7 times that of Fischer assay and the conversion and extract yield increase linearly with the increase of volatile matter of lignite and pressure. When a H-donor solvent (tetraline) is added to the solvent (toluene), the conversion and extract yield are increased.     

Source Rock Characterization Within the Stratigraphic Settings of the Orange Basin,South Africa

abstract

The petroleum source rock potential of different system tracts of a Cretaceous unit of the Orange Basin, South Africa, was evaluated using Rock-Eval pyrolysis. Forty rock samples from eight wells were obtained within the systems tract, Lowstand System Tracts (LST), Transgressive System Tracts (TST), and Highstand System Tracts (HST), in the basin. The results revealed that LST is characterized by mainly marginally organic rich shale samples with a few organic rich rocks, variable organic matter types ranging from Type II to Type IV, and a few samples that are thermally mature but have low organic matter quality. Four samples from two wells (A_F1 and O_A1) in the LST had good petroleum generative potential but were not sufficiently mature for petroleum generation. TST is characterized with a few samples being marginally organic rich, with only one being organic rich, mainly Type III kerogen with few Type IV kerogen, and only a few samples are thermally mature that have low organic matter quality. HST is characterized by many marginally organic rich rock samples, mainly Type III with a few mixed Type II/III kerogen, and only a few samples were thermally mature. The results of this study show that the LST has the best prospect in terms of petroleum generation potential, followed by HST and TST in that order. The study also reveals that limited petroleum source rocks exist, which are also impacted by low thermal maturity levels. The basin is more gas prone than oil.     

Analysis of influence factors of methane adsorption capacity of the Lower Silurian shale

Abstract

The Lower Silurian marine shale gas in South China has great potential. In order to study the influence factors of methane adsorption capacity of the marine shale in Sangzhi block, six samples from the Lower Silurian were investigated by a series of experiments. The total organic carbon (TOC) content ranges from 1.97 to 3.49% and organic matter are in the state of over-maturity. The dominant mineralogical compositions are quartz and clay minerals. The methane adsorption capacity of the studied shale ranges from 1.5627 to 2.2033?cm³/g, and is mainly influenced by the TOC content.     

Source Rock Characteristics,Organic Maturity,and Hydrocarbon Potential of the Lower Paleozoic Sequences in the Taurus Belt of Turkey

Abstract

Like elsewhere in the world, Lower Paleozoic (Cambrian-Ordovician-Silurian) formations in Turkey are also exposed in limited areas. Lower Paleozoic sequences are exposed at various parts of the Taurus belt in southern Turkey. In this study, organic matter content, type, and maturity of organic matter and their hydrocarbon potential were investigated. In addition, the Lower Paleozoic is very restricted with respect to species and their diversity. Therefore, it is very important to investigate type and content of organic matter within the Lower Paleozoic sediments. In general, total organic carbon (TOC) values of Lower Paleozoic sequences are extremely low. TOC could not be measured in Cambrian, Ovac?k, and Çaltepe limestones. Shales in the Emirgazi region have very low TOC values. Ordovician and Silurian units also have low TOC values. Total organic carbon in these sequences is residual carbon. In the S ₂-TOK kerogen diagram, all organic materials are plotted in the Type III kerogen field. All samples were composed dominantly of residual organic matter and lesser amounts of Type III kerogen. According to T _max values, the Cambrian, Ordovician, and Silurian formations are over maturity character. In addition, these sequences have very low S ₁, S ₂, and HI values.     

Source Rocks Evaluation of Sidi Salem-1 Well in the Onshore Nile Delta,Egypt

Abstract

Ten core samples representing the subsurface formation of Sidi Salem well No. 1, in the onshore Nile Delta, Egypt. The samples were subjected to comprehensive organic geochemical studies (such as rock-eval pyrolysis, gas chromatograph [GC] and gas chromatography-mass spectrometry [GC-MS]) aiming to evaluate potential source rocks, organic matters types, depositional environments, and maturation. The results revealed that the source rocks in the drilled sections are marginally mature to mature zone and have fair to good potential for generating oil and gas. These rocks are dominated by organic matter derived mainly from mixed organic matters (marine and terrestrial) with contributions from algae and bacteria deposited under anoxic to suboxic saline environments.     

