Brief details of IGI’s current training course modules are given below. Additional topics in the field of petroleum geochemistry and modelling can be covered on request, and emphasis can be placed on particular aspects of each module, as required. Many modules can be supported by examples from clients’ own areas of interest.
1. Geochemical interpretation – Introduction (Intro)
Petroleum geochemistry is best understood in terms of 5 geologically-driven processes, viz. source rock deposition, burial and maturation, oil and gas generation, migration and entrapment, and survival to the present day. Together with the volumes generated and trapped, timing and the range of hydrocarbon types, all major areas of risk in exploration and production can be addressed. This module introduces these key concepts so that they can be developed and built upon during subsequent modules.
2. Analysis – Selection & quality control (Analysis)
An analytical flow chart for screening is contrasted with mid resolution and high resolution analyses of source rocks, oils, gases and stained sediment extracts. Procedures and limitations are addressed.Criteria are suggested for the selection of mid and high resolution analyses to make best use of a fixed budget.Options for the designing and monitoring of a single well geochemical analytical programme are offered.Solutions to issues of sampling, transport and laboratory sample preparation are reviewed.
3. Source rock deposition (SR-Depo)
Hydrocarbon source rocks are characterised by abundant organic matter of an appropriate type. The type of organic matter normally depends more on the survival rates of various components rather than the intrinsic bioproductivity of the environment. Environments range from delta-top coals accumulating with humic acids under oxic conditions and high sedimentation rates to sub-aqueous accumulations with more modest sedimentation rates compensated by reduced dissolved oxygen levels (‘anoxia’). The mechanisms promoting anoxia are discussed and bacterial respiration, sulphate reduction and fermentation processes contrasted. Deposition in carbonate environments typically produces very rich high quality source rocks in restricted platform depressions. Combining anoxia & sedimentation rate, palaeogeography (plate tectonics) and particle hydrodynamics, source rock predictions can be made on a global scale and through time.
4. Recognising and characterising source rocks (SRID)
Kerogen quantities (TOC), and classifications based on microscopy (terminology and equivalences) and Rock-Eval pyrolysis are discussed in terms of the techniques and standard interpretation plots.Microscopy is based on visual inspection and defines more than 12 different types of particle which can be broadly grouped as oil-prone liptinites, gas-prone vitrinites and dead carbon or inertinite.In contrast Rock-Eval pyrolysis gives a bulk measure of the average properties of the rock, defining oil-prone Type I (algal), oil-prone Type II (bacterially degraded algal, land plant exinites or mixes), gas-prone Type III (ligno-cellulosic land plant tissues, vitrinite) and dead carbon Type IV (fossil charcoal or inertinite).Confirmatory evidence from pyrolysis-gas chromatography is recommended.Kerogen type can be generalised in terms of mapping organo-facies.
5. Measured maturity indicators (MeasMat)
Maturity is contrasted with inorganic metamorphism and generation.Vitrinite reflectance measurement procedures are discussed in terms of data quality (microscope standardisation, what to measure, number of particles measured and standard deviation of each reflectance population).Interpretation is then addressed for individual samples (contamination, bitumen, ‘in situ’ and reworked particles), and using depth plots at the single well and multi-well basin-wide scales.Errors are discussed.The effects of unconformities (uplift and erosion), igneous intrusions and hydrothermal flux on reflectance profiles are illustrated. Other maturity parameters such as spore and kerogen colour (SCI1-10 & TAI1-5) and Rock-Eval Tmax are discussed as calibrants for basin modelling.
6. Qualitative and quantitative hydrocarbon generation (Gen)
Generation, as opposed to maturation, is measured in terms of kerogen conversion (Transformation Ratio) and should be used to define the oil and gas windows. screening Rock-Eval or solvent extract data, the process can be monitored using the properties of the residual kerogen or from measurements of the masses (volumes) of generated oil or gas.The scaling problem of moving from a gram of source rock (Rock-Eval) to basin-scale volumes is identified.Generation is a kinetically controlled process, being a function of the effects of both temperature and time on the breakage of the kerogen’s chemical bonds.It can be modelled (Basin Modelling) using simple reactions or networks of competing or sequential reactions.A quantitative understanding of generation (in addition to maturation and expulsion) is essential for successful prospect evaluation.
