Joint reports


Azerbaijan Kura Basin. Report on the Geochemical Properties, Correlation and Provenance of Oils from the Azerbaijan Sector of the Kura Basin


  • The executive companies: Geology Institute, Moscow State University, Simon Petroleum Technology Limited
  • The year of publication: 1994
  • Code: EB017
  • Volumes: total 2
     volumes with appendixes in same amount: -


EXECUTIVE SUMMARY


The study has analysed 64 oils from the main hydrocarbon producing areas of Azerbaijan. A full range of petroleum geochemical analyses has been carried out and the data interpreted in the light of the known petroleum geological setting of the fields in the area. Detailed analyses, including gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), and carbon isotope (CI), have enabled the characterisation and correlation of the oils. Based on limited available source rock analytical data, speculative oil to source correlations are made.


The area studied can be divided into two principal hydrocarbon provinces. Firstly, The Lower Kura- South Caspian area which includes the well known and extensively explored Baku and Apsheron areas. Secondly, the Middle Kura Depression which is an intermontane basin between the Greater and Lesser Caucasus Mountains.


The Lower Kura-South Caspian area contains thick, regional, sandstone deposits of Pliocene and Quaternary age. The sandstones of the Middle Pliocene Productive Series are the main reservoirs for hydrocarbons in this area and total thickness can reach 5000m. Oil fields often contain multiple oil-bearing horizons within the Productive Series. The vast quantity of sediment deposited in the rapidly subsiding Pliocene basin has led to massive overpressuring of underlying Palaeogene - Miocene mudstones which in turn has led to shale diapirism, massive scale expulsion of formation waters and generated hydrocarbons into the overlying Pliocene sands and often the formation of mud volcanoes. The overpressuring plays a significant role in the accumulation and fate of hydrocarbons in this region. Shale diapirism creates structural traps for the accumulation of hydrocarbons. Expulsion of formation water and hydrocarbons from the overpressured shales is the main driving force for hydrocarbon migration. Formation waters being moved through the sediment at high pressures and high temperatures dissolve the volatile compounds from hydrocarbons which may be encountered in reservoirs or may be migrating as part of the same expulsion mechanism.


The Middle Kura Depression did not undergo the rapid Pliocene subsidence of the Lower Kura-South Caspian area and consequently does not have the thick Middle Pliocene sandstone deposits of the Productive Series. The main reservoirs are fractured carbonates of the Upper Cretaceous or sandstones of the Palaeogene - Miocene.


Oils from the Lower Kura-South Caspian area appear to be generally a mixture of two oils from different sources, although occasionally the individual oils do occur unmixed. The first oil to migrate was a waxy oil which has been generated from middle mature Tertiary shales or mudstones which were deposited in a saline lacustrine environment. In most of the samples this oil has suffered moderate biodegradation. The second oil which has mixed with the waxy biodegraded oil is a light oil or condensate which has probably been generated from a type I or type II kerogen. This light oil has had significant quantities of the volatile hydrocarbons removed by water washing.


The generally low temperature gradients, rapid subsidence and late formation of the structures in this area imply that the alteration of the first oil and the migration and mixing of the two oil types has occurred most likely during the migration process. The subsequent water flushing of the second light oil may also have occurred during this migration process.


The abundant evidence of the active leakage of hydrocarbons at surface and the generally low gas to oil ratios are also evidence of high levels of current activity in migration. The great depths from which the oils have been sourced, the tectonic/migration activity and the high subsurface pressure make it extremely difficult to predict oil type quality between structures.


There may localised facies variations in the source rocks but generally there appear to be only two main sources of hydrocarbons in this area. Also there may be minor contributions on a local scale from dispersed organic matter in other horizons.


Oils which were analysed from the Middle Kura are all related. They are waxy oils generated from middle mature Tertiary shales or mudstones which deposited in a saline lacustrine environment. These oils are also related to the waxy oils found in the Lower Kura-South Caspian.


A lack of published data from potential source rocks in Azerbaijan and no samples for analysis in this study means that definite correlations between the oils and source rocks cannot be made. The main source rock in the South Caspian hydrocarbon province is considered to comprise shales of the Maykop Formation and it is probable that this is the source of the waxy oils analysed in this study. The light oil may have been generated by diatomaceous shales of Miocene age.


Localised facies variations may alter the physical nature of the oils but in the Lower Kura-South Caspian area, the main controls on the specific gravity and the mobility of the oils are the relative proportions of the light oil and waxy oil in the final mixed oil and the degree of biodegradation and water washing that has affected the oils.


