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Results
Seven calculation methods are selected for testing: Beggs&Brill, Duns&Ros, Aziz, Ansari, Gray, OLGA and OIS. In addition, calculations were carried out for the «homogeneous model», which does not take into account the difference in the velocities of liquid and gas and the additional turbulence of the flow resulting therefrom, and therefore gives the lowest possible values of pressure loss. The quality of the methods was evaluated on the basis of two criteria: the completeness of tracking the parameters affecting the result and the absence of breaks in the calculated hydrodynamic functions at the boundaries of the flow modes, as well as during the transition between two-phase and single-phase flows. In the absence of a liquid phase, the methodology should yield results for the gas flow, at the boundary of the annular and slug structures it should approach the results of calculations for the slug structure, and at the lower boundary of the mist area shall approach the results of the calculations the «homogeneous model». The comparison was based on flows with parameters close to those of gas condensate wells and pipelines of product gathering systems. The physical properties of the products (density, viscosity of liquid and gas, surface tension) were calculated for one of the exploitation targets of the deposit located in Western Siberia. There are large differences in the calculation results for the different methodologies. The conducted analysis makes it possible to recommend the methods of Ansari, Gray and OIS for hydraulic calculation of the movement of gas-liquid mixtures at high speeds and low concentrations of liquid corresponding to the flow annular structure. The Gray method is only recommended for wells because it produces questionable results for large pipe diameters. The most promising method for the hydraulic calculations of both wells and receiving systems is the OIS method, as it takes into account the maximum number of parameters, is physically justified and works on limits. It is possible to adapt this methodology to actual data by adjusting the empirical coefficients that it contains.
Experience of killing and preserving wells with heavy fluids under autonomous conditions in the Danilovsky cluster fields (Russian)
Nikulin, V. Yu. (RN-BashNIPIneft LLC) | Britov, E. V. (Verkhnechonskneftegas JSC) | Mukminov, R. R. (RN-BashNIPIneft LLC) | Nigmatullin, T. E. (RN-BashNIPIneft LLC) | Polyakov, D. Yu. (Verkhnechonskneftegas JSC) | Shangin, A. V. (Verkhnechonskneftegas JSC)
The article deals with the peculiarities of killing wells in carbonate reservoirs of the East Siberian fields (Danilovsky cluster), complicated by abnormally high formation pressures. The process of killing is complicated by low temperatures of the environment and low reservoir temperatures of the object under operation. Taking into account the experience of previous works and risks of gas and water leakages it is recommended to consider application of blocking compounds in addition to high density killing fluids for the Verkhneosinskoye horizon (formation B1). The results of laboratory tests of heavy killing fluids with the density of up to 1.8 g/cm3 on the basis of combined solutions of bromine salts (fluid No.1) and chlorides with calcium nitrate (fluid No.2) are represented. If there is a necessity to use heavy technological fluids, including those for well preservation, the attention was paid to the corrosion rate during prolonged exposure of a heavy killing fluid to the well equipment. Based on the results of laboratory tests the combined calcium and zinc bromide solution was recommended for field tests. Field tests of killing technology with heavy fluid were carried out and no complications and negative effect on productivity were revealed - the fluid is recommended for killing in B1 formation conditions. There was also tested a suspension blocking compound on the basis of the said heavy fluid with the addition of calcium carbonate. When absorptions occurred the application of the blocking composition under consideration didn't allow absorptions control, the blocking composition was not recommended for application. Instant filtration composition was successfully used to restore circulation, applied in conditions of intensive absorptions, this technology is recommended for more detailed researches for conditions of the object under consideration.
