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Scientists have been interested in studying the lithological composition, geological structure and stratification of sections, reservoir properties, saturation, conditions and history of the development of Upper Cretaceous deposits (K2) of the Eastern Caucasus for more than 70 years. The problem of further study of Upper Cretaceous deposits and associated hydrocarbon deposits is very complex and relevant. In previos work the authors showed the similarities and differences of the geological structure and conditions of the development of Upper Cretaceous deposits within a number of regions of the Eastern Caucasus: Eastern Stavropol, the Republique of Ingushetia, and the Chechen Republic. The deposits are differentiated by the depths of their occurrence, the conditions of formation and maturity, the types of reservoirs, the presence of discontinuous faults, the intensity and composition of fluid inflows. The formed mature high-amplitude (over 250-500 m), complicated by discontinuous disturbances of various order, including intrawater dislocations, Upper Cretaceous traps of the Chechen Republic and the Republique of Ingushetia are characterized by initial fluid flow rates up to 200-3000 t/day and practically anhydrous hydrocarbons tributaries. For low-amplitude (less than 50 m) underformed deposits of Eastern Stavropol and Plain Dagestan, not rich in intra-water faults, less representative fluid flow rates (more often under 100-150 t/day) with a high water content at all stages of development are characteristic. The tendency of the dependence of the intensity and composition of tributaries on the amplitude of Upper Cretaceous deposits and a number of other factors was traced by the authors within the Eastern Stavropol territory. The differentiation of "non-standard" traps of the region according to the features of the lithological and stratigraphic structure, the potential of carbonate reservoirs, taking into account the tectonic, geochemical and geological prerequisites for their formation, is carried out. In this article specialists of Rosneft Company and its subsidiary Rosneft-NTC have identified and analyzed the signs of the most promising Maastricht zones of the Eastern Stavropol Region that are relevant when searching for missed traps, planning well interventions and contributing to improving the efficiency of the Company's field development. These features can be applied to other oil and gas bearing areas with similar geological conditions. Also, recommendations are given for optimizing the development processes of immature hydrocarbons deposits in carbonate cavern-crack rocks.
At the facilities of the oil and gas industry, underground water intakes are used for drinking, household, fire-fighting water supply, as well as for providing reservoir pressure maintenance systems, especially in the conditions of the Far North, when the use of surface water sources is difficult. According to statistical data, over the 10 years of operation, the flow rate decreases several times as a result of physical, chemical and biological colmatage. To solve this problem, a technology of high-pressure wave intensification of well flow rates in depression conditions has been developed, which ensures the removal of the products of aquifer dissociation at the wellhead, sparing cleaning of the filter zone, the sump and the entire wellbore. From the point of view of ensuring energy efficiency, the technology of low-pressure wave intensification of well flows, for shallow wells, is proposed due to the realized developed cavitation outflow and its accompanying secondary effects. When performing the work, probabilistic and statistical methods of processing the initial field information and experimental methods for studying the effect of vibration with different amplitude-frequency characteristics on rocks were used. Numerical simulation of turbulent submerged jets was performed using the STAR-CCM+ software package (CFD modeling). The optimal design parameters of axisymmetric cavitation generators of various designs were determined. The results provide satisfactory convergence with the experimental data. The novelty and uniqueness of the developed technological solutions is confirmed by the patents of the Russian Federation for inventions. Practical testing was carried out on more than 500 wells for drinking, economic and fire-fighting purposes in the Krasnodar, Stavropol and Perm territories, Rostov, Astrakhan, Saratov regions, Khanty-Mansiysk Yamalo-Nenets autonomous districts, and other regions of the Russian Federation. The success rate of treatments exceeds 95%, the minimum increase in the flow rate after treatments is 30-50%, the maximum recorded is 7800%. The effect is long-term.
