Petroleum Geochemistry and Exploration of Europe

Petroleum Geochemistry and Exploration of Europe Edited by J. Brooks Exploration Division Britoil pie, Glasgow

1983 Published for The Geological Society by Blackwell Scientific Publications Oxford London Edinburgh Boston Melbourne

Published by Blackwell Scientific Publications Editorial offices: Osney Mead, Oxford OX2 0EL 8 John Street, London WC1N 2ES 9 Forrest Road, Edinburgh EH1 2QH 52 Beacon Street, Boston, Massachusetts 02108, USA 99 Barry Street, Carlton, Victoria 3053, Australia First published 1983 9 1983 The Geological Society. Authorisation to photocopy items for internal or personal use, or the intemal or personal use of specific clients, is granted by The Geological Society for libraries and other users registered with the Copyright Clearance Center (CCC) Transactional Reporting Service, provided that the base fee of $02.00 per copy is paid directly to CCC, 21 Congress Street, Salem, MA 01970, USA. 0305-8719/83 $02.00. Set by Preface Ltd, Salisbury Printed at the Alden Press, Oxford and bound by Butler and Tanner Ltd, Frome and London.

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Contents

Page vii

Preface

ix

Introduction: BRooKs, J. GEOLOGICAL AND GEOCHEMICAL CONTINENTAL SHELF

STUDIES

ON NW EUROPE

WALMSLEY,P. J. The Role of the Department of Energy in Petroleum Exploration of the United Kingdom ............................................................................................................ MAKOURINE, m. Gas Exploration and Reserves in Europe ................................................. BARNARD, P. & COOPER, B. S. A Review of Geochemical Data Related to the Northwest European Gas Province ................................................................................................. GERVlRTZ, J. L., CAREY, B. D. Jr. & BLANCO, S. R. Surface Geochemical Exploration in the North Sea ................................................................................................................. FABER, E. & STAHL, W. J. Analytical Procedure and Results of an Isotope Geochemical Surface Survey in an Area of the British North Sea ..................................................... S1GALOVE,J. Petroleum Offshore Sniffer Exploration* ....................................................... CANDY, G. J. Petroleum Exploration Onshore U.K.t ......................................................... BRENNAND, T. P. North Sea Petroleum Exploration* .......................................................... RONNEVIK, H., EGGEN, S. & VOLLSET, J. Exploration of ihe Norwegian Shelf .................. MUDGE, D. C. & BLISS, G. M. Stratigraphy and Sedimentation of the Palaeocene Sands in the North Sea ................................................................................................................. CURTIS, C. D. Geochemistry of Porosity Enhancement and Reduction in Clastic Sediments IRWIN, H. & HURST, A. Applications of Geochemistry to Sandstone Reservoir Studies .... PEARSON, M. J. & WATKINS,D. Organofacies and Early Maturation Effects in Upper Jurassic Sediments from the Inner Moray Firth Basin, North Sea ................................ PEARSON, M. J., WATKINS, D., PI'ITION, J-L., CASTON, D. & SMALL, J. S. Aspects of Burial Diagenesis, Organic Maturation and Palaeothermal History of an Area in the South Viking Graben, North Sea ............................................................................................. CORNFORD, C., MORROW, J. A., TURR1NGTON, A., MILES, J. A. & BROOKS, J. Some Geological Controls on Oil Composition in the U.K. North Sea .................................. FISHER, M. J. & MILES, JENNIFER, A. Kerogen Types, Organic Maturation and Hydrocarbon Occurrences in the Moray Firth and South Viking Graben, North Sea Basin .............. REITSEMA, R. H. Geochemistry of the North and South Brae Areas, North Sea ............... GRIFFITH, A. E. The Search for Petroleum in Northern Ireland ......................................... ROBERTS, D. G. Frontier Exploration in Western and Northwest Europet ........................ PETROLEUM

EXPLORATION

3 11 19 35 51 65 67 69 71 95 113 127 147

161 175 195 203 21'3 223

OF EUROPE

MATrAVELLI, L., RICCHIUTIO, T., GRIGHANI, D. & SCHOELL, M. Origins of Natural Gas in the Po Valley, N. Italy* ................................................................................................. 227 WHITICAR,M. & SCHOELL,M. Isotope Geochemistry of Natural Gases in Central Europe* .. 229 KUCKELKORN, K., WEHNER, H. & HUFNAGEL, H. Geochemical Observations of Oil Generation in the German Alps and their Foreland ..................................................... 231

