Hesabatlar
Neogene Stratigraphy and Sedimentology of Eastern Azerbaijan and the South Caspian Basin
- The executive companies: Geology Institute, BP and STATOIL ALLIANCE
- The year of publication: May 1994
- Code: EXT 67815
- Volumes: total 2. Volumes with appendixes in same amount: 1
EXECUTIVE SUMMARY
The aim of the study was to develop a better understanding of the stratigraphy and sedimentology of the Neogene succession (Diatom Suite - Baku Beds) of eastern Azerbaijan and the South Caspian Basin. This succession is not only of great academic interest, but it also includes the Productive Series which contains the reservoirs for 99% of the hydrocarbon reserves of Azerbaijan. The Diatom Suite is considered by some to a potential source rock for these hydrocarbons, as mudstone interbeds within the Productive Series.
Our joint studies have concentrated on developing our knowledge of the biostratigraphy and palaeoenvironments through the study of microfossils, and of depositional setting and reservoir quality through petrography and sedimentary facies analysis.
The aims of the project have been achieved by studying outcrop sections on the Apsheron Peninsula and supplementing this information with subsurface data provided by the GIA. The outcrop sections were logged in detail and sampled extensively. These samples, together with subsurface materials, were analysed petrographically and biostratigraphically as appropriate. Analyses were carried out jointly by the GIA and the BP and Statoil Alliance.
Biostratigraphically, there is now a better understanding of the biozonation of the succession using a variety of microfossil groups and macrofossils. Palynology and nannopalaeontology have been applied to the Neogene sediments of Azerbaijan for almost the first time, and have given encouraging results, at least in terms of a broad zonation. Micropalaeontological analysis have also provided new, precise, data concerning the palaeoenvironments of the sediments studied.
The sedimentological studies carried out have led to the development of a new, detailed, depositional model for the studied succession, especially the Productive Series. This model, together with the extensive petrographic datasets studied in the course of this project, have enabled a predictive model for reservoir quality and reservoir distribution to be built. This will have significant impact on future hydrocarbon exploration within Azerbaijan and South Caspian Basin.
CONTENTS
(i) Executive summary
(ii) Contents List
1. INTRODUCTION
2. REGIONAL OVERVIEW
3. BIOSTRATIGRAPHY
4. SEDIMENTOLOGY & RESERVOIR QUALITY
4.1 Sedimentology of the Neogene Succession Excluding the Productive Series4.2 Productive Series Sedimentology in Outcrop4.3 Productive Series Sedimentology in Subsurface4.4 Controls on Reservoir Quality5. CONCLUSIONS
6. REFERENCES (Selected Bibliography)
- APPENDIX 1: Atlas of Key Fossils
- APPENDIX 2: Biostratigraphic Distribution Charts
- APPENDIX 3: Outcrop Sedimentology Summaries
- APPENDIX 4: Outcrop Petrographic Data
- APPENDIX 5: Subsurface Petrographic Data
Pre-Pliocene Prospectivity Study: Onshore Azerbaijan
- The executive companies: Geology Institute, BP and STATOIL ALLIANCE
- The year of publication: April 1995
- Code: EXT 67373
- Volumes: total 2. Volumes with appendixes in same amount: 1
At present a significant actual material dealing with tectonics and neotectonics of Azerbaijan has been accumulated. A recent tectonic structure of mountain zones of the Greater and Lesser Caucasus, Talysh, Nakhchyvan; deep structure of intermountain and marginal depressions, structure of Pre-Alpine basement and sedimentary cover was studied.
EXECUTIVE SUMMARY
The largely Pliocene "Productive Series" succession of Azerbaijan produces 99% of the hydrocarbons found in the South Caspian Basin to date. However, although exploration efforts have concentrated almost exclusively on the Productive Series, there is minor production in onshore Azerbaijan from the succession beneath the Productive Series (for example from Maastrichtian flysch and from the Maykop Suite (Oligocene - Early Miocene) sands). It has been a long-held belief of many Azeri geoscientists that considerable potential for hydrocarbon discoveries exists in the Pre-Pliocene succession. In order to test this, we visited numerous outcrops in eastern Azerbaijan in order to sample and study potential source and reservoir rocks and to develop structural models. We also reviewed the Pre-Pliocene exploration effort to date. This, in combination with the outcrop data, enabled potential play fairways to be identified and a hierarchy of prospective regions to be presented.