The interest in hard-to-recover hydrocarbon reserves has recently increased significantly, which is primarily due to the need to maintain the level of oil production in the late stage of development. Since all relatively large oil fields in Republic of Tatarstan have been identified and developed, in the last decade, the process of exploration extra-heavy oil deposits, whose reserves are enormous, has been rapidly developing. The object of the study is extra-heavy oil reservoir of the Kamyshla Beds of the Kazanian Stage, confined to the Gorskoye field, located in the marginal part of the Eastern side of the Melekess depression, near its junction with the western slope of the South Tatar arch. At the same time, the location of the field within the outer side zone of the Ust-Cheremshan trough of the Kama-Kinel trough system predetermined the significant influence of sedimentation processes on its formation. In order to establish the genesis, time of formation of the trap and Gorskoye extra-heavy oil deposit, the authors constructed a series of structural maps, carried out studies by methods of isopachic triangle and graph of structure growth. Paleotectonic reconstructions of the studied territory at various stages of ontogenesis allowed us to establish that the core of the Gorsky structure is an organogenic structure of Late Frasnian age, the growth of which was resumed repeatedly until the Early Kazanian age. The formation of the Gorskoye extra-heavy deposit occurred in the Late Permian age, and as a result of tectonic movements of the Alpine stage of tectogenesis, the deposit finally formed and began to collapse.
The PDF file of this paper is in Russian. Cavitation is accompanied by numerous secondary effectsю It is a powerful factor in intensifying the processes of dispergation, emulsifying, homogenization, cleaning of deposits etc. In this article authors generalized their long-term experience on the development of science-based theoretical and technological solutions in the equipment design and technology development using the cavitation jet flow to solve the problems of the oil and gas industry. We proposed multicomponent dispersed media (drilling muds and cement slurry) using cavitation, and achieved significant positive results in the processes of wells construction and workover. Cleaning of production and tubing strings from deposits with different chemical composition and strength cuts down capital expenditure and operating costs for replacement and repair of equipment, and increases the overhaul interval. We designed improved oil recovery methods by treatment of near-wellbore zones of the productive formation during vibrowave intensification or complex physical-chemical decolmatation. We developed technologies for bottom-hole cleaning from compacted cemented clay-sand plugs, completely or partially overlapping the perforation interval, including depression. The proposed technical solutions were tested in industrial objects of the oil and gas industry in Krasnodar and Stavropol, Rostov, Tyumen, Astrakhan, Sverdlovsk and Volgograd regions, Republics of Adygea, Kalmykia and Komi, in Khanty-Mansiysk and Yamal-Nenets autonomous districts. Scientific novelty and uniqueness of the offered devices and technologies is confirmed by patents of the Russian Federation and certificates on databases.
The PDF file of this paper is in Russian. One of the problems of the oil and gas complex enterprises is the handling of equipment contaminated with sediments of natural radionuclides. Sources of radioactive contamination are those contained in the earth's crust and brought to the surface of planet as a result of oil production of natural radionuclides of the uranium and thorium series - thorium, radium and potassium-40, the main component of the deposits is radio barites. There is a need to clean radiation contaminated equipment for subsequent operation or environmentally friendly disposal. The authors developed a technology for removing various deposits from the surfaces of oilfield equipment. Destruction of solid deposits is carried out by using the energy of the fluid flow supplied to the hydro-jet device — a pulsating cavitational flow of collapsing gas-vapor bubbles is generated, hydrodynamic force acting on salt deposits and high-amplitude vibrating microwave. The combined effect provides highly efficient cleaning at lower energy costs compared to conventional high-pressure cleaning. The amplitude-frequency and erosion characteristics of the jet flow are investigated. The substantiation of the profile of the internal channels of the nozzle-cavitators is made, the study of the optimal values of a number of technical and technological parameters of the cleaning process is carried out. A universal high-pressure apparatus was developed, manufactured and tested for the implementation of hydrodynamic cavitation cleaning of radiation-contaminated equipment. In carrying out the research methods of physical experiments, numerical simulation using software systems for hydrodynamics Star CCM+, ANSYS, FlowVision 2.3, analytical and numerical methods for solving problems were used. There is positive experience in pilot studies and the introduction of equipment and technology for the decontamination and cleaning of tubing, working bodies of electric centrifugal pumps, in the fields of the Stavropol region and in Ukraine.