Contents

vi PETROLEUM

GEOCHEMICAL

PRINCIPLES

AND TECHNIQUES

WELTE, D. H., YUKLER, M. A., RADKE, M., LEYTHAEUSER, D., MANN, U. & RITI'ER, U. Organic Geochemistry and Basin Modelling--Important Tools in Petroleum Exploration .................................................................................................................... McKENZIE, D. P. Basin Evolution and Hydrocarbon Generationt ...................................... DURAND, B. & PARATrE, M. Oil Potential of C o a l s - - A Geochemical Approach .............. SCHENK, P. A., de LEEUW, J. W., VIETS, T. C. & HAVERKAMP, J. Pyrolysis- Mass Spectrometry in Coal Chemistry: a study of the coalification of vitrinites and the typiciation of Australian Brown Coals ................................................................................................. BATI'EN, D. J. Identification of Amorphous Sedimentary Organic Matter by Transmitted Light Microscopy ........................................................................................................... SMITH, P. M. R. Spectral Correlation of Spore Coloration Standards ................................. BUISKOOL TOXOPEUS, J. M. A. Selection Criteria for the Use of Vitrinite Reflectance as a Maturity Tool ................................................................................................................. BARWlSE, A. J. G. Use of Porphyrins as a Maturity Parameter for Oils and Sediments ..... G E O L O G I C A L I N F O R M A T I O N ON H Y D R O C A R B O N ON T H E U . K . C O N T I N E N T A L S H E L F

237 253 255

267 275 289 295 309

EXPLORATION

Introduction: BAXTER, G . G . McKAY, D. J. The Compilation of an Earth Science Bibliography for the North Sea and Adjacent Areas .............................................................................................................. WIGLEY,P. Commercially Available Geological Databanks--U.K.C.S .............................. BROOKS, J. R. V. Geological Information from Hydrocarbon Exploration on the United Kingdom Continental Shelf ............................................................................................ CHEW, K. J. & STEPHENSON,H. E X P H S T - - A Program to Analyse the History of Exploration Success within a Basin or Country ....................................................................... BAXTER, G. G. The Use of Computerised Information in Britoil, Exploration Division*

319

Subject Index ........................................................................................................................

375

* indicates an abstract only t indicates an extended abstract

321 329 343 357 373

Preface In editing this volume of over thirty papers from the Conference: Petroleum Geochemistry and Exploration of Europe the main aim has been speed, but concern for accuracy and style, I hope has not been neglected. Attempts have been made to have a consistent format for each paper, but also to allow some freedom to individual authors. Some of the discussion on the various papers is included in the volume. My task has been eased by the assistance provided by Graham Baxter (Exploration Data Services Group, Britoil plc) who undertook the task of co-ordinating the papers in the section: Geological Information on Hydrocarbon Exploration on the UKCS, which was organised by The Geological Society m Geological Information Group. Thanks are also due to colleagues, who helped out with refereeing some of the papers and special thanks are made to Chris Cornford who willingly assisted in various ways in organising the Meeting, reading the manuscripts and even as 'stand-in' projectionist at the Conference. The papers are assembled from two Conferences: Petroleum Geochemistry and Exploration of Europe and Geological Information

on Hydrocarbon Exploration on the UKCS organised respectively by The Geological Society, Petroleum Geochemistry and Geological Information Groups; held within the British Isles Geological Congress at the University of Glasgow in September 1982. The compilation of the book would not, obviously have been possible without the contributions of the various authors. I sincerely thank each author for their contribution and continued assistance in submitting and checking manuscripts. The meeting was held under the

aegis of The Geological Society and the University of Glasgow and thanks are due to Professor Bernard Leake and Ted Tremlett for their assistance in the organisation of the Conference. Scientific support was given by the Institute of Petroleum. Financial and scientific support, a Conference reception and many other support facilities were provided by Britoil plc and all these are gratefully acknowledged. Assistance must also be acknowledged from Dick Fowle (LASMO), John Brooks (Department of Energy), Bernard Leake (University of Glasgow), Geoff Eglinton (University of Bristol) and Graham Baxter (Britoil) who chaired the various sessions. The Conference was attended by over 350 delegates from U.K., Europe, North America and some from even further afield. These delegates were mainly from oil companies, but consultant companies, research establishments, government organisations and universities were all well represented. It is hoped that the book will inform and assist workers in the oil industry and will be a useful reference for those working in petroleum exploration, not only in Europe but worldwide. The volume will also be a relevant reference work for academic researchers and students in earth sciences wishing to understand and appreciate some of the recent advances in petroleum exploration. I now leave the readers to explore the various papers and trust they will gain some of the flavour of a very enjoyable few days at the Conference. J. Brooks Glasgow, 1982

Introduction

Although the search for oil and gas in Europe, particularly in the North Sea, has been very successful, it has become progressively more difficult and costly in recent years. The need for continuing exploration success in finding accumulations of hydrocarbons has created a climate which favours the use of modern scientific and technological methods and techniques. Amongst these is petroleum geochemistry. Applications of petroleum geochemistry (integrated with petroleum geology) in petroleum exploration has drastically changed in recent years from a post-mortem science to a widely accepted exploration predictive tool. The oil industry, in its search for hydrocarbons, has in recent years extended its exploration activity to take in the entire continent of Europe, both on- and offshore basins. In addition to proving substantial oil and gas reserves, these studies have provided a vast amount of new geological and geochemical information from many different areas of Europe. These advances and applications are reflected in this present volume. The proceedings of Petroleum Geochemistry and Exploration of Europe contains papers by experts in geology, geochemistry, sedimentology, data analysis, petroleum exploration and U.K. government policy that were presented at an International Conference held within the British Isles Geological Congress at the University of Glasgow in September 1982.

