Reservoir Pressure Maintenance Research Articles

Simulation and Modelling of Water Injection for Reservoir Pressure Maintenance

Water injection has shown to be one of the most successful, efficient, and cost-effective reservoir management strategies. By re-injecting treated and filtered water into reservoirs, this approach can help maintain reservoir pressure, increase hydrocarbon output, and reduce the environmental effect. The goal of this project is to create a water injection model utilizing Eclipse reservoir simulation software to better understand water injection methods for reservoir pressure maintenance. A basic reservoir model is utilized in this investigation. For simulation designs, the reservoir length, breadth, and thickness may be changed to different levels. The water-oil contact was discovered at 7000 feet, and the reservoir pressure was recorded at 3000 pounds per square inch at a depth of 6900 feet. The aquifer chosen was of the Fetkovich type and was linked to the reservoir in the j+ direction. The porosity was estimated to be varied, ranging from 9% to 16%. The residual oil saturation was set to 25% and the irreducible water saturation was set at 20%. The vertical permeability was set at 50 md as a constant. Pressure Volume Temperature (PVT) data was used to estimate the gas and water characteristics.

Improvement of oil and gas production infrastructure as an effective tool for maintaining basic oil and gas production

The modern world is a complex mechanism in which each process, direction, sphere of activity, despite visual differences, ultimately creates a single complex element aimed at ensuring human life. One of the key processes occurring on the planet is the extraction of hydrocarbons. The article proposes to consider a solution that will contribute to ensuring the efficiency of oil and gas production processes, will extend the life cycle of mature oil and gas production assets of the Russian Federation (hereinafter referred to as the RF) and extend their economic profitability. Economic and technological efficiency from infrastructure reengineering measures is individual for each region, and directly depends on the volume of oil, water production and the state of the ground infrastructure. The described areas of infrastructure reengineering, in aggregate, represent an effective tool for optimizing operating and capital costs, increasing the reliability of technological equipment, removing infrastructure restrictions, which will contribute to the achievement of the set task - maintaining oil production at mature assets. Keywords: facilities for oil treatment; gas compression; reservoir pressure maintenance; power supply; engineering networks; operating costs; reengineering.

Methodological approaches to increasing the flooding system efficiency at the later stage of reservoir development

Based on the analysis of the efficiency of CVI.1 and CVI.2 oil reservoirs development, which partially coincide in structural terms, and the terrigenous strata of the Lower Carboniferous of one of Volga-Ural oil and gas province oil fields, an algorithm for assessing the efficiency of waterflooding was proposed, which takes into account the geological structure of the facility, the results of core and geophysical well surveys, as well as the historical performance of wells. The presented algorithm makes it possible to identify ineffective injection directions for making decisions on waterflooding system optimizing. The effect is the identified potential to cut costs by reducing inefficient injection, as well as identifying areas for the introduction of enhanced oil recovery techniques. Keywords: field development; reservoir pressure maintenance system; waterflooding efficiency; cost reduction.

Risk decreasing of water waste through spontaneous fracturing in injectors by integrated well-testing and production logging

Background. When creating an effective reservoir pressure maintenance system, unstable spontaneous hydraulic fractures can be created in injection wells. This can both negatively and positively affect hydrocarbon production. First, fracture improves reservoir connectivity, which increases injection efficiency. On the other hand, unstable fractures can cause behind-the-casing flows and unproductive injection into off-target layers or fingering. 
 
 Goal. The paper is devoted to the analysis of well testing (PTA) and production logging (PLT) improvement for the diagnosis of unstable fractures in injection wells. 
 
 Materials and methods. The analysis is based on the results of modeling the pressure in the reservoir system, describing the penetration reservoirs by an unrestricted conductivity unstable fracture. It is taken into account that the fracture can cross both the perforated formation and the thickness not penetrated by the perforation, and can grow with increasing overbalance. 
 
 The modeling results made it possible both to assess the potential informative capabilities of well testing and to substantiate recommendations for the practical use of the obtained results. 
 