The development of hydrocarbon deposits in the Eastern Siberian mega-province is largely determined by the need to replenish the oil and gas resource base of the Russian Federation. In this case a detailed geological study of the fields located on the territory of the Nepa-Botuoba anteclise and the Pre-Patom trough are mostly relevant, in connection with the commissioning of the Eastern Siberia - Pacific Ocean pipelines. It is known that sediment sections within the Siberian Platform are complex geological formations, which is due to the combination of fault-block tectonics with numerous halogen bodies, as well as trap magmatism. At the same time, the identification of similarities and differences in fault-block tectonics at the deposits of adjacent tectonic structures is of the greatest interest. In this article consisting of two parts the similarities and fundamental differences in fault tectonics of the objects under consideration are shown on the basis of sequential paleoprofiling while performing a detailed well-log correlation. In the first part it is shown how the Cambrian halogen-carbonate formations were block-formed along depositional faults with an amplitude of up to 400 meters using the example of the Markovskoye field, on the basis of sequential paleoprofiling. Subsequently, as a result of «keyboard» diving there was an alignment of the previously disturbed productive layers of the Osinsky horizon. In turn at the Yarakta deposit under high pressure and temperatures exceeding 1000°C faults became possible ways for subvertical intrusion of trap magmatism into sedimentary formations in the form of dikes and by subhorizontal intrusion into thin intersalt formations in the form of sills.
Changes in the composition of produced oil at the Strelovskoye field in the Samara region using aquathermolysis catalysts (Russian)
Slavkina, O. V. (RITEK LLC) | Tsvetkov, S. V. (RITEK-Samara-Nafta TIC) | Nikiforov, A. B. (RITEK-Samara-Nafta TIC) | Sennikov, N. Yu. (RITEK-Samara-Nafta TIC) | Bakumenko, E. A. (RITEK-Samara-Nafta TIC) | Volkov, D. A. (LUKOIL-Engineering LLC) | Mukhamatdinov, I. I. (RITEK-Samara-Nafta TIC) | Vakhin, A. V. (Kazan (Volga Region) Federal University)
The utilization of catalytic intensification for the compositional refinement of heavy crude oil during the extraction stage presents extensive prospects for enhancing the efficiency of employed thermal technologies for the development of unconventional hydrocarbon resources. The technology of catalytic aquathermolysis was applied at the Strelovskoye heavy oil reservoir. Field trials have demonstrated a sevenfold increase in the average oil flow rate per well compared to the previous non-catalytic steam treatment cycle, accompanied by a viscosity reduction of over fourfold. Analysis of oilfield samples has determined that the improved oil recovery and viscosity reduction effects are achieved through the chemical transformation of resinous-asphaltenic compounds, resulting in the generation of light hydrocarbons in the presence of injected catalytic complexes based on transition metals. The products of the destructive hydroprocessing of resinous-asphaltenic substances are sequestered within the fraction of aromatic hydrocarbons after the catalyst attains its active state in the reservoir. In addition to the breakdown of resins and asphaltenes, there is a notable degradation of high-molecular-weight paraffins, leading to an additional decrease in oil viscosity. The obtained results substantiate the potential application of the developed technology for enhancing the production efficiency of heavy oils. Currently, further scaling on other wells of the Strelovskoye field is planned.
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.34)
Acid fracturing treatment is the key technique for stimulation production in carbonate reservoirs In this technique acid is injected to erode the fracture walls. Conductive channels which remain after fracture closure are created because acid tends to etch the fracture faces in non-uniform patterns. The use of surfactants for thickening acid fracturing compositions has shown high efficiency due to their perspective and a number of advantages compared to other fluids. This article presents the research on the development of a hydrochloric acid thickening reagent for the preparation of acid fracturing fluid. The paper shows the results of experimental studies of the effect of the developed surfactants- based additive on rheological properties of 12 % hydrochloric acid, interfacial tension at the boundary with hydrocarbons and solubility of carbonate. The addition of the mixture of surfactants leads to a significant increase in the viscosity properties of the acid systems, which provides a decrease in the rate of acid leakoff during acid fracturing. Also, this acid thickener contributes to reduction of interfacial tension at the boundary between the acid composition and hydrocarbons, which positively affects the efficiency of the process of acid fracturing. The application of the developed acid thickener leads to a decrease of carbonate solubility, which ensures the creation of the required non-uniform patterns of the carbonate fracture as well as an increase of acid penetration length during the acid fracturing process. After prolonged interaction of the acid composition based on the developed thickening agent with carbonate rock there is a decrease in the viscosity properties of the composition which facilitates further development process.