7 Expulsion of oil & gas (Expel)
Expulsion is the first step in moving generally monophasic hydrocarbon (oil & gas) from the organic kerogen matrix and through fine grained source lithologies (claystone, coal, micrite) via silty laminae or fractures within the source rock interval to the secondary migration conduit.Though we can define the efficiency of the expulsion process relatively accurately, there is no clear consensus concerning the mechanism(s) involved. Currently fashionable front runners include permeable silty interbeds; transient micro-fractures; capillary movement through a kerogen wick within the source rock; diffusion down a concentration gradient away from kerogen particles; pressure driven flux of monophasic ‘oil’ via stylolites (carbonates). Expulsion efficiencies are calculated from pyrolysis or extract yields and commonly lie in the 30-70% range, increasing to 100% with extreme maturity (graphitic schists).
8. Migration of oil & gas (Migr)
Migration is the process by which expelled oil or gas moves from the source rock to the reservoir, from reservoir to reservoir (remigration), or from reservoir to the surface (dismigration or leakage). Once oil has left the source rock (expulsion) three progressively less important processes are involved in the movement of hydrocarbons: buoyancy due to density contrasts in the formation fluids; movement limited by capillary pressures; movement along pressure potential gradients. The mechanisms of, and scales at which, these processes work are currently the subject of debate. Current models envisage migration as occurring in focused conduits, either through an oil-wet network within porous beds or through faults. A description of ‘braided rivers of oil’ may be applied. Mainly propelled by buoyancy, migration can be a relatively efficient process, though models are only semi-qualitative.
9. Source rocks & wireline logs (LogSR)
Source rocks can be recognised from their gamma ray and sonic log response, while generation can arguably be estimated from the resistivity log values.The production of a simple continuous source rock profile from a calibrated gamma-log trace is illustrated and limitations discussed.The so-called 'Geochemical Log' utilising pulsed neutron logging has not been widely adopted, in contrast to the multi-log techniques (gamma, resistivity, sonic and neutron) which require local calibration. Once established, these correlations allow the continuous semi-quantitative monitoring of source richness over a given down-hole interval for source rock volumetric calculations.
10. Introduction to maturity and basin modelling for hydrocarbon exploration (IntroMod)
Modelling is introduced by comparison of the scope, building times, running times, flexibility of calibration and approximate current costs of 1-D, 2-D and 3-D commercial packages. Burial history plots based on 1-D models are discussed in terms of thermal geohistory and calibration against measured temperature and against measured maturity parameters. Maturation and generation windows may then be displayed on the burial history plot, with limits being placed on the timing of generation. Adding TOC values and kerogen (kinetics), produces a generation plot, showing quantitative generation (mg/gTOC, kg/tonne or bbls/acre.ft) as a function of geological time. The relationships to 2-D and 3-D modelling are briefly covered.
11. Inputs to maturity modelling (InMod)
The input of litho-, bio-, and chronostratigraphy to 1-D models is addressed in terms of stratigraphic tops (±datum levels) and thicknesses. The time/age equivalents of various American and European timescales are discussed and the implications of choices addressed.The addition of lithologies to each stratigraphic unit allow the modelling of (de)compaction and hence heat flow modelling.This is followed by a critical discussion of the commonly available compaction options and the implications of choices.The entry of present surface temperatures and the Horner correction of wire line log temperatures may be used to undertake geothermal gradient or heat flow modelling, with the modeller reconciling the differences. Constraints on palaeo-surface temperatures and palaeo-heat flow values are reviewed.
12. Temperature calibration of basin models (Cal_T)
As input data are refined, the concept of a cycle of calibration and re-calibration is introduced. This emphasises what is reasonable to change and what is not, in order to obtain a thermal calibration against (corrected) bottom hole temperatures.The benefits of gradients versus heat flow modelling are revisited, and the sometime paradoxical effects of unconformities on heat flow modelling are introduced. The effects of rapid changes in heat flow (crustal stretching, hydrothermal pulses), changes in sedimentation rates and rapid uplift (unconformities) on temperature transients are illustrated.The modelling of igneous intrusions and hydrothermal flow is addressed using delta heat and delta thickness functions.Deep modelling introduces the increasingly recognised effects of radioactive heat within the crust. The effects of temperature on the maturity and generation outputs of the modelling are investigated using various sensitivity analysis approaches.