Brief history of European petroleum exploration Exploration ofoil and gas has a long and varied history in Europe, but it is only during the last few decades that geological understanding of North-west Europe and its extensive continental shelves has been more fully understood. Since the late 1950s geological understanding of the North-west Europe offshore area has advanced significantly mainly due to exploration and development activities by the oil and gas industry. The oil industry has a long exploration history in onshore parts of Europe. For example, in North-west Germany, natural petroleum found at Hanover, Lower Saxony, was already used for lubrication and lighting as

early as 1546 (Kent 1980). In Britain, seepage oil was being used for medical purposes during the seventeenth century (Lees & Cox 1937). Oil sands were mined for oil recovery during the mid-1700s in the Pechelbronn area of the Rhine graben and it is estimated that in the period up to 1860, more than 4000 metric tons of oil had been produced (Kent 1980). Britain, during the 1850s, saw the first use of seepage oil recovered from a Derbyshire, U.K. coal mine. The first successful reported oil well was drilled in 1859 and discovered in the Wietze oil field north of Hanover in northern Germany (Zeigler 1980). In 1918, following from the problems of importing crude oil during the 19 i 4" 18 First World War, the British Government commissioned the first phase of U.K. deep exploration. The exploration programme was based on analogy with the Pennsylvanian Oil Fields and the objective was directed at Carboniferous limestone accumulations in the Southern Pennines and Scotland. A small oil field was discovered at Hardstoft near Chesterfield in 1922 and it was still producing oil on a very small scale over fifty years later. Exploration incentives lapsed during the 1920s and the second phase of deep exploration did not commence until the early 1930s when the anticlines in the Mesozoic basin of southern England became the exploration targets. This search for oil in southern England was encouraged by the occurrence of outcropping oil sands of Lower Cretaceous and Jurassic age (Lees & Tait 1946), together with probable Jurassic-aged source rocks at various locations from the Weald to Dorest (Gallois 1976; Douglas & Williams 1981). Following from the small oil discovery at Hardstoft, exploration activity later transferred back to the U.K. East Midlands in the hope of finding hydrocarbon discoveries beneath unconformable Mesozoic rocks (Kent 1980). The East Midland operations met with mixed success and the first commercial field was found at Eakring, Nottinghamshire in 1939, followed soon afterwards by three other discoveries. Exploration and some small commercial production has continued onshore U.K. in the Carboniferous (Southern Scotland; NW England and East Midland), Permian (Eastern England), Triassic (Western England) and Jurassic (Southern England) Formations. During the late 1950s and early 1960s BP ix

x

Introduction

drilled several wells in the Wessex Basin Dorset U.K. and commercial oil was found in fractured Cornbrash in Kimmeridge No. 1 (1959) and in a thin fractured Inferior Ooolite in Wareham No. 1 Well (1964). Further evaluation of the Wessex Basin suggested that the Bridport Sands were probably a better reservoir target than the fractured poor reservoir rocks believed to be producing in the Kimmeridge No. 1 and Wareham No. 1 Wells (Colter & Harvard 1981). Wytch Farm No. 1 Well was spudded in 1973 and discovered light oil in the Bridport sands. Subsequent exploration and appraisal of the Wytch Farm Field (Colter & Harvard 1981) has proved the largest known onshore U.K. oil field with light oil accumulation in both Bridport and Bunter sand reservoirs. However, it was not until the discovery of the vast natural gas field at Groningen in the Netherlands in 1959, that extensive offshore exploration activities commenced. After the Second World War, Shell-Esso carried out exploration over large areas of the Netherlands and drilled several tests in the Groningen region in the northern part of the country. In 1959, the Slochteren No. 1 Well was drilled through the Zechstein Formation and discovered that the underlying basal Permian (Rotliegendes) Sands were hundreds of feet thick and later shown to be more than 20 miles across, which was entirely gas-bearing and very porous. This unexpected discovery of recoverable gas (5.69 x 10 TM m 3) made the field one of the largest ever found. In addition to Groningen's economic importance, the discovery also provided a new scale of reference for potential NW Europe offshore discoveries. Explorationists now begin to anticipate the possibility of large hydrocarbon accumulations rather than reservoirs measured in only tens of feet vertical thickness and acres in extent. Just over 18 years ago, in 1965, the first gas discovery in U.K. waters was made by BP at the West Sole Field in the Southern North Sea Basin. This was followed immediately by the gas discovery of the Viking Field and, in rapid succession by discovery of the Leman Bank, Indefatigable and Hewett Fields in 1966. The major turning point in the exploration for oil in offshore NW Europe was the discovery of the giant Ekofisk Field in the Norwegian sector of the North Sea in December 1969. Following this major oil discovery, the North Sea has proved to be one of the best areas for petroleum exploration anywhere in the world and a number of large oil fields have been discovered.

