Oil and gas industry in the Russian Federation contribute more than 40% of federal budget revenues and thus its so crutial to find best solutions to its main challenges along with new opportunities for growth. One of the main challenges for the Russian oil and gas industry right now is to maintain and even develop its hydrocarbon resourse base in the regard of sustainable development of the country and its regions. According to the latest data of the State balance of natural resources of the Russian Federation from 01 of January 2016, during 140 years of oil and gas commissioning in Russia 3454 fields were discovered, among them 2462 oilfields, 572 oil and gas fields, 420 gas and gascondencate fields. Leading production area in Russia is Western-Siberian oil and gas megaprovince.
Multilateral drilling technology offers a highly effective method of enhanced oil recovery in fields characterized by complicated geological structure. This paper describes the analysis of sidetracks in an open hole by annular ledge formation with the use of a downhole motor in multilateral wells in Vostochno-Messoyakhskoye field.
Since May 2018, more than 130 sidetracks have been drilled in Vostochno-Messoyakhskoye field with the use of bottomhole assembly (BHA) with a downhole motor in open hole by annular ledge formation. The fundamental difference between this method and conventional sidetracking with a downhole motor is that during sidetracking the entire drill string constantly rotates, rather than just bit rotation produced by downhole motor operation. In the process of technology introduction a comparison was made on how different downhole and geological conditions influence the time and performance results.
The technology introduction resulted in the sidetracking time reduction from 9 hours to just 3 to 4 hours.
A number of additional advantages of sidetracking with annular ledge formation were confirmed in the process of operations:
The constant rotation of the drill string enables smooth weight transfer to the bit smooth, without failures. This contributes to effective and uniform ledge formation. Such sidetracking can be carried out at an extended length of open hole when it is difficult to ensure a free movement of the BHA which is necessary of conventional sidetracking. Constant rotation mitigates the risk of differential sticking. More favorable conditions are created for BHA movement in an interval of the holes diversion and subsequently for liner running in. It is possible to sidetrack with the use of a stiff BHA including a complete set of logging tools. In case of conventional sidetracking, it is preferable to use a short and flexible BHA.
The constant rotation of the drill string enables smooth weight transfer to the bit smooth, without failures. This contributes to effective and uniform ledge formation.
Such sidetracking can be carried out at an extended length of open hole when it is difficult to ensure a free movement of the BHA which is necessary of conventional sidetracking.
Constant rotation mitigates the risk of differential sticking.
More favorable conditions are created for BHA movement in an interval of the holes diversion and subsequently for liner running in.
It is possible to sidetrack with the use of a stiff BHA including a complete set of logging tools. In case of conventional sidetracking, it is preferable to use a short and flexible BHA.
The experience gained in Vostochno-Messoyakhskoye field can be extrapolate to other fields where multilateral wells are drilled with annular ledge formation.
Russia always plays an important role on iternational energy markets as one of the major oil and gas producers and exporters since the country entered international enrgy market in the middle of the last century. And this role will remain stable at least till the year 2040 according to current forecasts. BP estimates, that Russia will cover around 5% of the global energy demand by the year 2040. Though, Russia has around 17,4% of world gas reserves (OPEC's estimates its even more - around 24,6% due to the different methodology) and only around 6% in world oil reserves, Russia contributes 17,3% to world gas production and 12,2% to world oil production in 2018, according to BP's Statistical Review of World Energy. Developing of enormous gas and oil reserves was extraordinary challenging for the country due to harsh climate conditions, lack of infrastructure, unsufficient financing and need to develop not only fields but the whole remote areas of the country. Though the country was widely ctitised for its dominancy on the European gas market, in this paper it will be outline that developing of the European gas market was of mutual interest of Russia and European Union and both counterpart became beneficiary of it. This paper focuses on challengies with developing enormous gas reserves as Russia has several mega giant gas fields and its experience can be usefull in developing other mega projects around the world.
