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The accelerated development of horizontal drilling technology in combination with the multistage hydraulic fracturing of the reservoir has expanded the geological conditions for commercial oil production from tight reservoirs in North America. Geological and physical characteristics of tight reservoirs in North America are presented, as well as a comparison of the geological and physical properties of the reservoirs of the Western Canadian Sedimentary Basin and the Volga-Ural oil and gas province, in particular, in the territory of Tatarstan. The similarity of these basins is shown in terms of formation and deposition. New drilling technologies for horizontal wells (HW) and multistage hydraulic fracturing are considered. The drilling in tight reservoirs is carried out exclusively on hydrocarbon-based muds The multi-stage fracturing technology with the use of sliding sleeves, and also slick water – a low-viscous carrier for proppant is the most effective solution for conditions similar to tight reservoirs in the Devonian formation of Tatarstan. Tax incentives which are actively used for the development of HW and multistage fracturing technologies in Canada are described. wells, multistage fracturing

We suggest a laboratory test for assessing the effectiveness of solvents in technologies based on addition of liquid to steam to enhance oil recovery. To rank the test solvents for their effectiveness, we designed an integrated extraction–wettability criterion based on Harrington's function of desirability.

The research object is the middle part and the refectory overlap of the temple in the honor of the Holy Kosma and Domian Asiysky, located in the village of Ssezzhe of Bogatovsky district of Samara region. At the time of the works, the object was undergoing a large-scale reconstruction. Based on the data of the detailed technical condition survey of the building structures of the temple overlap, the authors made calculations in a physically nonlinear setting, allowing to fully assess the stress-strain state of the monolithic reinforced concrete structure of the middle part and refectory, which is a complex unified system of thin-walled spatial structures of different contours of the middle surfaces. The recommendations on the completion of the overlap construction and its further operation were developed on the basis of the calculations results analysis.

Diversity, geochemical activity, and biotechnological potential of the microorganisms from oil bed 302 of the Romashkinskoe oilfield (Tatarstan, Russia) are reported. The microbial community contained almost no aerobic microorganisms. Sulfatereducing (10 3 -10 6 cells/mL) and fermentative bacteria (10 2 -10 5 cells/mL) pre� dominated in the oilfield. Sulfate reduction was the predominant process in formation water with the rates up to 26.6 µg S 2- L/day. The number of methanogens and methanogenesis rate in formation water did not exceed 10 4 cells/mL and 8.19 µg CH4 L/day, respectively. Analysis of the 16S rRNA gene clone library revealed the sequences of denitrifying bacteria of the genera Sulfurimonas and Thauera. The oil recovery tech� nique combining the stimulation of fermentative bacteria and suppression of sulfate reducers in the oilfield was proposed for development of the bed 302. Fermentative bacteria could be activated by the traditional method, i.e., injection of molasses and nitrogen and phosphorus mineral salts through the injection wells. Introduction of high concentrations of nitrate will activate the growth of denitrifying bacteria, suppress the growth of sulfidogenic bacteria, and result in decreased sulfide concentration in formation water. The pro� posed biotechnology is technologically simple and environmentally friendly.