Extensive exploration for and development of oil and gas fields has provided a wealth of new data and during the last decade the geological understanding of Europe, particularly NW Europe, and its extensive continental shelves has been more fully understood, mainly due to the exploration and development activities by the oil and gas industry. The hydrocarbon potential of the various regions of Europe is by no means uniform and oil and gas accumulations have been encountered in sediments ranging in age from Pre-cambrian to Tertiary. Hydrocarbon accumulations can be correlated to specify depositional cycles and distinct mega-tectonic units (Ziegler 1980, 1981). A number of hydrocarbon provinces have been defined based upon the age of their major hydrocarbon source rocks and their principal reservoir formations, the type of reservoir trap and also the regional oil and gas assessment. Reviews of the evolution of major oil and gas plays in Europe are given by Kent (1975a, 1975b, 1980), Ziegler (1980, 1981), Burollett (1980), Naylor & Mounteney (1982) and Pergrum et al. (1982). Specific and detailed studies of regional geology and selected oil and gas fields are presented in two excellent Conference Volumes Petroleum Geology of the Continental Shelf o f NorthWest Europe (Eds. A. W. Woodland 1975 and L. V. Illing & G. D. Hobson 1981). A useful reference Geological Atlas of Western and rentral Europe, edited by P. A. Ziegler (1982) has recently been published. Annual reviews of European petroleum exploration activity are published in A A P G World Review (see Kat 1980, 1981).

Development of petroleum geochemistry The science of petroleum geochemistry is the application of chemical principles to the study of the origin, generation, migration, accumulation and alteration of petroleum, and the use of this knowledge in exploration and recovery of oil and gas (Hunt 1979). Although the concept of petroleum originating from organic-rich shales and migrating into sands was first observed by geologists in the late 1800s, these early theories about the controlling principle of petroleum occurrences were often limited in concept in that they mainly addressed the question of 'where' accumulations were located. It has become clear during the last twenty years, that to be able to better answer the question 'where', it is usually necessary to evaluate 'why, when and how much' petroleum

Introduction was present in a basin and to understand and establish the generation, migration and accumulation processes. This understanding is essential if the oil industry is to improve its petroleum exploration success ratio. Although hypotheses are periodically put forward for a non-biological, earth-mantle origin of petroleum, the generally accepted origin is from sediments rich in biologically derived organic matter found mostly on continental shelfs derived initially in quiet water environments such as in lagoons, estuaries and deep basins of restricted circulation (Demaison & Moore 1980). Another environment favourable for accumulation of organic matter are continental slopes (Dow 1978). The formation of hydrocarbons is currently understood as a complex series of geochemical processes within a source rock, by which the original organic components of biological materials are converted to hydrocarbons and other organic compounds of varying degrees of thermodynamic stability during sedimentation and burial at elevated temperature and pressure in the subsurface. The term hydrocarbon source rock is probably best defined as a 'fine-grained sediment that in its natural setting has or could generate and release significant amounts of oil and/or gas'. The classification of hydrocarbon source rocks (see Brooks & Fisher 1983) is defined in terms of amount and type of organic matter, its state or organic maturation (caused by temperatures in the range 50-180~ and by the nature and amount of hydrocarbons capable of being produced (Brooks 1981). The burial of a sedimentary basin results in the contained organic matter being subjected to increasingly higher temperature, which causes thermal and chemical degradation of the insoluble organic matter (kerogen) to form petroleum-like products. Primary migration of liquid and gaseous products out of the source rock and subsequent secondary migration (via carrier horizons, faults etc.) into porous reservoir rocks leads to formation of hydrocarbon accumulations where further migration is halted by a trap. During the last decade petroleum geochemistry has become a useful and increasingly applied aid in petroluem exploration. Although many oil explorations are now more familiar with the basic concepts of petroleum geochemistry, mainly due to the increase in the number of oil company research laboratories, service companies and the publication of two excellent petroleum geochemistry text books by Tissot & Welte (1978) and Hunt (1979), the oil industry is only very recently becoming

