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Classic Petroleum Provinces
Book reviews lithostratigraphy is placed in a sequence concept with palaeogeographic maps being used to illustrate lithostratigraphic variation and key issues such as reservoir and source distribution; well logs and core micrographs document the key reservoirs in each sequence and provide closer definition of depositional environments. The thermal history of the basin is addressed using a McKenzie stretching model. Source rock distribution is discussed in detail; the oils recovered in the Campos Basin are sourced entirely from the non-marine Lago di Feia source rock (synrift). Although originally overlain by salt, the soils have charged overlying reservoirs of various types ranging in age from Cretaceous to Miocene through gaps in the salt created by salt withdrawal. Representative oil fields in the Campos Basin are described in detail and illustrated with both seismic and well sections. There is also a brief discussion of the Marlim Field (8.2 billion bbl) reservoired in Miocene turbidites, illustrated by a spectacular seismic section. The step out to this successful deep water structural-stratigraphic play owes much to the recognition of the turbidite play in shallower water depths. The closely similar offshore and onshore basins of Gabon are described in a well written article by Teisserenc and Villemin. This paper also uses sequences to discuss the hydrocarbon habitat of the Gabon. Unlike Campos, however, the onshore and offshore basins show greater structural segmentation and synrift non-marine facies comprise non-marine sediments rather than volcanics. The successful play systems are discussed in terms of the influence of structure on reservoir distribution as well as source rock distribution and maturity. Seismic sections are used to illustrate both seismic facies and structural style. Although Cretaceous turbidites (notably in the Anguille Formation) are recognized as a play, the authors note the potential of a Tertiary turbidite play by analogy with the Campos. Unlike Campos, however, source rocks in the synrift (non-marine) as well as the post-rift contribute to the hydrocarbon charge in the basin. That new plays still remain to be found, is shown by a recent, reportedly major, discovery onshore Gabon. The two remaining review papers in the volume deal with the Niger delta and the north-west shelf of Australia. In basin development as well as hydrocarbon habitat, they bear no obvious linkage to each other or to the South Atlantic basins of the first five chapters. The chapter on the Niger Delta is an excellent summary of work published many years previously by Evamy and Whiteman, updated with a very useful regional seismic line that illustrates structural styles, and a discussion of source rock distribution in the Niger Delta. The writers identify the source rock as deltaic (marginal marine-lacustrine) but do not offer any conclusion as to its overall distribution and richness in the Niger Delta depocentre. As noted above, the paper draws heavily on a previously published account by Evamy et al. In this work, the progressive localization of
depocentres in an aggrading system by growth faults was recognized, as was the basinward younging of the growth systems. This principle will be familiar to many Gulf of Mexico geologists. However, the analysis (as is noted by the authors) predates the more modern approach used by Galloway and is capable of refinement in terms of the principles of sequence analysis. The fourth paper in the memoir deals with the north-west shelf of Australia and is a disappointment compared to the quality of the other three papers. The author does, however, comment in a footnote that the paper was written in 1985, submitted as long ago as 1986, and that it has been superseded by later published work (presumably this refers to the important new oil discoveries in the Vulcan and Dampier Sub-basins). Despite these caveats, only one highly reduced regional seismic section is shown in the paper; the fields and their reservoir are not described at all. Readers may question the interpretation of the boundary scarp of the Rankin Platform (c. 1.5 seconds relief) as an erosional unconformity. Inevitably, the reader is left with the impression that the paper has been based on internal company reports written in the 1970s. A particular weakness is the lack of a clear linkage between the sequence stratigraphy and the tectonic stratigraphic evolution of the Dampier Basin; in this context very little mention is made of the diachronous rift-drift history of the west margin of Australia. Recognizing that this region is a major gas province (and potentially an oil province), the paper does not adequately describe the hydrocarbon habitat of west and north-west Australia. A reviewer is also expected to recommend who should buy the book. In this case, I warmly recommend that the book is well worth the purchase price of $68.00 to A A P G members ($102.00 for non-members). This is because the four papers (despite the faults in one) offer a very useful synthesis. However, one might question how the editors can justify the publication of papers with so many analogues to the Gulf of Mexico without a chapter on the Gulf (or indeed other successful basins). In a valiant attempt to pull the analogies together, the editors have tried to synthesise the four chapters and make many references to the Atlantic margin of North America (a chapter on the Grand Banks would have been useful). However, in future volumes, it would be useful to analyse failure as much as success. The series is a very good concept but a set of four volumes may not be enough. It may well be worthwhile expanding the series into a succession of parts, set to a common analytical theme (regional to field specific) to include a wider range of successful as well as failed basins.
