Vol 5, No 2 (2023)
- Year: 2023
- Articles: 9
- URL: https://vestnik-ngo.kz/2707-4226/issue/view/5465
- DOI: https://doi.org/10.54859/kjogi.202352
Full Issue
Geology
Overview of seismic stratigraphic referencing methods in conditions of limited or substandard set of initial well data
Abstract
Background: Well tying is an integral part of seismic interpretation both at the stage of structural and dynamic analysis. Linking seismic and well data is a critical process that allows you to link geological objects identified from seismic data with actual data obtained from wells, because. it is based on the relationship between the lithological composition of the deposits that make up the section under study and the characteristics of the reflections. Seismic data are in most cases presented on a time scale, while well data are on a depth scale, and in order to calibrate them, it is necessary to select a velocity law and establish a time-depth relationship.
Aim: This article aims to deepen the understanding of the importance of quality control of initial well data to improve the result of seismic stratigraphic tying and increase the efficiency of geological exploration, as well as to propose methods to improve the quality and efficiency of tying..
Materials and methods: Methods for correcting the readings of acoustic logging are described, various algorithms for tying seismic and well data are given.
Results: The paper considers the reasons for the distortion of the values of the initial well data, examples of data quality analysis, suggests options for how to conduct a seismic stratigraphic tie in the conditions of a limited or initially substandard set of initial data and obtain reliable depth-velocity dependences for wells.
Conclusion: Conducting quality control and, if necessary, correcting the original well data is a critical step to improve the accuracy of the final results of seismic interpretation. It is important to note that even with limited and low quality input data, it is possible to obtain depth-time dependencies. However, the results of the work show that editing and amending the original logs significantly improve the quality and detail of the seismic stratigraphic tie.
Study of the pore structure and calculation of macroscopic characteristics of rocks based on X-ray microcomputed tomography images
Abstract
Background: Absolute and relative phase permeability and capillary pressure are important parameters in predicting oil and gas production from reservoirs, especially when acidizing the bottomhole zone of a well. They are mainly determined during long and resource-intensive laboratory experiments. Thus, additional approaches are required for the operational determination of the above parameters. The pore-network modeling based on microcomputed tomography data allows, firstly, to study the pore space of rock samples taking into account rock dissolution, secondly, to calculate the main macroscopic properties of rock samples without destroying them, and thirdly, to create a database of digital cores for further research
Aim: Study of the pore space of two carbonate rock samples and the flow of fluids in them using the General Electric V|tome|X S240 MT and using the Avizo and PNFLOW software package.
Materials and methods: This article uses microcomputed tomography with a spatial resolution of ~19 µm and pore-network modeling of fluid flow in porous media to study the pore space of carbonate rock samples and determine absolute and phase permeabilities, as well as capillary pressure.
Results: It is shown that an increase in the value of the Marker Extent parameter leads to a decrease in the number of pores and an overestimated absolute permeability due to improper pore separation, while a decrease in the value of this parameter made it possible to identify smaller pores. It is also shown that absolute permeability and porosity have different relationships before and after rock dissolution with high correlation coefficients that range from 0.62 to 0.81. It has been shown that rock dissolution will significantly affect the relative phase permeability of the samples.
Conclusion: The dissolution of the rock led to a decrease in the residual oil saturation in both samples. In the case of oil displacement by water, as a result of rock dissolution, the residual oil saturation decreased from 38% to 22% and from 53% to 43% for the two samples under study. These results are important for understanding the flow of fluids in carbonate samples.
Oil and gas field development and exploitation
Geotechnological regulation of the development of oil fields with hard-to-recover reserves
Abstract
Background: A significant proportion of the remaining oil reserves of the fields under development is confined to reservoir zones with low-permeability and undersaturated reservoir, thin reservoirs. Maintenance of oil production levels in such deposits is possible through methodological study and development of recommendations for optimizing and improving the development system, targeted application of technologies and methods for enhanced oil recovery. In turn, the methodological study for deposits with hard-to-recover reserves includes a systematic statistical and geological and technological analysis of the results of field development, an analysis of existing generally accepted methodologies, and theoretical studies. Thus, the creation of an integrated approach to regulating the development of oil fields, taking into account a detailed understanding of the geological structure, is an important task in the current state of the fields under development.