13. Maturity calibration of basin models and sensitivity analysis (Cal_M)
Calibrating against measured maturity parameters such as vitrinite reflectance, Rock-Eval Tmax and spore colour is at the heart of good modelling. standard cross-correlations between these parameters are critiqued, with the conclusion that they need to be checked with local data prior to their use for calibration.The modeller needs to gain a 'feel' for the model, with intuition as to how a change in input will affect the output. At the basic level, changes in heat flow and hence temperature gradients (given thermal conductivities) are seen to rotate maturity-depth trends, this being contrasted with the effects of variable amounts of uplift and erosion which translate the maturity-depth trends.The possibility of calibrating against molecular and isotopic parameters is introduced.In addition to geothermal controls, the effects of stratigraphy and tectonic inversion on the maturity and generation outputs of the modelling are investigated using various sensitivity analysis approaches.
14. Pressure calibration of basin models (Cal_P)
For a model with detailed lithology, fluid flow compaction allows the prediction of hydrostatic pressure, pore pressure, fracture pressure and lithostatic pressure. Effectively, only pore pressure is model driven, it being a function of the inability of pore fluid to escape as compaction progresses, expansion due to differential fluid heating and ‘generation pressure’ resulting from the volume changes associated with the reaction ‘kerogen ? oil + gas’.The correction of measured pressure parameters is discussed in the context of optimum calibration.The possibility of estimating palaeo-pressures from fluid inclusions is raised, and the effects of sedimentation rates and uplift (unconformities) on pressure transients are illustrated. The effects of stratigraphy and uplift on over-pressure, thermal conductivity and hence maturity and generation predictions are investigated using various sensitivity analysis approaches.
15. History of maturity modelling, and kinetics (Mod_hist)
History of modelling concepts is investigated by following the sequence depth ? temperature ? Effective Heating Time ? TTI ? single value kinetics ? distributed value kinetics ? n-component kerogen kinetic networks.The intellectual progression from Lopatin-TTI modelling to the use of the Arrhenius equation (activation energies and frequency factors) is followed and the central position of the Transformation Ratio is emphasised. The importance of calibration procedures is elaborated upon, with advice on establishing local calibrations of kinetically-derived Transformation Ratios against measured Rock-Eval and extract depth trends. The basis for the Lawrence Livermore (LLNL) and Easy-Ro methods for the kinetic calculation of vitrinite reflectance is reviewed.
16. Advanced geothermics (GeoTherm)
Geothermics are presented in the context of the structure of the lithosphere and mantle heat together with IGI’s own assembled global heatflow database. The calculation of geothermal gradients is discussed from present day and palaeo-surface temperatures and present day measured and Horner & other corrected temperatures. The recommended method is to calculate a heat flow from down-hole temperatures and the stacked thermal conductivities (based on lithology and compaction). Heat flow values should be consistent with crustal type (continental versus oceanic heat flow values), crustal age, tectonic styles (e.g. back-arc basins, orogenic foredeeps, etc), and, via McKenzie rifting models (beta-factors), to crustal stretching and tectonics. Palaeo-heat flow constraints from AFTA™ and the increasingly recognised role of the radiogenic heat production within the crust are also addressed. The limitations of explicit gradients are contrasted with the realism and flexibility of heat flow modelling.
17. Gas geochemistry (Gas)
A discussion of the significance of C-C gas composition is followed by the interpretation of gas wetness and i/nC ratios, together with kerogen type and maturity controls on dC, dC, dC, dC and DdC values. methane signatures are contrasted with thermogenic gas from various kerogen types; migrational fractionation possibilities are discussed.The effects of intra-reservoir bacterial degradation are highlighted as a decrease in gas wetness and the production of an isotopically heavy propane residue.The natural abundances and origins of non-hydrocarbon gases (CO, Nand HS) are discussed, and their genesis dealt with semi-quantitatively.