Tomashev, D. V. (NK Rosneft – NTC LLC, RF, Krasnodar) | Nelepov, M. V. (NK Rosneft – NTC LLC, RF, Krasnodar) | Paporotnaya, A. A. (NK Rosneft – NTC LLC, RF, Krasnodar) | Lutsenko, O. O. (NK Rosneft – NTC LLC, RF, Krasnodar)
The PDF file of this paper is in Russian. In the article, in addition to the existing scientific studies, the prospects of the oil and gas content of Paleogene clayey rocks of the Eastern Ciscaucasia are examined on the basis of a detailed study of the neotectonic development of the studied region. The main tectonic elements affecting the geodynamics of the entire Caucasus are the two large lithospheric plates - the Scythian and Arabian. As a result of the interaction of these plates, the North Caucasus region tectonically represents a zone of collision, characterized by a stretching in the sublatitudinal direction, compression deformation in the submeridional direction, and a general uplift with the mountain system of the Greater Caucasus. The degree of geodynamic activity of the territory under consideration was estimated from the velocity maps of modern vertical and horizontal movements, according to which the Eastern Ciscaucasia as a whole is subjected to intensive geotectonic processes, and in particular, experiences uneven ascent, which contributes to the formation of cracks and their opening. Due to the interaction of lithospheric plates accompanied by earthquakes, as is known, disruptive disturbances that affect the capacitive-filtration properties of rocks are formed. The paper analyzes the data on the strongest earthquakes within the study area. The authors built a map of the trend of movement of the foundation blocks. On the basis of which it turned out that the Stavropol arch and the Prikum system of uplifts rendered the greatest influence on the territory under consideration, as well as the depression region of the Tersko-Caspian advanced trough. The Nogai step and the Mineralovodsky protrusion move upward, without affecting the neighboring blocks. Depressions of the Manychy troughs zone drag only one adjacent block downward. The movement of all other blocks is subordinate. Thus, on the basis of the constructions, zones stretching and compression zones are identified. Geological and geochemical studies were carried out to assess the oil and gas potential of the study area. Based on the data of pyrolytic (in the Rock-Eval modification) and chemical-bituminological analysis methods, clayey rocks of the Paleogene (Khadum, Kumsko-Keresinsky formation) belong to oil and gas bearing strata with a high oil and gas generation potential. On the basis of neotectonic and geological-geochemical criteria, the paper proposes a scheme for the prospects of oil and gas potential of Paleogene clay rocks of the region under study. Thus, in the studied territory, Paleogene sediments have all the prerequisites for the industrial development of hydrocarbon accumulations. The main attention, from the position of neotectonics, deserves the zone of the greatest geodynamic activity: zones of epicenters of earthquakes, zones of faults or faults, zones of opening of cracks in hills foundation.
Abstract Carbonate acidizing is one of the main techniques for improving the production and injectivity in oil and gas fields. Various studies and field stimulation results were analyzed to develop a fit-for-purpose acid stimulation treatment design placed with coiled tubing in which diversion is achieved by using in-situ gelation, emulsified diverting acid, degradable fibers, or combinations of these methods. The lack of downhole fluid placement control during the pumping of stimulation treatments may cause these jobs to not achieve the maximum stimulation effect or even fail, which may eventually call for more costly solutions. An innovative stimulation approach was applied on a sour gas injector well in a carbonate oil field in the Caspian region. The field is characterized as a naturally fractured, thick, and prolific carbonate formation with high H2S content. To dispose of H2S and improve oil recovery, the produced sour gas is injected back into the reservoir through injector wells. An innovative method using fiber optic technology for acquiring distributed temperature survey (DTS) measurements and a real-time downhole sensor tool providing pressure and temperature measurements and casing collar location were used in this well to improve its injection potential. DTS technology was utilized to better understand the movement of stimulation fluids into the reservoir through real-time monitoring, thus providing the capability to optimize the acid injection along the target zone. The DTS analysis during the post-acid injection stage identified crossflow and provided good correlation between acid reaction with carbonates and proportional warm-back trends along the formation. The adoption of the technique enabled increased overall confidence in decision making during treatment execution, which allowed an improved placement strategy, resulting in increased stimulation effectiveness. This technology has the potential to become the next important step in the evolution of acid stimulation strategies in the Caspian region.
