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14GEOLOGICAL AND MINERALOGICAL SCIENCES
PROSPECTS OF OIL AND GAS BEARING IN THE JURASSIC SEDIMENTS OF THE PRISAMUR
PROSPECTIVE OIL AND GAS BEARING AREA
Aliyeva S.
Associate Professor of the
Department «Oil and Gas geology» of Azerbaijan State University of Oil and Industry
Sadiqov A. master 2-year DOI: 10.5281/zenodo.6532617
Abstract
The oil and gas potential of the Jurassic sediments of the Prisamur zone is estimated based on the analysis of a number of paleogeological, structural tectonic, facial-lithological, hydrochemical, etc. factors (criteria) of oil and gas formation and oil and gas accumulation and also according to the results of a comparative analysis of lithofacial features and data on the petroleum potential of these sediments in neighboring petroleum regions and regions.
Yalama-Samur, Samur-sea, Agzybirchala-sea, Khachmas-sea, Charkhy, Khachmas, it is necessary to consider the most promising for the search for deposits of oil and gas in sediments of the middle and lower Jurassic. A.G. Aliyeva (Guba-Deniz) and the Khudat buried uplifts, and on the Upper Jurassic deposits - the Imamkulykentskoe buried uplift.
Keywords: oil and gas potential, Prisamur prospective oil and gas bearing area, Yalama, Khudat, Khachmas, Kusary, Agzybirchala, Jurassic deposits, oil and gas deposits.
The Prisamur prospective-oil and gas-bearing region is geographically located in the most north-eastern part of Azerbaijan and in geomorphological terms is part of the Samur-Divichy lowland, formed as a result of prolonged accumulation of river, proluvial and marine sediments with a capacity of up to 500 m. In the western part, the promising-oil and gas-bearing area under consideration also partially covers the Kusar inclined plain [3].
The geological study of the Prisamur prospect-oil and gas-bearing region is still not complete enough. Analyzing the degree of study of the buried uplifts of the Prisamur prospect-oil and gas-bearing region of Azerbaijan, it should be noted that of the large number of local anticlinal structures identified by geophysical methods of exploration, drilling was mainly carried out only on five structures (Yalama, Khudat, Khachmas, Qusar and Agzybirchala), and on the last three - only single wells. The largest volume of drilling, at first glance, was carried out in the Yalama area. 14 wells were laid here. However, of these wells, two wells were drilled not on the Yalama Uplift, but on the distant dives of the northeastern wings, respectively, the Shir-van and Imamkulikend rises. Of the remaining 12 wells, 6 were eliminated during drilling and testing for technical reasons, without fulfilling the tasks assigned to them. An even smaller volume of drilling was carried out at the Khudat only 6 wells were laid, of which 4 were liquidated for technical reasons and only one was tested . In addition, according to the latest seismic surveys carried out in this area, the vaulted part of the anticlinal fold on Mesozoic sediments was located 4-5 km northeast of the previously pre-buried its whereabouts and thus was not affected by the search operations carried out [2].
In the area under consideration, in the areas of Yalama, Khudat, Khachmas and Qusar, Exploratory drilling revealed Middle Jurassic deposits with a capacity of up to 1700 m. These deposits here have a very uniform lithological composition (alternation of non-carbonate sandstones, siltstones with mudstones) and in various areas of the zone are inconsistently blocked by precipitation of different ages - from Apt-Neocomian to Sarmatian.
As a result of the work carried out on the correlation of the sections of the Middle Jurassic deposits of the district, it was possible to compile a summary section of these deposits and establish that the revealed Middle Jurassic sediments of the Prisamur district in terms of stratigraphic volume cover the upper reaches of the Lower Bayos sub-tier, the Upper Bayos sub-tier and the Bat sub-tier. tier [7]. In the areas of Yalama and Khudat, the Middle Jurassic deposits are presented in full stratigraphic volume. On the Khachmas area in the section of the Middle Jurassic there are no deposits of the Bat tier, in the Kusar area the Middle Jurassic is represented only by sediments of the upper reaches of the Lower Bayos sub-tier and more ancient sediments [1, 7]. The Bath tier with a capacity of 420-550 m, covering 1-VI sandy-siltstone packs of the consolidated section of the Middle Jurassic, contain 17-27% of the total capacity of sand-siltstone differences.
