LİTHOFACİES MODEL AND OİL-GAS PROSPECTS OF MESO-CENOZOİC DEPOSİTS İN SHAMAKHİ-GOBUSTAN DEPRESSİON
Creators: name: Gultar Nasibova
name: İsmat Mammadov
name: Gasimov, Emil
name: Sahila Nasibova
Publisher: name: Reliability: Theory & Applications
Year: 2024
Subjects: carbonation
porosity
permeability
reservoir
Maykop
Cretaceous
fracturedcarbonate
core

description: Shamakhi-Gobustan oil-gas-bearing region is one of the most promising regions of Azerbaijan due to the hydrocarbon potential of Meso-Cenozoic deposits. Mesozoic, Paleogene-Miocene and Pliocene deposits are widespread in the area. From north to south, the region divided into tectonic zones such as Northern Gobustan, Central Gobustan, Shamakhi, South-western Gobustan, South-eastern Gobustan and Alat. In each tectonic element, regional anticlinal zones are separated, which are composed of stratigraphic sedimentary layers of a large range on the earth's surface. Numerous core samples taken from the Meso-Cenozoic deposits in Shamakhi-Gobustan oil-gasbearing region were analyzed and their reservoir properties were studied. The reservoir properties of the rocks were analyzed for separate zones and different stratigraphic units. Carbonate content in the northern zone is relatively high, and the carbonation of the Cretaceous deposits varies in a wide range, from 24% to 93.4%. The average porosity of the rocks was more than 14%. However, these sediments are characterized by good reservoir properties, despite the low porosity in some areas. The highest porosity is typical for the Gizmeydan, Angikharan and Chikilchay areas. However, the areas of the northern zone are with low permeability. For this zone, there is an inverse relationship between carbonation and permeability. In the northern zone, the carbonate content of Maykop deposits is less than that of the Cretaceous sediments and varies in a small interval, it is 17.5% only in the Garayazi area. In most cases, the porosity varies in the range of 20-26 5% in the studied areas, and with these values, the characteristics of the reservoir can be well characterized. Permeability was not very high, it is 2070 x10-15 m² only in Tuva area. In the central zone, the deposits of the Upper Maykop and Chokrak horizons are characterized by low carbonate content and relatively high porosity and permeability. Lower Pliocene deposits (PS) in South Gobustan are characterized by a high reservoir properties. Based on the lithofacies analysis of the Shamakhi-Gobustan depression, the increase of the reservoir properties from the North zone to the South direction was determined. The prospect of oil and gas in Shamakhi-Gobustan oil-gas-bearing region is related to MesoCenozoic deposits. Industrially important oil accumulations were identified in the sandy reservoirs of the PS, upper Maykop and Chokrak horizons, which were uncovered during drilling in separate areas in the southeastern and southwestern tectonic zones of the area. Presence of oil and gas are noted in the Upper Cretaceous fractured limestone and marls, which are widespread in the northern zone. The density of these rocks varies in the range of 1.94-2.55 g/cm³ along the northern zone. The Upper Cretaceous deposits are buried under the Paleogene deposits in a south-southwest direction. Oil-filled formations and dolomites in the form of breccias lying in separate intervals along the section of the middle and upper Miocene in central Gobustan are of special interest. It should be noted that the natural reservoirs for collecting oil and gas cummulatives in the section of the Meso-Cenozoic deposits are the terrigenous and carbonate reservoirs. The sandy-siltstone reservoirs of Maykop suite and Chokrak horizon are oil-gas-bearing in Hajivalli, Umbaki, Maraza, Donguzlug areas. A short-duration oil flow was obtained in the upper Cretaceous fractured-carbonate reservoirs in Gizmeydan and Hilmilli areas.