D. G. Roberts BP Exp/orat/on, Houston, TX, USA
Classic Petroleum Provinces J. Brooks (Ed) Geological Society Special Publication No. 50; Geological Society Publishing House; 1990; ISBN 0 903317 48 6. Price: £89 (£39 to Fellows) Classic Petroleum Provinces has been assembled in the belief that there is much oil and gas still to be found and produced in mature provinces, a point of view reiterated by BP (Oil and Gas Journal, Aug 20 1990, p. 56) who estimate that North Sea reserves discovered but not yet produced amount to 10 billion bbl, a total equivalent to cumulative production to the end of 1989. Jim Brooks' main hope in publishing the volume was to inform everyone of some of the main advances in petroleum geology and exploration. As one would expect there are some fine review papers in this volume - - good all-round classical petroleum geology.
372
There are authoritative accounts on Venezuela, Ecuador, the Gulf Coast, Permian Basin and Compos Basin inter alia. Of particular note is the paper on the Russian Pre-Cambrian oil pools. There are also papers on areas not yet classic provinces. Of these, some, such as Yemen, may emerge sooner than others, such as Pakistan. Brooks himself tabulates 18 giant oil provinces, although the volume includes papers from only 10 of them: Mexico, Sirte-Libya, California, Sumatra and the Sahara are all missing. A few papers seem out of place, particularly part of a PhD thesis dealing with an individual field, and a detailed
Marine and Petroleum Geology, 1991, Vol 8, August
Book reviews treatment of the geochemistry of carbonate source rocks. It is a pity that a more balanced approach could not have been achieved. It was surely unbalanced to include so many papers on the Middle East, when this has recently been covered very successfully by Beydoun (1988). At the other extreme there are merely two abstracts on the Niger Delta, which is most unfortunate because the oral presentation at the conference, particularly by Weber, was so informative. In my view it is unacceptable to present an abstract without including an up-to-date reference list so that readers can find out more for themselves. This is not a volume that is brim-full of the latest advances, but it will certainly widen the horizons of most readers. Amongst its strong points are a range of papers demonstrating the effect of meteoric water influx on hydrocarbon accumulations (e.g. Ecuador and Western Canada), and a number of examples of the application of sequence stratigraphy (e.g. UK onshore, Campos, Gippsland). In a series of chronostratigraphic charts for growth faults on the Gulf Coast, one learns that hanging wall accumulation rates may exceed 6 km per my. The review of the North Sea by Pegrum and Spencer is wide ranging, but disappointing in the total absence of illustrative seismic or structural cross-sections, and in this respect the paper is worth comparing with Fraser et al.'s regional assessment of Northern England. BP are to be applauded for writing off most of the UK onshore prospectivity in such a beautiful, though possibly somewhat premature, fashion. The use of colour in a number of the papers will have helped readers assimilate the subject matter rapidly, and it is
used to good effect on seismic and photomicrographs. However it has to be said the the most disappointing aspect of the entire volume is the absurdly over-reduced size of many diagrams. Fraser's benchmark paper is sadly let down by Figures 5 and 8 which can only be read with a × 10 hand lens. The Geological Society should not put out such material - have a look at a recent Proceedings of the Geologists Association, for example. Re-publication of Hubbard et al.'s work on the Arctic Alaska microplate after only 3 years can only be regarded as regrettable. In its original generous format with seismic fold-outs (Mar. Pet. Geol., 1987, 4, 2-34) it was elegant and intelligible. In the smaller Special Publication format the seismic is fog-bound and the diagrams over-reduced. These deficiencies in the final product have prevented the volume itself being classic. A good deal of the subject matter would have lent itself to a more generous format, and with greater selectivity and the inclusion of additional papers on critical areas this could have reached such a status. Even so there is enough good solid material here, much of it not easily available elsewhere, that makes the Fellows' price good value. Have your hand lens ready! Reference Beydou n, Z. R. (1988) The Middle East: regional geology and petroleum resources. Reviewed by J. Goff, Mar. Pet. GeoL, 1990, 7, 315
George E. Farrow Croft Oil and Gas p/c, Glasgow, UK
Correlation in Hydrocarbon Exploration J. D. Collinson (ed) Graham and Trotman (for the Norwegian Petroleum Society); London; 1989; ISBN 1 85333 284 4; Price: Dfl. 424.00. US$110,00. U K £195,00 We all do it, and some of us do quite a lot of it, but what is it? Correlation is so utterly central to stratigraphy - - indeed, in a sense, it is stratigraphy-- that it almost seems unnecessary to try to define it. Correlation in Hydrocarbon Exploration was the topic of the eighth in a more or less biennial series of symposia of the Norwegian Petroleum Society (NPF), each resulting in a volume of published contributions. The meeting itself was reviewed in the November 1989 issue of Marine and Petroleum Geology, and many of the papers referred to in that review appear here in print. It is not unnatural that there is a predominance of papers on the Norwegian North Sea and Arctic shelf regions. The abundance of exploration-driven research on the area, much of it of high quality, demands a forum for public presentation and this is perhaps the strength of the NPF's symposia. This book is a treasure-house of case