It is clear from both outcrop and well data that there are several horizons in the Pre-Pliocene succession which contain reservoir quality sediments, leading to the recognition of several potential play fairways. These include horizons within the Eocene, Oligocene - Miocene, Late Cretaceous and Early Cretaceous successions. Particular attention has been placed on the potential of the Gobustan region. Here Tertiary and perhaps even Mesozoic sediments are most likely a potential play beneath the imbricate stack of the southern Greater Caucasus, although burial cementation may occlude porosity. At outcrop, potential Cretaceous and Early Tertiary reservoirs (e.g. the Kululin Sandstone and sands within Maykop Suite) contain a high degree of cementation, and individual beds are laterally discontinuous. The best reservoir quality sands seen in Gobustan were those of the Chokrak Horizon (Miocene) (close to where they produce oil at Umbaki). However, their thickness and areal distribution is thought likely to be limited.
Structural cross-sections across Eastern Azerbaijan suggest that anticlinal traps may exist in the autocthon beneath the thrusts of the Greater Caucasus. However, their existence is still the subject of agreement on a structural model for the region. In any case, it seems likely that these traps will be at considerable depth and difficult to recognise on seismic. A simpler option is to explore the existing structures of the Apsheron Peninsula, Kura Valley and southern Gobustan to greater depths in order to test the Maykop Suite, Chokrak Horizon and deeper reservoirs.
A subject of ongoing research is the probable source rock for potential Pre-Pliocene plays. Geochemical analysis of samples collected during field work indicates that the sediments of the Maykop Suite (and especially the lower part) form the best present-day source rocks. Sediments of parts of the Diatom Suite and Middle Jurassic succession also display reasonable present-day source quality. Potential reservoirs within the Tertiary succession may receive a charge from a Maykop Suite source rock. Autocthonous Mesozoic reservoirs may require a Jurassic source rock.
CONTENTS
(i) Executive summary
(ii) Contents List
1. INTRODUCTION
1.1 Aims and Scope of the Study1.2 Methods1.3 Report Organisation1.4 Roles and Responsibilities
2. GEOLOGICAL OVERVIEW
2.1 Geological Setting2.2 Lithostratigraphy/Chronostratigraphy Overview2.3 Major Play Fairways2.4 Geochemistry Overview
3. HYDROCARBON EXPLOITATION
3.1 History of Exploration and Production3.2 Prospectivity Concepts3.3 Onshore Azerbaijan Overview
4. PRE-PLIOCENE PROSPECTIVITY OF GOBUSTAN
4.1 Regional Introduction4.2 Potential Reservoir Horizons4.3 Structural Characteristics4.4 Hydrocarbon Distribution4.5 Hydrocarbon Prospects
5. FUTURE DIRECTIONS FOR HYDROCARBON EXPLORATION
6. SELECTED BIBLIOGRAPHY
- APPENDIX 1: The Joint GIA and the BP and Statoil Alliance Pre-Pliocene Prospectivity Field Trip
- APPENDIX 2: Pre-Pliocene Prospectivity Field Trip Guide
- APPENDIX 3: Pre-Pliocene Prospectivity Field Trip - Biostratigraphic Data
- APPENDIX 4: Summary of "Mesozoic and Cenozoic Phases of Tectonic Movements of the Eastern Caucasus" by Academician E.Sh. Shikhalibeily.
Neogene Prospectivity Review
- The executive companies: Geology Institute, BP and STATOIL ALLIANCE
- The year of publication: May 1995
- Code: EXT 69900
- Volumes: total 2. Volumes with appendixes in same amount: 1
EXECUTIVE SUMMARY
The South Caspian Basin contains prolific hydrocarbon reserves. An estimated 26 billion barrels (oil equivalent) have been found to date and some yet to find estimates are as high as a further 30 billion barrels oil equivalent. 99% of known reserves are within reservoirs of the Productive Series. However, hydrocarbon production in Azerbaijan is currently in decline and new reserves need to be located. This study therefore addresses the question of what prospects remain for finding more hydrocarbons within the Productive Series, and in particular, for locating them in regions outside of the main area of structures which have already been drilled and which have been producing hydrocarbons for many years.
