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The Tyumen formation is the main hydrocarbon-saturated layer of the Krasnoleninskoe oil and gas condensate field located in Western Siberia. This formation is characterized by significantly changing structural dips and represented as thin, interbedded shale and sandstone layers. Such a formation structure complicates the real-time evaluation of formation properties, well correlation and proper well placement. This paper presents the results of horizontal well drilling at the Krasnoleninskoe field using advanced resistivity logging technology.
Advanced resistivity logging technology is used in field operations for various applications. This technology includes logging-while-drilling (LWD), a deep-azimuthal resistivity tool, and sophisticated data interpretation software. The tool performs multi-component, multi-spacing and multi-frequency measurements downhole. The measurement set can be configured individually for each particular geology and application type to ensure effective operations. Next, these measurements are transmitted to the surface, where high-performance multi-parametric inversion recovers formation parameters of interest in real-time. The inversion software enables the processing of any combination of tool measurements and is based on a 1D layer-cake model with an arbitrary number of layers to operate with complex multi-layer formations.
Besides the complex laminated structure of the Tyumen formation, an additional challenge is the low resistivity contrast between the shale and sandstone interlayers. This factor is typical for many West-Siberian fields; it complicates the resolution of interlayers and degrades the evaluation accuracy of their parameters.
To overcome these challenges, a set of deep-azimuthal resistivity tool measurements, suitable to resolve thinly laminated formations, was identified and transmitted uphole while drilling. Real-time inversion was performed in a user-controlled mode to ensure the careful tracking of geology changes. These results enabled operational geologists to monitor the formation properties during the drilling.
Data inversion software ensured the accurate evaluation of formation properties and structural dips estimation in complex conditions of the Krasnoleninskoe field. Structural dips recovered by inversion significantly differed from values observed at offset wells, i.e., 5 to 12 degrees, instead of 0 to 2 degrees. A perfect match between the measured and synthetic resistivity data confirmed high confidence of inversion results. Moreover, there was a strong correlation between the structural dip angles estimated from resistivity data and derived from LWD natural gamma-ray (GR) image. Many of shale and sandstone layers observed in the GR curves were resolved by resistivity inversion.
The depth of the remote layer detection was estimated during the job; it enabled geoscientists to delineate the reservoir volume that contributed to the tool measurements.
This case study describes the first application of advanced resistivity logging technology in a complex laminated formation of the Krasnoleninskoe field. This technology enables the resolution of thin interlayers, evaluation of their properties and estimation of structural dips in real time. These parameters are important for proper well placement and accurate petrophysical interpretation. The presented technology is able to increase the efficiency of oil recovery in the complex laminated formations of the Russian West-Siberian fields.
Avramenko, Esther (LLC Tyumen Petroleum Research Center) | Grischenko, Marina (LLC Tyumen Petroleum Research Center) | Akhmadishin, Alisher (JSC RN-Nyaganneftegas) | Kudamanov, Alexander (LLC Tyumen Petroleum Research Center) | Smyshlyaeva, Marina (LLC Tyumen Petroleum Research Center) | Kuzmina, Svetlana (LLC Tyumen Petroleum Research Center) | Marinov, Vladimir (LLC Tyumen Petroleum Research Center) | Potapova, Anastasia (LLC Tyumen Petroleum Research Center)
The interests of many leading oil companies of the world have turned to the oil shales. Significant volumes of hydrocarbons concentrated in oil source rocks stimulate a constant search for technologies for the evaluation and production of hard-to-recover reserves both from operators and the state.
The segment strategy of hard-to-recover stocks (TRIZ) is formed in Rosneft Oil Company. According to strategy, a nonconventional reservoirs of the Bazhenov-Abalak complex (BAC) of developed by JSC RN-Nyaganneftegaz the Krasnoleninsky District are defined in the first group of effectiveness.
The reservoirs contain significant oil reserves in YK0 and YK1 layers, but at the moment recovery from initial recoverable reserves is only 10%. Production is mainly in the Central section of the Em-Yegovsky field, which is characterized by the high density of the reserves.