 Conclusions. The proposed approaches to the technology of well testing and production logging and the interpretation of their results make it possible to estimate the additional thicknesses of the reservoirs connected by the spontaneous hydraulic fracturing to injection, the proportion of nonproductive injection in the total volume of the well. The research technology used by the authors is based on continuous measurements of pressure and flow rate during cyclic change of pressure and assessment of the effective transmissibility of the formation system at different heights of unstable fractures. 
 
 The role of the PLT is to determine the effective production thickness of the reservoirs. When assessing the injectivity profile when penetrating the injector with the spontaneous hydraulic fracturing, the key role belongs to non-stationary temperature logging. In this case, it is necessary to take into account the specific features of temperature relaxation in the wellbore after the injection cycle, related to hydraulic fracturing, primarily the increase in the relaxation rate with increasing fracture length.

Метод оценки энергетических параметров и потенциала энергосбережения насосных агрегатов, работающих вне допустимого рабочего диапазона, в системах поддержания давления в нефтяных пластах

Oil reservoir pressure maintenance pumps are often pushed to operate significantly outside of their original design parameters. This can cause operating problems which impact their reliability and efficiency. The author offers the evaluation methodology for energy parameters and energy saving potential of oil reservoir pressure maintenance pumps in order to develop major pump parameters like efficiency, pressure, and specific electric power. The methodology was tested on 42 pump units. The values of variations of basic parameters indicate the energy saving potential of pump units.

Failure prediction of reservoir pressure maintenance system at the Prirazlomnoye Arctic Offshore field

Failures of reservoir pressure maintenance system at offshore facilities cause production losses and a significant increase in OPEX. Predicting failures of a water injection pump or its parts can highly improve the overall performance by promptly adjusting operating parameters to prevent failure occurrence or by scheduling maintenance to reduce unplanned repairs and to minimize downtime. This is particularly relevant for Arctic offshore projects, characterized by considerable logistical challenges and substantial environmental safety risks. The paper presents a data-analytic approach for failure prediction for the water injection pump operated at the ice-resistant GBS Prirazlomnaya. The study used pump failure history and field sensor data to predict the technical condition and identify a failed component in advance. An ARIMA model implemented in the R software environment was developed for the analysis. The results demonstrate that the approach works appropriately based on the generalized risk assessment and feedback from subject matter experts.

Research and application experience of water Huff and Puff technology on low-permeability oil field

Background. This paper presents a study of the applicability and the first results of pilot works of the technology of periodic water injection into production wells with subsequent oil production (Huff and Puff ), which was not previously used in Russia. The oil field of the company “Gazprom Neft” with a terrigenous reservoir of low permeability is considered. Aim. It is planned to use the technology at marginal waterless wells with hydraulic fracturing, which are on the verge of profitability, to increase oil production. Materials and methods. The physical principles of capillary impregnation in a hydrophilic reservoir were presented, which, under given conditions, should lead to an increase in oil production in waterless wells during cyclic water injection and shutdown with subsequent production. Since this technology was not previously used in Russia, a review and analysis of the unsuccessful application in the United States and the successful experience in China in fields with similar properties and wells was carried out. For the design of pilot works, calculations were made on a synthetic hydrodynamic model with double porosity and permeability, according to which a significant increase in oil production in a marginal well was obtained relative to standard operation. Pilot work was carried out on four oil wells of the company’s field, which were previously planned to be transferred to the reservoir pressure maintenance stock. Only two of them managed to meet the required injection and shutdown periods. Results. Pilot work didn’t show significant increase in oil production after the application of the technology. At the same time, there was no decrease in representative wells, which should have occurred due to a decrease in the phase permeability of oil, which indicates the work of the effect of capillary imbibition during water injection. Conclusions. Based on the analysis of the ambiguous results of pilot works, a conclusion is made about the ineffectiveness of the huff and puff technology in the specified modes, the necessity of their optimization and further research.