Selection of promising technologies to limit water and gas flow in horizontal wells of the Kuyumbinskoye field (Russian)
Nikulin, V. Yu. (RN-BashNIPIneft LLC) | Mukminov, R. R. (RN-BashNIPIneft LLC) | Shaymardanov, A. R. (RN-BashNIPIneft LLC) | Nigmatullin, T. E. (RN-BashNIPIneft LLC) | Kovtun, A. S. (Slavneft-Krasnoyarskneftegas LLC) | Kulakov, D. P. (Slavneft-Krasnoyarskneftegas LLC)
The article considers the main approaches to the choice of water and gas flow restriction technologies in horizontal wells of the Kuyumbinskoye oil-gas-condensate field. Characteristics of carbonate Riphean reservoir is given, relevance of water and gas flow limitation in all intervals of horizontal wellbore – «heel», «middle» and «toe» is noted. Taking into account and using the field experience in applying technologies with similar conditions, the main types of insulating compositions with the potential to limit the inflow of water and gas in carbonate reservoirs, including polymer compositions, organosilicon compositions and high-viscosity emulsions, are considered. The results of laboratory studies of three brands of gel-forming compositions capable of forming extended insulating screens with a different mechanism of formation of the insulating mass (two compositions based on organosilicon compounds and one composition based on cross-linked polyacrylamide with the addition of reinforcing components) are presented. Filtration studies used fracture models of different openness – from 50 to 650 μm. The results of the studies show that all studied compositions are technologically simple to prepare and are able to form an insulating mass for blocking water and gas inflow. In order to apply under field conditions the technology of water shutoff by means of controlled injection of plugging compound into the target interval of the drilled hole, the organosilicon compound with the highest values of residual resistance factors both for water and gas was chosen. A two-packer arrangement with an injection port in the inter-packer space was used for injection. After the work was done, a significant decrease in fluid flow rate was observed.
- Asia > Russia > Siberian Federal District > Krasnoyarsk Krai > Kuyumbinskoye Field (0.99)
- Asia > Russia > Siberian Federal District > Krasnoyarsk Krai > Baykit High Basin > Yurubcheno-Tokhomskoye Field (0.99)
- Asia > Russia > Ural Federal District > Yamalo-Nenets Autonomous Okrug > West Siberian Basin > Central Basin > North Komsomolskoye Field (0.98)
Deposits of Eastern Siberia characterized by a complex geological structure as well as cavity-fractured reservoir in Riphean dolomite deposits. The uniqueness is caused by high anisotropy of permeability, absence of permeability of rock matrix, ultra-low porosity of formation (1-2%), abundance of tectonic disturbances, subvertical fracturing. These special aspects create significant difficulties in assessment of residual reserves and saturation nature when selecting wells-candidates for wellwork operations. The absence of reliable methods for forecasting distribution of poroperm properties in interwell space and impossibility of the definition of the carbonate reservoir saturation with porosity less than 2% lead to the high risks of unprofitability of the activities. The article summarizes the accumulated experience of geological and technological measures implementation at the wells of the Kuyumbinskoye oil-gas-condensate field. The main method of improved oil recovery for carbonate reservoir is treatment by compositions on the basis of hydrochloric acid, including the use of diverters due to the specific distribution of permeability. Besides acid treatment methods, additional reservoir perforation is used as a tool to increase the coverage. New for this reservoir is the method of limiting water inflow by lowering liners with sleeves to enable bridging of water / gas breakthrough intervals during operation. In 2022, work began on testing multistage hydraulic fracturing technology. The uniqueness of such works lies in the properties of the rock matrix - it is impermeable and has almost zero porosity (0.5-0.7%). Under such conditions, multistage hydraulic fracturing has not been performed in the Russian Federation. Pilot work is scheduled to be completed in 2023. The tested and potentially effective technologies mentioned in the article have been reworked and adapted to the geological conditions of the field.
