The composition of hydrocarbon systems plays an essential role in ensuring reliability in field operation processes, the design of oil onshore facilities, and the availability of reliable information about the PVT properties of systems. In this article, experimental and numerical methods are used to obtain data on the component composition of the extracted oil products and their PVT properties. These methods help obtaining a detailed composition and phase state of the hydrocarbon system. The numerical delumping method is utilized in this article. It is worth noting that all calculations were made on the basis of data on the component composition of Kazakhstani oil samples. The results and comparative evaluation show that the proposed delumping mix-method has excellent consistency with the data obtained with experiments and with the Nichita’s analytical approach. In the future, the results on the detailed composition can improve and link the compositional modeling of the reservoir with the modeling of surface structures.

In compositional modeling, the phase characteristics and behavior of reservoir fluids are calculated using the equation of state. To simplify the calculations and speed them up, the components of the heptane plus fraction (C7+) are grouped into pseudo-components. However, after this procedure, the results of compositional modelling of the reservoir containing the pseudo-components need to be delumped so that they can be used in surface models. It follows from this that the problem lies in the fact that the grouped composition cannot be applied to the modeling of ground structures. The object of the study is Kazakhstani oil, on the example of which a detailed component composition was obtained by analytical delumping based on reduction parameters. In laboratory conditions, the component composition of oil, and other fluid properties were determined. The study presents the results that prove the importance of applying the delumping algorithm in the context of compositional modeling. The results obtained analytically correspond quite accurately to the numerical calculations of the PVTsim software and laboratory experiments. A comparison of existing methods showed a difference of 5 %, which suggests that delumping is an excellent method for describing and obtaining a detailed composition of the hydrocarbon mixture. In practice, the results of the detailed composition of hydrocarbons can be used for the design of refineries. Also, the findings from this research can enhance the planning and design of surface facilities, particularly when developed under reservoir conditions where the pressure exceeds the saturation pressure

Compositional modeling of the reservoir isn’t complete without calculations of phase equilibrium and is a complex process involving many calculations. In nature, hydrocarbons don’t occur as separate components, they’re mainly mixtures. When modeling the reservoir composition for phase equilibrium calculations, in order to reduce computational costs, in practice, hydrocarbon mixtures are grouped into pseudo-components. The number of grouped pseudo-components varies from 4 to 10. This grouping process is called lumping. However, when crude oil comes to the surface, it’s important to know its detailed composition, since mixtures grouped into pseudo-components don’t allow you to know this. In this regard, modeling of the detailed composition of hydrocarbons is the main tool for understanding the detailed phase separation and design of surface facilities. In practice, this process is called delumping. In the case of this process, the detailed composition of the fluid is presented and the amount reaches up to 36 components, sometimes more. The delumping process, due to the precise separation of heavy plus fractions into carbons with single ordinal numbers (C7, C8, etc.), makes it possible to clearly recognize non-zero BIP’s in the equation of state. The new analytical approach has not previously been applied to the oils of the Caspian region, so this approach has an important role for the oil industry in the Caspian region. Analytical delumping in this paper was done to improve the PVT modeling. This paper presents the results of PVT research of Caspian oil and presents a comparison of analytical and numerical methods of delumping. As a result of the study, it was found that the analytical approach is in excellent agreement with experimental data and data from software such as PVTsim Композиційне моделювання пласта не обходиться без розрахунків фазової рівноваги і є складним процесом, що включає безліч розрахунків. У природі вуглеводні не зустрічаються у вигляді окремих компонентів, а в основному являють собою суміші. При моделюванні складу пласта для розрахунків фазової рівноваги з метою зниження обчислювальних витрат на практиці суміші вуглеводнів групуються в псевдокомпоненти. Кількість згрупованих псевдокомпонентів варіюється від 4 до 10. Цей процес групування називається лампінгом. Однак, при виході сирої нафти на поверхню, важливо знати її детальний склад, оскільки суміші, згруповані в псевдокомпоненти, цього не дозволяють. У зв'язку з цим моделювання детального складу вуглеводнів є основним інструментом для розуміння детального фазового поділу та проектування наземних споруд. На практиці цей процес називається делампінгом. У цьому процесі представляється детальний склад рідини, а кількість досягає 36 компонентів, іноді більше. Процес делампінгу завдяки точному поділу важких плюсових фракцій на атоми вуглецю з одиночними порядковими номерами (C7, C8 і т. д.) дозволяє чітко розпізнати ненульові значення ПБВ в рівнянні стану. Новий аналітичний підхід раніше не застосовувався до нафт Каспійського регіону, тому такий підхід відіграє важливу роль для нафтової промисловості Каспійського регіону. У даній роботі аналітичний делампінг був проведений для поліпшення PVT-моделювання. У статті представлені результати PVT-дослідження каспійської нафти і наведено порівняння аналітичних та чисельних методів делампінгу. В результаті дослідження було встановлено, що аналітичний підхід відмінно узгоджується з експериментальними даними та даними такого програмного забезпечення, як PVTsim

Currently, the oil and gas segment of Kazakhstan is facing such a problem as paraffin deposits. The problem associated with the deposition and crystallization of paraffin causes large-scale difficulties, and models for predicting wax precipitation are limited to specific types of oil, and therefore there is a need to improve them. The authors of this article analyzed and developed a predictive model of paraffin deposition from crude oil for Kazakhstani fields. The work is based on the study of Lira-Galeana et al., which considers the multicomponent deposition of immiscible solids from an oil mixture - a multi-solid model. During the study, it was found out that the Lira-Galeana model uses the equation of state, the volatility properties of the components and the activity coefficient. The Poynting effect was considered at high pressures in the system. For experimental studies, oil samples were taken from two fields. The component composition of the oil, the pour point and loss of fluidity of the oil, as well as the melting point temperatures were determined in laboratory conditions. The amount of paraffin sludge from the oil was estimated experimentally. The results obtained are fully consistent with the analytical solution. During laboratory tests, it was found that the oil from the second field was heavier, and the degree of crystallization of paraffin was more significant than that of oil from the first field under the same conditions. Using this predictive model, the authors were able to predict the amount of solid precipitation from crude oil during the year, depending on changes in ambient temperature.