xi

aware of the wide scope of different modern geochemical analytical techniques and methods applicable to assist in petroleum exploration at different phases from the initial frontier basin study through many different topics even to a better understanding of the origin and properties of reservoired heavy crude oil. Exploration drilling is becoming more expensive and less successful and petroleum geochemistry has now a recognised role to play in exploration programmes. When a new exploration programme, especially offshore regions, is designed only a limited amount of general geological information is normally available. Initial geochemical studies, include the collection of outcrop samples (if possible) at the rim of basins being evaluated, followed by evaluation of the available information on the filling of the basin (stratigraphic and facies analysis) which may give preliminary indications of potential source rocks and reservoirs. Rapidly reducing oil and gas reserves in mature basins, together with increasingly remote locations and hostile environments of the world's remaining unexplored sedimentary basins is placing increasing economic and technological needs on oil explorationists. These requirements together with an increasing geochemical understanding of the origin, generation, migration and accumulation of petroleum has resulted in the increasing use of predictive models for locating new petroleum reserves. The scope of these models (see Yukler & Welte 1980; Waples 1983; Yukler & Kokesh 1983) range from qualitative and descriptive treatment of limited exploration information to sophisticated models which relate complex geological, geophysical and geochemical data into comprehensive and systematic basin analyses and prediction of petroleum accumulations. The determination of the most favourable petroleum exploration targets, depends upon the best use o; our geochemical knowledge of source rocks, generation, migration and accumulation, combined with the geology of the basin.

Petroleum geochemistry and exploration of Europe conference The main emphasis in this book is on various aspects of petroleum exploration in Europe with particular reference to petroleum geochemistry. The papers are divided into 4 sections.

xii

Introduction

Geological and geochemical studies of NW Europe Continental Sheff The opening paper in the book 'The r01e of the Department of Energy in petroleum exploration of the United Kingdom' by Peter Walmsley (Department of Energy, London) describes the structure and function of the U.K. Department of Energy. There are two divisions within the U.K. Department of Energy that have responsibility for petroleum exploration. Petroleum Production Division administers Licensing policy. All technical matters relating to exploration, development and safety are handled by Petroleum Engineering Division. The principal function of these divisions is to advise Government Ministers on exploration policy and to carry out policy decisions. A review of 'Gas exploration and reserves in Europe' by A. Makourine (USSR: Member of the ECE Gas Committee-Geneva) presents data and summary of the official information supplied by European Governments to the participating ECE Group on natural gas resources and exploration for natural gas in Europe (including the USSR). The theme of natural gas is continued in the next paper 'A review of geochemical data related to the southern North Sea gas province' by Patrick Barnard and Brian Cooper (RRI). This paper reviews the complex history of the Southem North Sea Basin, the occurrence, maturity and location of the gas source rocks timing, composition and generation of the gas. The next group of papers deals in detail with the somewhat contentious topic of geochemical surface prospecting. Joel Gervirtz, B. D. Carey Jr and Steve Blanco (Tenneco Oil Company) in their paper 'Surface geochemical exploration in the North Sea' propose that their studies demonstrate that correct interpretation of geochemical data from gravity cores (and integrated with geological and geophysical data) can be a great aid in the evaluation of the hydrocarbon potential of prospects. Gaseous light hydrocarbons recovered from near-surface sediments from the North Sea Central and Viking Grabens have been studied and are reported in E. Faber and W. J. Stahl's paper 'Analytical procedure and results of an isotope geochemical surface survey in an area of the British North Sea'. This paper reports that geochemical data from shallow sediments reflects the underlying sub-surface petroleum accumulations and allows the differentiation of dry areas from areas containing hydrocarbon accumulations. Inter-Ocean Systems U.S.A. carry out geochemical prospectivity using their 'Sniffer Method' and Joel Sigalove reported on

'Petroleum Offshore Sniffer Exploration'. This paper reviewed the developments in electronic and analytical techniques which now permit comprehensive geochemical analyses to be carried out for trace amounts of dissolved hydrocarbons in water. Low level micro-seeps (10-11g/litre) can be detected and used to assist in evaluating hydrocarbon potential of a basin presence/absence of structures and determine whether the accumulation is likely to be gas or oil. These three papers on geochemical prospecting provided much critical discussion and comment, some of which is recorded in the volume. A series of papers on U.K. and North Sea Exploration were presented. 'Petroleum exploration onshore U.K.' by Graham Candy (SheI1-U.K.) reviewed the onshore exploration activity in the U.K. and discussed some of Shell's exploration activities in the West Midlands. Much exploration and commercial activity has taken place in the UKCS and this was discussed by Tim Brennand (ShelI-UK) in his paper 'North Sea petroleum exploration'. This paper reviewed the history of North Sea exploration and the development of the main hydrocarbon plays was integrated into a synopsis of the complex North Sea Basin evolution, sedimentary fill characteristics, development of hydrocarbon traps and timing of hydrocarbon generation from relevant organic-rich source rocks. Similar theme and approach is used in 'Exploration of the Norwegian Shelf' by Hans ROnnevik, T. Vollset and S. Eggen (Norwegian Petroleum Directorate) who report on exploration drilling on the Norwegian Shelf and the results of successful exploration in the North Sea and north of 62 ~. Recent exploration work on three areas north of 62 ~ (Haltenbanken, Traenabaken and Tromsflaket) is given and geological information shows the existence of two new petroleum provinces and possibility for additional discoveries in other areas. A study on 'Stratigraphy and sedimentation of the Palaeocene sands in the North Sea' is given by David Mudge and Graham Bliss (BritoilGlasgow). The Palaeocene of the North Sea Basin between 58 ~ and 62~ contains a number of important reservoir sands and this paper reviews the regional tectonic setting and deposition of sediments, which was dominated by subsidence in the Viking Graben and Witch Ground Graben areas and its importance in developing the thickness and distribution of the Palaeocene sands. The diagenetic history of reservoir sands is discussed in'Geochemistry of porosity enhancement and reduction in clastic sediments' by

