Filtration-capacity Properties Research Articles

Detection of potential reservoirs of the Mezen syneclise of the Eastern European platform

The possibility of discovering new hydrocarbon deposits within the north-eastern segment of the European part of Russia will reduce the cost of transporting hydrocarbons to major industrial centres. And access to Russia’s most important transport artery, the Northern Sea Route, in the context of the growing importance of the tanker fleet and reorientation of sales markets proves the need to build up the region’s resource base. However, it is necessary to take into account the environmental and climatic risks associated with hydrocarbon production in the Arctic conditions, as well as their transport. This paper presents the data of paleoreconstructions of sedimentation settings of Precambrian sedimentary strata in the light of updating the history of development of the Mezen-Belomr region and studying the reservoir properties of the Riphean-Wendian part of the sedimentary cover section. As a result, formations with enhanced filtration-capacity properties were identified. The Vendian part of the section is characterised by good values of open porosity (up to 20.89%).

Hydrocarbon prospectivity of pinch-out zone of Jurassic deposits in Southwestern part of South Taimyr Monocline

A comprehensive analysis has been conducted on the geological structure of the entire Jurassic interval within the southwestern part of the South Taymyr Monocline, which has allowed a more precise understanding of the structure of the Khabei gas field and the identification of prospective objects of similar geological pattern. The study utilized CDP 2D seismic data, covering a total length of 7835 kilometers, as well as results from exploratory and appraisal drilling. Based on visual analysis of temporal cross-sections, an assumption has been made regarding the correlation between reservoir development zones and paleo-channel systems of the Lower-Middle Jurassic deposits. In order to identify and locate such systems, an analysis of temporal cross-sections, maps of total Jurassic deposit thickness, and maps of dynamic attributes were conducted. As a result, areas of development of large paleo-channel systems (paleo-valleys) within the South Taymyr Monocline have been delineated through integration. These identified zones are characterized by relatively shallow burial depths of up to 2.5 km, the absence of abnormally high reservoir pressures (AHBP), and comparably high filtration-capacity properties for Jurassic reservoirs (porosity – 22%, permeability – 25–50 mD). However, considering the complexity of these objects’ structures and the uncertainties caused by the low degree of geological-geophysical exploration in the study area, it is recommended to conduct additional seismic surveys (CDP 3D) to maturate the objects for exploration drilling.

ON THE POSSIBILITY OF IMPLEMENTING CCS PROJECTS IN THE CARBONATE RESERVOIRS OF THE SIBERIAN PLATFORM

Link for citation: Nikitenkov A.N., Novikov D.A., Maksimova A.A., Penigin A.V., Varaksina I.V., Zhukovskaya E.A. On the possibility of implementing CCS projects in the carbonate reservoirs of the Siberian Platform. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 8, рр. 68-78. In Rus. The relevance. Carbon capture utilization and storage technology involving geological storage of carbon dioxide in deep aquifers is widely used in the world as this technology is aimed at decreasing the emission of greenhouse gases into the Earth’s atmosphere and minimizing the influence of these gases on the global climate change. Objective: to carry out preliminary investigation of the features of water – rock – carbon dioxide interactions in application to carbonate collectors, which are widespread in hydrogeological basins over the territory of the Russian Federation and are potentially suitable as carbon dioxide storage facilities. These processes are considered by the example of the ancient Siberian Platform, where industrial production of hydrocarbons is currently increasing, and a series of large-scale projects in the area of petroleum and gas chemistry are under implementation. Methods. Mathematical physical and chemical modeling was applied to solve the problem. The calculations were implemented by the HydroGeo software package, in which the achievement of chemical equilibria for the «water–rock» system is implemented on the basis of the method of equilibrium constants. Results. The obtained results allow us to evaluate the directions of geochemical processes in the collectors under consideration and to provide qualitative estimation of changes in the pore space under the conditions of its saturation with carbon dioxide, with respect to different saturation degrees. It is established that solution acidification is observed as a result of its saturation with СО2, with the transition of chemical elements to the prevailing forms of complex ions bound with hydrocarbonate and chloride ions (Mn, Na, K). At the same time, saturation with carbon dioxide does not have so substantial effect on the forms of Ca and Fe migration. Special attention is attracted to Al, which is transformed almost completely from complex forms into Al3+ in the presence of carbon dioxide. In the studied reference samples, rather intense transformation of collector rocks with redistribution of elements between the primary and secondary mineral phases is observed (both rock dissolution and precipitation up to several hundred g/dm3) with comparatively small absolute changes in open porosity. In a series of the considered objects, the dissolution of calcite and dolomite proceeds due to a decrease in pH. The directions of transformations, as well as the trend of changes in filtration-capacity properties, are determined by the specific mineralogical combination of collector rocks and the brine present in them, as well as by the stage of evolution of the system under consideration (the first part of the considered combinations is initially far from the equilibrium and continues interacting, while the second part is close to the equilibrium and is transformed into non-equilibrium state due to saturation with carbon dioxide).

