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Grishchenko, V. A. (RN-BashNIPIneft LLC) | Yakupov, R. F. (Bashneft-Dobycha LLC) | Mukhametshin, V. Sh. (Ufa State Petroleum Technological University) | Mukhamadiev, B. M. (RN-BashNIPIneft LLC) | Pozdnyakova, T. V. (RN-BashNIPIneft LLC) | Trofimov, Vyach. E. (RN-BashNIPIneft LLC)
The article is devoted to the localization of residual reserves in the deposits of the Pashian horizon (the main object of development of the unique Tuymazinskoye field) and the development strategy. The object is at the final stage of development, due to the formed effective development system, it is characterized by high recovery factor. At the same time, because of geological structure heterogeneity the layers of the object differ in the degree of development. The layer D3ps1 has worse filtration and capacitance properties and is more heterogeneous than the layer D3ps2-3. Comprehensive analysis was performed using information about the actual operation of wells, field data, results of field and geophysical studies, results of compaction drilling and geological and hydrodynamic modeling. It was found that the remaining recoverable reserves are localized mainly in the layer D3ps1. Based on the results of field studies and well performance analysis, geological and technical measures were carried out, the success of which confirmed the correctness of the conclusion about the presence of residual reserves in the upper part of the section. Since 2013, 78 hydraulic fracturing operations have been performed, including the introduction of linear gel technology in thin bridges (between the target reservoir and the underlying aquifer, or watered due to efficient production), which allows increasing the number of candidates and intensifying production in the most difficult conditions. Based on the created geological filtration model confirmed and refined the localization of stocks at the square, and the slit formed programme of activities (drilling of wells and sidetracks, hydraulic fracturing, remedial cementing work, the organization of the new waterflooding, differential fix, etc.), the implementation of which will allow us to maintain levels of oil production and increase reserve recovery main object of the development of the unique Tuimazinskoye field.
Abstract With high reservoir heterogeneity in terms of permeability and fluid properties, substantial amounts of oil are produced along with water. At water cuts higher than 96–98%, wells become uneconomic and are shut in or undergo water shut-off treatments. For this reason, shutting off water flow through thief zones in flooded reservoirs to prevent it from entering wells is one of the biggest technical challenges in enhancing oil recovery from mature multi-reservoir oil fields. As the water cut increases, water flow through thief zones must be reduced, along with the amount of water entering the well, to enhance sweep efficiency in lower-permeability portions of the reservoir. A new technology employing polymer dispersed systems (PDS) shuts off formation and injected water flows by increasing flow resistance in thief zones. This process redistributes the energy of the injected water in the reservoir and helps produce oil from unswept zones, thus increasing flooding efficiency and oil recovery. PDSs do not require drastic changes in existing development systems and are employed together with conventional water-flooding methods. This paper presents studies of basic and modified PDS versions for oil recovery enhancement adapted for conditions existing in the Vyatka area of the Arlan oil field containing poorly continuous reservoirs with lithofacies heterogeneity. This depleted area had a stable, high water cut. The new method for enhancing water flooding efficiency using polymer dispersed systems presented in the paper selectively increases flow resistance in the thief zones of productive formations with a resulting increase in sweep efficiency.
The PDF file of this paper is in Russian. The unique Arlanskoye oilfield has been successfully developed for 60 years. Since 2010, there has been a growing trend in oil production. Due to the use of high-performance technologies, such as horizontal drilling with multi-stage hydraulic fracturing, proppant and acid fracturing, optimization of reservoir pressure maintenance system, oil production was increased by 17%. Main object development – terrigenous low carbonic thick series is in the final stages of development, at the same time second largest recoverable reserves the Kashirskian-Podolskian object is actively being developed. Actual tasks for further development of the field are localization of current recoverable oil reserves terrigenous low carbonic thick series and the Kashirskian-Podolskian object development system organization. For the localization of current oil reserves, a geological field analysis with sector geological and hydrodynamic modeling was used. For both objects, taking into account the peculiarities of their geological structure, fluid properties and the current state of development, a detailed development strategy has been developed, which provides systematic application of advanced development methods (horizontal drilling with multi-stage hydraulic fracturing, proppant and acid fracturing), use of differentiated influence system and measures to regulate the development process in the production and injection wells. The implementation of the strategy will increase the oil production field, create an effective development system of Kashirskian-Podolskian object, reduce the amount of produced water at the main object development and improve the production efficiency of the object's reserves.