Introduction

xiii

Charles Curtis (University of Sheffield). The Northern Ireland and more widely in frontier diagenetic history is considered in three stages: areas of western and northwestern Europe. the first includes destruction of primary 'The search for petroleum in Northern Ireland' porosity by grain coatings and pore-filling by Tony Griffith (Geological Survey of Northern cements, followed by a period of leaching after Ireland) summarises the brief history of which the original trend of porosity reduction is exploration in Northern Ireland and reviews the re-established. The paper evaluates the scale of prospect that petroleum sourced by carbondiagenetic modification at different stages and iferous sediments may be potential targets. A relates this to solute transport, solubilities and broad overview of 'Frontier exploration in chemical composition. The paper 'Applications 'Western and Northwest Europe' by David of geochemistry to sandstone reservoir studies' Roberts (BP-London) discusses the outer areas by Hilary Irwin and Andrew Hurst (Statoil- of the NW Europe continental shelf, their Norway) deals with the mineralogy, chemical hydrocarbon potential and divides the area into composition and physical properties of a number of geological provinces characterised reservoir sandstones and uses this information by differences in age, tectonic style and geologto establish the burial history of the reservoir ical history related to rifting and spreading of sediments and prediction of potential produc- the North Atlantic Ocean. tion problems. Geochemical parameters are used in reconstructing the burial history of a Petroleum exploration of Europe North Sea sandstone sequence. Two papers by David Watkins and Mike The first paper in this section 'Origins of Pearson (University of Aberdeen) on 'Organo- Natural Gas in the Po Valley, North Italy' is by facies and early maturation effects in Upper L. Mattavelli and co-workers (AGIP-Milan) Jurassic sediments from the Inner Moray Firth, and examines some of the problems which North Sea' and 'Aspects of burial diagenesis, occurred during their geochemical studies of organic maturation and palaeothermal history natural gases sampled from 48 gas fields in the of an area in the South Viking Graben, North Po Basin. Using stable carbon isotope data it is Sea' (with co-authors) deals with an oil-source possible to distinguish methane from three rock characterisation and organic maturation different sources in the Po Basin. The next study on a thick Kimmeridge Clay succession paper: 'Isotope geochemistry of natural gases from the inner part of the Moray Firth Basin in central Europe' by Michael Whiticar and and with a geochemical and mineralogy study Martin Schoell (Hanover) presented stable of a well in the South Viking Graben, North carbon and deuterium isotope data together Sea. The next paper in this section 'Kerogen- with light hydrocarbon gas content to charactypes, organic maturation and hydrocarbon terise and correlate the principle gas provinces occurrences in the Moray Firth and South of Central Europe. The final paper in this Viking Graben, North Sea Basin' by Michael section: 'Geochemical observations of oil Fisher and Jenny Miles (Britoil, Glasgow) generation in the German Alps and their forediscusses kerogen palaeofacies and maturation land' by H. Wehner and co-workers (Hanover) history and relates these studies to the vari- reports on geochemical exploration studies used ations in hydrocarbon types found in these to follow migration paths from deeply buried areas of the North Sea. Further geochemical Tertiary and Mesozoic source rocks below the studies applied to North Sea exploration are Alpine overthrusts. given in 'Some geological controls on oil composition in the U.K. North Sea' by Chris Petroleum geochemical principles and Cornford and co-workers (Britoil-Glasgow) and in 'Geochemistry of the North and South techniques Brae Areas, North Sea '~ by Bob Reitsema The opening paper of this section: 'Organic (Marathon Oil-Denver). The first paper uses geochemistry and basin modelling--important the North Sea dominant source rock tools in petroleum exploration' by Dietrich (Kimmeridge Clay Formation) as a model for Welte and colleagues (KFA-Julich) describes studying the geological controls on the oil modern applications of geochemistry to petroproperties of some hundred North Sea samples. leum exploration and highlights the changing The Marathon paper identified at least two role of petroleum geochemistry from a 'posttypes of crude oil in the Brae Area, but uses mortem' science into a widely accepted predicgeochemical techniques to correlate both oils tive exploration tool. The paper also details the with a Kimmeridge shale source rock. use of petroleum geochemistry in predictive The next two papers, whilst studying the geological basin modelling. Dan MacKenzie UKCS, report recent exploration work in (Cambridge) discusses 'Organic reactions in