18. Geochemistry of gasoline-range compounds (Gasolines)
The naming and identification of the complex mix of gasolines (C, C and C normal, branched, cyclic and aromatic) is discussed together with the calculation of some common ratios.The interpretations of Thompson, Mango and Odden are summarised and contrasted.Variations in gasoline composition are interpreted in terms of hydrocarbon source, maturity, migration (fractionation and phase-separation) and intra-reservoir processes (biodegradation, gas flushing, water washing and intra-reservoir cracking).Though useful for blind correlations, a rather uninformative complex picture emerges in terms of the controlling processes.
19. Gas chromatography: Saturate & aromatic fractions of source rock extracts & oils (GC)
Gas chromatography (GC, the technique) is illustrated and typical fingerprints of whole oil and saturate fractions are viewed.Methods for the reliable identification of pristane (Pr), phytane (Ph), nC, nC, light ends and waxes are followed by the interpretation of derived ratios of Pr/Ph, Pr/17, Ph/18 and various measures of the maturity-controlled carbon preference indices (CPIs). The effects of kerogen type and maturity are compared with migrational fractionation and intra-reservoir alteration. The characteristic ‘hump’ of biodegraded oil is illustrated, and partially degraded oil is contrasted with ‘co-mingled’ mixes of degraded and fresh oil.Aromatic fraction gas chromatograms are discussed in terms of methyl naphthalene, methyl phenanthrene and methyl dibenzothiophene peaks and the derived ratios interpreted mainly in terms of maturity.
20. Application of stable isotopes in hydrocarbon exploration (Isotopes)
The theory of isotopic fractionation in the atmosphere and hydrosphere (oceans, lakes) is discussed, together with the common isotopic ratios of some dominant kerogen-forming plants.Stable carbon isotope ratios of kerogens, extracts & oils, and fractions thereof (dC , dC , etc) are interpreted interms of kerogen type, maturity effects, fractionation and biodegradation. Interpretation of deuterium and sulphur isotopes is briefly addressed by contrasting ‘open’ and ‘closed’ chemical systems.The lack of a full understanding of the processes controlling oil and fraction isotope data is emphasised.
21. Biomarker applications for exploration & production (Biom)
Gas chromatography-mass spectrometry (GC-MS, the technique) is discussed in terms of mass spectra, single ion mass fragmentograms and MS-MS Parent ? Daughter ion transitions. The identification and nomenclature of the C to Csteranes (m/z 217, m/z 218) and the C to C terpanes (m/z 191, m/z 177) is detailed, and the interpretation of presence/absence of peaks and derivative ratios is illustrated in terms of kerogen type, source rock depositional conditions and stratigraphic age, the degree of generation, migrational fractionation and intra-reservoir processes.The interpretation of methyl phenanthrenes and dibenzothiophenes (from GC-MS) in terms of maturity is also covered.
22. Oil-oil & oil-source rock correlation methods (OSC)
Oil-source rock and oil-oil correlation, based on bulk, molecular and isotopic parameters, can be undertaken at three levels: fingerprinting identifying groups, statistically defined families possibly suggesting processes, and correlation based on selected properties indicative of specific geological processes. The latter, tied in with the geological history of the area provides the greatest reduction in exploration risk. The use of simple correlations, of cluster analysis and of multivariate (principal component) statistics is illustrated. common applications and misconceptions are discussed.
23. Reservoir geochemistry (ResGC)
It has been said that an understanding of how a reservoir filled will greatly improve your chances of emptying it efficiently.A trap can be envisaged as a transient interruption of the migration process; traps will thus have ‘fill’ as well as ‘spill’ points, the fill point being charged from the drainage polygon for the structure. Alteration processes operating on oil and gas within the reservoir at a bulk, molecular and isotopic level are identified as compositional compartments, both vertical and horizontal, and relate to the timing of the arrival of oil and gas at (and of changes occurring within) the reservoir. Intra-reservoir pressure potential gradients are important, but may or may not equate to the compositional gradients.