Aim: The aim of the work is to develop an integrated approach to regulating the development of oil fields with hard-to-recover reserves based on methodological solutions of technological and statistical analysis, differentiation of research objects, retrospective analysis of the use of technologies and methods aimed at increasing oil recovery. The aim of the work is to form an integrated approach to regulating the development of oil fields with hard-to-recover reserves based on methodological solutions for geological-technological and geological-statistical analysis, differentiation of research objects, retrospective analysis of the use of technologies and methods aimed at increasing oil recovery.
Materials and methods: Achieving this goal is possible using the following methods: statistical analysis, geological and field analysis, methodological solutions for studying the relationship "rock – fluid", differentiation of research objects according to geological, geophysical and geological and field data. On the example of some stages, research algorithms are proposed.
Results: A methodological solution is proposed for regulating the development of oil fields with hard-to-recover oil reserves.
Conclusion: The proposed geotechnological approach to the development control will improve the technological efficiency of hydrocarbon reserves development due to a detailed understanding of the reservoir structure, differentiation into zones (areas) of the reservoir, study and analysis of their state of development, reasonable selection of priority and promising technologies and technical solutions to increase their production.
The Effectiveness of the Introduction of the Water-Alternated-Gas Injection on the example of a Carbonate Field in Kazakhstan
Abstract
Background: Water-Alternated-Gas Injection (hereinafter referred to as WAG) is considered to be a suitable analogue of gas injection and waterflooding, which increase the efficiency of displacement. With continuous gas injection, the displacement front is unstable due to the low viscosity of the gas, which leads to the formation of gas “tongues” due to a significant difference in the mobility of gas and oil. Alternate injection of water and gas is considered a suitable option in eliminating this problem and in stabilizing the displacement front.
Aim: The purpose of this work was to generalize the main factors affecting the efficiency of the process, based on the world experience in applying the WAG technology. The effectiveness of this technology application in a carbonate field was also considered.
Materials and methods: This article analyzes the efficiency of oil displacement using the WAG method in a carbonate field in Kazakhstan. In order to study the proposed oil production technology, the alternate injection of water and gas into the reservoir was simulated on the ECLIPSE 100 simulator. First of all, the process of optimizing the parameters was carried out based on two injection wells. As a result, it was found that for the studied field, the duration of water and gas cycles of 3 months and the sequence of "gas – water" are the optimal conditions for observing the greatest effect from WAG. Further, based on the selected parameters, WAG was scaled to the entire field, for the implementation of which several options were developed with 3, 5, 6 and 12 injection wells.
Results: As a result of the research, the optimal oil displacement option was selected, which involves 5 injection wells with high injectivity and a large volume of injected gas.
Conclusion: Due to the hydrophilicity of the reservoir, the effect of alternating WAG turned out to be not as significant as it could be expected, due to the effect of hysteresis of relative phase permeabilities, which can be a topic for future research.
Determination of uniform criteria for the applicability of technologies for enhanced oil recovery methods and development of a tool for screening these technologies
Abstract
Nowadays, many literature sources exist, containing the applicability criteria for enhanced oil recovery methods (hereinafter - EOR). The criteria were developed by the world experts, specialized oil and gas companies, determined in the laboratory and confirmed by field experience. In a number of cases, the authors compile databases with the fields, where different EOR technologies were used, evaluate their effectiveness, the complexity of the application, and the peculiarities of the implementation of the EOR technologies for certain geological and physical conditions of the fields. Based on the results of such analytical work, it is possible to determine the optimal ranges for the application of certain EOR technologies, and recommend their use in screening in order to further evaluate potentially suitable technologies under the laboratory and field conditions.
This paper presents the uniform criteria for the applicability of the key technologies of chemical, thermal, gas and microbiological EOR. To unify these criteria, an extensive literature review, a retrospective analysis of the previously tested EOR technologies, an analysis of the geological, physical and technological conditions for the use of the EOR technologies have been carried out. In order to compare the geological and physical parameters of the reservoirs and the technological parameters of the fields with certain unified applicability criteria, a screening tool has been developed, which takes into account all the necessary criteria for identifying the priority EOR technologies.
