Hesabatlar

EXECUTIVE SUMMARY

It was studied a total of eight (80) thin sections from the South Caspian Basin of Azerbaijan and Turkmenistan to Reservoirs, Inc. for petrographic analysis. These thin section examples had been impregnated with blue-dyed epoxy to highlight porosity and stained with sodium cobaltinitrate to distinguish potassium feldspar grains. Point count modal analysis (250 points) was conducted on seventy-eight of the seventy-nine thin sections to provide semiquantitative estimates of framework grain components, pore-filling constituents, and types of visible pore space. The other sample consisted predominantly of drilling mud solids so no point counting was conducted. Point count results accompany each of the thin section photomicrograph plates.

The samples are moderately to well-sorted (rarely poorly sorted), coarse siltstones to lower coarse sandstones. Compositionally, they are lithic arkoses, litharenites, feldspathic litharenites, subarkoses and sublitharenites.

Undifferentiated carbonate cement is the principal pore-filling constituent along with locally abundant anhydrite. Undifferentiated (authigenic clays) are locally abundant.

In some samples, integranular pores are well preserved and well interconnected.

CONTENTS

1. Tectonic features, geological structure of shelf zones of the South Caspian
2. Petrographic analysis of clastic rocks from the South Caspian Basin
3. Reservoirs quality in oil fields and prospective structures

3.1 Lower Kura depression3.2 Baku Archipelago3.3 Absheron Archipelago and Absheron-PreBalkhan sill3.4 Absheron p-la

4. Appendix. Litho-geological profiles and litho-stratigraphic sections

SUMMARY

This report presents field observations of the Mesozoic (Mid Jurassic to Late Cretaceous) section of the eastern Greater Caucasus of Azerbaijan, following a field campaign in October-November 2004.  Understanding the Mesozoic geology and evolution of the area is relevant for exploration of the offshore Central Caspian Basin, to the northeast. Preliminary sedimentological and paleontological field results are discussed. The geological context and database of the samples selected for paleontological and heavy mineral sandstone provenance analysis is presented.

The examined Mid Jurassic succession consists of  low energy basinal deposits and sandstone turbidites.  Clastic deposits are derived from source areas to the north and ?northeast. The Late Jurassic succession, when present, consists of carbonate reefs and associated slope deposits. The Late Jurassic section however is often missing, and an important unconformity separating the Mid Jurassic and Early Cretaceous sections is deduced. Ongoing palaeontological studies will constrain these observations.

The Early Cretaceous succession consists of carbonate distal shelf deposits, grading into Mid Cretaceous forereef deposits and organic-rich shelf/turbiditic deposits. A prominent unconformity, probably of Cenomanian age, separates the mid and Late Cretaceous strata. This erosional event is marked in the southern flank of the Greater Caucasus by widespread volcanic activity. This event can be correlated with similar events in the Lesser Caucasus, where it has been related to reactivation of northward-directed subduction. Late Cretaceous deposits consist of turbiditic distal shelf and basinal deposits.

Sediment provenance during the Jurassic and Cretaceous, from paleocurrent indicators, is from source areas to the north-northeast in the northern Greater Caucasus. Provenance is however from the south during the mid and Late Cretaceous in the southern flank of the Greater Caucasus anticlinorium. This southern sediment provenance for the mid and Late Cretaceous sediments in the southern flank had not been previously described.

Two major changes in basin evolution, with associated unconformity development, have been identified in the Mid-Late Jurassic to Early Cretaceous, and in the Late Cretaceous (Cenomanian). The main tectono-stratigraphic events identified in the eastern Greater Caucasus are likely to be present in the Central Caspian Basin, given its evolution in a similar tectonic setting, and have an influence on sediment distribution patterns. A preliminary view of the possible facies distribution in the Central Caspian during the Jurassic and Cretaceous, based on fieldwork observations, is given. Results of ongoing paleontological and provenance analysis, as well as future fieldwork in the Mangystau Mountains of Kazakstan will help constrain these preliminary interpretations.

 

CONTENTS

1 SUMMARY

2 INTRODUCTION

3 GEOLOGICAL SETTING

4 FIELD GEOLOGY OF THE EASTERN GREATER CAUCASUS

4.1 AREA 1, NORTHERN FLANK. KONAKHKEND-YERFI, Localities 1-31 (Panels 1-6)

4.1.1 Mid Jurassic (Panel 3)

4.1.2 Late Jurassic section (Panel 6)

4.1.3 Early Cretaceous section (Panel 2, 4, 6)

4.1.4 Mid Cretaceous section (Panel 2, 5, 6)

4.1.5 Late Cretaceous (Panel 2, 4)

4.2 AREA 2,  NORTHERN FLANK. CHIRAX-GIULE, Localities 32-40 (Panels 7, 8)

4.2.1 Mid Jurassic

4.2.2 Late Jurassic (Early Cretaceous)

4.3 AREA 3, NORTHERN FLANK. ALTYAGACH, Localities 41-50 (panel 9, 10)

4.3.1 Mid Cretaceous

4.3.2 Late Cretaceous

4.4 AREA 4, SOUTHERN FLANK. LAGICH, Localities 50-53 (Panels 11, 12)

4.4.1 Mid Cretaceous

4.4.2 Late Cretaceous

5 GEOLOGICAL EVOLUTION: DISCUSSION 


6 CONCLUSIONS

7 ONGOING ANALYSIS AND FUTURE WORK

8 REFERENCES

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