TIOGE 2003 Geological potential of the Turkmen sector of the Caspian Sea. Implementing the geological program Good morning I am …….. WG presentation today is to show you the potential of the Caspian for offshore Turkmenistan. Allied to this at the end I will show you what WG and Turkmenistan plan for the future. We all know that Turkmenistan has enormous potential, it is up to us all here today to realise that potential. G/Turkmenistan_2003/TIOGE2003/TIOGE2003.ppt Mr Andrew Bishop Business Development Marketing Manager, WesternGeco, London

The Caspian Sea Unique geologic Province Prolific hydrocarbon region Fields along Chelekin ridge Turkmen sector at early stage Promise for the future The Caspian Sea, a unique geologic province, ranks among the most prolific hydrocarbon regions of the world. Several large fields exist along the Chelekin ridge and along the West Coast of Turkmenistan, that forms the eastern border of the South Caspian Basin. Exploration over large areas of the Caspian Sea Turkmen sector is at an early stage and shows considerable promise for the future. Much of the WG data you will see today is drawn from the area highlighted in yellow

Offshore Turkmenistan 2D Seismic Basemap MAERSK BLOCKS 11&12 LICENSED WesternGeco acquired over 16,000 km of 2D seismic data in three phases over the complete area in deep, shallow and transition areas. The new interpretation has allowed us to bring together the wealth of reports and drilling information into a consistent model. This synthesis shows how a producible reservoir, petroleum charge system, regional topseal and traps may combine to produce hydrocarbon accumulations at specific stratigraphic levels. The model is thus suitable for planning future exploration of the region. Much of the background understanding of the structural and stratigraphic evolution of the depositional sequences for this presentation comes from papers and reports in Russian. These describe petroleum systems unfamiliar to Western geoscientists. The collaboration and active participation of Geoscientists from Turkmenistan, WesternGeco and Exploration Consultants Limited has lead to an understanding of the Petroleum System. Many publications, too numerous to fully acknowledge from other countries around the Caspian, have allowed us to place the area in context. The high quality of the new seismic dataset provides us with constraints on the proposed geological model.

Satellite Image with main features Kopet Dag Greater Caucasus Foredeep Scythian Turan Platform part of continental plate South Caspian Basin Kura Trough compression West Turkmenistan Basin Elburz Binalud Talesh Volcanic arc Fundamental tectonic and thermal processes controlled the Caspian Basin formation, We consider the geology of the Turkmenistan offshore area in two areas, the central Caspian Sea and the southern Caspian Sea. The boundary lies along an important trend that extends in an almost straight line from Ashgabat to the Greater Caucus Mountains and beyond. To the south lies the South Caspian Basin that has accumulated a thick sedimentary sequence. The South Caspian Sea represents a relic of the Paratethyan Basin.. The main Paleo-Tethys Ocean that separated Laurasia from Gondwana lay well to the South. To the north of the south Caspian Basin lies the Scythian Turan Platform a stable area that has been underlain by thick continental crust since before the Mesozoic The oceanic crust was subducted throughout the Jurassic and Cretaceous until about Oligocene time as the ocean closed. As the oceanic plate subducted an Island arc and back-arc basin developed. The back arc basin extended from the Black Sea to the Caspian. At this time, the tectonic forces were pulling the area apart. During the early Cretaceous, it is likely that the basin floor was oceanic to sub-oceanic crust resulting from local spreading centres. Once collision had consumed the main ocean far to the south further collision continued between the many continental islands. Converging plates squeezed the previously tensional basin. The Island Arc system was compressed north south to form the southern boundary of the South Caspian Basin. This compression lead to the inversion of the normal faults and grabens. These Mesozoic sediments built into mountains to form the Caucus and Kopet Dag ranges. Erosion associated with the rapid uplift rapidly filled basins to the north of the Mountains. Due to the uneven shape of the continental collisions, only part of the oceanic crust between the Black Sea and the Caspian was subducted. The Greater Caucus Mountains represent the accretion and compression of this tectonic movement. A later collision when India collided with Asia lead to further disturbances. Associated with the compression was significant lateral movement along the Ashkhabad fault trend. This may well account for the very linearity of this feature. Bold means hit the return key to activate cartoon