Shturn, Dmitriy (Achimgaz) | Zavyalov, Nikolay (Achimgaz) | Perfilyev, Dmitriy (Achimgaz) | Kamenskiy, Leonid (Wintershall) | Tyurin, Victor (Independent consultant) | Astafyev, Vladimir (Halliburton) | Osipov, Ilya (Halliburton) | Zolnikov, Denis (Oil Energy)
The primary objective of large fracturing treatments (from 150 to 300 tons of proppant) in the Urengoyskoe (Urengoy) field is to increase the drained volume of the producing zone of the target reservoir by increasing the fracture length and placing a larger mass of proppant while maintaining similar fracture widths and heights.
The basic goal of fracturing is to increase production from the target reservoir. In this study, to increase the fracture length and propped fracture length in the target zone, linear gel fluid was used for the main fracture pad stage instead of the traditional cross-linked fluid pad. Because of the high filtration rate of linear fluids and their reduced efficiency, pads of larger volumes were used and were pumped at a higher rate. An additional goal of this strategy was to increase the formation coverage. The fracturing treatment proppant stages were pumped using crosslinked fracturing fluid, which helped to reduce the risk of screenout.
Large fracturing treatments using linear fluid pads increase risk because of the high possibility of screening out and because of undetermined economic efficiency. The initial strategy of the Achimov formation development for the given section of the field planned to complete wells using standard large fracturing treatments on S-type wells with crosslinked fracturing fluid throughout all of the main stages. Because of similar geological conditions across the field, the significant number of previous well stimulation operations performed, and the use of extensive logging by the operating company (including bottomhole pressure and temperature online monitoring during fracturing job, and production logging), it was possible to evaluate and compare the economic efficiency of large fracturing treatments using linear fluid pads and large fracturing treatments using crosslinked pads. The comparison of the results from geophysical studies after the fracturing and the subsequent well productivity analysis have been performed.
The described operations enabled fracturing risks and economic efficiency to be understood, both in the Achimov formations of the Urengoy field and in similar gas reservoirs with low permeability. Well productivity after fracturing with a linear pad increased in comparison with offset wells treated with crosslinked fracturing pad fluid.
Practically all large gas deposits of Russia are developed on the elastic water-pressure mode. At initial stages of their development owing to a lack of data on a productive layers structure there are considerable uncertainty at creation of 3D geological and hydrodynamic models of a deposit. At the same time relevant regulations on drawing up design and technological documentation provide calculation of indicators for the entire period of development of an object before the fullest extraction of reserves of gas. As practice shows, 3D digital models of large gas deposits are exposed to periodic specification on a measure of replenishment of geological field information what leads to essential change of initial estimates of technological indicators and efficiency of investments. In these conditions gain development and application of proxy models of the bedded systems using the steadiest characteristics of heterogeneity of collectors and geometry of deposits. It is also relevant to use such models for the developed fields at expert assessment of results of 3D hydrodynamic modeling. Simultaneous using of several approaches and tools when calculating process of development will allow to reduce risks and to narrow area of change of probable values of technological and technical and economic indicators of gas production.
Considered methodology assumes creation of zone and layered and non-uniform model of a gas deposit with use of the probabilistic determined approach to distribution of filtrational parameters on deposit model volume. Intake of reservoir water in a deposit happens to plantar water both on bedding, and in the vertical direction taking into account anisotropy of layers. When forecasting flood of a well stock mechanisms of accounting of a variability of wells on gas and water due to selective flood of productive thickness on interlayer, distributions of reservoir pressure in a zone of placement of wells and the differentiated opening of the allocated interlayer of productive thickness in wells are put. Groups of wells on a state are allocated for each timepoint: not flooded, flooded – capable to take out the water arriving from layer and waters, flooded – incapable of full and continuous carrying out. The moment of a spontaneous stop of the flooded wells is defined on the basis of hydrodynamic calculations of a gas-liquid stream in lift columns of wells.
The algorithm is developed and the computer program of calculation of selective flood of productive thickness of a gas deposit and fund of production wells is created. The technique is approved on Cenomanian deposits of the Yamburg, Urengoy and Medveghiy fields. The received results on indicators of stock of flood well satisfactory are coordinated with historical data.