Optimization model of material balance for reservoir energy survey analysis and control

Introduction. When monitoring the development of hydrocarbon fields, the energy state of the reservoirs is monitored. An inaccurate understanding of the current distribution of reservoir pressure leads to the wrong strategy for the development of residual oil reserves. Isobar maps are constructed to assess reservoir pressure for productive formation. The simplest and most common method of map generation (by interpolating the values of the measurements) has a high sensitivity to the coverage of the well stock by well tests and does not take into account the dynamics and compensation of fluid withdrawals. To eliminate these shortcomings, it is proposed to use the method of multi-tank material balance. Objectives. The purpose of the work is to show the possibility of using the multi-tank material balance method (MMB) to reduce the risks related to low current reservoir pressure at the stage of well workover planning under conditions of limitations on the number and duration of well tests and taking into account the history of production / injection, as well as to predict the dynamics of reservoir pressure in the drainage area. Methods. In the MMB model, for each well, its own block (tank) is specified, for which the mathematical balance equation is drawn up, taking into account the crossflow between the blocks. The transmissibility values are obtained iteratively by numerically solving the problem of minimizing the loss function of the discrepancy between the calculated reservoir and bottom hole pressures and their actual values. Results. The paper provides examples of good convergence of the calculated pressures by the MMB method to the actual build-up test results at the wells of the Ural-Volga fields. The possibility of predictive calculations to optimize the reservoir pressure maintenance system is shown. The practical advantages of the method are: relative simplicity of model, automated adjustment of interblock transmissibility. Discussion. The field of application of the MMB method is determined by the tasks in which it is necessary to determine the reservoir pressure in conditions of a lack of fresh measurements. The MMB methodology is applicable to assess reservoir pressure in order to remove risks before well workovers, as well as to predict the optimization of the reservoir pressure maintenance system.

MATRIXES OF APPLICABILITY OF TRACER RESEARCH ON THE EXAMPLE OF THE ELEMENT OF NINE-POINT DEVELOPMENT SYSTEM WITH HYDRAULIC FRACTURING

This paper discusses the results of hydrodynamic modeling of tracer testing (TT) in the element of a nine-point development system with hydraulic fracturing. In the hydrodynamic simulator «RN-KIM» multi-parameter calculations of the movement of the labeled fluid were carried out for various parameters of the spontaneous growth of induced fractures (permeability, halflength), and formation permeability. An auto-hydraulic fracture is modeled as a highly permeable channel. Based on the results obtained from the hydrodynamic model, matrices of TI applicability were constructed depending on the formation permeability, permeability and half-length of the spontaneous growth of induced fractures. The research results can be used to tune hydrodynamic models, while monitoring the efficiency of the reservoir pressure maintenance system, which in turn will improve the efficiency of well operation control, reduce the risks of gas and oil water inflows during sidetracking and justify the planning of geological and technological measures aimed at increasing oil recovery and intensification of oil production.

Updating a reservoir geological model in order to optimize waterflooding when extracting residual oil reserves from stagnant zones

Background. In the Russian Federation, as well as in many other oil and gas producing countries, waterflooding technology is frequently used as a secondary method of oil production. This technology is aimed, on the one hand, at reservoir pressure maintenance (RPM), and, on the other, at enhancing oil recovery and intensifying oil production. The negative consequences of non-stationary waterflooding can be the premature watering of the produced wells and the imbalance of the reservoir pressure maintenance system, as well as the formation of stagnant and weakly drained zones of the reservoir with residual reserves of hard-to-recover oil.Aim. To improve the efficiency of non-stationary waterflooding under the conditions of high geological and anthropogenic heterogeneity of oil and gas reservoirs in a floating oil reservoir propped up by edge and bottom waters.Materials and methods. We used geological and field information collected on the site of the AB1-2 development object of the Kechimovskoye field in the Western Siberian region. A new methodological approach to optimizing the process of non-stationary waterflooding under complicated conditions of geological and anthropogenic heterogeneity is proposed, including the construction of an improved geological model and the solution of a number of experimental problems using the Hurst method, the Pareto distribution principle and the theory of catastrophes.Results. Using a new version of the geological model of the area of the AB1-2 development object of the Kechimovskoye field and the available geological and field information, we clarified the position of the oil-water contact (OWC) and the correlation of the well section, taking into account the working intervals of production and injection wells. Geological and technical measures were formulated to improve the efficiency of the object under development.Conclusions. An effective development of the geologically complex AB1-2object of the Kechimovskoye field is impossible without updating its geological model. Such updating should be aimed at determining the location of residual reserves in the area and section of the reservoirs, identifying the regularities of the mechanism of oil reserve recovery, assessing the efficiency of the reservoir pressure maintenance system, and developing complex geological-technological measures for achieving the approved value of the final oil recovery factor. The expected efficiency of the proposed optimization methodology provides for additional oil production, a reduction in the flow rate of injected and withdrawal of produced water.