studies, few of which fail to include the word 'correlation', but surprisingly there is no preface, foreword, summary or any other such contribution by the editor. This leaves me with the feeling that a significant opportunity has been missed; we are neither informed as to the intended purpose of the symposium and the resulting papers, nor given any guidance as to the success or otherwise in addressing the matter of what correlation is all about. This task being left to the reviewer, let us briefly scan the contents for messages. The 28 papers are grouped into five sections. Large-scale Controls (two papers) is perhaps inevitably concerned mainly with the eustasy versus tectonics issue. Methods and Principles (six papers) is more concerned with the former than the latter. Bakke and Griffiths remind us of Walther Schwarzacher's insistence that most of what passes for correlation is better described as matching, and they apply gene-typing algorithms to well log correlation in a way that is more controllable and repeatable than eyeballing. Tipper's
paper on seismic facies calls into question some of our intuitive (or at least generally accepted) seismo-stratigraphic principles and points to the alarming gap between what is actually done in the name of seismic stratigraphy and what can be truly justified through experimental modelling. Four out of the five papers under Regional Correlation: Arctic Areas are concerned with the remarkable degree of correlation that exists between the Barents Shelf and the Sverdrup Basin, with extension also to North Greenland and the Alaskan North Slope. A common theme is the explicit inability to decide between tectonic and eustatic explanations of the degree of similarity described across this huge area. This has the interesting implication that the 'correlations' that are made are independent of any underlying model - - in other words they are 'matches' in Schwarzacher's sense, and not correlations at all. Perhaps it is worth trying to restrict the use of 'correlation' to the sense in which it implies causal connection, which brings it a little closer to the sense in which the statistician uses the word. Regional Correlation: North Sea (seven papers) includes two papers that depend on sediment provenance to achieve a correlation. Heavy mineral analysis has been so unfashionable that most people have forgotton what the M in SEPM stands for! Morton et al. apply the technique to reservoir correlation with a discussion of how to filter out the various signals that attempt to overprint that of provenance on which the method depends; do I detect the influence of newly revived interest in 'event stratigraphy' in the renaissance of the heavy mineral method? N d - S m isotope stratigraphy (Mearns) seems to me an expensive way of doing the same thing, but specialized applications may well be on the way. Without wishing to pick unkindly on individual authors, there are some quotes in this section that usefully
Marine and Petroleum Geology, 1991, Vol 8, August
373
depocentres in an aggrading system by growth faults was recognized, as was the basinward younging of the growth systems. This principle will be familiar to many Gulf of Mexico geologists. However, the analysis (as is noted by the authors) predates the more modern approach used by Galloway and is capable of refinement in terms of the principles of sequence analysis. The fourth paper in the memoir deals with the north-west shelf of Australia and is a disappointment compared to the quality of the other three papers. The author does, however, comment in a footnote that the paper was written in 1985, submitted as long ago as 1986, and that it has been superseded by later published work (presumably this refers to the important new oil discoveries in the Vulcan and Dampier Sub-basins). Despite these caveats, only one highly reduced regional seismic section is shown in the paper; the fields and their reservoir are not described at all. Readers may question the interpretation of the boundary scarp of the Rankin Platform (c. 1.5 seconds relief) as an erosional unconformity. Inevitably, the reader is left with the impression that the paper has been based on internal company reports written in the 1970s. A particular weakness is the lack of a clear linkage between the sequence stratigraphy and the tectonic stratigraphic evolution of the Dampier Basin; in this context very little mention is made of the diachronous rift-drift history of the west margin of Australia. Recognizing that this region is a major gas province (and potentially an oil province), the paper does not adequately describe the hydrocarbon habitat of west and north-west Australia. A reviewer is also expected to recommend who should buy the book. In this case, I warmly recommend that the book is well worth the purchase price of $68.00 to A A P G members ($102.00 for non-members). This is because the four papers (despite the faults in one) offer a very useful synthesis. However, one might question how the editors can justify the publication of papers with so many analogues to the Gulf of Mexico without a chapter on the Gulf (or indeed other successful basins). In a valiant attempt to pull the analogies together, the editors have tried to synthesise the four chapters and make many references to the Atlantic margin of North America (a chapter on the Grand Banks would have been useful). However, in future volumes, it would be useful to analyse failure as much as success. The series is a very good concept but a set of four volumes may not be enough. It may well be worthwhile expanding the series into a succession of parts, set to a common analytical theme (regional to field specific) to include a wider range of successful as well as failed basins.