Digital technologies have a huge impact on our everyday life, including manufacturing industry, becoming a foundation for operations of large enterprises and corporations. Digital age offers unlimited opportunities while specifying rigorous requirements. Being essential for national economy oil and gas industry is not an exception: easy-to-reach oil is running low, hydrocarbon production is getting more accurate and science-based at all stages. It is necessary to search for different creative ways by using latest technologies to take the lead. Industry leaders create entire structures which provide analytical and scientific support of oil production and oil processing at all levels of manufacturing.
Litvinets, I. V. (Institute of Petroleum Chemistry, Siberian Branch of RAS, RF, Tomsk) | Yudina, N. V. (Institute of Petroleum Chemistry, Siberian Branch of RAS, RF, Tomsk) | Loskutova, Yu. V. (Institute of Petroleum Chemistry, Siberian Branch of RAS, RF, Tomsk) | Prozorova, I. V. (Institute of Petroleum Chemistry, Siberian Branch of RAS, RF, Tomsk)
The PDF file of this paper is in Russian.
The process of deposit formation in a sample of highly paraffinic crude oil, two samples of gas condensates and their mixtures is investigated. The amount of deposit in the oil is observed to increase with decreasing ambient temperature and hence it is significantly higher than the mass fraction of paraffins, asphaltenes, and resins due to the occlusion of liquid hydrocarbon in the crystal lattice cells. Using the method of gas-liquid chromatography, the individual compositions of n-alkanes responsible for the formation of deposits in the samples under study are determined. A monomodal distribution of n-alkanes in oil and gas condensate samples is observed. The deposits isolated from the crude oil and gas condensates are characterized by a bimodal molecular mass distribution of n-alkanes and an increased content of high molecular hydrocarbons. The efficiency of additives inhibiting the formation of deposits in the oil sample and its mixtures with condensates is investigated. The experimental K-210 additive is found to exhibit better inhibitor and depressor properties in the highly paraffinic crude oil. An addition of 0.05 % wt. of K-210 into the oil sample allowed reducing the deposition rate by 81-85 %. The inhibiting effect of K-210 however decreases in the oil - gas mixtures. It is shown that the inhibitory effect of the additives based on poly (alkyl) acrylates depends on the composition of paraffin hydrocarbons and resin components of the oil systems under study. The stages of nucleating seed formation and spontaneous crystallization are determined from the cloud point, spontaneous crystallization temperature, and pour point. A possibility of adjusting the structural phase transition in the cases where the temperature decreases during crystallite nucleation and growth is shown. The decrease in the spontaneous crystallization temperature upon introduction of 0.05% wt. of additives into the oil-gas mixture is negligible and is found to be about 3–5 °C, while the pour point of oil with an additive decreased by 13–17 °C and that of the oil-gas mixtures − by 18–20 °C.
Проведено исследование процесса осадкообразования в двух видах газоконденсатов, высокопарафинистой нефти и их смесях. Количество осадка в нефти с понижением температуры среды значительно превысило массовую долю парафинов, смол и асфальтенов за счет окклюдирования жидких углеводородов в ячейках кристаллической решетки. Методом газожидкостной хроматографии установлен индивидуальный состав н-алканов, определяющих формирование отложений в исследуемых образцах. В нефти и газоконденсатах наблюдалось мономодальное распределение н-алканов. Осадки, выделенные из нефти и газоконденсатов, характеризовались бимодальным молекулярно-массовым распределением н-алканов, повышением содержания в них высокомолекулярных углеводородов. Изучена эффективность присадок, ингибирующих осадкообразование в высокопарафинистой нефти и ее смесях с конденсатами. Установлено, что экспериментальная присадка К-210 обладает более высокой ингибирующей и депрессорной способностью в высокопарафинистой нефти. Добавка в нефть присадки К-210 массовой концентрацией 0,05 % позволила снизить интенсивность осадкообразования на 81-85 %. Эффективность ингибирующего действия присадок уменьшалась в нефтегазоконденсатных смесях. Показано, что ингибирующая способность присадок на основе поли(алкил)акрилатов зависит от состава парафиновых углеводородов и смолистых компонентов исследуемых образцов нефтяных систем. Стадию образования зародышевых кристаллов и стадию спонтанной кристаллизации определяли по значениям температуры помутнения, температуры спонтанной кристаллизации и температуры застывания. Показана возможность регулирования структурных фазовых переходов при снижении температуры, как на стадии зарождения, так и на стадии роста кристаллитов. Депрессия температуры спонтанной кристаллизации при введении в нефтегазоконденсатные смеси 0,05 % (по массе) присадок незначительна и составила около 3 – 5 °С. Температура застывания нефти с присадкой снизилась на 13 – 17 °С, а нефтегазоконденсатных смесей – на 18 – 20 °С.