Two case studies are presented, one looking at the potential of the Lower Kura region (particularly in the relatively unexplored Lower Productive Series); the other considering the prospectivity of the Mugan Homocline region (south-west of the Kura Valley), where pinch-out of the Productive Series provides a series of underexplored plays.
To supplement these case studies and to build on previous collaborative studies between the GIA and the BP and Statoil Alliance, field work and various sample analyses have been carried out. This field work has concentrated on two aspects of Productive Series geology: firstly, the upper part of the Productive Series, which was relatively unexamined during our earlier joint work; and secondly, localities outside the Apsheron Peninsula region, which allow for a comparison of the sedimentation styles, petrography and prospectivity of the Palaeo-Kura and Palaeo-Volga river systems which were the prevalent depositional controls during Productive Series sedimentation. Detailed sedimentological logging, followed by petrographic and biostratigraphic analyses have improved our understanding of the depositional environments, stratigraphy, reservoir connectivity, reservoir architecture and reservoir quality of the Productive Series and thus provided major insights into the future hydrocarbon prospectivity of Azerbaijan.
CONTENTS
(i) Executive summary
(ii) Contents List
1. INTRODUCTION
1.1 Aims and Scope of the Study
1.2 Methods
1.3 Report Organisation
1.4 Roles and Responsibilities
2. SEDIMENTOLOGY
2.1 Introduction
2.2 Outcrop Sedimentology
2.3 Petrography and Reservoir Quality
2.4 Conclusions
3. FAULTING WITHIN THE PRODUCTIVE SERIES
3.1 Introduction and Objectives
3.2 Kirmaky Valley
3.3 Balakhany Quarry
3.4 Balakhany Foreshore
3.5 Aktapa Bridge
3.6 Conclusions
4. BIOSTRATIGRAPHY
4.1 Introduction
4.2 Results of Outcrop Studies
4.3 Conclusions
5. PROSPECTIVITY WITHIN THE PRODUCTIVE SERIES OF THE LOWER KURA VALLEY
5.1 Introduction
5.2 History of Exploration and Production
5.3 Lithofacies Characterisation
5.4 Depositional Environments
5.5 Future Prospectivity
6. PROSPECTIVITY WITHIN THE MUGAN HOMOCLINE REGION
6.1 Introduction
6.2 History of Research
6.3 Lithostratigraphy
6.4 Structure and Tectonics
6.5 Future Prospectivity
6.6 Conclusions
7. SELECTED BIBLIOGRAPHY
APPENDIX 1: Graphic Logs
APPENDIX 2: Petrographic Analyses
APPENDIX 3: Reservoir Quality Tables
APPENDIX 4: Biostratigraphic Data
Onshore Azerbaijan Source Rock and Seep Study
- The executive companies: Geology Institute, Geochem Group Limited
- The year of publication: December 1994
- Code: 94/9140
- Volumes: total 5
volumes with appendixes in same amount: 5
EXECUTIVE SUMMARY
Within this suite of four hundred and ninety two (492) sediment samples from thirty seven (37) outcrop localities, good, very good and rich source rocks are most extensive in the Maykop and particularly in the (Middle and) Upper Maykop. Effective Maykopian source facies occur in an east-west zone from Shemakha and Angicharan in the west to Yunusdag and Gezdeg in the east (Figure 1). The available data suggest that the Maykopian is a poor source facies in the south of the study area but within the east-west zone, it is richest in the east. Good source rocks should be more extensive and dependable in the offshore.
Both the Koun and the Productive Series are lean and ineffective, but good to rich source rocks occur in the Diatom Suite, the Cretaceous and the Bathonian-Callovian. At most localities the Diatom Suite is poor, but there are a few metres of good to very good source in the Umbaki area and more significantly an extremely rich oil source facies at Deali in the west. Data suggest an hypersaline environment, in which case the rich facies could be fairly widespread in the onshore but absent in the offshore. A degree of restriction and therefore the same risk, is implied for the extremely rich oil source in the Late Cretaceous at Atacay. Unfortunately this was collected from a debris flow and so the thickness of this source unit cannot be defined.