Efficiency of reservoir pressure maintenance system in low-permeable heterogeneous reservoirs

The article presents a generalization of experience in organizing the reservoir pressure maintenance system in low-permeability reservoirs of Tyumen suite. The author of the article considers the issues of influence of the density of the grid of directional wells and the intensity of waterflooding on the efficiency of the reservoir pressure maintenance system. The question of the need to take into account the orientation of the horizontal wells with multistage hydraulic fracturing system with respect to regional stress in order to minimize the breakthrough of the injected water is disclosed in detail. A comparative characteristic of the efficiency of the reservoir pressure maintenance in the system "along" and "across" of stress is given. A new express method is described for determining the optimal oil production period individually for each injection well, which allows maximizing oil production without additional costs. The author of the article gives recommendations for monitoring and regulating water injection.

Geochemical and hydrogeological parameters informativity in oil and gas geology

The article discusses the fundamental possibilities of using the results of geochemical and hydrogeochemical studies of organic matter, oils and waters in oil and gas geology, including for objects at the stage of development. It is shown that complex geochemical studies of oils and waters make it possible to get more correct conclusions about the presence or absence of fluid-dynamic connectivity of different horizons. Studies of organic matter and oils allow (by basin modeling instrument) to understand the contribution of different source rocks to formation of oils of different reservoirs. Hydrogeochemical studies of associated waters and waters used in the reservoir pressure maintenance system in a complex of works not only actively complements the knowledge about the presence or absence of fluid-dynamic connections between reservoirs and production objects, but also make it possible to predict, for example, salt deposition on equipment and in the reservoirs, and therefore allow you to prevent the possibility of unwanted salt deposition. The conclusions are based on the results of comprehensive geological and geochemical studies carried out by the authors for one of the deposits of the Krasnoleninsky arch of Western Siberia, which is at the development stage, as well as on the previous experience of the authors.

Justification on Choosing Screw Pumping Units as Energy Efficient Artificial Lift Technology

The paper analyzes the main techniques and technologies of oil fluid recovery in the context of energy consumption, significantly rising over the latest decade. It is recognized that the number of publications in the area of energy efficiency is growing steadily. Currently Russian oil and gas industry are facing the task of accelerating reduction of energy consumption while preserving, or even increasing, production rates. The task is complicated by the fact that the majority of deposits in Russia either have already entered (primarily, Volga-Ural region) or are now entering (West Siberia) their last stage of exploration, whereas new deposits in East Siberia are only being brought into production. Furthermore, a lot of new deposits, which provide for high recovery rates, are profitable a priori as at the first stage of exploration they do not need any artificial lift due to their free flow production without any oil well pumps. However, there is a significant share of new deposits with low-permeability reservoirs, which require either a system of reservoir pressure maintenance or periodic hydraulic fracturing. At the same time deposits at the late stages of exploration, apart from the use of pump units, systems of reservoir pressure maintenance and hydraulic fracturing, require regular repair and restoration, measures against salt and heavy oil sediments, mechanical impurities, flooding, etc., which all has a negative effect on well profitability. In order to solve these problems, the authors review existing methods and calculate specific energy consumption using various pump systems for hypothetical wells, varying in yield. According to the research results, it has been revealed that from the point of view of energy efficiency, it is desirable to equip low- and low-yield wells with sucker rod progressive cavity pump units, medium-yield ones – with electric progressive cavity pumps driven by permanent magnet motor, medium- and high-yield wells – with electric progressive cavity pumps or electric submersible pumps driven by permanent magnet motor, depending on the characteristics of the pumpedout oil fluid.