Central Caspian Play Concepts Platform: Mesozoic Carbonate and clastics Passive margin shallow seas Normal Faulting: local grabens Geographically let us look at the potential for the Central Caspian first….. Oil and Gas on the platform is associated with Mesozoic carbonate and clastic sediments deposited on a passive margin in shallow seas. Normal faulting lead to local grabens where the sediments are thick and are associated with source rocks. Directly to the north in Kazakhstan, large hydrocarbon deposits accumulated in strata of Palaeozoic age. (From Bedout and Loucks, 1974)

Central Caspian Seismic Line Top Miocene Top Cretaceous Garabogaz High The central Caspian prospectivity derives from onlapping Tertiary sediments of the south Caspian basin onto the Garabogaz high. This is a slide of a recently acquired offshore 2D regional line across the area. Production as many of you know is from the Chelekin ridge, eg Dragon, Petronas….etc However WG believe there is additional potential further up the platform on the shelf margins where the Miocene and Cretaceous sediments are within drilling constraints. Cheleken Ridge

Reefal buildup over faulted high Bright amplitude S4 Intra Red Beds S6 Top Miocene and to earlier sediments preserved in structures formed in the compression. On seismic data, we observe patterns that indicate possible structures similar to those found onshore to the east. In addition, we see evidence of shelf edge reefs or build-ups on the flank of the high. This slide shows a possible reefal accumulation at Miocene level from an area slightly north of the Chelekin ridge. Although the central Caspian seismic does not show any appreciable structural closure, it may possess good stratigraphic potential in a different play concept. Namely the Miocene and cretaceous carbonates could have some potential on the edges of the shelf margin where the water conditions are more favourable to carbonate accumulation. S7 Top Cretaceous Central Caspian north of Cheleken Ridge

Seismic Base Pontian depth map S6 Central Caspian Platform / Shelf edge Highly faulted Possible fault closure ? Irregular line spacing Reef potential on shelf margin The sediments thin considerably over the Garabogaz high then thicken again to the north. The seismic line spacing is wide in this area so only the largest leads could be mapped. Close onshore there are Jurassic and Triassic discoveries near the border between southern Kazakhstan and north-western Turkmenistan. These discoveries are associated with a graben that preserved the older sediments. This is the structural map for the Miocene. Compared to the south caspian NB the abundance of faulting in the shelf area. It is proposed the subducted plate margin is somewhere beneath this part of the Caspian. As a result the structuration and faulting seen can be attributed to this deep seated plate movements. Trapping in this area is limited to fault closures or stratigraphical onlap against the shelf margin and reefal buildup against the shelf edge

Central Caspian Play Concepts older plays Deepest seismic reflector Tazeda-1 Possibility of older plays as found in Northern Turkmenistan and Kazakhstan Kuduk-1 Galkynysh-1 During the course of our interpretation Turkmen specialists asked if we could see on the seismic evidence of any deep reflectors possibly Jurassic. This is a map of what we called the deep acoustic reflector, we do not put an age to it as no wells have penetrated this level. But it is possibly Jurassic or Triassic. However onshore the Mesozoic sediments are clearly visible. Indeed there are Jurassic and Triassic discoveries near the border between southern Kazakhstan and north-western Turkmenistan. These discoveries are associated with a graben that preserved the older sediments. Perhaps similar features exist in the Central region ? From the magnetic data in the area we see a clear compartmentalisation or graben features at the deeper levels which closely follows our interpretation © 2000 Baker Hughes Incorporated ALL RIGHTS RESERVED

Play Concepts for South Caspian Petroleum Charge & Source: Maikop Shales Reservoir and seal: Palaeo-delta Structure: Compression of basin Timing: Migration and Maturation Now let us look at the South Caspian….. The main controls on the South Caspian Basin stratigraphy are tectonic and change in sea level. Oceanic crust is denser than continental crust so is usually associated with deep water. As heating ceased, the crust cooled and further subsided to maintain isostatic equilibrium. Compression around the basin may have added to the downward motion. The rapid subsidence lead to a large accommodation space for sediments resulting from the rapid erosion associated with the mountain building. Listed here are the 4 key elements that make up a viable play concept. All are present in the SCB