Оценка коллекторских свойств карбонатных пород Юрубчено-Тохомской зоны нефтегазонакопления

The article is devoted to the study of reservoir properties of productive Riphean sediments within the Yurubcheno- Tokhomskaya oil and gas accumulation zone. The description of the filtration-capacity properties of the deposits is given, the structure and characteristics of the void space are investigated. The influence of fracturing and cavernousness on the development and forecast of the productivity of deposits has been investigated.

ГЕОМЕХАНИЧЕСКОЕ МОДЕЛИРОВАНИЕ СТРОЕНИЙ НЕФТЕГАЗОВЫХ МЕСТОРОЖДЕНИЙ

The presence of areas of accumulation of hydrocarbons in the sedimentary strata is genetically related both to the conditions of sedimentation and to secondary changes in the properties of the geological environment, caused along with other and geodynamic processes. At the same time, it is the stress-strain state that is the key characteristic of the environment, the analysis of which makes it possible to predict the influence of geodynamic factors that cause deformation processes in the sedimentary stratum, on the formation of zones of decompaction and increased fracturing, areas of increased filtration-capacity properties of reservoir rocks, the direction of natural migration of hydrocarbons. Using the example of 3D seismic data obtained at the Akshabulak area, the possibility of integrating geomechanical modeling and additional express analysis of seismic data in solving problems related to determining the probable places of accumulations and directions of natural migration of hydrocarbons is shown.

STUDY OF THE INFLUENCE OF GRAIN SIZE ON PETROPHYSICAL PROPERTIES AND NMR CHARACTERISTICS OF ARTIFICIAL SAMPLES

The article presents the results of studies of petrophysical properties and the study of samples by the method of nuclear magnetic resonance (NMR). The measurements were carried out on a collection of artificial core samples with different grain sizes. The procedure for preparing the samples is described, and the comparison of the results of measuring the petrophysical properties by different methods is given. The quantitative relationships between the size of the sand grains from which the samples are made, the filtration-capacity properties and the distribution of the relaxation times of the NMR spectrum of the samples are investigated.

Разделение коллекторов парфеновского горизонта Ковыктинского месторождения на литотипы с использованием материалов геофизических исследований скважин

The purpose of the work is to study the heterogeneity of the composition, structure, and filtration-capacity properties of the sandstones in the Parfenovsky horizon of the Chora formation, the Kovykta gas condensate field. An analysis of the behavior of the well geophysical survey curves and differential distributions of the geophysical parameters (double difference parameters of the gamma-ray logging and neutron logging) in the Parfenovsky horizon interval has been conducted. The differential distributions of the geophysical parameters before and after dividing the reservoirs of the Parfenovsky horizon into lithotypes have been compared. The analysis of the logging data and the geophysical parameters obtained based on the above has made it possible to identify three lithotypes of the sandstone reservoirs in the Parfenovsky horizon section. Based on the well survey data, quantitative criteria for dividing the sandstone reservoirs of the Parfenovsky horizon into lithotypes have been substantiated. Directions for the further studies of the structure of the reservoirs in the Parfenovsky horizon have been determined. The study has concluded that there are reservoirs with improved and degraded filtration-capacity properties in the Parfenovsky horizon. The presence of reservoirs with different properties and composition in the deposits of the Parfenovsky horizon shows that it is necessary to revise the petrophysical model and methodological support for the complex interpretation of the well geophysical survey data used in the recalculation of the hydrocarbon reserves of the Kovykta gas condensate field in 2013.

ПРОГНОЗИРОВАНИЕ СОЛЕОТЛОЖЕНИЯ В ПРИЗАБОЙНОЙ ЗОНЕ ПЛАСТА НЕФТЕДОБЫВАЮЩИХ СКВАЖИН

The processes of formation inorganic salts in the bottomhole formation zone contribute to the deterioration of its filtration-capacity properties and significantly reduce the productivity of oil producing wells. Analysis of the studies made it possible to identify the main indicators on which the decrease in the permeability of rocks due to salt deposition during water-flooding mainly depends. The paper proposes a thermodynamic model developed to predict the processes of salt deposition in the bottomhole zone of oil producing wells.