Increasing of the drilling efficiency and a perspective of development is constrained not only by the lack of methods of forecasting productive zones and technologies for effective extraction of reserves from non-traditional reservoirs, but also by the extremely low level of study of the object. With the purpose of preparing reserves for industrial development, it is required to create a set of methods for studying and laboratory core research, estimation of reservoir parameters, methods for assessing the influence of process fluids, and non-standard approaches for forecasting productive zones and efficient extraction of non-traditional reserves.
In 2017, RN-Nyaganneftegaz JSC for the implementation of the 5-year project in order to select technologies for localization and extraction of reserves allocated a test site with an area of 400 square kilometers in the territory of the Em-Yegovsky license block. The explored polygon covers zones of different types of the Bazhenov-Abalak structure: there are areas of different density of faults and fractures (from low to extremely high), as well as different degrees of maturity of organic matter.
The central part of the local structure is covered by 3D seismic studies with increased multiplicity, as well as characterized by exploratory and operational drilling, which provided the core from the interval in 2016-2017.
At present, RN-Nyaganneftegaz JSC jointly with the Tyumen Petroleum Research Center is carrying out the research work based on a comprehensive study of the Bazhenov-Abalak complex in the Em-Yegovsky field. The program of scientific project includes: Complex core studies: routine, special, mineralogical, lithological, geochemical, pyrolytic, thermophysical and geomechanical studies, determination of porosity and permeability, study of the structure and maturity of organic matter, pore space structure by microtomography, mercury porosimetry. Construction of mechanical and petrophysical models of reservoirs and sediment coverings based on core data and geophysical data. Testing various techniques for processing and interpreting seismic data to predict the properties of the deposits (porosity, permeability, brittleness, fracturing). Improvement of methods and tools of geological modeling for mapping of productive zones of reservoirs.
Complex core studies: routine, special, mineralogical, lithological, geochemical, pyrolytic, thermophysical and geomechanical studies, determination of porosity and permeability, study of the structure and maturity of organic matter, pore space structure by microtomography, mercury porosimetry.
Construction of mechanical and petrophysical models of reservoirs and sediment coverings based on core data and geophysical data.
Testing various techniques for processing and interpreting seismic data to predict the properties of the deposits (porosity, permeability, brittleness, fracturing).
Improvement of methods and tools of geological modeling for mapping of productive zones of reservoirs.
According to the R & D program the types and volumes of research performed are multifaceted and cover various areas of knowledge. Within the framework of this article, the authors confine themselves to the results of a complex study of the material composition in order to clarify sedimentation environments in the sediments of the Bazhenov-Abalak complex of the Krasnoleninsky District.
Core studies were performed on 11 wells with maximum core removal and an extended geophysical complex.
Based on the core study results, the hypothesis of the facial conditions of sedimentation was put forward for further geological modeling of the object.
Krasnoleninsky fold is located in the southwest of the West Siberian oil and gas province and includes a number of areas, including the Em-Yegovsky field ( Overview of the work area
Overview of the work area
The Bazhenov-Abalak complex is widely developed on the territory of the Em-Yegovsky field and includes the Tutleima (analogue of the Bazhenov) formation and the underlying Abalak suite. In general, the object is maintained in area and is characterized by the following parameters ( Parameters of objects
Parameters Tutleima Formation (Bazhen) Abalak formation Depth, TVDSS, m −2230 −2265 Thickness, m 35 25 Formation temperature, °C 100 100 Reservoir pressure, atm – 235
Parameters of objects
Based on the results of testing and the history of wells, the main productive interval is confined to the top of the Abalak suite.
The received inflows are characterized by high initial oil rates up to 300 m3/day and a rapid decline in production and reservoir pressure, which indicates the presence of high-permeability filtration channels and limited drainage area. Individual wells have a significant cumulative production to hundreds of thousands of tons and a long period stable operation.