ABSTRACT This technique is based on the principles that hydrocarbon reservoirs as a multi-fluids system in porous medium has an unconventional (non linear) transfer characteristics for acoustic waves. Hydrocarbon fluid in porous system can be detected as a characteristic deformation of the natural earth noise spectra in the acoustic low frequency range between 0.2 and 10 Hz. The anomalous absorption/emission of micro-seismic noise is used as source for direct detection of oil/gas accumulation (OGA) trapped in a porous matrix/reservoir. In these conditions, the OGA passes in generation of its proper infra-acoustic waves. The mechanical energy of hydrodynamic nature is simply transforming in acoustic energy generating the IPDS waves/signals (downward conversion). The spectral amplitude of background micro-seismic emission above the OGA exceeds considerably that of outside the OGA in the frequency range of 0.1–30 Hz. Measuring and processing the characteristic spectral amplitude of this generated and amplified natural micro-seismic noise defines the presence or absence of OGA. Applying this technology to three important fields in the North Caspian basin has shown that it provides a detailed spatial hydrocarbon distribution, reservoir delineation and monitoring and reliable estimation of hydrocarbon potential reserves or resting un-produced oils. Correlation of field production data with the passive seismic monitoring results shows an enough satisfactory output of the applied technology for reservoir monitoring. This technology could be also promising for EOR/IOR projects, as well as for horizontal and vertical well drilling projects. However, in faulted disintegrated zones owing to increased heterogeneous stress as factor of both micro- and macro-seismic instability the IPDS signals are somewhat deformed. This fact implies some ambiguities, which have to be clarified and resolved. INTRODUCTION Passive seismic technologies for hydrocarbon exploration and reservoir monitoring are considerably developing last years. However this technique is still requiring further investigations as related both conceptual and experimentation elaborations. This paper reveals the general trends conditioning the reservoir behavior and clarify the correlations between the IPDS survey findings and field production data. A lot of oil and gas accumulations are revealed and detailed reservoir monitoring is provided for all the areas for which production data were available. An attempt is made to clarify the real processes taking place during the field's exploitation and conditioning anomalies manifesting during oil and gas production. These processes are, to large extent, creating some apparent inconsistency between the field production data and the IPDS results, particularly in zones of intensive development of faulted systems in the studied fields.
Abstract Formation resistivity measurements through a metal casing allow the determination of water saturation of a (developed) hydrocarbon reservoir even in low porosity conditions where the use of pulsed neutron measurements is problematic. In order to evaluate the performance of a newly designed through-casing resistivity tool a field trial was performed during the summer of 2005 in Alberta, Canada. The field test was conducted in different reservoir provinces throughout Alberta to cover varying field conditions. The age and condition of the test wells ranged from "newly drilled" to fifty-plus year-old producers. Formation resistivities also covered a wide range, from sub-1 Ohm*m formations to 100-plus Ohm*m producing horizons. Measurements are stationary and typically performed at 1 meter (39.4 inches) intervals. The time of data acquisition per station depends on the condition of the casing, but ranges in the few minutes range, even for the worst encountered scaling damage. The instrument produces a table of data on the surface equipment computer screen which is immediately evaluated by the operator. The table contains (for each measurement location) depth, number of measurements at location, resistivity, potential measured from top and bottom electrode accentuation, the 1st and 2nd differences measured at this location, and casing resistance. The instrument performed very well throughout the field trial period. A subsequent comparison of the resistivity data yielded an excellent agreement with open hole logging data. This paper will present the field trial results, data comparison with open-hole data and discuss design and performance details of the instrument. Introduction Electric logging is the oldest and one of the most informative well logging technologies. Today a resistivity log is considered a "staple" for any borehole formation analysis. Electric logging through a metal casing was considered as early as the 1940s (Stewart, 1945), but developments were hampered by the state of technology. There was simply no suitable electronic circuitry to measure the small signals which are encountered when metal casing is involved along the signal path. Around the same time there were also active developments in the former Soviet Union. Notably, the works by L.M. Alpin (1938) are referenced here. While theoretical developments were ongoing the realization of the measurement had to wait until the 1980s (Kaufmann, 1989) (Vail, 1989). The improvements in electronic design, operational procedure and an increase in applications in maturing oil and gas fields sparked interest among major service companies and led to ever-improving tool development of through-casing resistivity technology. Essentially all current through casing resistivity equipment used in the West dates its heritage to these principles. In the early part of this decade development work was done to aid production testing in the oil and gas fields of Stavropol, Russia, and Western Siberia. The technological developments led to the hardware as it is used today. Measurement The through-casing resistivity instrument that was used is a five-electrode two-pole inverse lateral logging tool. Current emitting electrodes are at the top and bottom of the tool, while the measurement electrodes are placed in between at fixed separation. The currents return to an electrode at the surface.