The lower-lying sediments of the Upper Bayosian sub-tier (VII-XIV sand-siltstone packs) with a capacity of 700-900 m contain 260-280 m of total capacity of sand-siltstone sediments, which is an average of 3638% of the total capacity of these deposits.
Rice. 1. Schematic map of the sandiness of the Upper Bayos deposits of the Middle Jurassic of the Prisamur prospective-oil and gas-bearing region of Azerbaijan.
Symbols: 1- exploratory wells in the areas (from north to south) of Yalama, Khudat, Khachmas, which opened the Upper Bayos deposits (in the numerator - .№ wells, in the denominator - the percentage of sandiness of upper Bayos deposits); 2-lines of equal percentage content of silt-sand differences of the upper Bayoss.
The Lower Bayos deposits (XV sand-siltstone pack) with an open capacity of 250-300 m contain 67% of the power of sandy-siltstone differences. Within the area under consideration, the development of Lower Jurassic deposits is also expected in limited areas of the zone - sediments of the Upper Jurassic.
Rice. 2. Schematic map of the sandiness of the Bat deposits of the Middle Jurassic of the Prisamur perspective-
oil and gas-bearing region of Azerbaijan.
Symbols: 1- exploratory wells in the areas of Yalama and Khudat, which opened the Bath deposits (in the numerator-. of wells, in the denominator - the percentage of baht sandiness). 2 - lines of equal percentage content of silt-sand differences of Bath deposits.
The prospects for the oil and gas content of the Jurassic deposits of the Prisamur zone are assessed on the basis of an analysis of a number of factors (criteria) of oil and gas formation and oil and gas accumulation (paleogeological, structural-tectonic, fecal-lithological, hydrochemical, etc.), as well as on the results of a comparative analysis of lithologic-facial features and data on the oil and gas content of these deposits in neighboring oil and gas bearing areas and areas [7].
Considering the prospects for the oil and gas content of the Lower Jurassic deposits of the Prisamur district, it should be noted that the paleogeographic conditions for the sedimentation of these sediments were favorable for the processes of bitumen formation, since in this era the research area was a zone of stable immersion, where mainly powerful layers of clay sediments accumulated. Bituminological studies conducted in neighboring areas of Southern Dagestan showed (Kon-yukhov I.A., 1958) that the Lower Jurassic rocks contain in their composition scattered organic matter, including bitumen, the concentration of which in some areas reaches 0.4% and these deposits, according to a number of researchers [6, 8], can be considered as oil and gas producing.
Within these sediments, in the sections of the Toar tier and the Lower Aalen sub-tier, there are sand-silt-stone formations that can serve as reservoirs for oil and gas [4, 5].
The Lower Jurassic deposits are blocked by a powerful clay stratum of the Upper Aalen deposits, which creates favorable conditions for protecting possible deposits of oil and gas from destruction.
Precipitation of the Lower Jurassic age is associated with intensive oil and gas manifestations both in the areas of exits of these deposits to the daytime surface in Southern Dagestan and in the mountainous regions of Northern Azerbaijan, and oil and gas manifestations noted during drilling and testing of wells in a number of areas of Southern Dagestan and the Khizina zone of Azerbaijan [4, 5].
Thus, within the Lower Jurassic deposits of the Prisamur region of Azerbaijan, the sandy-siltstone-silt-stone horizons of the Toar and Lower Aalen tiers of the Lower Jurassic are distinguished as prospective-oil-and-gas-bearing.
Within the buried uplifts of the Kusar-Khachmas (Agzybirchala) protrusion, syngenetic reservoir deposits of oil and gas are possible in these horizons, confined to the structural traps of the Khachmas, Charkha, Kusar and other buried uplifts (Fig. 3). The formation of these deposits is possible due to the lateral (intra-for-mational) migration of hydrocarbon fluids from the potential zone of oil and gas formation of the Guba-Div-ichy trough after the uplifts of the Upper Jurassic-Lower Neocom stage, when structural traps formed within this protrusion.