The existing methods of oil field exploitation give the opportunity to extract no more than half of the geological resources of oil; from carbonate oil collectors, only 20% of oil is extracted [1]. Furthermore, the portion of recovered oil is tending to decrease due to the development of deposits of viscous oils under difficult geological and physical conditions. Thus, new methods for enhancing oil recovery are needed to at least maintain oil extraction at a constant level. There are various chemical and physicochemical methods for enhancing oil recovery. The method of secondary flooding, developed by the Soviet academician A.P. Krylov in the 1930s, is widely used in many oilproducing countries. Surface water is pumped into the oil stratum through a system of water-injection wells, which results in an increase in the stratal pressure. This technology is highly efficient. Chemical methods, used in combination with secondary flooding, belong to the so-called tertiary methods of oil recovery enhancement. These include immiscible flooding (alkaline or polymeric) and miscible flooding with solvents and acids, as well as flooding with the use of surface-active compounds (surfactant flooding, or microemulsion flooding). The surfactants widely used in Europe and North America are chemically synthesized oil sulfonates. Gas injection is also applied, with CO 2 , N 2 , and hydrocarbon gases being mainly used. Thermal methods include injection of a heat carrier (hot water or vapor) or intrastratal combustion. Selective plugging of highly permeable layers for the improvement of flooding is little used in Europe and Siberia but is widely applied in North America, Canada in particular [2]. The development of methods for microbial enhancement of oil recovery started in the middle of the 20th century. They are highly efficient and diverse, environmentally safe, and relatively cheap, although science-intensive. Three substantial prerequisites exist that allow us to believe in the prospects for the development of new efficient biotechnologies for enhancing oil recovery based on the geochemical activity of microorganisms. First, oil fields exploited with water flooding are widely inhabited by aerobic and anaerobic microorganisms belonging to various physiological groups, which retain viability and biochemical activity in oil strata. Second, microorganisms are able to degrade oil hydrocarbons to smaller and more labile organic molecules and to synthesize such oil-releasing agents as ee 2 , ec 4 , fatty acids, alcohols, polysaccharides, surfactants, and other technologically active substances. Third, microorganisms are capable of in situ production of oil-releasing substances directly in zones and microzones containing residual oil. Present research that aims at the development of biotechnologies for oil recovery enhancement should be concerned with study of the regularities of microbial distribution and geochemical activity in oil fields under different geophysical conditions, as well as with advanced investigation of physiological and biochemical characteristics of microorganisms and development of methods for regulation of microbial processes in oil fields [3].

Modern horizontal well completion technologies consisting of cased or openhole wellbores and multiple hydraulic fractures have revolutionized production from very low permeability oil and gas reservoirs. This paper extends the application of these completions to production systems using thermal Enhanced Oil Recovery (EOR) processes. It reports the results of an extensive simulation study to evaluate the performance of different completion technologies using horizontal wells with and without multiple hydraulic fractures. The results indicate that combination of horizontal wells with multiple fractures increases access to the reservoir and enhances fluid injectivity, improves sweep efficiency and time, accelerates oil production rates and increases ultimate oil recovery. Proposed production system is especially beneficial in reservoirs with high heterogeneity in fluid and rock properties. It lowers the risk of injected fluid channeling through high permeability segments and natural fractures; thereby improving the injection profile and reducing by-passing of the reservoir fluid. In addition, the paper provides completion recommendations for avoiding some of the operational issues that usually come up when considering horizontal wells, and, hydraulic fracturing for EOR systems.

To-date, more than 450 heavy oil fields and deposits have been identified in the Republic of Tatarstan with oil-in-places ranging between 1.4 and 7.0 billion tons, according to different estimates. Thermal recovery has proved itself as a reliable method and seemed a logical solution however it did not work properly in vertical wells. Building on the experience of development of the Yaregskoye field (the Komi Republic, Russia) and oilsands in the Canadian province of Alberta, the focus was shifted on working out of recovery methods involving horizontal wells. Engineering solutions accounting for concrete geologic environment and the steam assisted gravity drainage method used for production of heavy oil aim at high-quality casing, leak control in the interstring space, sand control, etc. In shallow heavy oil reservoirs with variable oil saturation of utmost importance are production control practices to ensure profitable oil production, to maintain optimal steam-oil ratio and safe operating pressure to ensure cap rock integrity.