The article describes an approach to the study of the effect of low-volume chemical enhanced oil recovery (EOR) methods using the control group method on the example of the Vankorskoye oil-gas-condensate field. The study involved comparing the performance indicators of the producing wells in the waterflooding blocks that had their injection wells treated with cross-linked polymer compounds and the performance indicators of wells in neighboring waterflooding blocks with similar properties that did not have their injection wells subjected to such treatments. The study has been motivated by the general features of the low-volume chemical EOR methods: they have an effect that is small relative to the flow rates of the reactive wells; this effect is not bound to the wells treated; and the effect manifests itself gradually over a sufficiently long time. These features lead to the possibility of a systematic error significant in the scale of the effect of the low-volume chemical EOR methods when assessing said effect by predicting watercut using standard displacement characteristics for a specific reservoir. The choice of the control group method in addition to the means of instrumental control and assessment by displacement characteristics has been necessitated by the relative simplicity of this approach, as well as the possibility of its application without additional costs, using already available field data. Through the application of this method, the real effect of the low-volume chemical EOR method for the Vankorskoye field has been verified. The absence of a significant systematic error in the forecast of watercut for the displacement characteristics used in the methodology adopted by Rosneft Oil Company has been confirmed. As a result, it became possible to proceed with the full-scale implementation of the low-volume chemical EOR method throughout the Vankorskoye field.
Acid treatment practice in a high temperature carbonate formation using a drill-stem tester tool (Russian)
Folomeev, A. E. (RN-BashNIPIneft LLC) | Taipov, I. A. (RN-BashNIPIneft LLC) | Skvortsov, A. M. (RN-Shelf-Arctic LLC) | Eliseev, S. Yu. (RN-Shelf-Arctic LLC) | Golovanov, D. Yu. (RN-Shelf-Arctic LLC) | Mingalishev, F. K. (RN-BashNIPIneft LLC) | Nazarova, S. V. (RN-BashNIPIneft LLC) | Garifullin, A. R. (RN-BashNIPIneft LLC) | Malinin, A. V. (RN-BashNIPIneft LLC)
The peculiarity of the initial opening of productive intervals makes it necessary to clean the bottomhole formation zone of the well before conducting hydrodynamic studies. The article presents the results of an extensive set of works on the selection of the optimal technology for acid treatment of an exploratory well in a high-temperature carbonate reservoir, confined to the Timan-Pechora oil and gas province. The paper presents the main geological and physical characteristics of the object under study, which also reduce the effectiveness of the acid treatment. The selection of an acid composition for conducting a well treatment was made taking into account the experience of working at an analogous field. The results of physicochemical studies to identify the risks of the negative impact of the acid composition on the rock, the study of the kinetics of the interaction of the acid composition with the rock and the physical modeling of acidizing are presented. A semi-empirical mathematical model of acid dissolution based on Damköller and Pecklet numbers and acid capacity was chosen to determine optimal treatment parameters (injection rate, acid volume) and develop recommendations for treatments. The treatment was performed using a high-tech tubing test assembly to combine all process operations in a single tripping operation, minimize time gaps between operations, eliminate the well killing stage after treatment, and eliminate risks associated with pulling the assembly out of the well after perforation of the pay interval. According to test results, the proposed solution showed its technological efficiency. The prospects for further development of this technology are outlined in relation to the geological and physical features of this reservoir.
- Europe > Russia > Northwestern Federal District > Nenets Autonomous Okrug (0.47)
- Europe > Russia > Northwestern Federal District > Komi Republic (0.47)
The article discusses results of core flooding studies to determine optimal filtration modes of acid compositions in cores from different producing fields, as well as comparison of mathematical models matched with the laboratory studies results to be applied in the software engineering tools for carbonate acidizing design. Various approaches to the mathematical description of wormholes formation in core samples have been considered and, finally, it was decided upon semiempirical models as best-suited for complex engineering tool for carbonate acidizing design. For model matching, a series of core flooding experiments were performed. Different initial concentrations of hydrochloric acid, and different additives to control reaction rate were used. A good match between the models and the forecast data was obtained. To extrapolate these models to field conditions, two universal models based on two different approaches, a simplified pseudostationary single-phase isothermal model and a non-stationary multi-phase non-isothermal model, were developed, which were integrated with the semiempirical models. It was found that the non-stationary multi-phase non-isothermal model has a greater potential for forecast of matrix acidizing performance, however the simplified pseudostationary single-phase model can be useful as a proxy-model to perform quick calculations. The results demonstrate that the models can be successfully realized in the acidizing design software tools. The developed models were the basis of the software package for modeling and design of carbonate acidizing in fields operated by PJSC TATNEFT.
- Information Technology > Modeling & Simulation (0.91)
- Information Technology > Software (0.88)