Modeling of Heavy-Oil Flow with Regard to Their Rheological Properties

With the depletion of traditional energy resources, the share of heavy-oil production has been increasing recently. According to some estimates, their reserves account for 80% of the world’s oil resources. Costs for extraction of heavy oil and natural bitumen are 3–4 times higher than the costs of extracting light oil, which is due not only to higher density and viscosity indicators but also to insufficient development of equipment and technologies for the extraction, transportation, and processing of such oils. Currently, a single pipeline system is used to pump both light and heavy oil. Therefore, it is necessary to take into account the features of the heavy-oil pumping mode. This paper presents mathematical models of heavy-oil flow in oil-field pipelines. The rheological properties of several heavy-oil samples were determined by experiments. The dependencies obtained were used as input data for a simulation model using computational fluid dynamics (CFD) methods. The modeling condition investigates the range of shear rates up to 300 s−1. At the same time, results up to 30 s−1 are considered in the developed computational models. The methodology of the research is, thus, based on a CFD approach with experimental confirmation of the results obtained. The proposed rheological flow model for heavy oil reflects the dynamics of the internal structural transformation during petroleum transportation. The validity of the model is confirmed by a comparison between the theoretical and the obtained experimental results. The results of the conducted research can be considered during the selection of heavy-oil treatment techniques for its efficient transportation.publishedVersio

System of Comprehensive Energy-Efficient Utilization of Associated Petroleum Gas with Reduced Carbon Footprint in the Field Conditions

This paper considers the issue of associated petroleum gas utilization during hydrocarbon production in remote petroleum fields. Due to the depletion of conventional oil and gas deposits around the globe, production shifts to hard-to-recover resources, such as heavy and high-viscosity oil that requires a greater amount of energy to be recovered. At the same time, large quantities of associated petroleum gas are extracted along with the oil. The gas can be utilized as a fuel for power generation. However, even the application of combined power modes (combined heat and power and combined cooling heat and power) cannot guarantee full utilization of the associated petroleum gas. Analysis of the electrical and heat loads’ graphs of several oil fields revealed that the generated thermal energy could not always be fully used. To improve the efficiency of the fuel’s energy potential conversion, an energy system with a binary power generation cycle was developed, consisting of two power installations—a main gas microturbine and an auxiliary steam turbine unit designed to power the technological objects in accordance with the enterprise’s power load charts. To provide for the most complete utilization of associated petroleum gas, a gas-to-liquid system is introduced, which converts the rest of the gas into synthetic liquid hydrocarbons that are used at the field. Processing of gas into various products also lowers the carbon footprint of the petroleum production. Application of an energy system with a binary power generation cycle makes it possible to achieve an electrical efficiency up to 55%, at the same time maintaining high efficiency of consumers’ energy supply during the year. The utilization of the associated petroleum gas in the developed system can reach 100%.publishedVersio

Study on the rheological properties of barite-free drilling mud with high density

Improved drilling and reservoir penetration efficiency is directly related to the quality of the drilling mud used. The right choice of mud type and its components will preserve formation productivity, stability of the well walls and reduce the probability of other complications. Oil and gas operators use barite, less often siderite or hematite weighting agent as a weighting component in the composition of drilling muds for the conditions of increased pressure. But the use of these additives for the penetration of the productive formation leads to the reduction of filtration characteristics of the reservoir, as it is almost impossible to remove them from the pore channels. Therefore, barite-free drilling mud of increased density based on formic acid salts with the addition of carbonate weighting agent as an acid-soluble bridging agent is proposed. The results of experimental investigations on rheological parameters of barite-free solutions are given and the obtained data are analyzed. Based on the comparison of results it is recommended to use high-density drilling mud on the basis of formic acid salts (sodium and potassium formate) and with the addition of partially hydrolyzed polyacrylamide with molecular mass of 27 million

Development of the drilling mud composition for directional wellbore drilling considering rheological parameters of the fluid

Article presents investigations on the development of a drilling mud composition for directional wells in an oil field located in the Republic of Tatarstan (Russia). Various rheological models of fluid flow and their applicability for drilling muds are analyzed. Laboratory experiments to measure the main rheological parameters of a solution, such as plastic viscosity, dynamic shear stress, as well as indicators of non-linearity and consistency are presented. On the basis of laboratory investigations, it was concluded that high molecular weight polymer reagents (for example, xanthan gum) can give tangible pseudoplastic properties to the washing fluid, and their combination with a linear high molecular weight polymer (for example, polyacrylamide) reduces the value of dynamic shear stress. Thus, when selecting polymer reagents for treating drilling muds at directional drilling, it is necessary to take into account their structure, molecular weight and properties. Combination of different types of reagents in the composition of the drilling mud can lead to a synergistic effect and increase the efficiency of the drilling process as a whole

Dependence of the Equivalent Circulation Density of Formate Drilling Fluids on the Molecular Mass of the Polymer Reagent

Construction of offshore gas wells is characterized by increased requirements for both the technological process in general and the technological parameters of drilling fluids in particular. Parameters and properties of the used drilling muds must meet a large number of requirements. The main one is the preservation of the permeability of the reservoirs, in addition to the environmental and technological concerns. At the same time, pressures in the productive formation at offshore fields are often high; the anomaly coefficient is 1.2 and higher. The use of barite in such conditions can lead to contamination of the formation and a decrease in future well flow rates. In this regard, the development and study of the compositions for weighted drilling muds is necessary and relevant. The paper presents investigations on the development of such a composition based on salts of formic acid (formates) and evaluates the effect of the molecular weight of the polymer reagent (partially hydrolyzed polyacrylamide) on the equivalent circulation density of the drilling fluid. The result of the work is a formate-based high-density drilling mud with no barite added. Application of such a mud will preserve the permeability of the productive formation

