Vol 3, No 4 (2021)

The problem associated with low-resistance reservoirs in the fields of Western Siberia has been relevant since the end of the last century. According to the materials of geophysical well surveys (GIS), productive low-resistance reservoirs are often interpreted as water-saturated, as a result of which they are not used in the further operation of the well. The aim of the research is to illustrate the use of such parameters as statistical intensities of secondary changes in rocks (superimposed-epigenetic processes) as indicators of oil and gas saturation of low-resistance sand reservoirs at the unique field of the Surgut arch. The analysis is based on the method of statistical interpretation of the data of geophysical studies of wells developed by I. A. Melnik, who has achieved great success in studying this problem. Comparison of the results of these calculations with the results of processing the seismic data of the surface of the reflecting horizons confirmed the effectiveness of the proposed algorithm. The dependence of the intensity of secondary pyritization on tectonic disturbances and the distance to them was also determined. Recommendations for testing new intervals are given.

The success of a development strategy for any field depends on the degree of knowledge of the geological structure of its main reservoirs. As the area is drilled out, the concept of the structure of the hydrocarbon accumulation is refined, but in the case of a complex structure of the void space of the reservoirs and the lithological heterogeneity of the section over the area, geological uncertainties and risks during the subsequent placement of wells remain high. For these reasons, one of the main problems in hydrocarbon production is predicting rock types and the distribution of fluids throughout the reservoir away from wells, since the determination of rock properties is a major source of uncertainty in reservoir modeling studies [1, 2]. The proposed project will demonstrate algorithms based on machine learning methods that allow predicting the distribution of lithology and the uncertainty of lithofacies variability in the section.

The article describes the main features of the geological structure of the Jurassic-Cretaceous productive strata of the Karazhanbas field, located on the Buzachi Peninsula (Western Kazakhstan), and the effectiveness of thermal methods and their modifications to enhance oil recovery, which have been used in the field since the 80s of the last century. The use of thermal steam stimulation in the form of thermal slugs allows not only to cover most of the formation with thermal steam stimulation by switching to unheated water injection in a number of wells and transferring steam injection to other wells, but also to intensify the movement of the thermal slug in the formation during the cold water injection process. As a result, the steam-oil ratio when using thermal rims and increasing the steam injection rate can be several times less than with continuous slow steam injection. The use of thermal steam treatment allows increasing oil recovery by 35–45% of the initial balance oil reserves. Testing and implementation of new equipment and technology, as well as the study of world experience in the development of high-viscosity oil are currently relevant for the development of the Karazhanbas field.

In order to study and control microbiological contamination with sulfate-reducing bacteria of oilfield fluids we have monitored the performance of bactericidal reagents at the Uzen field.

Water samples were taken at the equipped control points for the content of SRB cells before and after the injection of the bactericide.

Due to the increase in the content of hydrogen sulfide in November – December 2020 at the fields of Ozenmunaygas JSC, a technical inspection of the NSM-4 facility and the reagent injection unit was carried out by KazNIPImunaygas together with specialists from the structural divisions of the Department for Oil Treatment and Production Services of OMG and the Office on chemistry and OMG. Further, KazNIPI performed laboratory tests to determine the miscibility of the bactericide with seawater at different temperatures.

Based on the results of the studies performed, following recommendations were developed: seawater tank biocide treatment recommendation, biocide injection system and injection point improvement in order to ensure proper mixing of the biocide with seawater. We also recommended to perform field trial of new biocides in order to avoid the development of bactericide resistance in the bacteria.

Oils with anomalous properties are characterized by large values of density, viscosity, high content of paraffinic hydrocarbons and asphaltene-resinous substances (up to 30%), high pour point (35–38°C), which increases the likelihood of complications in the processes of production, field gathering and oil treatment. Therefore, for many countries with cold climatic conditions, the problem of improving the low-temperature properties of oils is one of the most pressing problems in the production and transportation of hard-to-recover oils. Recent studies show that the rates of heating / cooling processes have a great influence on the rheological properties of natural oil mixtures during heat treatment. The experience of operating oil fields shows that in oil gathering and transportation systems, due to the water cut of oils and the aggressiveness of formation waters, persistent oil emulsions are often formed, which complicate the commercial preparation of oils.

The article presents the results of studies of the influence of the water cut factor on the transportation of well products, as well as the effect of the cooling rate on the pour point of oil emulsions. Laboratory studies have shown that an increase in the water content in emulsions of more than 40% leads to a significant increase in viscosity over the entire temperature range. It is also shown that an increase in water cut increases the pour point of oil by 7-14°С.