Similar in type deposits are possible within the buried uplifts of the Yalama-Khudat the protrusion and its water area (Yalama, South Yalama, Khudat, A. G. Aliyev Uplift (Guba-deniz), Yalama-Samur, Samur Sea, for which the Kasumkent (Zeykhur) trough and submerged areas could serve as hydrocarbon fluids feeding areas. Of the listed, the most promising are the uplifts located near the areas of possible oil and gas formation (the A. G. Aliyev Uplift (Guba -deniz), the Khudat Uplift and the Rises on the Caspian Shelf). On the southwestern board of the Yalama-Khudat strati-graphic deposits are also possible, timed to the zone of disagreement between the Lower and Middle Jurassic deposits revealed by seismic works.
When assessing the prospects for the oil and gas content of the Middle Jurassic deposits of the Prisamur region of Azerbaijan, it should be noted that the paleo-geographic conditions for the sedimentation of these deposits were also favorable for the processes of bitumen formation. The available data on the areas of Yalama and Khudat indicate a high content of bitumen in these sediments (up to 0.294%) and the existence of a restorative geochemical situation during their formation, which allows us to attribute the Middle Jurassic sediments to the category of oil and gas producers.
On the constructed schematic map of the sandstone of the Upper Bayos deposits (Fig. 1) the greatest relative sandiness, according to drilling data, is confined to the arched parts of the Yalama and Khudat uplifts, where the sandiness reaches 40% (Khudat); significant sandiness (up to 3 8%) is noted in the section of the Upper Bayos deposits in square No. 2 of Khachmas.
On a similar map of sandstone built for the Bat deposits of the Yalama and Khudat areas (Fig. 2), a relative increase in sandiness is noted within the arched part of the Yalama uplift (up to 27%), while on the wings of the fold the content of sandy-siltstone differences decreases to 19-21%. In the adjacent part of the Khudat fold, the sandiness of these deposits reaches 38%.
Sandstones and siltstones of the Upper Bayos and Bath deposits in the areas of Yalama and Khudat, according to a limited number of analyzes, have average porosity values of the order of 13-14%, and permeability - about 17 m.darsi. Data from the testing of these deposits, as a result of which fountain inflows of highly mineralized reservoir waters of the chlorcalcium type (Sa + k = = 188.4-382.0 mg per 100 ml) were obtained in a number of wells. weight of 1.0410-1.0861 g / cm3 (salinity 5.7-11.6 ° Ve), characteristic of areas of difficult water exchange with flow rates from 10-20 to 50312 m3 / day sometimes with signs of oil and gas, it is possible to consider the sand-aleurite layers of the sandy horizons of the Upper Bayos and Bath deposits as reservoirs with satisfactory, and in some cases good reservoir properties. In well No. 18 Yalama when drilling in deposits of the upper Bayos in the range of 39723976 m took a sample of sandstone with the smell of gas, but due to the accident this well could not be tested.
It should also be noted that reservoirs in middle Jurassic sediments of a similar class at the fields of the Prikum-Tyulenev shaft are industrially oil and gas bearing (Brod I.O. et al., 1958).
The above reservoirs are sufficiently isolated from each other by powerful clay-mudstone sections. Hydro-geological and hydrochemical conditions in these reservoirs were favorable for the formation and preservation of possible deposits from destruction.
Thus, the sandy-siltstone horizons of the Upper Bayos-Bat deposits are distinguished as perspective-oil-bearing lithological-stratigraphic complexes in the Middle Jurassic deposits of the Prisamur district.
In the area of the Yalam-Khudat and Samur sea ledges, these horizons are most promising within the Khudat, Yalam-Samur, A. G. Aliyev (Guba -deniz) and Samur burial uplifts. On the Khudat area, an increase in the sandiness of the Upper Bayos-Bat rocks, the vault of the Khudat elevations along the Middle Jurassic deposits are gypsometrically 600 m higher than the neighboring Yalama Uplift, and within the neighboring sea uplifts of the Yalama-Samur, A. G. Aliyev (Guba-deniz) and Samur burial uplifts, due to a decrease in tectonic intensity, an improvement in the reservoir properties of the sandy-siltstone differences of the Upper Bayos-Bat is expected due to a decrease in tectonic intensity deposits. Other buried elevations of the ledge (Yalama, South Yalama, Shirvan), as well as the Imamkulikent rise - on the sinking of the SW of the side of the ledge, are also promising for these deposits.