Barite-Free Muds for Drilling-in the Formations with Abnormally High Pressure

This paper discusses problems associated with water-based drilling fluids used for drilling formations with abnormally high pressure. The available solutions are suitable for a narrow range of applications, especially when weighted muds should be used. This paper reviews the experience of searching and developing a new type of drilling mud based on saturated brines. With the referenced papers as the basis, the authors developed compositions of such brine-based drilling muds. A distinctive feature of the considered compositions is the absence of barite, which is often used as a weighting agent. The paper presents a methodology for creating and investigating the proposed drilling fluids. The rheological properties and thermal stability of the muds at various temperatures were studied. The results show that proposed drilling fluids can be efficiently used for drilling formations with abnormally high pressure. It is assumed that the developed muds have greater versatility than analogues

Development of a Weighted Barite-Free Formate Drilling Mud for Well Construction under Complicated Conditions

Construction of oil and gas wells at offshore fields often involves high formation pressure and the presence of swellable clay rocks in the section. In addition, productivity preservation is also an important aspect. For this purpose, it is necessary to reduce the solids content of the drilling mud. The purpose of this work is to develop, improve, and study compositions of weighted drilling muds with low content of solids, on the basis of organic salts of alkali metals and polymers for the construction of wells prone to rock swelling and/or cavings, as well as drilling fluids for drilling-in the formation. In order to achieve the set goal the following is required: Analysis of existing drilling muds of higher density for drilling wells in unstable rock intervals and for drilling in the productive formation; analysis of experience in using drilling systems on the formic acid salts base and substantiation of requirements for flushing fluids during well construction; development and investigation of drilling mud compositions on the formate base; and the evaluation of inhibiting effect of systems containing organic salts, polymer reagents, and calcium carbonate on clay samples. The developed drilling mud is characterized by a high inhibiting ability that allows minimized mud-weighting by the natural solid phase. This reduces the volume of prepared mud and facilitates the regulation of its properties by reducing the dispersion of drilled cuttings; it eliminates problems related to hydration and the swelling of active clay rocks; and stabilizes unstable argillites prone to caving. The low solids content, low filtration rates, and inhibitory nature of the mud allows high stability of the rheological properties of the mud, and preserves oil and gas reservoir productivity under conditions of elevated formation pressure

Современные тенденции освоения углеводородных ресурсов

Значение углеводородных ресурсов и нефтегазового комплекса в настоящее время сложно переоценить. На территории Российской Федерации сосредоточена примерно третья часть мировых запасов природного газа, по запасам нефти Россия уступает всего пяти государствам, но даже этого достаточно, чтобы развивать и совершенствовать эту отрасль производства. Вопросы обеспечения рационального использования созданной минерально-сырьевой базы за счет вовлечения в эксплуатацию трудноизвлекаемых запасов нефти и газа, неразрабатываемых месторождений твердых полезных ископаемых, снижения негативного влияния освоения недр на окружающую среду, качественного улучшение системы информационного обеспечения недропользования, мониторинга и контроля развития минерально-сырьевой базы Российской ФедерацииЗакрыть панель путем развития информационных технологий, в том числе за счет внедрения автоматизированных систем управления и регулирования в сфере геологии и недропользования, систем обработки, интерпретации, хранения и предоставления в пользование геологических данных являются задачами в «Стратегии развития минерально-сырьевой базы Российской Федерации до 2035 года

LOW-DENSITY CEMENT COMPOSITIONS FOR WELL CEMENTING UNDER ABNORMALLY LOW RESERVOIR PRESSURE CONDITIONS

The paper considers variants of lightweight cement compositions with additives of various substances, such as clay components, ash systems, silica additives, kerogen, gilsonite, microspheres, as well as the process of cement slurry aeration. Recommendations on the use of compositions in different conditions are presented. A decrease in the density of the solution is achieved not only due to the low density of the materials used, but also as a result of an increase in the water-cement ratio. In such conditions, it is not possible to ensure the formation of a durable and impermeable cement stone in the well, which creates high quality inter-reservoir insulation. The characteristics of the physical and mechanical properties of existing lightening additives are given, which allows determining the most rational conditions for the use of cement slurries for improvement of the well cementing quality

A Numerical Study on the Application of Stress Cage Technology

Lost circulation is considered a time-consuming, costly problem during the construction of oil and gas wells. There are several preventive techniques to mitigate this problem. Stress cage technology is a mechanical lost circulation method, in which the formation at the wellbore wall is strengthened to stop the creation of induced fractures as one of the main causes of lost circulation. In this research, a two-dimensional numerical model, considering the elastic, poro-elastic, and thermo-poro-elastic behavior of the rock, is built to investigate the effectiveness of the stress cage method. Results show that better performance of the technology is achieved if the fractures are bridged close to their apertures. Additionally, it was found that the difference between the elastic, poro-elastic, and thermo-poro-elastic models is slightly visible. The conclusion states that the application of the stress cage methods leads to an increase in hoop stress and subsequent formation fracture gradient