CHEMICAL CHARACTERIZATION OF ASPHALT USING THERMAL CHROMATOGRAPHY WITH MASS SPECTROMETRY

ABSTRACT

We have delineated similarities and differences in chemical composition among neat asphalt samples obtained from the Strategic Highway Research Program (SHRP) Materials Reference Library in Austin, TX, and oxidized materials prepared by SHRP contractors using thermal chromatography (TC). This unique method for disassembling complex materials for analysis using precise temperature programming in a controlled and well characterized environment was combined with flamie ionization detection (FID) and with gas chromatographic (GC) separation and mass spectral (MS) detection. Our TC/FID analyses provided thermal profiles of materials under study-quantity of evolved species as a function of temperature--, while our TC/MS studies allowed structures to be assigned to the various components evolved from the asphalt matrix. Distinct differences among neat samples and between neat samples and their oxidized counterparts were easily discerned, both in comparisons of thermal profiles and of compound-specific identifications of components     

The Comparison of Bitumens from Oil Sands with Different Recovery Profiles

Abstract

It has been proposed that, regardless of origin, the recovery of bitumen from oil sands is related to its viscosity. Asphaltene and resin contents are known to affect the viscosity of bitumen. In this article we compare the composition of solvent-extracted bitumens from several Athabasca oil sands with very different recovery profiles. After careful removal of any associated mineral matter by ultra-centrifugation, each bitumen sample was separated into saturate, aromatic, resin, and asphaltene (SARA) fractions by an enhanced SARA technique. The individual components were then characterized by several complementary analytical techniques, including carbon, nitrogen, nitrogen, sulfur, size exclusion chromatography molecular weight (MW_n) plus proton and ¹³C nuclear magnetic resonance spectroscopy. Based on this comparison, we see no correlation between the recovery of bitumen and its composition.     

13NMR CHARACTERIZATION OF HUMIC MATTER PRESENT IN DIFFERENT OIL SANDS

ABSTRACT

Insoluble organic matter (humic matter) present in oil sands can alter the wettability of the inorganic matrix and thereby cause serious problems during bitumen recovery.

Using a cold water agitation test, solids rich in organic matter were isolated from various oil sands which were chosen to reflect different behavior in the hot water extraction process.¹³C NMR examination of these separated solids showed significant structural variations between samples isolated from different oil sands. Humic matter from Utah oil sand appeared to be more aliphatic than that derived from Athabasca oil sand.

Humic acids extracted from organic rich solids as a result of prolonged treatment with 2% NaOH show remarkable similarity in their ¹³C NMR spectra. Humins differ substantially in the relative contribution of the terrestrial and marine source material. There was apparent correspondence between poor bitumen separation and the presence of humin with highly paraffinic structures.     

New Energetic Derivatives of 1-Amino-3-Nitroguanidine

Two new energetic derivatives of 1-amino-3-nitroguanidine were synthesized. The furoxan moiety and 2,4,6-trinitrophenyl moiety were introduced to the nitroguanidine frame. The resulting compounds 3-methyl-4-((2-(N′-nitrocarbamimidoyl)hydrazono)methyl)-1,2,5-oxadiazole-2-oxide (1, C₅H₇N₇O₄) and N′-nitro-2-(2,4,6-trinitrobenzylidene)hydrazinecarboximidamide (2, C₈H₆N₈O₈) were characterized by infrared (IR) spectroscopy, multinuclear nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetry (TG), as well as elemental analysis. The structure of 1 was confirmed by X-ray diffraction. Both compounds possess good thermal stability with the decomposition onset temperature above 180°C. Their sensitivity and explosive properties were investigated by experimental and theoretical methods.     

Evaluation of empirically derived PVT properties for Pakistani crude oils

This study evaluates the most frequently used pressure-volume-temperature (PVT) empirical correlations for Pakistani crude oil samples. The evaluation is performed by using an unpublished data set of 22 bottomhole fluid samples collected from different locations in Pakistan. Based on statistical error analysis, suitable correlations for field applications are recommended for estimating bubblepoint pressure, oil formation volume factor (FVF), oil compressibility and oil viscosity.     

Spectroscopic Studies on Some Crude Oils from The North Western Desert,Egypt

Abstract

A direct method for crude oil evaluation based on spectral techniques is demonstrated in this article. This method is demonstrated for four crude oils from the El-Faras and Raml oil fields in the North Western Desert in Abu Gharadeg Basin, Egypt. The crude oils have been studied by ¹³C nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. Several parameters calculated from the ¹³C NMR and FTIR spectra provide useful information about the maturity of the organic matter in term of relative aliphatic, aromatic, and carbonyl/carboxyl concentrations; aliphatic chain length; and type and degree of substitution of aromatic structures. These spectra techniques may provide valuable information about the aromaticity and diverse functionalities that are important to the thermal history of the crude oil samples. Results showed that the composition of crude oil samples have higher aliphatic compounds than that of the aromatic compounds.