Analysis of the Reservoir Pressure Maintenance Pipeline System Using Polymer Flooding

Analysis of the Reservoir Pressure Maintenance Pipeline System Using Polymer Flooding

Предотвращение осложнений при использовании несовместимых вод в системе поддержания пластового давления

A pressing task in the operation of a reservoir pressure maintenance system is the prediction and monitoring of the state of the internal surface of pipelines and the total amount of sediment. The article examines the mechanism of formation of salts of carbonate and sulphate groups in the process of mixing reservoir and artesian waters, which are incompatible, when used in the system for maintaining reservoir pressure. The mechanism of formation of iron compounds when mixing waters with different pH values is considered. The effect of bacteriological contamination of the production media on the increase in the amount of iron sulfides in the production media, as well as the development of equipment biocorrosion is shown. The features of biodegradation of the field pipeline system under conditions of low reservoir temperatures are considered. The most promising methods of dealing with scaling and biocorrosion under conditions of low temperatures of field fluids are noted.

Вопросы сходимости гидродинамических моделей систем поддержания пластового давления

The article presents the problems of correctness of input of initial data, convergence of hydrodynamic models based on the results of calculating the hydraulic characteristics of the ground pipeline network of the reservoir pressure maintenance system using an automated calculation software package.

Oilfield wastewater treatment

Installations for the treatment of oilfield wastewater have been developed. The article presents a solution of hydrocyclone installations for the treatment of oilfield wastewater based on the use of swirling flows. Due to the centrifugal forces in the hydrocyclone and the turbulent movement of water, the armor shells of oil droplets are destroyed, they are enlarged, and the monodispersity increases. The forces acting in the hydrocyclone are considered, and the efficiency of centrifugal forces in separating solid particles is estimated. The main parameters and requirements for the quality of oilfield wastewater are given, recommended for calculation in the development of new and improving existing oilfield wastewater treatment plants for oil reservoir flooding, which allows increasing oil recovery by 1,5-2 times. Improving the systems of field preparation of products includes both the development of new effective technical means, including hydrocyclones, and the improvement of traditionally used equipment. Gidrocyclone can be used as the main element in the wastewater treatment system, provided that the regime is observed, in which there is no over-dispersion of the remaining oil in the water, (water in oil). Thus, the device implements a mechanism for separating light (oil, gas) and heavier fractions (sediment, water, oil). To protect the environment from reservoir water pollution, the following measures are necessary: ensuring deep treatment of oilfield wastewater; extensive use of anti-corrosion coatings and chemical reagents for corrosion protection of oil-producing equipment; full use of waste water obtained in the field in the reservoir pressure maintenance system; monitoring of the state of surface water and the quality of waste water used in the reservoir pressure maintenance system.

УТИЛИЗАЦИЯ БАЛЛАСТНОЙ ПОПУТНО ДОБЫВАЕМОЙ ВОДЫ С ПРИМЕНЕНИЕМ ТЕХНОЛОГИИ СКВАЖИННОЙ СЕПАРАЦИИ ВОДОНЕФТЯНЫХ ЭМУЛЬСИЙ

Актуальность. Одной из основных проблем нефтедобывающей промышленности в сфере добычи нефти и газа является добыча больших объемов балластной воды. Средняя кратность перекачиваемой воды к нефти может составлять 4:1 и более. На территории Пермского края данная проблема является особенно актуальной, так как многие месторождения находятся на 3 и 4 стадиях разработки и требуют внедрения новых технологий для более рентабельной добычи нефти. В связи с перекачкой больших объемов жидкости происходит более быстрый процесс износа оборудования и появляются дополнительные затраты электроэнергии для его использования. В связи с этим внедрение технологии скважинной и кустовой сепарации водонефтяной эмульсии является одним из наиболее эффективных способов решения производственной задачи путем децентрализации системы сбора и подготовки скважинной продукции. Цель:уменьшение затрат на сбор и подготовку скважинной продукции путем применения технологии кустовой сепарации водонефтяной эмульсии при децентрализованной системе подготовки. Объект: кусты скважин со средней обводненностью65–70% и более. Методы:обзор научной литературы, моделирование процесса кустовой сепарации в Aspen HYSYS; лабораторные исследования на созданном макете, имитирующем скважину. Результаты.Представлена технология кустового разделения продукции скважин на нефть и воду с дальнейшимиспользованием попутнодобываемой воды в системе поддержания пластового давления. Представлена принципиальная технологическая схема установки. Проведены лабораторные испытания, выявлены оптимальные параметры её работы.Приведена технико-экономическое оценка реализации технологии и обоснованные технические решения.