D. G. Roberts BP Exp/orat/on, Houston, TX, USA
Classic Petroleum Provinces J. Brooks (Ed) Geological Society Special Publication No. 50; Geological Society Publishing House; 1990; ISBN 0 903317 48 6. Price: £89 (£39 to Fellows) Classic Petroleum Provinces has been assembled in the belief that there is much oil and gas still to be found and produced in mature provinces, a point of view reiterated by BP (Oil and Gas Journal, Aug 20 1990, p. 56) who estimate that North Sea reserves discovered but not yet produced amount to 10 billion bbl, a total equivalent to cumulative production to the end of 1989. Jim Brooks' main hope in publishing the volume was to inform everyone of some of the main advances in petroleum geology and exploration. As one would expect there are some fine review papers in this volume - - good all-round classical petroleum geology.
372
There are authoritative accounts on Venezuela, Ecuador, the Gulf Coast, Permian Basin and Compos Basin inter alia. Of particular note is the paper on the Russian Pre-Cambrian oil pools. There are also papers on areas not yet classic provinces. Of these, some, such as Yemen, may emerge sooner than others, such as Pakistan. Brooks himself tabulates 18 giant oil provinces, although the volume includes papers from only 10 of them: Mexico, Sirte-Libya, California, Sumatra and the Sahara are all missing. A few papers seem out of place, particularly part of a PhD thesis dealing with an individual field, and a detailed
Marine and Petroleum Geology, 1991, Vol 8, August
Book reviews treatment of the geochemistry of carbonate source rocks. It is a pity that a more balanced approach could not have been achieved. It was surely unbalanced to include so many papers on the Middle East, when this has recently been covered very successfully by Beydoun (1988). At the other extreme there are merely two abstracts on the Niger Delta, which is most unfortunate because the oral presentation at the conference, particularly by Weber, was so informative. In my view it is unacceptable to present an abstract without including an up-to-date reference list so that readers can find out more for themselves. This is not a volume that is brim-full of the latest advances, but it will certainly widen the horizons of most readers. Amongst its strong points are a range of papers demonstrating the effect of meteoric water influx on hydrocarbon accumulations (e.g. Ecuador and Western Canada), and a number of examples of the application of sequence stratigraphy (e.g. UK onshore, Campos, Gippsland). In a series of chronostratigraphic charts for growth faults on the Gulf Coast, one learns that hanging wall accumulation rates may exceed 6 km per my. The review of the North Sea by Pegrum and Spencer is wide ranging, but disappointing in the total absence of illustrative seismic or structural cross-sections, and in this respect the paper is worth comparing with Fraser et al.'s regional assessment of Northern England. BP are to be applauded for writing off most of the UK onshore prospectivity in such a beautiful, though possibly somewhat premature, fashion. The use of colour in a number of the papers will have helped readers assimilate the subject matter rapidly, and it is
used to good effect on seismic and photomicrographs. However it has to be said the the most disappointing aspect of the entire volume is the absurdly over-reduced size of many diagrams. Fraser's benchmark paper is sadly let down by Figures 5 and 8 which can only be read with a × 10 hand lens. The Geological Society should not put out such material - have a look at a recent Proceedings of the Geologists Association, for example. Re-publication of Hubbard et al.'s work on the Arctic Alaska microplate after only 3 years can only be regarded as regrettable. In its original generous format with seismic fold-outs (Mar. Pet. Geol., 1987, 4, 2-34) it was elegant and intelligible. In the smaller Special Publication format the seismic is fog-bound and the diagrams over-reduced. These deficiencies in the final product have prevented the volume itself being classic. A good deal of the subject matter would have lent itself to a more generous format, and with greater selectivity and the inclusion of additional papers on critical areas this could have reached such a status. Even so there is enough good solid material here, much of it not easily available elsewhere, that makes the Fellows' price good value. Have your hand lens ready! Reference Beydou n, Z. R. (1988) The Middle East: regional geology and petroleum resources. Reviewed by J. Goff, Mar. Pet. GeoL, 1990, 7, 315
