THE RISK OF CHANGE IN THE THICKNESS, SAND AND OIL-GAS CONTENT OF THE PRODUCTIVE SERİES SEDIMENTS ON THE NORTHERN SLOPE OF THE SOUTH CASPIAN DEPRESSİON
Creators: name: Shura Ganbarova
name: Zeynalova, Sevil
name: Tamella Zahidova
Publisher: name: Reliability: Theory & Applications
Year: 2024
Subjects: deposits
gas-condensate
suites
anticlinal zone
fault
vertical and lateral migrations
subduction zone
differential entrapment

description: Studies were carried out on Pirallahi, Gurgan-deniz, Khali, Chilov, Janub, Janub-2, Azi Aslanov, Palchig-Pilpilesi, Neft Dashlari, Gunashli, Chirag, Azeri and Kapaz structures in the Absheron-Balkan oil and gas-bearing zone. Paleogene-Quaternary sediments are represented in the section of the sedimentary cover of the Absheron-Balkan zone. The industrially productive oil and gas deposits discovered in this zone are related to the suites of the lower and upper stages of the Productive series (Pliocene). The changes risk of the total thicknesses and sand content of the suites of Productive series in the structures of the study area were analyzed in the direction of four anticlinal zones. To determine the change risk of thickness and sand content of individual suites of the PS and the phase zonation of hydrocarbons corresponding graphs were constructed and analyzed. The graphs are constructed based on average values of thickness and sand content. According to the conducted analyses, the thickness and sand content of the suites of the lower and upper stages of the PS on the Pirallahi-Janub-2, Khali-Neft Dashlari, Gunashli-Kapaz anticlinal zones are increas from the northwest to the southeast along the northeast and southwest limbs. The characteristics of the thickness changes risk of the PS suites show that the tectonic movements and the relief of the basin bottom play a key role in the thickness distribution. Based on the change of sand content in the study area, it can be noted that the paleogeographical conditions in the basin during the formation of PS sediments were quite favorable. The Kapaz structure, located at the southeastern end of the Gunashli-Kapaz anticlinal zone, is similar in geological structure with other folds of the anticlinal zone where it is located. It can be noted that the GaS, PK, PKS, Balakhani suites with gas-condensate-oil bearing in the adjacent fields are also highly promising here. In the Azeri field, which is located in this anticlinal zone, the PKS suite of the Productive series is gas-condensate bearing. The PK and GaS are oil-gas-condensate-bearing in the neighboring Chirag and Gunashli fields, so, they are also can be promising here. The complexity level of the folds noted here is different. İt is play a fundamental role in the distribution of oil and gas fields. İt should be noted that longitudinal faults play a key role in the distribution of hydrocarbon accumulations in the fields of Absheron oil and gas region. Due to influence of the transverse faults folds are placed in a stepped form. İt is lead to reshape the oil fields in Pliocene sediments. Regarding the formation of oil and gas deposits, it should be noted that this process is formed as a result of the alternating activity of vertical and lateral migrations. Therefore, in the chain-arranged ascents within the mentioned zone, in the southeast-northwest direction, so, the differential entrapment of oil and gas along up dip is justified. That is, along the Pirallahi-Janub-2 anticlinal zone, gas-condensate deposits are replaced by oil-gas, in turn, the oil-gas deposits are replaced by oil deposits in the southeast-northwest direction. The lower suites of the PS on the Gunashli-Kapaz anticlinal zone are mainly characterized by gas-condensate, and the upper suites are mainly characterized by the presence of oil-gas accumulations.