Cement has been the main form of annular zone isolation for oil well construction since the beginning of the industry. It is a science in its own right comprised of technical experts continually improving materials and processes. Often the failure of cement to achieve zonal isolation can be traced to the lack of best practices. When the cement does not provide required annular isolation, the result can be one of the following: Excessive water productionLost production from cross flowGas migration revealed as sustained casing pressure / sustained casing flowContamination of shallow water zones Excessive water production diminishes the value of an asset and results in extra capex/opex for remedial operations. It can also result in delayed oil production. By concentrating on the zonal isolation process during the completion phase, many zonal isolation issues can be mitigated. A detailed evaluation of the cement program can highlight areas of improvement in both materials and operations. This is especially critical for areas where there are multiple stacked productive zones (oil on water) and varying reservoir pressures. An approach to improve annular integrity and the overall cementing process is the use of swellable packers. This practice has become more commonly accepted over the past few years. This paper will discuss the best practices adopted to mitigate water production up to the time of implementing swellable packers followed by the additional improvement achieved by including swellable packers with the best practices.

During last decades the air injection or the in situ combustion has found a wide application as a heavy oil IOR process in the world. The idea of the in-situ coal gasification process was initially suggested by Academician D.I. Mendeleev in 1888. In the 1930s Soviet scientists A.B. Sheinman and K.K. Dubrovai performed first attempts to initiate in-situ oxidation of oil in one of the Krasnodar region heavy oil fields. In the USSR successful heavy oil in-situ combustion (ISC) applications have been implemented at the Pavlova Gora field in Krasnodar and at Shodnitza field in Ukraine in the sixties. A review of the ISC heavy oil field application experience in the USSR will be given in this paper. The Republic of Tatarstan has the largest in the Russian Federation resources of natural bitumen, ranging from 4 to 7 billion tons. Today the air injection process is conducted by the operator "Tatneft" on two field projects at Ashalchinskoye and Mordovo-Karmalskoye (MK) fields. Natural bitumen has been produced at MK field since 1978. In this paper we will present results of our simulation study of the MK's ISC project. The simulation model of the pilot area including combustion and pyrolysis reactions, oxidation parameters was calibrated using available experimental data to match the production history of the field. The advanced dynamic gridding numerical solutions were used for modeling and history matching of the ISC process. Dynamic gridding allows achieving the accurate modeling and material balance calculations of the complex physical and chemical processes taking place at the combustion and displacement fronts in the reservoir under air injection. It allows the saving computer time required for the process modeling. Automatic history matching routines were used to properly calibrate matching parameters and to adjust the reservoir and the reaction characteristics of the simulation model. The established simulation model can be used as a tool for the ISC process monitoring at the field. The model allows also to interpret and to evaluate the pilot results, to optimize its application and to predict the IOR potential.

Main fields of the Republic of Tatarstan in Russia entered late stage of development. In recent years more than 60 methods on enhanced oil recovery and stimulation of producing wells have undergone comprehensive tests in a wide range of geologic conditions. Based on geologic information and experience of fields development there have been created geologic and hydrodynamic models for analysis and forecasting of technological indices of oil production, as well as data bases on application of methods for enhanced oil recovery and stimulation of wells. Based on artificial intelligence, procedure is developed for selection of enhanced oil recovery method using model of residual reserves for different structures of development. Models apply neural network, capable to synthesize recommendations based on training by data base for realization of more than 60 methods on enhanced oil recovery and wells stimulation at similar structures of Tatarstan fields. These technologies are characterized by a set of criteria, including data on reservoir, formation fluids, operating conditions of wells, information on peculiarities of the technologies application. Models are trained on more than 2200 examples, reflecting correct conditions of realization of EOR and stimulation technologies, using considered technologies. During testing more than 70% of data sets are confidently recognized, which correspond to criteria of application of enhanced oil recovery methods, realized through injection wells, and more than 90% of methods on wells stimulation. The developed procedure allows to forecast and rank the application of different methods for enhanced oil recovery and stimulation of wells at specific producing and injection wells in real-time operation mode. This procedure is used in conditions of fields development in the Republic of Tatarstan. The conducted work allows to combine two modern approaches - modeling of field development and application of artificial intelligence for selection of most effective technologies on enhanced oil recovery and stimulation of wells. Data base has been developed for methods of enhanced oil recovery and stimulation of wells for conditions of Tatarstan fields.