xiv

Introduction

extentional basins' in the following paper and uses these reactions to predict thermal and subsidence history of a stretched basin and to estimate organic geochemical reaction constants, using observations on organic-rich shales and siltstones from the North Sea and the Pennonian Basin. The following two papers deal with coal studies. There has been long and extended discussion on oil potential of coals and Bernard Durand (IFP-France) in his paper 'Oil potential of coals--a geochemical approach' suggests that coals have a fair potential for oil (and gas) a n d t h e poor association between coal measures and oil accumulations is probably due to geological rather than geochemical reasons. Studies on coal are continued and reported by Pieter Schenck and co-workers (Delft-Netherlands) in the paper 'Pyrolysis-mass spectrometry in coal chemistry', where modern geochemical techniques are applied to analyze a series of vitrinite macerals and to relate these to their biological precursors. In recent years, transmitted light microscopy of dispersed kerogen components (organic macerals) has become important, not only in studying organic maturation, but also in more fully assessing petroleum potential of sedimentary basins. In 'Identification of amorphous sedimentary organic matter by transmitted light microscopy' David Batten (University of Aberdeen) describes the main components of sedimentary organic matter, palynofacies and methods to determine organic maturation levels and their increasing applications in assessing source rock potential for hydrocarbons. Spore coloration is an important parameter in determining the organic maturation of hydrocarbon source rocks and in 'Transmitted light spectra of spore coloration standards as a maturation indicator', 'Trica Smith (University of Newcastle) reports a comparison between various oil industry spore coloration standards. Organic maturation of source rocks is also widely studied microscopically using reflected light by measuring vitrinite reflectance and in the paper 'Selection criteria for the use of vitrinite reflectance as a maturity tool in petroleum exploration' by T. Buiskool Toxopeus (Shell-Rijswijk) discusses different types of vitrinite and reports on the importance of selecting the highest reflecting vitrinite particles for measurement of organic maturation and the implication to exploration. In addition to microscopic studies to evaluate organic maturation of source rocks, there have been recent major advances in the application

of biological marker studies as maturity parameters for oils and source rocks. In the paper 'Porphyrins as maturity parameters for crude oils and sediments extracts', Tony Barwise (BP Research-Sunbury) describes the origin and occurrence of porphyrins in oils and rock extracts and the application of changes in molecular structure and distribution in determining thermal maturity of oil and sediments. Geological information on hydrocarbon exploration on the U.K. Continental Shelf

The final section of the book deals with 'Geological information on hydrocarbon exploration on the U.K. continental shelf' assembled from a Conference of the same name and organised by the Geological Society's Geological Information Group. The theme and papers are briefly reviewed in the Introduction by Graham Baxter (Conference Organiser). The first paper in this section 'The compilation of an earth science bibliography for the North Sea and adjacent areas' by Duncan McKay (Britoil) reports on the bibliography of data being compiled by Britoil's Exploration Library and gives an overview of Earth Science literature. 'Commercially available geological databanks--UKCS' by Peter Wigley (ERICO) reviews the major commercially available systems which contain geological data from the UKCS. Information on the geological and geophysical information from the UKCS available from the Department of Energy is described by John Brooks (Department of Energy) in his paper 'Geological information from hydrocarbon exploration on the UKCS'. Further details on commercially available information is provided in ' E X P H S T - - a programme to analyse the history of exploration success within a basin or country' by Kenneth Chew and Helen Stephenson (Petroconsultants) which reports on EXPHST programme written to search for, extract and manipulate information contained on commercial petroleum exploration data banks. In the final paper 'The use of computerized information in Britoil, Exploration Division', Graham Baxter (Britoil) summarises the work of Britoil's Geodata Group who provide six computerised information systems for oil explorationists within the Company. All the systems have been developed in response to specific requirements of geologists and geophysicists. The book is completed with a Subject Index, which aims to provide a usable reference to the volume, but is not claimed to be too extensive.