24. Source rock volumetrics (Vol)
The basis for all prospect evaluations is to estimate the volume and timing of the hydrocarbon (oil and gas) charge reaching the prospect structure. The starting point for this calculation is to estimate the amount of oil and gas yield that can be generated in a unit volume (mass) of source rock.The units are either on a weight or volume basis (kilograms of oil and gas per tonne of source rock, cubic metres of oil or gas per cubic kilometres of source rock, or bbls of oil/acre.foot). Pyrolysis is the main analytical approach used to estimate these parameters (S1 and S2 expressed in units of kilogram of pyrolysate per tonne of rock).The S1 peak comprises the free (or migratable) hydrocarbon while S2 represents the future potential of the rock. The fraction of the volumes of oil and gas generated is related to maturity (%Ro, Tmax) and transformation ratios (via kinetics and basin modelling). Recalculation of original hydrocarbon yields is outlined and calibration procedures are discussed.
25. Calculation of charge to trap: An illustrative worked example (Charge)
The reduction of exploration risk is discussed in terms of quantifying petroleum systems.Calculation of oil and gas charge in terms of source rock yields, volumes and timing are based on the efficiencies of generation, expulsion, migration, entrapment and leakage.Workflow for Quantitative Prospect Evaluation is described in the context of regional geology, defining source rock, and calculating initial yield; establishing measured maturity-depth trends, calibrating models and predicting generation; defining source rock kitchens; estimating migration efficiencies; calculating prospect charge; and predicting in-place volumes and properties.The final step is to compare the predictions with the bulk molecular and isotopic properties of the oils and gases discovered.
26. Risking oil & gas charge to trap using IGI’s @Risk Excel spreadsheet (Risk)
Following a discussion of realistic geological distributions for source rock properties and processes, Monte Carlo and Latin Hypercube sampling techniques are reviewed.This workshop element is undertaken using an Excel spreadsheet.The spreadsheet assumes that the basin contains 3 source rock intervals and that each may be encountered at one of four maturity levels (early mature, peak oil mature, late oil mature, main gas mature). Twelve parallel calculations result and are detailed in the spreadsheet rows. The spreadsheet columns cover rock volumes, source rock yields, and amounts of oil and gas generated, migrated and accumulated.The basic inputs are source rock kitchen areas for the required maturity levels, source rock thickness, and source rock TOC and pyrolysis parameters. A number of secondary variables can also be edited to investigate basin sensitivities.Inputs that may be changed are found in variously coloured cells.
Advanced Molecular Geochemistry Modules:
27. Introduction to biomarkers
Introducing what biological marker compounds are and what kinds of information are preserved in their occurrence and composition. The common types of biomarkers are presented, along with a discussion of their origins and preservation in sediments, source rocks and ultimately oils. This module serves as an introduction to the following modules which cover the interpretation of biomarkers in oils and source rocks.
28. Biomarker interpretation: Origin and source
Biomarkers are compounds with recognisable origins in the lipids of organisms, and as such tend to preserve information about the sources of organic matter that contributed to a source rock. This module considers the source -related information that can be obtained from the major classes of biomarker, including standard molecular ratios and interpretive plots.
29. Biomarker interpretation: Source rock environment
Biomarker composition is also sensitive to various aspects of the depositional environment, including organic matter inputs, environmental conditions (oxygenation, salinity) and lithology. These characteristics can often be imparted to oils generated from source rocks, and thus form the basis of oil-oil and oil-source rock correlations. This module presents various biomarkers that preserve information relating to the depositional environment of the source rock, and introduces industry-standard parameters and plots.
30. Biomarker interpretation: Source rock age
As the primary producers of sedimentary organic matter have evolved over geological time, so too has the biomarker record in petroleum source rocks and oils. Known systematic changes in the composition of biomarkers through time can be used to distinguish between Tertiary, Cretaceous, Jurassic and earlier oils. However, it is always prudent to use more than one biomarker parameter to base an evaluation of geological age. This module considers a range of biomarker types that contain age-diagnostic information, and provides guidelines for the evaluation of the geological age of the source rock of an oil.
31. Non-biomarker compounds
This course module introduces other types of molecules that can contain useful information to the petroleum geochemist. Some of these are routinely analysed (gasoline-range and aromatic hydrocarbons), some are becoming more commonly employed (diamondoids), whilst others have to date been mainly used in research applications but offer potential for future application (polar compounds including carbazoles, phenols and sulphur-containing compounds). These different compounds have various developed or potential applications in petroleum geochemistry.
