Hesabatlar

SUMMARY

The Modern Kura delta in Azerbaijan has been studied as a possible analogue for that part of the Productive Series in the South Caspian Basin that is supposed to have been deposited by that same river in its Pliocene delta. During three field campaigns 40 augerings up to 7m depth were made in the onshore delta, and offshore 18 sparker profiles were shot in lines parallel and perpendicular to the delta contours, and 14 piston cores down to 3 m and 8 wells down to 20 m were drilled. Laboratory analysis comprised grain size analysis by sieving and laser methods, light and heavy fraction petrography, chemical analysis of CaCO3 and organic matter, biostratigraphical analysis using ostracod, foraminifera, molluse and diatom countings, and radiometric dating using 210Pb and 14C analysis. 3-D stochastic and 2-D numerical modeling complements the onshore data.

The data have given a concise insight in the development of the delta during the last ~1500 years. They show at least three and possible four phases of delta progradation during highstands of the Caspian Sea, interrupted by erosional phases during lowstands, recognisable in the sparker profiles as prominent reflectors. The first phase is represented by reddened fluvial (?) clays (Regressive Systems Tract, RST1) possibly  affected by soil formation during a lowstands at -80 m absolute depth (Sequence Boundary, SB1). These are overlain by several metres of laminated clays and silts, 14C dated at >1400-900 BP on shelly intervals, and shown by microfauna to have deposited in a shallowing sea (RST2). This succession is truncated by the prominent SB2 reflector, corresponding to a lowstand at about -48m absolute depth and correlated with the 11th century Derbent Regression known from hisrorical and archaeological data. It is overlain by another metres-thick, undated succession of laminated deltaic clays and silts, passing locally to organic clays with fluvial diatom assemblages (RST3). This horizon is also truncated by an erosional event, SB3, probably related to a lowstand in the 16th century. During the Little Ice age highstand the Kura River was diverted southwards to the Qizilagac Bay and the barrier coast at the apex of the modern delta was formed. The last phase RST4 is represented by the formation of the onshore Kura delta since the end of the 18th century and an offshore correlative veneer of clays and silts,dated using 210Pb as having also been deposited during the last 200 years. The onshore delta consists of progradational sequences of channel-levee sands and floodplain silts and clays deposited on top of stage RST3 clays during gradual sea-level fall, overlain by clays and silts reflecting the last phase of rapid sea-level rise since 1977. Along the northern shore of the delta sands are deposited in narrow coastal barriers and beaches. Overall sedimentation rates in the delta determined by various methods range between 1.5-3.0 cm/year. Numerical modelling reproduces a realistic stratigraphy of the onshore delta.


Except for the thin and narrow sand bodies in the channels and barriers of the onshore plain, the whole Kura delta consists of clays and silts with virtually no reservoir capacity. Most of the Kura sand is probably trapped further upstream, where subsidence of the Kura trough is greatest. Kura sands are also found in Khvalyn (Pleistocene) highstand deposits far upstream. The presence of  large amounts of sand in the Productive Series outcrops in Babazanan suggests that downstream transport of sand was more effective in the Pliocene than at present. Therefore, also the offshore Pliocene Kura deposits in the fields at present targeted for exploration are probably more sandy than the present-day Kura delta.

 
INTRODUCTION

"Joint study agreement" for the purpose of study of geological style of Mesozoic and Cenozoic deposits in Azerbaijan sector of the Middle Caspian has been concluded between Institute of Geology of National Academy of Sciences of the Republic of Azerbaijan and "Kaspmomeftegeofizrazvedka" trust. The tasks of studies оn seismic data interpretation were as follows:

- determination of velocity model;

- stratigraphic allocation of seismic horizons;

- production of isochron maps of and structural maps оп 4 siesmic horizons;

- production of isopach maps оn 3 intervals.

Data provided bу the institute were mainly used during studies. Studies were carried out in computer center of "Kaspmomeftegeofizrazvedka" trust with application of program package "LANDМARК". The interpretation module, which seismic and well data were downloaded to, was created at the beginning of studies.

During interpretation works obtained results were jointly discussed and relevant amendments were made. Recommendations for further studies were also made in the process of work.

Studies were carried out under management of general director of the "Kaspmomeftegeofizrazvedka" trust ВаЬауеу D.Кh., chief engineer Agayev Кh.B. and chief geologist Hajiyev A.N.