Krylov, N. A. (Institute of Geology and Exploration of Combustible Fuels, Moscow, U.S.S.R.) | Semenovich, V. V. (Ministry of Geology of the U.S.S.R.) | Zhabrev, I. P. (Ministry of Gas Industry, Moscow, U.S.S.R.) | Zubov, I. P. (All-Union Geological Research Institute for the Oil Industry, Moscow, U.S.S.R.)
Abstract This paper describes the principal structural and stratigraphic features of the oil and gas-bearing basins of the Epi-Paleozoic platforms of the USSR. The basins in question are the West Siberian, Karakum, South Mangyshlak, North Ustyurt, Tersko-Kumskiy and Azovo-Kubanskiy basins. The distribution of the oil and gas accumulations in the stratigraphic sequence, the tectonic setting of the petroleum and gas-bearing provinces, as well as a discussion on the stratigraphic range of the source-beds, are presented. The structural style as well as the oil and gas prospects of the Intermediate Complex (Triassic and p.p. Paleozoic Sediments) of these Epi-Paleozoic platforms are briefly discussed. The prospects for the discovery of new oil and gas fields on the Epi-Paleozoic platforms are also examined. Résumé Cette communication expose les principales caractéristiques structurals et stratigraphiques des bassins de pétrole et de gaz des plates-formes épi-paléozoïques de l'URSS. I1 s'agit des bassins de la Sibérie Occidentale, du Kara-Koum, du Sud Mangychlak, du Nord-Oustyart, du Terek-Koum et d'Azov-Kouban. On indique la répartition des gisements de pétrole et de gaz dans la coupe stratigraphique, la situation tectonique des régions productives et on discute la répartition stratigraphique des roches-mères. On discute brièvement du style structural et des possibilités pétrolières du complexe intermédiaire (à sédiments triasiques et paléozoïques p.p.) de ces plates-formes épi-paléozoïques. Enfin on examine les possibilités de découvertes nouvelles sur les platesformes épi-paléozoïques. 1. INTRODUCTION last twenty years resulted in the discovery of large reserves (predominantly of gas) and determined to a Young (Epi-Paleozoic) plates cover a vast area of large extent the development of oil and gas production about 40 million km', i.e. about 35 % of all the pros- for future decades. pective areas of the USSR territory. Three major young In 1960 91.1 % of the total crude oil reserves and plates have been distinguished: West Siberian, 57% of the natural gas reserves were located on the Turanian and Scythian (Fig. 1). The study of their East European platform and in the basins of the geological structure and oil and gas potential in the folded areas, while the reserves of the young platforms accounted for only 3 % and 43 %, respectively. By 1973 by I. P. ZHABREV, the young platforms already accounted for 47.1 % and Mingasprom, Geological Department, 73.5% of total crude oil and natural gas reserves, Ministry of Gas Industry, 11731 1 Moscow, U.S.S.R., respectively. I. P. ZUBOV, As a result, the distribution of the oil and gas re-All- Union Geological Research Institute for the serves over the stratigraphic unit