Malshakov, A. V. (TNNC LLC, RF, Tyumen) | Oshnyakov, I. O. (TNNC LLC, RF, Tyumen) | Kuznetsov, E. G. (TNNC LLC, RF, Tyumen) | Loznyuk, O. A. (Rosneft Oil Company PJSC, RF, Moscow) | Surtaev, V. N. (Rosneft Oil Company PJSC, RF, Moscow) | Shaybakov, R. A. (Rosneft Oil Company PJSC, RF, Moscow)
The pdf file of this paper is in Russian.
The main explored oil and gas reserves in Western Siberia are associated with chalk and upper Jurassic deposits. Above-Cenomanian stratum is a complex object of study and is referred to hard-to-recover reserves of crude hydrocarbons, which cannot be effectively selected with the application of traditional development methods for geological and technological reasons. Despite the fact, that potential of Turonian deposits was proved by well testing on the many fields in the North of Western Siberia and that the given interval is considered as a development target, the reservoir properties of these deposits are not explored enough and its potential is not clear. Structural and textural features of Turonian reservoir structures can be reasons for that, particularly, extra thin interbedding (bioturbation) of sandstones/ siltstones- shale interlayers, with a thickness of mm factions, so the heterogeneity is observed up to thin section scale. Such textural feature can be the reason for significant uncertainties when studying the complex reservoir not only by logging methods, but also by laboratory studies of core samples, it determines the application of individual approaches to analyze core and log data to study heterogeneous anisotropic Turonian reservoirs. Much attention is given to reliable determination of the portion of permeable layers and reconstruction of its true properties based on the logging data interpretation. Methods of estimation reservoir properties including heterogeneous reservoir structure were considered. Imaging of full-size core is presented in this work; it allows building 3D model of x-ray density of full-size core. The processing procedure of 3D x-ray tomography of full-size core is presented; it allows estimating the vertical portion of the permeable component of anisotropic reservoir (NTG). Estimation results of portion of the permeable component of heterogeneous anisotropic reservoir (NTG) are presented on the basis of special logging complex methods, particularly, on the basis of formation micro imager and triaxial induction logging. The triaxial induction logging was also used to estimate electrical resistance anisotropy of studied reservoirs and allowed estimating electrical resistance of permeable variations. Results of evaluation of the reservoir gas saturation coefficient were achieved by the specific interpretation of triaxial IRR and better correlated with well testing results. Ignoring the textural heterogeneity of the deposits considering anisotropy of its physical properties can cause undervaluation of the resource potential of Turonian deposits. Whereas, the petrophysical assessments of anisotropic reservoir model improve the reliability of evaluation of hydrocarbons reserves, optimize geological and hydrodynamic modeling, increase prediction validity of gas recovery factor.
Основные разведанные запасы нефти и газа Западной Сибири приурочены к меловым и верхнеюрским отложениям. Надсеноманские отложения являются сложным для нефтегазовой геологии объектом изучения и содержат трудноизвлекаемые запасы углеводородного сырья, которые не могут эффективно отбираться с применением традиционных методов разработки по геологическим и технологическим причинам. Несмотря на то, что продуктивность отложений турона доказана испытаниями скважин на многих месторождениях севера Западной Сибири и данный интервал рассматривается на ряде месторождений в качестве объекта разработки, фильтрационно-емкостные свойства коллекторов в настоящее время изучены недостаточно. Действительный ресурсный потенциал этих отложений неясен. Это обусловлено очень тонким переслаиванием (биотурбация) песчано/алеврито-глинистых прослоев: неоднородность прослеживается до масштаба шлифа. Такая текстурная особенность отложений является причиной существенных трудностей при их изучении не только с помощью методов геофизических исследований скважин (ГИС), но и путем лабораторных исследований образцов керна, что в свою очередь предопределяет использование специальных подходов к анализу керновой и каротажной информации для изучения гетерогенных анизотропных коллекторов туронских отложений. Большое внимание уделено вопросу достоверного определения доли проницаемых прослоев и восстановления их истинных свойств по результатам интерпретации данных ГИС. Рассмотрены методы оценки фильтрационно-емкостных свойств с учетом гетерогенной структуры коллекторов. Представлены результаты томографических исследований полноразмерного керна, а также методика обработки материалов 3D рентгеновской томографии, которая позволяет оценить долю проницаемого компонента гетерогенного анизотропного коллектора по разрезу скважины. Приведены результаты оценки доли проницаемого компонента гетерогенного анизотропного коллектора по данным методов специального комплекса ГИС (пластового микроимиджера и триаксиального индукционного каротажа). Триаксиальный индукционный каротаж использован также для оценки анизотропии удельного электрического сопротивления изучаемых коллекторов. Коэффициенты газонасыщенности коллекторов, полученные по результатам специальной интерпретации данных триаксиального индукционного каротажа, лучше коррелируют с результатами испытаний скважин. Игнорирование текстурной неоднородности туронских отложений, неучет анизотропии их физических свойств может привести к недооценке ресурсного потенциала. Петрофизические оценки, выполненные с использованием модели анизотропного коллектора, позволяют повысить достоверность оценки запасов углеводородов, улучшить геологические и гидродинамические модели.