32. Stable isotopes in petroleum geochemistry
Carbon isotopes are most routinely employed in petroleum geochemistry, and can be analysed for whole oils/extracts, various fractions (kerogen, saturated hydrocarbons, aromatic hydrocarbons, etc.) or for individual molecules. This module introduces the concepts of isotopes, their measurement and significance, and their interpretation and application in petroleum exploration.
33. Maturity assessment: Biomarkers
The biomarkers in a source rock progressively change in composition during burial and consequent increasing temperature. A wide range of molecular parameters have been developed and applied by petroleum geochemists in order to measure the degree of maturation of a source rock. Although these maturity parameters are mainly based on empirical observation rather than a true understanding of the underlying processes, in this module we consider the various processes involved in the operation of a molecular maturity parameter. Significantly, when oil is expelled from a source rock, the biomarkers in that oil preserve a record of the maturity of the source rock at the time of expulsion. We also consider which maturity parameters are most useful, and at which levels of maturity.
34. Maturity assessment: Other molecular tools
Many other compounds in petroleum and source rock extracts contain information about maturity; these include the gasoline range hydrocarbons and diamondoids, which can be particularly important for condensates and light oils. Aromatic hydrocarbons are particularly useful for determining maturity levels, and in some cases have been calibrated against vitrinite reflectance for source rocks/coals. This module presents the various maturity parameters that can be employed for non-biomarkers, and a discussion of the different maturity ranges over which they operate.
35. Petroleum alteration: Migration & fractionation
In this module, the first of two considering various processes of alteration that can occur in oils, we consider the processes operating during petroleum migration and various fractionations that can result from partition of different components into different phases (gas and liquid). Oil can interact with minerals, water and organic matter during migration, losing components as it migrates, to leave oil depleted in certain compounds; this has the potential for oil composition to contain information regarding migration distance. In addition, migrating oil can become contaminated by sedimentary organic matter in rocks along the migration path or within the reservoir, serving to overprint the real oil composition. Phase-related fractionation has little effect on biomarker composition, but can strongly influence the composition of gasoline-range hydrocarbons. All these processes are considered in terms of their effects on the molecular composition of oils.
36. Petroleum alteration: Biodegradation & water washing
The related processes of biodegradation and water washing lead to the removal of various components of an oil. Biodegradation is the most problematic, leading to a reduction in oil quality and value, and often removing compounds in the oil that are used in determination of source rock source, environment and maturity, and making correlations difficult. This module concentrates on the effects of biodegradation, so that you can recognize that this process has occurred and what impact it has had on the composition of an oil.
37. Reservoir geochemistry
Interpretation of the composition of oil samples from within a field, structure or reservoir unit can lead to improved understanding of the filling history, and potentially guide optimal production from the field. This module considers the types of geochemical tools that can show the fill point(s) of a field, compartmentalization within a field, and the presence of tar mats that might result from various events in a field’s history.
38. Oil-oil and oil-source correlations
This module introduces the theory and various approaches that are used in correlating different oils, or oils to their source rocks. Correlations seek to identify a genetic relationship between two or more samples (oil-oil or oil-source), and have applications in petroleum exploration and production. Source/facies characteristics are the key, as these are inherited from the source rock, and geochemical parameters that are little modified by maturity and various alteration processes are the most useful in correlations. This module introduces the standard correlation approaches using molecular parameters and plots, and also the application of multivariate statistics in correlations.
39. Correlations: Examples and case histories
Here we present four examples of correlations to serve as illustrative case histories showcasing the various types of approaches that can be used. They cover three petroleum exploration examples in Brazil, Czech Republic and Oman, and an environmental (oil spill) case history. Various compound types are used as well as stable carbon isotopes, and examples from the application of multivariate statistics are also included.
40. Recognising and deconvoluting oil mixtures
All oils should be considered to be mixtures – either of oil charges of different maturity, or in some cases of oils from different source rocks. An accumulation of oil that has been biodegraded can receive a charge of fresh oil, resulting in a mixture of biodegraded and undegraded oil. Oil charges of different maturity contain different amounts of the different compound classes, so that different maturity parameters can give different maturity information, being biased to one particular charge. This module introduces these various concepts and looks at geochemical approaches to the identification of mixed oils and possible approaches to quantifying the mixtures.