However, as the Late Cretaceous is the postulated source for the two analysed seeps from the Shemakha area, it is presumably extensive. The seeps around and to the northwest of Umbaki were probably sourced from the Early Maykop whilst those on the Apsheron Peninsula are from the Upper Maykop.
None of the analysed seeps relate to the Diatom Suite or to the Late Bathonian - Early Callovian at Tengi Alti in the north, which includes a substantial thickness of good and very good source rocks for oil. However, shows are present in the Jurassic at Jimichai and the Jurassic source facies could be extensive.
There are therefore, good source rocks in the Diatom Suite, Upper Maykop, Middle Maykop, Early Maykop, Late Cretaceous and Middle Jurassic. The Upper and Middle Maykop belong to a geochemical continuum but otherwise, each of these units and their products can be distinguished geochemically.
Following a presentation of the Stratigraphy and Palaeogeography (Chapters 3 and 4), the Geochemical interpretations and conclusions produced in this study are discussed in detail in Chapters 6 through 10.
CONTENTS
1. EXECUTIVE SUMMARY
Text Figure 1: Summary
2. INTRODUCTION
Text Figure 2: Source Rock and Seep Locations2.1 Objectives2.2 Report Format2.3 Source Rock SamplesText Figure 3: Stratigraphy of Study Area
2.4 Seep Samples2.5 Analytical Data Base2.6 Analytical Techniques2.7 Interpretation ParametersA. Source Richness and Organic FaciesB. Maturity2.8 Sample Quality - Weathering
3. STRATIGRAPHY OF THE STUDY AREA3.1 Jurassic3.2 Cretaceous3.3 TertiaryText Table 1: Maykop - Composite Section of the Northern Argillaceous FaciesText Table 2: Maykop - Composite Section of the Southern Sandy and Argillaceous Facies
4. ALAEOGEOGRAPHIC RECONSTRUCTION4.1 HauterivianText Figure 4: Palaeogeography - Hauterivian4.2 KounText Figure 5: Palaeogeography - Koun4.3 MaykopText Figure 6: Palaeogeography - Maykop4.4 ChokrakText Figure 7: Palaeogeography - Chokrak4.5 Karaganian - Konkian (Diatom)Text Figure 8: Palaeogeography - Karaganian - Konkian4.6 SarmatianText Figure 9: Palaeogeography - Sarmatian
5. SOURCE ROCK IMPLICATIONS FROM STRATIGRAPHY AND GIA ARCHIVE
Text Table 3: Natural Radioactivity from the Rocks of Azerbaijan
6. REGIONAL SOURCE ROCK GEOCHEMISTRY
Text Figure 10: Source Rock Distribution6.1 JurassicText Figure 11: Regional Source Facies - Jurassic6.2 CretaceousText Figure 12: Regional Source Facies - Cretaceous6.3 KounText Figure 13: Regional Source Facies - Koun6.4 Early MaykopText Figure 14: Regional Source Facies - Early Maykop6.5 Middle MaykopText Figure 15: Regional Source Facies - Middle Maykop6.6 Upper MaykopText Figure 16: Regional Source Facies - Upper Maykop6.7 Diatom SuiteText Figure 17: Regional Source Facies - Diatom Suite6.8 SarmatianText Figure 18: Regional Source Facies - Sarmatian6.9 Productive SeriesText Figure 19: Regional Source Facies - Productive Series
