THE GEOLOGICAL RISK OF CHANGING THE PARAMETERS OF THE RESERVOİRS DEPENDING ON THE DEPTH IN A NUMBER OF FIELDS OF THE BAKU ARCHIPELAGO
Creators: name: Gultar Nasibova
name: Khuraman Mukhtarova 
name: Shura Ganbarova 
name: Sahila Nasibova
Publisher: name: Reliability: Theory & Applications
Year: 2024
Subjects: porosity
permeability
mechanical analysis
section
clay
graphs of the dependence
sandy-silty rocks

description: Geological risk belongs to the doubt and variableness of the reservoir characteristics and internal structure, like as porosity, permeability, heterogeneity, thickness, faults, crucks, and seals. These characteristics identify the amount and quality of the hydrocarbons in deposits, as well as the recovery coefficient and the production rate. Geological risk possible to reduce by acquiring and analyzing more data, like as seismic, well logs, core sampling, and producing history. In addition, by using suitable methods and models to assess the range of possible outcomes. So, this paper discusses the results of studying terrigenous Mesozoic and Cenozoic rocks of the Sangachal-deniz-Duvanny-deniz-Khara-Zira oil and gas bearing region of the Baku archipelago element of the South Caspian depression as possible reservoirs of oil and gas, its characteristics and geological risk in changing of reservoir parameters [1]. To explain the nature of the change in rocks by depth, graphs of the dependencedependence of porosity on depths were plotted. The depth of occurrence of these rocks along the well sections varies from several hundred meters (Khara-Zira field) to 5500-6000 m (Sangachal-deniz, Duvanny-deniz fields). The wells uncovered rocks from the Quaternary to the middle Miocene (Chokrak). Well sections are represented by alternation of sands, sandstones, dolomites and clays. The wells completely uncovered the section of the Productive Series (PS). The maximum thickness of the PS in the Sangachal-deniz field and in the north-east part of Khara-Zira is 3950-4000 m. Hypsometrically elevated parts of the Sangachal-deniz and Duvanny-deniz structures, the thickness of the PT varies within 2960-3600 m. The minimum thickness of the PS was discovered by wells in the southwestern limb of the Sangachal-deniz uplift up to 3000 m. The type of structure is brachianticline, which are associated fields. The arch part is fragmented by faults into blocks that these blocks are oil and gas-condensate. In the oil of the field, the amount of resin is 8-27%, asphaltene mass0.2-1.1%, paraffins6.0-20.1%. The content of light fractions, which have a boiling point of up to 300° C, varies between 31.4-40.0%, gasoline4.5%, naphtha12.1%. The hydrocarbon composition of oil is noted in the following order: methane52.1-66.8%, aromatic hydrocarbons12.2-21.5%, naphthenes12.3-35.1%. The density of reservoir oil ranges from 0.729 to 0.780 g/cm³, and the density of degassed oil is 0.8690.889 g/cm³, condensate 0.759-0.797 g/cm³. The results of determining the porosity of samples taken from drilled wells were used, in addition, the density and permeability of rocks were studied by mechanical analysis of numerous samples. The porosity of the studied samples varies from 1.5 to 38%, the density in wet samples varies from 1.72 to 2.97 g/cm³, and in dry samples from 1.72 to 2.97 g/cm³, permeability from 0 to 863·10-15 m². But at some depth, the permeability reaches 1910·10-15 m².