The report with participation of the following specialists of the trust were produced under results of studies:

Agayev Кhanlar-                    section 5

Hajiyev Adil-                         sections 1,4,6,7

Hajiyeva Rena-                      sections 2,3,4,5,6,

Abilhasanova Lala-                sections 2,3,4,6

More over, the following specialists of "КМNGR" were involved in implementation of data interpretation:

Aliyeva Nina                                                                                Hasanova Nailya

CONTENTS

Part I

List of figures in text

List of tables

List of figures attachments

 

1. Introduction

2. Geological and geophysical history of the studies/surveys done over study area

3. Stratigraphy and lithofacia1 characteristic of deposits

4. Tectonic style of deeper horizons

5. Stratigraphic allocation of seismic horizons

6. Specific features of structural zones of northwest part of Azerbaijan offshore area of the Middle Caspian

7. Conclusion and recommendations

 

Part II

1. Geological status and development history of the study area.

      1.1. Study area brief geological description

      1.2. Information about some fields and prospects of the region

      1.3. Paleo-ana1ysis of the sedimentation history of lower PS

2. Oil-gas generation conditions in western part of Absheron archipelago

      2.1.1. НС potentia1 of rocks in Pa1eogene-Neogene section of study area

      2.1.2. Maturity stage of Organic Matter (ОМ)

      2.2. Geochemistry of oils and gases and regularities of their changes

3. Lithofacial conditions of oil-gas accumulation in lower Pliocene rocks of NW part of Absheron archipelago

4. Hydrocarbon perspectivity of the study area

References

 

Part I

List of Figures

Figure 1.1. Schematic тар of study area

Figure.5.1. Stratigraphic allocation оn two lines line I-I and line II-II

Figure 6.1. Fragment from time section. Line No. 9611 08А

Figure 6.2. Fragment from time section. Line No. 960987

Figure 6.3. Fragment from time section. Line No. 951031

Figure 6.4. Fragment from time section. Line No. 901215

Figure 6.5. Fragment from time section. Line No. 961102

Figure 6.6. Fragment from time section. Line No. 960981

Figure 6.7. Fragment from time section. Line No. 960993

List оf tables

Таblе 5.1. Occurrence depths of target stratigraphic horizons

               Based оn well data оn Middle Caspian

 

List of figures attachments

1.  Depth Structure mар оn seismic horizon near top of Middle Pliocene (Surakhany suitе)(СГ-I). Scale 1:200000

2.  Depth Structure mар оn seismic horizon near top of Nadkirmakinskaya sandy suite (СГ-IIв). Scale 1 :200000

3.  Depth Structure mар оn seismic horizon in Maykop suite (СГ-IV). Scale 1 :200000

4.  Depth Structure mар оn seismic horizon near top of Cretaceous (СГ-V). Scale 1 :200000

5.  Isopach mар between seismic horizons: near top of Middle Pliocene (CГ-I) and top of Nadkirmakinskaya sandy suite (СГ -IIв). Scale 1 :200000

6.  Isopach mар between seismic horizons: top of Nadkirmakinskaya sandy (СГ-IIв) and Maykop suites (СГ- IV). Scale 1:200000

7.  Isopach mар between seismic horizons of Maykop suite (СГ-1V) and near top of Cretaceous (СГ-V). Scale 1:200000

8.  Correlation section оп seismic lines between wells оn line I-I

9. Correlation section оn seismic lines between wells оn line II-II

10.  Correlation section between wells оn line I-I

11.  Correlation section between wells оn line II-II

12.  Deep Line 901405

13.  Deep Line 95-1031

14.  Deep Line 96-1108А

INTRODUCTION

Some of the deepest sedimentary basins (and largest sources of hydrocarbons) in the world (occur within intra-continental settings, but they are poorly understood in terms of the mechanisms that have controlled their subsidence history. The aim of this project is to investigate the geological and geodynamic processes that have controlled the evolution of one of the deepest intra-continental basins, namely the South Caspian basin. Although it is widely accepted that the basin was initiated Ьу Mesozoic back-arc extension related to the subduction of the Tethys plate to the south (e.g. Zonenshain and Le Pichon, 1986), more than half of the 20 km subsidence presently observed occurred within the framework of the Alpine-Himalayan orogenic belt. Work, to date, has shown that this basin cannot bе attributed entirely to either extensional or compressional tectonics. Indeed, offshore seismic data shows а lack of extensional faulting within the basin, while compressional deformation is dominant at the basin edges. Our aim is to decipher the role of the main subsidence mechanisms and their timing: mainly extensional with crustallmantle changes during the Mesozoic and compressional deformation during most of the Cainozoic history.

The project provides an excellent opportunity to gain insights into the evolution of one of the most interesting and, as yet, poorly understood basins within the geological record. Project resu1ts will also have economic implications bу elucidating how the magnitude and frequency of tectonic movements have controlled depocentre-migration and hydrocarbon generation within the South Caspian Sea region. Primarily, however, this investigation will offer the prospect of significantly advancing our understanding at а global scale of the role played bу deep crustal and mantle lithosphere processes during the evolution of basins trapped between continental blocks (e.g. the Black Sea, the Pannonian basin, the Precaspian basin).

 

CONTENTS

Introduction

The Geological Evolution of the South Caspian Basin

Offshore Data

Fieldwork in Eastern Great Caucasus, Azerbaijan

Integrated structural and geodynamic modeling

Summary and future work

References

Contact details