Within the Kusar-Khachmas (Charkhy) salient, the main prospects of the Upper Bayos deposits are associated with the east-southeast end of the protrusion
and its continuation in the shelf zone of the Caspian Sea (Khachmas, Charkhy, Agzybirchala-Sea, Khachmas-Sea buried uplifts), where there is an increase in sandi-ness and due to the weakening of metamorphism, the reservoir properties of sand sediments are expected to improve. In all these uplifts, structural vaulted synge-netic reservoir deposits of oil and gas are possible, which could have been formed as a result of intraformation migration from the Kuba-Divichy trough located in the immediate vicinity [1]. In the northwestern part of the Kusar-Khachmas (Charkhy) protrusion, in the area of immersion of the wings and periclinals of the Kusar. Only stratigraphic deposits are possible, since the Upper Bayos-Bat deposits in the vault of this uplift are blurred. Similar conditions of possible oil and gas content exist for the Bat deposits of the east-southeastern end of the Kusar-Khachmas salient. Limited prospects for oil and gas content in the zone under consideration are associated with the Upper Jurassic deposits, since in the studied ones By drilling areas of the zone, they are absent in the section and are only assumed - by analogy with the neighboring areas of the Sudur zone - in the NW part of the Kasumkent (Zey-khur) trough, within the Imamkulikent buried fold, where they can be represented in a carbonate-chemo-genic facies.
Fig.3. Map ofprospects of oil and gas content of Jurassic deposits of the Prisamur prospective-oil and gas-bearing region of Azerbaijan.
Symbols: I—Yalama-Khudat ledge and its offshore extension; Ia—group of Yalama buried uplifts: 1—Yalama, 2—North-Yalama, 3-West-Yalama, 4-South-Yalama, 5-Samur. Ib - southwestern part of the ledge: 6-Khudat, 7-Shirvan. Ic—Samur marine ledge; 8-raising them. A. G. Alieva (Guba-deniz); 20-Yalama-Samur; 21-Samur-Sea (Samur-deniz) II—Kasumkent
(Zeykhur) trough: 9-Imamkulikent. III - Kusar-Khach-mas (Agzybirchala) ledge: 10-Adzhiakhur; 11-Khazry; 12-Kusar; 13-Zizik; 14-South Khachmas; 15-Khach-mas; 16-Velvelichay; 17-Charkhy; 18-Agzybirchala-sea (Agzybirchala-deniz); 19-Khachmas-sea (Khach-mas-deniz). IV - Guba-Divichy trough.
a—boundaries of tectonic elements of the II order; b—boundaries of tectonic zones, anticlinal belts; c— Samur deep fault; g—contours of local uplifts along Jurassic sediments according to seismic exploration and drilling data; d—presumed contours of local uplifts along Jurassic sediments along a rare network of seismic profiles; e—contours of local uplifts of Mesozoic (Jurassic) rocks according to gravimetry data; f—pro-spective-oil and gas bearing areas on separate tiers of Jurassic sediments within buried local uplifts; j— possibly promising areas on separate tiers of Jurassic sediments within buried local uplifts identified from seismic and gravity exploration data that require clarification by parametric drilling and detailed seismic exploration; i —zones of possible image stratigraphic traps in separate tiers of the Jurassic; j — wells that have uncovered Jurassic deposits; k — proposed exploratory well; l — proposed parametric wells.
The most promising for the search for oil and gas deposits in the sediments of the Middle and Lower Jurassic should be considered Yalama-Samur, Samur-Sea, Agzybirchala-Sea, Khachmas-Sea, Charkhy, Khachmas, named after A. G. Aliyev (Guba-deniz) and Khudat buried uplifts, and according to the Upper Jurassic deposits - Imamkulikent burial uplift.
Of all the above uplifts, the largest is the Yalama-Samur uplift, located within the shelf zone near the coast of the Prisamur zone. It is a multi-dome rise with a total area of more than 900 km2. Prospective oil and gas bearing Jurassic-Cretaceous deposits lie within this uplift at depths from 1500 to 2500 m at water depths from 300 to 700 m.
References
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