Malshakov, A. V. (Tyumen Petroleum Research Center) | Oshnyakov, I. O. (Tyumen Petroleum Research Center) | Zhadaeva, E. A. (ITERA) | Weinheber, P.. (Schlumberger) | Ezersky, D. M. (Schlumberger) | Filimonov, A. Y. (Schlumberger) | Novikov, S. V. (Schlumberger)
Abstract Commercial production from the thinly-laminated Turonian deposits of North West Siberia has been proven in many wells. But despite the fact that we see these layers in many fields and they are in fact the primary development target, the reservoir properties are not well studied and thus their ultimate potential is unclear. To date, the obstacle has been the sand shale laminations that we encounter are on the order of a few millimeters to even fractions of a millimeter thick. Standard log interpretation method have proven to be inadequate, including the application of the latest deconvolution techniques of using a high resolution measurement such as a microimager to inform the layering of standard resolution devices. Even core analysis is ambiguous due to the heterogeneous and anisotropic nature of the reservoirs. In this paper we discuss a complete method of analyzing these thinly-laminated layers with a view to resolving a fuller petrophysical understanding.
Summary This paper describes the main issues and challenges complicated the full-field development of the Jurassic deposits of the Tyumen Formation (JK2-9), Krasnoleninskoye Field. The paper summarizes the conclusions of actual wells operation, as well as substantiates the development strategy for heterogeneous low-permeable reservoirs. The results obtained were used as a base for HW+MSF technology piloting on Em-Egovskaya area, the most promising area in terms of reserves of the Tyumen Formation, Krasnoleninskoye field. At the time of paper generation, the pilot project moved to the next stage – rolling-out of engineering solutions on contingent areas (drilling of additional well clusters). However, the main focus of this paper is placed on the first stage of the pilot project including development strategy definition.
The pdf file of this paper is in Russian.
This paper was prepared for presentation at the Young Professional Session of the SPE Russian Oil and Gas Exploration and Production Technical Conference and Exhibition held in Moscow, Russia, 14–16 October 2014.
This paper describes the main issues and challenges complicated the full-field development of the Jurassic deposits of the Tyumen Formation (JK2-9), Krasnoleninskoye Field. The paper summarizes the conclusions of actual wells operation, as well as substantiates the development strategy for heterogeneous low-permeable reservoirs. The results obtained were used as a base for HW+MSF technology piloting on Em-Egovskaya area, the most promising area in terms of reserves of the Tyumen Formation, Krasnoleninskoye field. At the time of paper generation, the pilot project moved to the next stage – rolling-out of engineering solutions on contingent areas (drilling of additional well clusters). However, the main focus of this paper is placed on the first stage of the pilot project including development strategy definition.