Coupled Flow/Geomechanics Modeling of Interfracture Water Injection To Enhance Oil Recovery in Tight Reservoirs

Summary Unconventional tight reservoirs that are typically characterized by low permeability and low porosity have contributed significantly to the global hydrocarbon production in recent years. Although hydraulic fracturing, along with horizontal well drilling, enables the economic development of such reservoirs, the production rate often declines sharply and results in low primary hydrocarbon recovery. The application of enhanced-oil-recovery (EOR) techniques in tight reservoirs has received much interest. In this study, the feasibility and efficiency of interfracture water injection to enhance oil recovery in multistage fractured tight oil reservoirs are analyzed through an efficient coupled flow/geomechanics model with an embedded discrete-fracture model (EDFM). A combined finite-volume/finite-element scheme is used to discretize the governing equations for flow and geomechanics, and the coupled problem is solved sequentially using a fixed-stress splitting algorithm. A basic numerical model consisting of a 15-stage fractured horizontal well is constructed using the petrophysical and geomechanical properties of a tight oil formation in Ordos Basin, China. Fractures indexed with even numbers are switched into injecting fractures when the production rate has dropped to less than a certain threshold. The improvement of oil recovery is analyzed by comparing the production profiles with and without water injection. In this coupled model, the fracture closure/opening during production/injection is considered according to the constitutive relations between fracture aperture and effective normal stress acting on the fracture faces. The poromechanical response of matrix is modeled by the Biot (1941) theory. The effects of fracture spacing, injection rate, and the presence of a natural-fracture network on oil-recovery enhancement are discussed through sensitivity analysis. The main mechanisms of interfracture water injection for enhancing oil recovery are waterflooding and reservoir-pressure maintenance. Small fracture spacing tends to reduce the oil recovery because of fracture interference and a limited drainage area; therefore, the primary depletion stage is shortened as the fracture spacing is reduced. The influence of interfracture water injection is more pronounced with smaller fracture spacing because the pressure-transient responses near the producing fractures are more dramatic considering the close proximity between the injecting fracture and the producing fracture. Although a higher injection rate results in higher oil recovery, the injectivity in low-permeability reservoirs limits the maximum-allowable injection rate. When secondary (natural)-fracture networks are considered, neighboring hydraulic fractures can be connected to one another via the secondary fractures, particularly if the interfracture spacing is small. Water can break through in the producing fractures quickly, which could also lead to high water cut and suboptimal oil-recovery performance. This study tests the feasibility and efficiency of interfracture injection to enhance tight oil recovery. The results indicate that interfracture injection can be a promising EOR technique for tight oil reservoirs, which sheds lights on future completion strategies and production design in tight reservoirs.

Air assisted in situ upgrading via underground heating for ultra heavy oil: Experimental and numerical simulation study

In situ upgrading (ISU) via underground heating and thermal cracking is regarded as an effective technique for exploiting ultra heavy oils, in which the heavy oil components can be cracked into light oils and gases for production. However, the slow heating rate via conduction from wellbore to oil formation is the main issue concerned in the conventional ISU process. Herein, an air injection assisted ISU technique (AAISU) is proposed to improve heat transfer by gas convection and along with the thermal effect of oil oxidation due to the oxygen in the injected air. Air injection can also provide extra energy for oil production and reservoir pressure maintenance. To illustrate the advantage of the proposed AAISU technique, thermal cracking experiments of ultra heavy oil samples in the presence of air under high pressure were conducted to investigate the reaction mechanisms and to establish the kinetics models of the oxidation and cracking reactions. Moreover, reservoir numerical simulation studies are performed to evaluate the effects of air injection during the ISU process. The experiment results indicate that the ultra heavy oil can be effectively cracked into gases, light oils and coke-like substances in the presence of air at temperature over 350 °C. The activation energy of the thermal cracking derived is around 248 kJ/mol. The numerical simulation results show that the heat transfer rate can be effectively enhanced by air injection because of the heat convection of the air flow and the thermal effect of the low temperature oxidation reactions of oil components. The total oil recovery factor can be increased via air injection with improved energy conversion efficiency from 6.51 GJ/GJ to 8.42 GJ/GJ.