Hydraulic fracturing using high-boiling fraction of oil as a fracturing fluid
Abstract
Background: In recent years, there has been a trend towards deterioration in the structure of residual reserves at the fields of Kazakhstan. A significant part of the reserves is located in low-permeability reservoirs and in the zones not covered by flooding. The main factor negatively affecting the productivity and efficiency of development is the heterogeneity of oil reservoirs.
Oil-saturated formations are an alternation of permeable oil-saturated sand or limestone and impermeable clay or dolomite layers, lenses and interlayers. Up to 10–20 interlayers can be distinguished within the reservoir, which indicates a strong compartmentalization of the reservoirs. Due to the complexity of the structure of oil deposits, it is very difficult or impossible to ensure complete drainage of the entire volume of the deposit and complete coverage of oil displacement by water into production wells through injection wells.
Aim: Increasing oil recovery in a cost-effective way.
Materials and methods: Experimental studies of the processes of impact on the bottomhole formation zone with high-boiling oil components were carried out using a laboratory machine for diamond drilling, an installation for determining the permeability of a rock in terms of liquid and gas, an installation for determining oil viscosity, and an installation for pumping fracturing fluid into the reservoir model.
Results: As a result of applying the hydraulic fracturing method using high-boiling oil components, it is possible to increase the permeability of low-permeability formations and significantly increase oil recovery.
Conclusion: Due to the geological structure of multi-layer oilfields, water-based gel fracturing fluids to increase oil flow to wells are considered ineffective due to the adsorption of gels with long molecules in the pores of the formation and swelling of the clay particles of the reservoir when they interact with the water-based fluid.
Application of the software "ZHULDYZ". Adaptation and work with models
Abstract
Background: One of the conditions for the effective development of oil and gas fields is reliable forecasting of its exploitation, including using the capabilities of modern software. As a result of many years of work, the first and only Kazakhstani import-substituting software product "Zhuldyz" was developed which helps to control the implementation of process solutions at the field.
Aim: Implement a single software platform covering the complete cycle of exploration and development of the fields.
Materials and methods: This paper presents the experience of using the “Zhuldyz” software at the Karatobe Yuzhnoye field, as well as software modules for optimizing modeling processes.
Results: Using software accounting a set of geological and physical results and the production history of the Karatobe Yuzhnoye deposit, data were obtained for constructing development maps, assessing reservoir connectivity and distribution of injected water, analyzing field performance for wells, selecting candidate wells for well interventions, as well as software modules for optimizing modeling processes. Additional opportunities for assessing and comparing field development indicators have also been identified.
Conclusion: Based on the results of the analysis carried out in the Zhuldyz software, solutions were developed to improve the reservoir pressure maintenance system at the Karatobe Yuzhnoye deposit. The selection of wells for well interventions and the calculation of efficiency were carried out, which will reduce the number of unsuccessful well interventions by increasing the quality of selected candidate wells through a new appraisal approach from a geological and technological point of view.
By-product procrssing
Investigation and comparison of technologies and methods of sulfur recovery and production processes
Abstract
Sulfur is found at the land's surface, in quarries, and as a natural sulfur resource. However, most of the part sulfur is obtained during the sulfur removal processes from crude oil or gas. These recovery processes are essential for the global energy resource market. Approaches to sulfur mining and recovering techniques are discussed and compared during the literature review and description analysis. Methods that are majorly used in the industry, their process flow diagrams, and principal of work are explained and compared relative to the modern methods of sulfur removal processes.
Ecology
Prospects for the use of energy-accumulating substances in solving environmental problems in the oil industry
Abstract
The prospects for using new-generation energy-accumulating substances based on aluminum alloys activated with activating metals (indium, gallium, tin, eutectics of low-melting metals) as non-traditional environmentally friendly sources for hydrogen production from water and energy accumulation methods, the formation of various forms of aluminum hydroxides, are discussed, which can be used in solving environmental problems in the oil industry: in technologies for complex oil treatment, destruction of abnormally stable water-oil emulsions and oil sludge, demetallization and desulphurization of hydrocarbon raw materials, for the treatment of industrial waste, recycled and natural waters, as well as the reclamation of oil-contaminated areas with low and average levels of pollution, restoration of their fertility when used together with organomineral (humic) fertilizers.