Fedorenko, N. V. (BashNIPIneft LLC, RF, Ufa) | Lozin, E. V. (BashNIPIneft LLC, RF, Ufa) | Gareev, A. G. (BashNIPIneft LLC, RF, Ufa) | Nurov, S. R. (BashNIPIneft LLC, RF, Ufa) | Sibaev, T. V. (BashNIPIneft LLC, RF, Ufa)
The PDF file of this paper is in Russian. Main object development unique Arlanskoye oilfield has exceptionally complex subsurface geology and contains heavy oil with increased viscosity. In section of terrigenous low carbonic thick series, eight productive layers have been identified. Taking into account the heterogeneity of the filtration-capacitive properties of these layers, in the section of the object, it is lawful to single out three packs. The upper one, uniting mainly of three highly permeable layers, predominantly sustained in area, middle pack with four thin middle-permeable layers, and a lower pack, represented by a single high-permeable layer with an extensive aquifer. The layers of the middle pack have deteriorated reservoir properties in comparison with the layers of the upper and lower packs, which influences the development of the multi-layered object. According to the results of development survey and geophysical studies, with the joint operation of packs of the object, the middle pack is characterized by the worst output, both qualitatively and quantitatively. These facts point to the unevenness of the coverage of the layers by waterflooding and the lesser degree of production efficiency from the middle pack. To assess the localization of current oil reserves in the conditions of a multi-layered object, a deep geological and field analysis of production was carried out with the involvement of sectoral geological and hydrodynamic modeling. The carried out analysis made it possible to identify the zones of localization of current oil reserves by section and area. The application of differentiated influence systems on packs and layers - partial disaggregation of the object in the zones of localization of current oil reserves in production and injection wells and application of the targeted program of geological and technical measures will significantly improve the production efficiency of the object's reserves.
Lozin, E. V. (BashNIPIneft LLC, RF, Ufa) | Arzhilovskiy, A. V. (BashNIPIneft LLC, RF, Ufa) | Chervyakova, A. N. (BashNIPIneft LLC, RF, Ufa) | Gareev, A. T. (BashNIPIneft LLC, RF, Ufa) | Nurov, S. R. (BashNIPIneft LLC, RF, Ufa) | Sibaev, T. V. (BashNIPIneft LLC, RF, Ufa)
The PDF file of this paper is in Russian. Prof. V.N. Schelkachev at first made theory of elastic regime for oil-gas bedding systems on based the investigations the plural outage wells in Grozny's oil field at war conditions in 1942 ye. After putting in operation the wells (for increase it amount there no having finance and physical resources) have more dynamic levels than before and start to more production. This are explained with elastic reaction of porosity-permeability medium and saturation liquid. Analogy conditions were being in Russian oil industry at beginning 90's last century: there were not turn-over capitals to putting in operation outage wells; its amount were growth. Average period downtime of one well set up 5–7 years. Main these wells put in operation after downtime. In article were made analyses of hydrodynamics effect from long downtime of many produce wells at main object development Arlanskoye oil field – terrigenous low carbonic thick series. Criterions on representative wells are work out and analyses made only for its. Representative wells make up 24.0% from total quantity of outage ones. In result objective geology & petroleum date confirmed main statement of theory elastic regime: elastic energy content growth up; in conformity with present process growth seam pressure and hydrodynamic conditions support the increase of summary producing of oil from terrigenous low carbonic thick series and Arlanskoye oil field common.
