The onshore Gograndag-Okarem province is located in the eastern flank of the Caspian Basin in western Turkmenistan. The South Caspian Basin intracontinental depression registered complex accretion and rifting phases from the late Paleozoic to the late Neogene, when collisional orogenies occurred in the surrounding thrust belts of the Alborz and Kopet Dagh Mountains. Combined flexure loading and thermal cooling resulted in high subsidence rates, evidenced by thick high-frequency third-order sequences. A large Pliocene westward-prograding deltaic system from the paleo-Amu Darya river deposited a clastic section of nearly 6000 m (19,686 ft) in thickness known as the Red Color group. This large, deltaic wedge was initially deposited possibly during a global sea level fall (5.5 Ma?) and progressed from backstepping to progradational arrangements during the Pliocene and Quaternary. This unit is thought to be roughly equivalent to the Productive Series in Azerbaijan. Late Pliocene detachment tectonics, as a result of dextral transcurrent motions in the Kopet Dagh thrust belt (Himalayan orogeny), resulted in a series of parallel, northeast–southwest fold trends, where hydrocarbons were trapped by four-way dip anticlines. Commercial accumulations were found only in the first and second of the five known anticline trends with modest discoveries in the third trend. Multistacked overpressured reservoirs in the Lower and Upper Red Color formations are interpreted as distributary channels, distributary mouth bars, and flood sandstones deposited in a fluvial-dominated low-energy deltaic setting. Climatically controlled third-order sequences of 100– 150m (330–492ft) in thickness were identified in well log sandseismicdata. Well-developed lowstand systems tracts (fluvial-distributary channels) are the main producing intervals and are capped by a transgressive systems tract or a dark shale unit (maximum flooding surface) (outer shelf, prodelta). Although present, high-stand systems tract sandstones (delta front) have less productive potential. Inter-granular effective porosity ranges from 16 to 27%, permeabilities range from 50 to 1000 md, and overpressures range from 10.5 to 16.5 ppg. Maturity studies indicate immature indigenous source rocks, and the present depth of the oil-window top is approximately at 4000 m (13,124 ft) in the producing areas. The postulated source rock is interpreted as the Maikop Series (Oligocene–lower Miocene), according to studies in Azerbaijan. Mud volcanoes, thrust and accommodation faulting, and vertical migration are thought to be suitable effective migration pathways. A multistacked gas and oil column and varying hydrocarbon properties reveal a complex multiphase migration history. The Gograndag-Okarem province petroleum system is designated as Maikop/Red Color group(.). Wells produce an average of 300 BOPD from a single reservoir, with gas-oil ratios that range from 600 to 5500 bbl/ft3 of gas in undersaturated and saturated systems, respectively. Oil is sweet, with 15–348 API, and paraffinic (13–20%). Postulated exploration scenarios include Red Color group deeper pools and Miocene unconformity traps. Further potential in the third structural trend is thought to be limited because of westward-diminishing reservoir quality, migration shadows, and late trap charging.
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Throughout time, the greater Caspian area has maintained its position as one of the major petroleum provinces in the world. Its early history as a prolific producer of oil is well known. Caspian region exploration dates to the seventh century B.C., during the time of the Median Kingdom in today's southern Azerbaijan. Oil played an important role in the everyday lives of these ancient tribes of the region, and it is still a very important commodity today. The past two decades have seen many important advances in our knowledge of the geological evolution of hydrocarbon-bearing sedimentary basins. The success of modern exploration is, to a large extent, based on new advances in both deep and 3-D seismic imaging, as well as improved pressure-prediction and pre-drill oil and gas quality predictive methodologies, to mention just a few. Nevertheless, large areas of the greater Caspian region have remained unexplored due to a variety of factors such as deep-water conditions and zones with high pore-pressures in the South Caspian Sea and The Black Sea, and vast shallow-water regions with harsh winter ice conditions in the North Caspian Sea. This publication contains 12 extended abstracts and 6 full-length papers that discuss technology development, challenges in estimating proven and potential reserves, outcrop-based studies of potential reservoirs, regional tectonics and geodynamic evolution, and source rock and stratigraphic analyses of the greater Caspian area.