Perm Journal of Petroleum and Mining Engineering

One of the most important tasks in the oil and gas industry is to predict the values of geological parameters of productive formations in the interwell space. The accuracy of estimating the effective oil-saturated thickness or the values of filtration and capacity properties at the locations of the project well stock directly affects the efficiency of oil and gas assets development and economic indicators.The task of predicting the values of geological parameters is complicated by the fact that the geological environment has been studied by wells in fragments, and sources of information about the interwell space, despite continuous technological progress, have limited accuracy. In addition, the real geological structure in most cases is much more complex than our understanding of it. The vertical and lateral heterogeneity of productive formations and the high degree of geological properties variability do not allow the effective use of interpolation methods.This paper presents the results of testing the author's methodology aimed at finding the most reliable implementations of a three-dimensional lithology model.The proposed approach is based on the use of Bayesian optimization to determine the most optimal values of variogram ranges along the X and Y axes during the modeling of a three-dimensional lithology cube. The mean absolute error of the predicted total effective thickness of the reservoir, calculated using cross-validation, was employed as the primary metric to evaluate the reliability of the three-dimensional lithology model. The results demonstrate the advantages of applying Bayesian optimization compared to the classical grid search method for parameter optimization. Firstly, the proposed approach enabled the creation of a three-dimensional lithology model with higher predictive capability. Secondly, the developed methodology significantly reduced the computational resources required for the calculations.

Oil production in the Arctic is associated with the risk of accidental oil spills. In this regard, the sensitivity of the Arctic environment to oil pollution and its extremely low resilience are of growing concern. Apparently an effective environmental management system is needed to ensure safe operation of the petroleum facilities in this area. The article presents a case study of the Varandey terminal, which is a unique facility located beyond the Arctic Circle, in the permafrost zone, on the coast of the Barents Sea. The terminal combines an onshore tank farm, an offshore loading facility and an underwater pipeline connecting them. The extreme environment of the Far North (permafrost, low temperatures, long high water floods) complicates the engineering and geological conditions of the oil infrastructure facilities. Their safe operation is largely determined by the structural features of the upper part of the terrain and its stability. What in its turn, depends on the permafrost condition. Changes in the thermal regime of the frozen rocks in the foundation of the facilities during their operation trigger dangerous engineering and geocryological processes. As practice has shown, now and then it leads to emergencies at the petroleum facilities with severe logistical, environmental, social, financial and economic consequences. Working out a technology to control the thermal regime of the foundation soils to ensure reliable and safe operation of the engineering facilities of the coastal and marine oil loading complex is among the most essential and pressing necessities of the petroleum industry in the region. Engineering and geocryological monitoring is one of the effective tools to address this issue. It also allows mitigating the potential environmental and economic damage. The conducted research substantiates the relevance of creating a geocryological monitoring system for continuous control over the frozen soils beneath the facilities in order to detect troubles at an early stage of their development. The main elements of the system are presented. Two types of foundations are considered that are designed to maintain the temperature of the soil beneath the facilities within acceptable limits.

The evidence base of supporters of the need for hydrophobization of the reservoir surface in the bottomhole formation zone when exposed to aqueous process fluids is based on erroneous ideas about the improvement of oil filtration in this case compared to water. A critical analysis of literary sources on the topic of hydrophobization of the bottomhole formation zone indicates an incorrect premise of many domestic researchers in the interpretation of the main provisions of the mechanism of its action in the real reservoir space on the flow of formation fluids under the influence of hydraulic pressure. The efficiency achieved in field conditions from the presence of, in particular, cationic surfactants is explained not by its conversion to a hydrophobic state, but, at best, by partial hydrophilization and a number of other associated effects: hydrocarbon saturation of the bottomhole formation zone, complex action of acidic compositions, etc. A more acceptable and explainable is the need to maintain a hydrophilic state of the reservoir surface in the bottomhole formation zone, which is ensured by non-ionic surfactants and/or polar non-electrolytes. This is confirmed by oil field practice and analytical calculations of the real role of capillary forces. The impossibility of achieving complete hydrophobization of a heterogeneously wetted reservoir space along the length of penetration of filtrate with cationic surfactants deep into the formation from the wellbore was confirmed by both laboratory experiments and calculations of their adsorption on polymictic rock. Based on the materials presented in the three parts of this article, it is necessary to more consciously approach the selection of surfactants for process fluids in the methods of influencing the bottomhole formation zone based on the fundamental principles of formation fluids filtration, the role of reservoir surface wettability, colmatation processes, their prevention and elimination.

CCUS (Carbon Capture, Utilization and Storage) is becoming a key technology for achieving a significant reduction in global carbon emissions over the next century, which is why the issues of carbon sequestration in natural porous media have recently received increasing attention in the scientific community. Foreign scientists have obtained some laboratory developments, and carbon sequestration projects have already been implemented in a number of countries. For Russia, carbon sequestration in porous geological media is promising due to the significant potential of underground CO2 storage tanks, the possibility of using CO2 to enhance oil recovery, as well as the developed infrastructure of oil and gas fields. The Volga-Ural oil and gas province may become one of the promising regions for the creation of a CCUS cluster due to a combination of such factors on the territory as a significant number of CO2-emitting enterprises and a huge number of oil and gas traps potentially suitable for the use of enhanced oil recovery methods and / or CO2 disposal. The article discusses the principles of carbon sequestration in reservoir rocks, the main mechanisms of capture that operate when CO2 enters a geological repository; it is shown that research in the field of underground CO2 storage is aimed at reducing the uncertainty in the efficiency of CO2 storage in rocks, however, the effect of CO2 on natural porous media is currently poorly understood. Laboratory studies are required, followed by the development of mathematical models of the rocks interaction with various carbon gases types to develop recommendations for optimal modes of carbon injection into the reservoir for the purpose of additional oil recovery in the short term and carbon absorption by the rock and its storage in the long term.