Gafarov, Sh. A. (Ufa State Petroleum Technical University, RF, Ufa) | Lysenkov, A. V. (Ufa State Petroleum Technical University, RF, Ufa) | Gafarov, A. Sh. (Gazprom VNIIGAZ LLC, RF, Moscow) | Akimkin, A. V. (Bashneft PJSC, RF, Ufa)
The PDF file of this paper is in Russian. In the article experience of use of monocarboxylic acid in oil well treatment are reviewed. Noted range of advantages of monocarboxylic acid compared to usually used hydrochloric acid solutions. Main advantages are: slower rate of interaction with carbonate matrix; lower corrosion rate; better iron and aluminum ions stability features. Monocarboxylic acid can be used as additives to hydrochloric acid solutions at oil well treatments (acetic acid, formic acid etc.). To optimize cost of treatments we tested out hydrocarbon liquid-phase oxidation products (hereafter referred to as ‘mono-mix’) - mixture of monocarboxylic acids and organic solvents. Production of mono-mix is well spread at gasoline plants or in situ at oil fields treating facilities. Mono-mix manufactured from co-produced gas or gas and condensate from gas fields. To define reservoir condition limitation for mono-mix well treatment series of laboratory tests was conducted. It is shown that mono-mix reaction with carbonate is exothermic. Neutralization rate of mono-mix as well as it's solutions with HCl considerably slower compared to pure HCl. Mono-mix solutions (fresh or spent) bear low coefficient of surface tension at mono-mix – oil border. Mono-mix shows quite high stabilizing and bactericidal features. Fresh and spent mono-mix solutions significantly depress the swelling ability of formation clays as well as filtered from drilling mud, destroy and disperse clay structure supporting the takeaway from the reservoir, possessing anti-corrosion features.Using theoretical and experimental data one-fluid and two-fluids solutions for field testing proposed. 11 oil well exploiting Kashirskian-Podolskian horizon of Arlanskoye oilfield were treated with mono-mix solution. Before pilot test those wells were treated with HCl numerous times as well as with oil-acid emulsion. Treatment with mono-mix solutions complete in pilot test display much better result compared to previous standard HCl-solution treatments and can be recommended for common use.
Yakupov, R. F. (Bashneft-Dobycha LLC, RF, Ufa) | Mukhametshin, V. Sh. (Oktyabrsky Branch of Ufa State Petroleum Technological University, RF, Oktyabrsky) | Zejgman, Yu. V. (Ufa State Petroleum Technological University, RF, Ufa) | Chervyakova, A. N. (BashNIPIneft LLC, RF, Ufa) | Valeev, M. D. (NPP VM Sistema OOO, RF, Ufa)
The PDF file of this paper is in Russian. The analysis of the Tuymazinskoye oil-field Devonian layer terrigenous deposits reserves recovery status was carried out. It is shown that, as a result of long-time development processes, the residual reserves have localized in the roof part of monolithic benches, or in low permeability benches and interlayers. These results are verified by the oil saturation assessment during the operation drilling and the stock restoring by sidetracking. The 80 drilled into the D2ps Tuymazinskoye deposit wells' operation records show that the initial oil recovery does not exceed 5–6 t/24h and the initial water-cut is more than 85 per cent. The cause of the low production rate is coning, i.e. raising the water-oil sector surface along the borehole axis. In order to assess contact or floating area's size impact on the basic parameters of the reserves recovery, the D2ml Tuymazinskoye oil field Devonian layer terrigenous deposits reservoir compartments having a different floating zone share in the site area recovery analysis has been made. The resulting dependence of the oil recovery factor on the contact space areas shows that the zones with the maximum size contact areas are characterized by low oil recovery factor and poor recovery efficiency. It is shown that, for the floating areas, the recovery is characterized by unfavorably high initial water cut values and its intensive growth in oil recovery range of 0.1 to 0.3. The high accumulated floating areas water-oil ratio tends to be accompanied by high oil well water-cut and a high watering time of the recovered product from the beginning of the site development. To obtain the residual oil reserves higher recovery, a technology has been developed to extract oil reserves from the roofing area, which is based on the phased formation drilling. Multiple regression equations have been worked out to calculate the oil cone formation periods and the subsequent water cone formation period in the contact areas, depending on the reservoir geological and physical parameters and the rate of fluid withdrawals.
Kanevskaya, R. D. (BashNIPIneft LLC, RF, Ufa) | Isakova, T. G. (BashNIPIneft LLC, RF, Ufa) | Korobkin, S. V. (BashNIPIneft LLC, RF, Ufa) | Budkin, K. D. (BashNIPIneft LLC, RF, Ufa) | Markova, A. Yu. (BashNIPIneft LLC, RF, Ufa) | Lyubimova, O. V. (BashNIPIneft LLC, RF, Ufa) | Rafikov, R. Ya. (BashNIPIneft LLC, RF, Ufa)
The PDF file of this paper is in Russian. Rock wettability and its transformation in the process of formation and development of oil deposits is a crucial factor influencing fluid content and many aspects of reservoir performance, especially during water flooding and application of enhanced oil recovery techniques. The concept of saturation of the complex carbonate reservoir with the variable wettability is presented. This concept is applied to the Kizelovsky horizon of Tuymazinskoye field. The results of analysis of the geophysical characteristics show that the cross section is divided into three geological units with significantly different values of the electrical resistivity. By means of joint analysis of core examination and geophysical well logging it is demonstrated that zones of the low-resistivity geological unit are chiefly characterized by hydrophilic type of rock wettability, while limestone of the high-resistivity geological unit – by hydrophobic. Oil saturation model is designed with the assistance of field data and core data based on the capillary gravitational equilibrium concept taking into account variable rock wettability. The results of the relative permeability experiments together with information about the initial water cut of well production, in correspondence with geological unit and perforation depth, allow to identify initial saturation distribution in reservoir. The presented approach to the creating of the saturation model enables to consider previously ignored factors that affect the efficiency of the reservoir pressure maintenance system and recovery of reserves of particular areas, such as the electrical resistivity of the geological units, the presence of bridges between them, etc. In particular, the identification of the thick lower unit with high water saturation makes it possible to explain the reasons of watering rates of the production wells. Development of detailed reservoir simulation model, that takes into account the presence of three geological units with the variable wettability, helps to clarify the distribution of oil reserves, adequately perform history matching, predict well performance and improve the recovery of reserves.