Filimonov, Anton (Schlumberger) | Ezersky, Dmitry (Schlumberger) | Shray, Frank (Schlumberger) | Martynov, Mikhail (RN-Nyaganneftegaz) | Khabarov, Aleksey (RN-TPRC) | Shkunov, Evgeny (LLC Novatek Scientific and Technical Center) | Baybikov, Chingiz (CJSC )
Future energy for Russia will come from additional investment justified by an increased valuation of reserves. Western Siberia is well known for its abundance of laminated, siliciclastic reservoirs. Due to technical limitations of the past, the value of the oil or gas reserves within such reservoirs has been difficult to quantify and typically undervalued. Laminated, hydrocarbon-bearing reservoirs are electrically anisotropic; evaluating them with conventional resistivity tools and computational methods commonly provide pessimistic results. A new generation of wireline tools and analytical methods were purposely developed to provide accurate valuation of reserves within such reservoirs. Triaxial induction measurements of horizontal and vertical resistivity, as well as formation dip and azimuth, are used to determine the true resistivity of the oil-bearing sand laminations. Integrated, high-resolution bulk density and neutron porosity measurements quantify total formation porosity as well as the porosity of the important sand laminations. Magnetic resonance measurements provide essential information on the fluid properties and rock quality. The comprehensive volumetric analysis for the laminated formation provides an accurate reservoir summation for reserves valuation. As our field examples demonstrate, the oil company and Russia have added significant value to their oil reserves that may otherwise have been underestimated, undervalued, or bypassed.
Western Siberia represents the heart of the oil industry of Russia. Approximately two-thirds of Russia’s oil production comes from fields in Western Siberia. While this region is mature, West Siberian production potential is still significant, but will depend on improving the economics of production at fields which are more complex than once thought. Complexity stems, in part, from laminated formations which are ubiquitous in the region.
Some of the well-known, laminated formations there include the Vikulovskaya, Achimovskaya, Tyumenskaya, and other Cretaceous and Jurassic intervals. We shall illustrate the application of new technology that addresses – and likely improves - the issue of reserves valuation within laminated formations in Western Siberia. We believe that the volume of oil and gas in these formations has been generally underestimated. This results in the underestimation of the asset value of the oil company; and this affects every economic decision within the company from the top down.
The new technology is composed of two parts. The first part is hardware: a triaxial induction logging tool. The second part includes a fresh, new analytical approach to thinking about laminated formations coupled with a modern log analysis computational workflow. All of this new technology, hardware and software, has been applied in Western Siberia with good results for the Russian oil companies.
Platunov, A.. (OJSC Rosneft Oil Company) | Martynov, M.. (OJSC Rosneft Oil Company) | Nikolaev, M.. (OJSC Rosneft Oil Company) | Leskin, F.. (OJSC Rosneft Oil Company) | Davidenko, I.. (OJSC Rosneft Oil Company)
Abstract This paper is based on study of formations in Bazhenov and Tyumenskoe horizons of Em-Yoga field Krasnoleninsky arch West Siberia with the aim of defining the geomechanical concepts of studied area. Hydrocarbon production from Bazhenov and Tyumenskoe formations in West Siberia is actually established through number of pilot wells with production testing. Economic profitability of producing wells depends on the efficiency of hydraulic fracturing in cases where the technology is predefined by reservoir development project. This article describes the principles and prerequisites of hydraulic fracturing mechanics under geomechanical conditions of the studied rocks. Tyumenskoe and Bazhenov formations are dated to Upper and Middle Jurassic geological time. Geological depositional environment and posterior transformations in time have created specific conditions for rock geomechanics. Rock mechanics in studied formations practically predetermines the concept of how rock is fractured. This work presumes basis for typification and description of fractures occurred naturally and created as a result of hydraulic fracturing and how those interfere with each other. This work is stand on the accumulated results of the ongoing study and actual data from producing wells in Em-Yoga field Krasnoleninsky arch West Siberia. The Jurassic rocks studied in this article are stratigraphically divided into formations of Tyumenskoe, Abalak and Bazhenov horizons. Enacted stratigraphic cross-sectional classification describes the formations of Tyumenskoe horizon as porous rock, Abalak horizon as cavernous-porous naturally fractured and Bazhenov as naturally fractured and micro-porous types of rock.