Introduction

xv

References BROOKS, J. 1981. Organic maturation of sedimentary organic matter and petroleum exploration. In: Brooks, J. (ed.) Organic Maturation Studies and Fossil Fuel Exploration. Academic Press, New York. BROOKS,J. & FISHER,M. J. 1983. Hydrocarbon source rocks and maturation indicators. In: Brooks, J. & Welte, D. H. (eds.) Recent Advances in Petroleum Geochemistry Vol. 1. Academic Press, New York (in press). BUROLLET, P. F. (1980). Petroleum potential of the Mediterranean basins. In: Miall, A. D. (ed.) Facts and Principles o f World Petroleum Occurrence. Canadian Society of Petroleum Geologists, Calgary. COLTER, V. S. & HARVARD, D. J. 1981. The Wytch Farm Oil Field, Dorset. In: Illing, L. V. & Hobson, G. D. (eds.)Petroleum Geology o f the Continental Shelf of N W Europe. Heyden, London. DEMAISON, G. T. & MOORE, G. T. (1980). Anoxic Environments and Oil Source Rock Genesis. AAPG Bull. 64, 1179-1209. DOUGLAS, A. G. & WILLIAMS, P. F. V. 1981. Kimmeridge Oil Shale--a study of organic maturation. In: Brooks, J. (ed.) Organic Maturation Studies and Fossil Fuel Exploration. Academic Press, New York. Dow, W. G. 1978. Petroleum source beds on continental slopes and rises. AAPG. Bull. 62, 1584-1606. GALLOIS, R. W. 1976. Coccolith blooms in Kimmeridge clay and origin of North Sea oil. Nature 259, 473-5. HUNT, J. M. 1979. Petroleum Geochemistry and Geology. Freeman, San Francisco. KAT, C. 1980. Europe.AAPG Bull. 64, 1961-2011. KAT, C. 1981. Europe. AAPG Bull. 65, 1996-2046. KENT, P. E. 1975a. Origins of hydrocarbon basins of NW Europe. In: Offshore Europe 75. Spear Publications. pp. 201. 1-6. KENT, P. E. 1975b. The tectonic development of Great Britain and surrounding seas. In: Woodhead, A. V. (ed.) Petroleum and the Continental Shelf of NW Europe Vol. 1. Applied Science Publishers, England. pp. 3-28. KENT, P. E. (1980). The North Sea--evolution of a major oil and gas play. In: Miall, A. D. (ed.) Facts and Principles of World Petroleum Occurrences. Canadian Society of Petroleum Geologists, Calgary.

ILLING, L. V. & HOBSON, G. D. (eds). 1981. Petroleum Geology o f the Continental Shelf of NW Europe. Heyden, London. LEES, G. M. & Cox, P. T. 1937. The Geological Basis of the Present Search for Oil in Great Britain by the D'Arcy Exploration Co. Limited. Quart. J. Geol. Soc., London 93, 156-194. LEES, G. M. & TAIT, A. H. 1946. The Geological Results of the Search for Oil Fields in Great Britain. Quart. J. Geol. Soc., London 101, 255-317. NAVLOR, D. & MOUNTENEV, N. 1982. The West British Self. Bordas Publications, France. PZRGRUM, R., REES, G. & NAYLOR, D. 1982. The North Sea. Bordas Publications, France. T~SSOT, B. P. & WEL-rZ, D. H. 1978. Petroleum Formation and Occurrence. Springer-Verlag, Berlin. WAPLES, D. W. 1983. Thermal models for oil generation. In: Brooks, J. & Welte, D. H. (eds) Advances in Petroleum Geochemistry, Vol. 1. Academic Press, New York (in press). WOODHEAD, A. W. (ed.) 1975. Petroleum and the Continental Shelf o f NW Europe Volume 1. Applied Science Publishers, England. YUKLER, M. A. & WELTE, D. H. 1980. A 3-D Deterministic Dynamic Model to determine Geologic History and Hydrocarbon Generation, Migration and Accumulation in a Sedimentary Basin. In: Fossil Fuels. Editions Technip, Paris. pp. 267-285. YUKLER, M. A. & KOKESH, F. 1983. A Review of Models used in Petroleum Resource Estimation and Organic Geochemistry. In: Brooks, J. & Welte, D. H. (eds). Recent Advances in Petroleum Geochemistry. Academic Press, New York (in press). ZIEGLER, P. A. 1980. Northwest European Basin: Geology and Hydrocarbon Provinces. In: Miall, A. D. (ed.) Facts and Principles o f World Petroleum Occurrences. Canadian Society of Petroleum Geologists, Calgary. Z1EGLER, P. A. 1981. Evolution of Sedimentary Basins in NW Europe. In: Illing, L. V. & Hobson, G. D. (eds). Petroleum Geology o f the Continental Shelf of NW Europe. Heyden, London. ZJEGLER, P. A. 1982. Geological Atlas of Western and Central Europe. Elsevier, Amsterdam.

J. BROOKS, Exploration Division, Britoil plc, 150 St. Vincent Street, Glasgow, 0 2 5L J, U.K.