Parkhonyuk, Sergey (Schlumberger) | Klyubin, Artem (Schlumberger) | Vernigora, Denis (Schlumberger) | Olennikova, Olesya (Schlumberger) | Lisitsyn, Andrey (Schlumberger) | Konchenko, Andrey (Schlumberger) | Sitdikov, Dmitry (Bashneft) | Bildanov, Vladislav (Bashneft) | Gaponov, Mikhail (Bashneft)
Abstract Development of traditional oil reservoirs is becoming increasingly challenging with time as more reservoirs move to brown state. The Bashkiria field complex is typical example of such reservoir: development started in 1932 and as of today, more than 80% of initial oil reserves have been produced. Thus, the only method to make wells produce economically is hydraulic fracturing. Particularities of the region are viscous crude oils, small net height of the reservoir, and low bottomhole static temperatures coupled with depleted reservoir pressure. This imposes additional constraints on the hydraulic fracturing design. The typical practice in region is to employ an aggressive pumping strategy to maximize fracture conductivity and minimize the amount of fluid pumped into the reservoir. Robust fluid is required to avoid premature screenout due to proppant settling. Another essential component of the fracture conductivity is fracturing fluid breakers. The goal in using breakers is to reduce fluid viscosity and break polymer residues in the proppant pack after treatment to facilitate fracture cleanup. Traditionally, breakers based on ammonium persulfate (APS) (both live and encapsulated) are used in Russian oil fields. They have proved successful in the typical conditions of Western Siberia (80 to 120°C). Enzyme-based breakers have limitations on temperature range and fluid viscosity range. In this paper, we focus on development of novel fracturing fluid tailored for Bashkiria oilfield conditions. An enzyme breaker was compared with traditional oxidative breakers. Production analyses were performed using actual treatment data and post-fracturing production data and comparing them with conventional treatment results. Laboratory testing proved that in terms of fracture-pack conductivity, the new enzyme breaker produced approximately twice the conductivity, as did oxidative breakers over the temperature range of the Bashkiria region. Implementation of novel fluid with pressure-independent viscosity behavior led to a reduction of more than twice the screenout rate with zero fluid-related screen outs. Up to 9 times production increase resulted based on a dimensionless productivity index.
The pdf file of this paper is in Russian. Based on the field research of Arlanskoye field it is shown that current gas factors of the main development objects are less than initial reservoir gas-oil ratios. With reference to the field and laboratory investigations of other authors, we adduced the main causes of gas factor loss in process of Arlanskoye field development. The main causes of gas factor loss at Arlanskoye field are the maintenance of production wells with bottomhole pressure below the bubble-point pressure and move some of gas oil component to download and bottom water at their contact. For example, total producing water oil ratio of the one development object amounts to 9.1 t/t. Today we cannot definitely say which of the above reasons have the most value in the process of reducing the reservoir gasoil ratio. The systematic monitoring of the gas factor on the basis of instrumental measurements in wells throughout the period of Arlanskoye field development was not made. Therefore, we don't know in time gasoil ratio dynamics. Also, we note that it necessary to conduct the control of the gas factor on the core network of wells for indirect estimation of current oil reservoir gas content, as on date, the Arlanskoye field has no conditions for the selection of representative samples of deep oil. The reasons for the lack of conditions for the selection of deep oil samples are high water cut wells production, operation of wells with bottomhole pressure below the bubble point pressure.