7. SOURCE ROCK GROUPINGS7.1 Saturates ChromatogramsText Figure 20: Source Rocks: CPI vs jC19/jC207.2 BiomarkersText Figure 21: Jurassic BiomarkersText Figure 22: Environmental Changes with Time, Upper Bathonian - Early Callovian, Tengi AltiText Figure 23: Early Maykop Type BiomarkersText Figure 24: Middle Maykop Biomarker GroupsText Figure 25: Upper Maykop Biomarker GroupsText Figure 26: Diatom Suite Biomarkers - SteranesText Figure 27: Diatom Suite Biomarkers - TerpanesText Figure 28: Biomarker Differences by Age7.3 IsotopesText Figure 29: Source Rock Pyrolysate Carbon Isotope CompositionText Figure 30: Carbon Isotope Profile, Locality 28 (RAM), Diatom SuiteText Figure 31: Carbon Isotope Profile, Locality 23 (MAY) Upper Maykop and Locality 8(KR) Middle Maykop7.4 Conclusions
8. SEEP EVALUATION8.1 Chromatographic AnalysesText Figure 32: Organosulphur Chromatograms of Seeps8.2 BiomarkersText Figure 33: Oil Seep Biomarkers, Group A and Group BText Figure 34: Oil Seep Biomarkers, Group C and Group D8.3 Isotopic compositionsText Figure 35: Oil Seeps - Deuterium and Sulphur IsotopesText Figure 36: Oil Seeps and Source Rocks. Carbon Isotope Composition8.4 Seep to Seep CorrelationText Figure 37: Oil Seep Families8.5 Seep to Source Correlation
9. SUMMARY AND CONCLUSIONSText Figure 38: Source Rock DistributionText Figure 39: Summary
10. GEOCHEMICAL EVALUATION OF OUTCROP LOCALITIES
Unless noted otherwise, Text Figures with the prefix "L" are photographs and sketches of the sampling localities. Those without a prefix refer to plots of source facies and pyrolysis results against logs. Chromatograms, histograms, mass fragmentograms and tabulated data are located in the Appendices. Numbers in the left hand margin are the Locality numbers
- QORDUCOY RIVER (AG)
- MESARINSK (MS)
- ANGICHARAN (ANG) Text Figures L-1, 3-1, 2
- SHIKHZAIRLY (SZG) Text Figures L-1, L-2, 4-1, 2
- ANGICHARAN VALLEY (AV) Text Figure L-3
- XILMILLI RIVER (K) Text Figures L-3, L-4, 6-1, 2
- XILMILLI VALLEY (KV)
- KOZLYCHAI RIVER (KR) Text Figures L-5, 8-1, 2
- LAHIC RIVER (LE) Text Figures 9-1, 2
- GALA ALTI CASTLE (T)
10 A LAHIC (LG)
- ATACAY RIVER (ALR)
- ALTIAGAC VILLAGE (ALT) Text Figures L-8, 12-1, 2
- ATACAY DEBRIS FLOW (ALD)
- GILGILCAY RIVER (GCR)
- GILGILCAY RIVER - JURASSIC RIDGE (GCR)
- GILGILCAY RIVER (GCR) Text Figure L-8
- GILGILCAY RIVER (GCR) Text Figures L-9, 17-1, 2
17A GILGILCAY RIVER (GCR)
- TENGI ALTI GORGE (TAG) Text Figures L-9, 18-1, 2
- TUGCAY RIVER (AGA)
- GYADYSU (GYA) Text Figure L-10
- PEREKYUSHKYUL (PER) Text Figures L-10, 11, 12, 21-1, 2
- YUNUSDAG (YUN) Text Figure L-13
- XILMILLI (MAY, MAYB) Text Figures 23-1,2. See L-5
- UMBAKI (UMB) Text Figure L-3
- UMBAKI (UMB)
- UMBAKI (UMB)
- UMBAKI (UMB) Text Figures 27-1, 2
- UMBAKI (RAM) Text Figures L-16, 17, 28-1, 2
- SHIKHZAIRLY (SZG) Text Figures 29-1, 2
- SHIKHZAIRLY (SZG) Text Figures L18, 30-1, 2
- GEZDEG (GUZ Text Figure L-17
- BADIRI (BD) Text Figures L-19, 32-1, 2
- BOYANATA (BO) Text Figures 33-1, 2
- SIYAKI (S) Text Figures L-22, 34, 2
35A KIRMAKY VALLEY (KV/MS) Text Figure L-2335B KIRMAKY VALLEY (KV/GIA)
- DEALI (DE)
- JIMICHAI (J) Text Figures L-24, L-25, 37-1, 2