History of giant Romashkino field exploration and development includes more than 50 years. Huge information bases on its geologic structure and exploitation is accumulated by now. The field presents asymmetric uplift of areal extent about 100 × 100 km. Commercial oil inflows have been obtained from 18 horizons. Some differences in formation fluid characteristics are observed throughout the field. By present the field is divided into 21 independently developed areas. Initial division of structures was made under conditions of insufficient information and was adjusted later. In connection with uncertainty in geologic structure there might be crossflows between structures of contour division. These conditions make difficult modeling and monitoring of the whole field development. For conductance of geologic and hydrodynamic modeling we have determined the following main principles: structure-by-structure modeling of the field, uniform procedure principles for all being modeled structures, parallel modeling of main field elements – areas. At present 3D geologic and hydrodynamic models for 5 areas of Romashkino field are developed and used. This is more than 6000 wells. 3D models are being brought now into commercial operation, i.e. realization of idea for continuously operating models of areas, blocks and experimental sections. This is practically possible based on fiber-optics system of communication applied in the field, which ensures interaction of all company structures. This will enable to provide application of efficient technologies and software for solution of applied tasks to most number of users. Uniform monitoring of the whole field development as a complex of all areas will be provided upon completion of hydrodynamic modeling of all areas.

In field experiments, we tested an original technology to enhance oil recovery based on the activation of the stratal microflora of flooded oil fields. The technology includes the injection of aerated fresh water with added mineral salts. The activity of microflora (aerobic and anaerobic) increased sharply in the near-bottom zone of the injection well. The microbiological processes occurred in two stages. The first stage includes the activation of aerobic oxidation of organic matter in the oil, which leads to the formation of oil displacement agents, such as organic acids, surfactants, polysaccharides, and carbonic acid. During the second, anaerobic stage gases, methane, and carbonic acid were formed. The field tests were carried out in three pilot tests of different waterflooded areas of the Romashkino field. The additional oil that was recovered reached a total of 41.08 t.t, that was 32.9% of the total pilot production. The enhancement of oil recovery correlated with the rate of methanogenesis. The carbon isotope composition of the carbonates of stratal waters and the concentration of one of the main degradation products (acetate) were changed.

The Republic of Tatarstan possesses significant reserves of heavy oil and bitumen (more than 1.4 bln. tons), major portion of which are found in the Ufimian and Kazanian stages of Permian age. About 450 deposits have been discovered at rather shallow depths, 50 - 250 m subsurface. The first pilot project on heavy oil production through vertical wells dates back to 1970-ies. A number of thermal methods were tested including in-situ combustion, cyclic steam stimulation and gas-steam mixture injection. However, all these methods demonstrated their insufficiency. In 2006, a new pilot project was launched. This is a modified technology of steam stimulation through a pair of U-shaped horizontal wells. To date, three pairs of U-shaped horizontal wells have been drilled with the lengths of horizontal wellbores from 200 to 400 m. The wells were spudded vertically with a vertical drilling rig, hitting the surface at an angle, having thus two wellheads, vertical and slanted. The wells were completed from the surface: the casing with the sand screen was pulled from the slanted wellhead for the entire length of the wellbore. Two parallel horizontal wells were drilled through the producing formation, one above the other, at a vertical distance of 5 m. The bi-wellhead design contributed significantly to production increase. Based on modeling with STARS package, various operating practices have been proposed. The flow management was achieved through change of the produced fluid and injected steam volumes, as well as change of steam injection and pump setting points. All these made it possible to form steam chamber uniformly, avoid steam breakthrough, and increase oil production with minimum steam-bitumen ratio. The average production rate of the experimental horizontal wells is ten times higher than that of the offset vertical wells. Current steam-bitumen ratio makes 3.5 t/t.