Kayumov, Rifat (Schlumberger) | Klyubin, Artem (Schlumberger) | Yudin, Alexey (Schlumberger) | Enkababian, Philippe (Schlumberger) | Leskin, Fedor (TNK-BP) | Davidenko, Igor (TNK-BP) | Kaluder, Zdenko (TNK-BP)
Abstract In the last two decades, hydraulic fracturing has become a routine completion practice in most oilfields producing from the low- and medium-permeability Jurassic formations in western Siberia. To optimize hydraulic fracture conductivity, operators and service companies were progressively decreasing polymer loading in fracturing fluids, developing new polymer-free fluids, implementing foams as fracturing fluids, increasing proppant size and concentration, enhancing polymer breaker performance, increasing breaker concentration, and implementing the tip screenout technique. All these methods have some positive impact on proppant pack conductivity but lead to higher risk of premature screenout. The intrinsic limitations stem from the fact that conductivity is created by the proppant pack, which physically limits permeability. The new channel fracturing technique allows development of an open network of flow channels within the proppant pack; thus, the fracture conductivity is enabled by such channels rather than by flow through the pores between proppant grains in the proppant pack. The channel fracturing technique is capable of increasing fracture conductivity by up to two orders of magnitude. Talinskoe field, located near Nyagan, Russia, produces from a series of Jurassic sublayers at depths of 2270 to 2700 m. Several oil-saturated sandstone sublayers are separated by shale barriers, and their development is conducted separately. For some wells, production from bottom sublayers JK10 and JK11 became uneconomical due to injection water breakthrough or low liquid rates. Production in these wells was switched to upper layers JK2 through JK9 after perforation and stimulation operations. Five of these wells were stimulated with the channel fracturing technique. Six-month of post-frac production data were compared with production data from eight offset wells stimulated recently via conventional hydraulic fracturing. The wells stimulated with the channel fracturing technology showed an average productivity index about 51% higher. This production effect still remains positive. The absence of screenouts confirmed reliability in proppant placement observed in other projects worldwide. The successful implementation of the channel fracturing technique in brownfield development is described in detail with a theoretical and operational review, results from laboratory experiments, and analysis of the production results in comparison with conventional fracturing.
Parkhonyuk, Sergey (Schlumberger Oleg Sosenko) | Levanyuk, Olesya (Schlumberger Oleg Sosenko) | Oparin, Maxim (Schlumberger Oleg Sosenko) | Sadykov, Almaz (Schlumberger Oleg Sosenko) | Mullen, Kevin (Schlumberger Oleg Sosenko) | Lungwitz, Bernhard (Schlumberger Oleg Sosenko) | Enkababian, Philippe (Schlumberger Oleg Sosenko) | Mauth, Kevin (Schlumberger Oleg Sosenko) | Alexander, Karpukhin (TNK-BP.)
Abstract Excess water production is a major concern for Russian oil companies. Maturing fields are producing at ever-increasing water cut resulting in problems such as the cost of disposal and environmental issues. In recent years, operators have shown a rising interest in Relative Permeability Modifiers (RPMs) as a potential solution to reduce water production. RPMs are designed to disproportionately reduce the relative permeability to one phase (water) over the oil phase. RPMs are a preventive approach to reduce water production. Ideally, they should completely block water flow without affecting oil flow. While RPMs are used worldwide, they must be adjusted to the reservoir conditions. This becomes even more important in the case of hydraulic fracturing of formations with nearby water-saturated layers. Commonly, service companies recommend one type of RPM which fits all reservoirs. This paper demonstrates how RPM selection on reservoir cores is critical for successful application in the field. We describe laboratory testing and review field trial results of RPMs in a low permeability (2 to 14 mD), highly laminated formation. Because RPMs are typically used only in high-permeability reservoirs, this application is unique. We evaluated chemically different RPMs on actual core material and found strong performance variations of the tested RPMs. We selected a suitable RPM following both core flow testing and compatibility testing. For the field test, wells in the Krasnoleninskoe oilfield were selected for RPM treatments. Oil production was increased in most cases while the water cut was reduced or only slightly increased by up to 5% during 6 months following the treatment. These results show that with proper evaluation, RPMs can also be successfully used in low-permeability reservoirs. We demonstrated also that otherwise proven successful RPMs may not fit every reservoir and proper evaluation and monitoring is critical for success.