Numerical simulation of oil formation with regulated disturbances. Oil recovery quality simulation

The article discusses the method of numerical modeling of a functioning reservoir based on the oil recovery hydromechanics model in the hyperbolic Cauchy problem. Optimization results for reservoir formation channels (RFC) modeling reveal integer values of new models with linear parameters of hydro-resistance, piezo capacitances and piezo inductances in the dimensionless values. The solution result is an effective tool for current prediction of filtration capacity properties (FCP) of the reservoir in the elastic water-pressure mode. The deduced numerical simulation methods based on long-term reactive RFC resistances make it possible to specify the limits of quality of oil displacement with controlled excitations at its coordinate-discontinuous controls.

Role of Elisional Water Exchange in the Hydrodynamic Field Formation in the Yamal–Kara Depression

Unique material pertaining to the hydrodynamics of petroliferous rocks in the Yamal–Kara Depression has been summarized for the first time in the last 30 years. The region is distinguished by a wide development of anomalous high formation pressure (Ca up to 2.21) in both Jurassic and Lower Cretaceous rocks. Results of the study of filtration-capacity properties and hydrodynamic characteristics of reservoir rocks in the Jurassic–Cretaceous section suggest a dominant role of the elisional water exchange in the formation of modern structure of the hydrodynamic field. Elisional lithostatic system located at a depth of about 2–2.5 km begins to acquire features of elisional thermodehydration. At the current development stage of the basinal aquifer system, spacious piezomaximum zones (Bol’shaya Kheta and Kara megasyneclises) became internal water load (supply) zones with the maximal hydrogeological closedness in the Earth’s interior. Piezominimum zones extending along the main centers of oil-and-gas generation match the largest oil-and-gas fields (Vankor–Suzun, Bovanenkovo, Urengoi, and others). At present, we can define in the study region two types of natural aquifer systems: (i) elisional type prevailing in the internal sectors (e.g., Yamal–Kara Depression); (ii) infiltrational type prevailing in the external (marginal) sectors (West Siberian sedimentary basin).

Substantiation of the BFZP Technology Application at the Object YUS<sub>1</sub><sup>1</sup> of the Fainsk Oil Field

Bottomhole formation zone processing (BFZP) is performed at all phases of oil field development to restore and improve the filtration-capacity properties of the bottomhole formation zone to improve the oil yield. The choice of the BFZP technology is made basing on the study of the reasons for low well yield with account for the collector properties of productive sediments and rheological characteristics of the formation fluids, as well as a special geologic-geophysical and development-hydrodynamic study for the assessment of the porosity and permeability properties of BFZ. The research objective is to develop the criteria and assess the conditions for the application of bottomhole formation zone processing technologies for the upper Jurassic formations. Analysis of the results of laboratory and industrial research allowed offering the most efficient technologies for the influence on the upper Jurassic deposits.

Modern Geodynamics and its Influence on the Secondary Filtration Properties of the Reservoirs of the Northeastern Part of the Sakhalin Shelf

The complex tectonic structure of the Okhotsk Sea shelf and the high level of geodynamic activity necessitate the use of geodynamic simulations to forecast the secondary filtration-capacity properties of reservoirs. The 3D geomechanical models were built and the forecasting of the fractured porosity and permeability was conducted for the Kirinskaya, Ayashskaya, and East-Odoptinskaya license areas. The simulation revealed filtration channels, where both vertical and horizontal migration of hydrocarbons occur. It was found that the secondary permeability of the upper and the lower stratigraphic horizons of the studied area significantly differ. The Okobykai clayey member is the boundary surface and serves as the regional cap. All calculations were performed on the 3D-grid geological model, which allows us to use the data for hydrodynamic simulation.

ALGORITHM OF LOCATION OF WATER INFLUX INTERVALS IN GAS WELLS

A method is proposed for identifying the well caused the pad flooding in the active operating well stock for locating the interval of water-influx interlayer in order to perform water isolation jobs based on the diagnostics of the producing formation current model. The searching for the pad flooding well is run in three steps: 1) Locating the group of potential wells capable to flood a pad based on estimation of the vapor phase, dynamic characteristics (velocity, flow rate), collection of dropping liquid samples for determination of additional water salinity. 2) Running the monitoring studies of the selected group of wells under the conditions variation (pressure depression) for identifying a well in this group producing with additional water and effecting the gas flow rates in the adjacent wells, the observation system offered being run without the wells shutin with a fast coverage of the entire well stock and with a higher reliability, ensuring safety and cost efficiency. 3) Performing the wide-range spectral neutron gamma-ray logging for diagnostics of the current model of the producing formation based on which the active water-influx intervals and their filtration-capacity properties can be identified to choose a way to perform the water isolation operations.