The Yamal mega project - new evolving area, that combines production and infrastructure facilities and will have to replace the Nadym-Pur-Taz area - major gas production area in Russia since 1970s, that's became legend by suppling almost all soviet and than Russian export contracts and securing domestic consumption at the same time. But currently Nadym-Pur-Taz is in its decreasing production phase and thus the need to provide substitution for this area is shaping the impotrtance of Yamal mega project for the Russian and international gas market development and security. The Yamal Peninsula and adjacent offshore areas have an enormous potential: the explored gas reserves with estimated and prospective resources total are 26.5 trillion cubic meters, 1,6 billion tonnes of gas condernsate and 300 million tons of oil and represented by 32 fields in total.
Alexey, Yudin (Schlumberger) | Dmitry, Kubyshkin (Schlumberger) | Konstantin, Lyapunov (Schlumberger) | Yuriy, Zakharzhevskiy (Rosneft) | Alexey, Snokhin (Rosneft) | Sergey, Romashkin (Rosneft) | Alexey, Prokhorov (Rosneft)
Urengoyskoe oil and gas condensate field is second large conventional reserve of gas condensate in the world. Active development of Achimov deposits of this field is in progress now. Specific features of Achimov layers are low permeability, extremely high reservoir pressure and 15-90 meters of Net Pay. Increase of hydraulic fracture frac half-length is main strategy for such environment to optimize well productivity and reservoir fluid recovery. Logistic in tough arctic conditions is challenge here. Method to increase volume of hydraulic fracturing treatment and its effect on well productivity is described in this article.
Some technological tasks were solved to optimize hydraulic fracturing process of Achimov deposits. Pumped proppant volume was a main one. Treatment design was modified to be more aggressive step by step to decrease used slurry volume and enhance fracture geometry. Full laboratory support was provided for this project. Fracturing fluid composition was optimized to provide fluid stability during approx. 7 hours fracturing job as well as fluid friction decrease to meet surface limitations of treatment pressure. Using open channel fracturing technology allowed to optimize logistics in limited space well pads without additional pad construction works and increase job efficiency. The technology provides required size of hydraulic fracture due to proppant pulsing method with proppant consumption decrease.
Before 2014, fracturing treatment size was in a range from 50 to 300 tons of proppant. It did not provide parameters of optimal fracture geometry for pay zones having average Net Pays of 76 m. Increase of frac tanks amount and special frac fleet equipment units combined with permanent technological and laboratory support allowed increasing pumped proppant volume per job up to 400 tons providing high quality of operations. Implementation of open channel fracturing technology was next step in direction of frac job volume increase (up to equivalent of 700 tons of proppant) keeping the same resources and from the same size of well pad. Analysis of efficiency of open channel fracturing technology in comparison with conventional fracturing treatment in wells having similar geological conditions and stimulated with the same slurry volumes was done. It confirmed success of channel fracturing technology using results of the conducted well tests.
Implemented hydraulic fracturing optimization workflow was effective to increase well productivity in turbidite reservoir. To date, sizes of hydraulic fractures created in Urengoyskoe field are one of the largest worldwide. Experience accumulated in Achimov deposits development could be successfully used in other hydrocarbon fields having similar geological challenges.