CONTENTS


Volume 1: Text


1. SUMMARY


2. INTRODUCTION

2.1 Scope and Purpose of the Study
2.2 Materials and Data Sources
2.3 Analytical Methods
2.4 Data Presentation


3. REGIONAL GEOLOGICAL SYNOPSIS

3.1 Physiography
3.2 Geological History
3.3 Tectonics
3.4 Stratigraphy
3.4.1 Pre-Mesozoic
3.4.2 Jurassic
3.4.3 Cretaceous
3.4.4 Cenozoic
3.5 Oil and Gas Occurrences
3.6 Source Rocks
3.6.1 Jurassic
3.6.2 Upper Cretaceous
3.6.3 Eocene
3.6.4 Oligocene - Lower Miocene
3.6.5 Pliocene
3.7 History of Oil Exploration
3.7.1 Summary
3.7.2 Exploration and Production Figures


4. GEOCHEMICAL EVALUATION

4.1 Middle Kura Depression
4.1.1 Introduction
4.1.2 Geochemical Characteristics
4.1.3 Conclusions
4.2 Shemakhino Kobustanskiy Depression
4.2.1 Introduction
4.2.2 Geochemical Characteristics
4.2.3 Conclusions
4.3 Apsheron - Lower Kura Area
4.3.1 Introduction
4.3.2 Geochemical Characteristics
4.3.3 Conclusions


5. REGIONAL GEOCHEMICAL CORRELATION OF OILS

5.1 Conventional Geochemical Interpretation in the Geological Context
5.2 Statistical Treatment of the Data


6. CONCLUSIONS


7. REFERENCES


TABLES

2.1 Summary Listing of Oils Analysed in the Azerbaijan Kura Basin Oilbank Study
3.1 Major Oil Fields of Azerbaijan in 1991
3.2 Reported Oil and Gas Production in Azerbaijan from 1930 to 1993
3.3 Historical Drilling Statistics for Azerbaijan
3.4 Average Organic Carbon Contents for Sediments in Azerbaijan
4.1 Physical Properties and Fractionation Data
4.2 Carbon Isotope Data and Terpane Biomarker Ratios
4.3 Sterane Biomarker Ratios
5.1 Relative Contributions of Variables to Principal Components


APPENDICES

  1. List of Abbreviations
  2. Analytical Procedures and Techniques
  3. Index of Alkane and Aromatic Molecular Biomarker GC-MS Peak Assignments and Interpretational Guidelines


ENCLOSURES

  1. Hydrocarbon Occurrences and Principal Hydrocarbon Provinces
  2. Basement Structure Map
  3. Contour Map of Top Mesozoic Sediments and Top of Middle Pliocene Productive Series
  4. Summary of Oil Correlation and Provenance


Volume 2: AnalyticalData


1. INTRODUCTION

1.1 Data Presentation
1.2 Notes to Accompany Data Tables


2. ANALYTICAL DATA FOR KURA-IORI INTERFLUVE AND PREDMALOKAUSIS DEPRESSION OILS

2.1 Demir Tepe Udabno-7
2.2 West Gyurzundag-1
2.3 Palantekian-2
2.4 Tars Dallier-1
2.5 Naftalan


3. ANALYTICAL DATA FOR TALISH VANDAMSKIY ARCH OILS

3.1 Zardob-7
3.2 Shaftakhal-250
3.3 Muradhanli-27
3.4 Muradhanli-37
3.5 Muradhanli-232
3.6 Muradhanli-246
3.7 Dzhafarly-21


4. ANALYTICAL DATA FOR SHEMAKHINO KOBUSTANSKIY DEPRESSION OILS

4.1 Dzhengi Mud Volcano
4.2 Adjively-12
4.3 Umbaki-114
4.4 Umbaki-135
4.5 Kergez-263
4.6 Gezdek-210
4.7 Karadag-1
4.8 Kianizadag-29
4.9 Dashgil-15
4.10 Duvanny More-320
4.11 Sangachaly More
4.12 Astrakhanka-1


5. ANALYTICAL DATA FOR APSHERONSKIY DEPRESSION OILS

5.1 Binagady-1167
5.2 Romany-3312
5.3 Buzovny-14
5.4 Buzovny-1057
5.5 Surahany-945
5.6 Surahany-1618
5.7 Gousany-1701
5.8 Karachuhur-64
5.9 Zykh-314
5.10 Bibi-Eibat-2566
5.11 Peschany More-3
5.12 Peschany More-348
5.13 Bahar-148
5.14 Bahar-182


6. ANALYTICAL DATA FOR APSHERONO PREBALKHANSKIY ANTICLINE OILS

6.1 Banka Apsheronsky-4
6.2 Artem-654
6.3 Octiabrskaya Revolutsia-3
6.4 Yuzhnoe-57
6.5 Neftiany Kamni-303
6.6 Neftiany Kamni-2001
6.7 28 April-16
6.8 28 April-189
6.9 Kaverochkina-260
6.10 26 Bakinski Komisarov-1
6.11 Nachishevanskyoe-224


7. ANALYTICAL DATA FOR NIZNIKURINSKIY DEPRESSION OILS

7.1 Kalamadin-161
7.2 Malyi Kharami-3
7.3 Kyurovdag-24
7.4 Kyurovdag-889
7.5 Kyurovdag-958
7.6 Kyursanglia North-401
7.7 Kyursanglia South-4
7.8 Pirsagat-21
7.9 Pirsagat-85
7.10 Garasu-122
7.11 Hilli-15
7.12 Hilli-418
7.13 Hilli-423
7.14 Neftechala-709
7.15 Neftechala-1083


APPENDICES

  1. List of Abbreviations
  2. Analytical Procedures and Techniques
  3. Index of Alkane and Aromatic Molecular Biomarker GC-MS Peak Assignments and Interpretational Guidelines