George E. Farrow Croft Oil and Gas p/c, Glasgow, UK
Correlation in Hydrocarbon Exploration J. D. Collinson (ed) Graham and Trotman (for the Norwegian Petroleum Society); London; 1989; ISBN 1 85333 284 4; Price: Dfl. 424.00. US$110,00. U K £195,00 We all do it, and some of us do quite a lot of it, but what is it? Correlation is so utterly central to stratigraphy - - indeed, in a sense, it is stratigraphy-- that it almost seems unnecessary to try to define it. Correlation in Hydrocarbon Exploration was the topic of the eighth in a more or less biennial series of symposia of the Norwegian Petroleum Society (NPF), each resulting in a volume of published contributions. The meeting itself was reviewed in the November 1989 issue of Marine and Petroleum Geology, and many of the papers referred to in that review appear here in print. It is not unnatural that there is a predominance of papers on the Norwegian North Sea and Arctic shelf regions. The abundance of exploration-driven research on the area, much of it of high quality, demands a forum for public presentation and this is perhaps the strength of the NPF's symposia. This book is a treasure-house of case studies, few of which fail to include the word 'correlation', but surprisingly there is no preface, foreword, summary or any other such contribution by the editor. This leaves me with the feeling that a significant opportunity has been missed; we are neither informed as to the intended purpose of the symposium and the resulting papers, nor given any guidance as to the success or otherwise in addressing the matter of what correlation is all about. This task being left to the reviewer, let us briefly scan the contents for messages. The 28 papers are grouped into five sections. Large-scale Controls (two papers) is perhaps inevitably concerned mainly with the eustasy versus tectonics issue. Methods and Principles (six papers) is more concerned with the former than the latter. Bakke and Griffiths remind us of Walther Schwarzacher's insistence that most of what passes for correlation is better described as matching, and they apply gene-typing algorithms to well log correlation in a way that is more controllable and repeatable than eyeballing. Tipper's
paper on seismic facies calls into question some of our intuitive (or at least generally accepted) seismo-stratigraphic principles and points to the alarming gap between what is actually done in the name of seismic stratigraphy and what can be truly justified through experimental modelling. Four out of the five papers under Regional Correlation: Arctic Areas are concerned with the remarkable degree of correlation that exists between the Barents Shelf and the Sverdrup Basin, with extension also to North Greenland and the Alaskan North Slope. A common theme is the explicit inability to decide between tectonic and eustatic explanations of the degree of similarity described across this huge area. This has the interesting implication that the 'correlations' that are made are independent of any underlying model - - in other words they are 'matches' in Schwarzacher's sense, and not correlations at all. Perhaps it is worth trying to restrict the use of 'correlation' to the sense in which it implies causal connection, which brings it a little closer to the sense in which the statistician uses the word. Regional Correlation: North Sea (seven papers) includes two papers that depend on sediment provenance to achieve a correlation. Heavy mineral analysis has been so unfashionable that most people have forgotton what the M in SEPM stands for! Morton et al. apply the technique to reservoir correlation with a discussion of how to filter out the various signals that attempt to overprint that of provenance on which the method depends; do I detect the influence of newly revived interest in 'event stratigraphy' in the renaissance of the heavy mineral method? N d - S m isotope stratigraphy (Mearns) seems to me an expensive way of doing the same thing, but specialized applications may well be on the way. Without wishing to pick unkindly on individual authors, there are some quotes in this section that usefully
Marine and Petroleum Geology, 1991, Vol 8, August
373