Secondary processes in reservoir rocks of the Yarakta Horizon on the southeastern slope of the Nepa-Botuoba anteclise

Basic regularities of secondary processes in reservoir rocks of the Yarakta Horizon are described with rocks in the Yarakta field as example. To achieve the formulated goal, we elucidated rock types in the studied section, its structure and distribution of reservoir rocks, as well as types of secondary alterations and their influence on filtration-capacity properties. The studies revealed that reservoir rocks of the Yarakta Horizon were formed on an alluvial-deltaic plain on the southeastern slope of the Nepa-Botuoba anteclise. The pore space of reservoir rocks is determined by conditions of their formation and peculiarities of secondary alterations. Maximal filtration-capacity values are characteristic of gritstones, as well as coarse-grained and inequigranular sandstones developed in the lower and middle parts of the Yarakta Horizon. The intergranular space of reservoir rocks in the lower part of the reservoir is substantially “healed” by secondary processes (regeneration, dolomitization, sulfatization, and salinization), probably, due to the gravitational seepage of stratal fluids, mineralization of which increased with time.

Oil and gas pools in weathering crusts on the sedimentary basin basement

Weathering crusts of the sedimentary basin basement are collectors in several regions of the world. They enclose huge reserves of oil and gas. The paper considers the geochemical, mineral, and petrophysical heterogeneities of weathering crusts that should be taken into consideration in the prospecting, exploration, and development of hydrocarbon raw material therein. Areal and linear-fissure types of weathering crust are defined. They were formed before the overlapping of basement by rocks of the sedimentary cover. Areal crusts are pervasive at the basement roof, whereas linear-fissure crusts are formed along fractures. A complete weathering crust profile includes the following zones (from the bottom to top): disintegration, leaching and hydration, hydrolysis, and final hydrolysis. Rocks of the lower two zones represent the cavernous-fissure collector, while rocks of the upper zones are impermeable. In the arches of uplifted blocks of the basement, weathering crusts are subjected to erosion during marine transgressions. In such places, the roof is composed of rocks of the lower permeable zones that often make up a single heterogeneous natural reservoir overlapped by sandy collectors of sedimentary sequences. Linear-fissure weathering crusts show zonal distribution with good filtration-capacity properties. Several large oil and gas pools have been discovered in them.

Lithology and formation conditions of paleogene rocks in the Dongying Depression (Bohai Bay Basin, China)

The Dongying Depression is one of the largest depressions in terms of hydrocarbon reserves not only within the Bohai Basin, but also in the whole Pacific region. This is related to the inherited pattern of geological evolution, as well as the optimal combination of oil source rocks, reservoirs, and caprocks, which alternate in both lateral and vertical directions. Diversity of the lithofacies composition of Eocene and Oligocene sediments in thick (proluvial, deltaic, fan deltaic, and deep-water) hemipelagic and gravitational deposits in the composition of various fans, predetermined the wide distribution of sandstone and gritstone beds with good filtration-capacity properties. The beds were filled with hydrocarbons that migrated from the adjacent layers of oil shales and clays. The role of the principal reservoirs was played by sandstones, which were deposited in distributary channels of Eocene deep-water fans. The detailed study of these underwater fans will make it possible to expand the reserves of hydrocarbons explored now in the Dongying Basin.

Influence of processes of the formation of authigenic clay minerals of terrigenous rocks on reservoir properties: Evidence from the rocks of the Vartov Arch

Filtration-capacity properties of terrigenous reservoir rocks significantly depend on catagenetic transformations of clay minerals. Results of our research revealed the authigenic nature and formation stages of kaolinite and chlorite. The volume and shape of pore space define the morphology of clay particles. Depending on the pore volume, kaolinite crystallizes either as thick tabular aggregates or as fan-shaped intergrowths. The formation of authigenic clays in pores of terrigenous reservoirs decreases filtration-capacity properties of rocks with low permeability and, conversely, increases filtration-capacity properties of rocks with high primary permeability and large pore volume.