Oilfield Exploitation Research Articles

A Novel Analytical Solution of Radial Diffusion Equation with Constant Terminal Rate of Slightly Compressible Fluid

In reservoir engineering, the flow and type of fluids crossing porous media, are associated with pressure drops leading to variations on hydrodynamic parameters and the filtration stages which are of interest to be assessed as they impact the production efficiency of oil and gas industry. These parameters are the key to the practical solutions of numerous subjects faced during oil field exploitation. Dealing with the problem of sound field development initiatives requires a rigorous examination of unsteady filtration of slightly compressible fluid in the reserves layer. The state of the art of the proposed scientific work is to present an innovative mathematical approach that gives unique results, in the mathematical connection and combination of the equations used versus existing diffusion equation in the case of the constant terminal rate solution. This model helps the designers in the field of oil and gas to better and faster evaluate the diffusivity of the pay zones, the different hydrodynamic parameters, and the different variables that take part in the development of fluid filtration processes in the porous medium expressed as in the dependence of time, distance, and other variables, all of which together impact the well testing and long-term projections.

Effect of Solid Particles in Polymer Waste Liquid on Grinding Tool Wall Erosion

Abstract With the continuous accumulation of polymer waste liquid in the third oil recovery process, the treatment of wellhead return waste liquid has become a key issue in oilfield exploitation and environmental protection. In this paper, the erosion failure of the cutter caused by sand-containing particles in the waste liquid during the shear grinding process is studied. The influence of the main structural parameters of the grinding tool and the erosion failure is studied by using the comprehensive numerical simulation method to reduce the erosion rate of the polymer flooding waste liquid on the cutter. Firstly, the flow field model of the solid-liquid fluid is established, and the erosion phenomenon on the tool wall is studied by combining the model with field experiments. In addition, the relationship between the different cutters structure and erosion rate of the grinding tool is studied, and the mathematical model is established. The optimized structural parameters are given to enhance the erosion resistance of the grinding tool in the process of polymer flooding wellhead waste liquid treatment and prolong its service life.

Research on wax removal and prevention technology of White Wolf City oil well

Abstract Oil well wax removal technology is an important subject in the process of oil field exploitation. This paper analyzes the mechanism and characteristics of wax formation in oil Wells by measuring the amount of wax in crude oil in Baiwolcheng oil area. When the waxy component, which usually exists in liquid form, is accompanied by crude oil from underground to the ground, the waxy crystal precipitates and deposits in the inner wall of oil pipe due to the gradual decrease of the temperature of crude oil. The phenomenon of paraffin formation, paraffin formation process and paraffin formation law of oil well are studied, and chemical paraffin removal and anti-wax technology is determined as the main research object, evaluation and optimization of paraffin removal and anti-wax agent, and determination of dosage concentration and dosage.

Exploring source-specific ecological risks of PAHs near oil platforms in the Yellow River Estuary, Bohai Sea

The Yellow River Estuary (YRE) is one of highly remarkable regions profoundly impacted by human activities, with numerous oil platforms dispersed throughout. In this area, offshore oil exploitation may pose significant ecological risks. To comprehensively evaluate the quantitative impacts of oil field exploitation on the marine coastal ecosystem, this study investigated the occurrence, sources, and ecological risks associated with 16 polycyclic aromatic hydrocarbons (PAHs) in seawater and sediment near oil platforms in the YRE. We found that 1) The concentrations of PAHs decreased from the surface seawater to sediments; 2) The ecological risk level of PAHs in seawater exceeded that in sediments; 3) terrestrial sources (combustion), rather than offshore oil drilling activities, significantly influenced regional ecological risks through processes of atmospheric deposition and surface runoff. These findings provide essential data for future estuarine research efforts while supporting mitigation measures aimed at addressing marine environmental pollution related to oil production activities.

Analysis of the Effects of Partially Hydrolyzed Polyamide on Oil Reservoir Rocks

The exploitation of heavy oil fields has recently gained momentum due to increased investment in new oil and gas fields and especially due to environmental legislative constraints. That is why in this article I have described the possibility of using partially hydrolyzed polyacrylamide in the exploitation of heavy crude oil deposits, by injecting it into reservoir rocks followed by injection of reservoir water. The role of this polymer is to provide lubrication of the crude oil and water flow channels and especially to block (by reverse osmosis) the large pore communication channels in order to limit pressure leaks in uncontrollable areas. In the study we created two polymers that were used in order to increase the flow rate and decrease the viscosity and the freezing point (additives that are easy to procure and especially with spectacular results in the treatment of stills and without affecting the stability and quality of the final products refinery). We also studied the flow of the polymer through carbonate reservoir rocks, managing to obtain a numerical model that provides data on the rock resistance factor to the flow of partially fluidized polyacrylamide. The adsorption on the surface of the rocks determined the reduction of the mobility of the polymer but also the modification of the gel structure by the modification (crossing) of the polymer (of the polymer chains) which led to clogging (blocking of the pores) and increasing the possibility of fluid flow. In the laboratory we determined the adsorption of silicon for a solution of polyacrylamide of 0.05% partially hydrolyzed concentration in water, it increases from the value of 0.01 mg/m2 to 0.05 mg/m2 when the concentration in NaCl increases from 0 .5% to 10% in are we showed that adsorption increases for pH values ​​lower than 7, and it is stated that for a porous sand medium with a permeability of 140 mD, replacing saline water with 20 g/l NaCl, a presence of the polymer with a concentration of 400 ppm was observed in the effluent, and this value being approximately stabilized after 5 injected pore volumes.

Research on the corrosion inhibition performance and mechanism of pyrimidine quaternary ammonium salt

PurposeAt present, research on the preparation of corrosion inhibitors using modified pyrimidine derivatives is still blank. The purpose of this study is to synthesize a new cationic mercaptopyrimidine derivative quaternary ammonium salt, known as DTEBTAC, that can be used as a corrosion inhibitor to slow down the metal corrosion problems encountered in oil and gas extraction processes.Design/methodology/approachA new corrosion inhibitor was synthesized by the reaction of anti-Markovnikov addition and nucleophilic substitution. The weight loss method was used to study the corrosion inhibition characteristics of synthetic corrosion inhibitors. Electrochemical and surface topography analyses were used to determine the type of inhibitor and the adsorption state formed on the surface of N80 steel. Molecular dynamics simulations and quantum chemistry calculations were used to investigate the synthetic corrosion inhibitor’s molecular structure and corrosion inhibition mechanisms.FindingsThe results of the weight loss method show that when the dosage of DTEBTAC is 1%, the corrosion rate of N80 steel in hydrochloric acid solution at 90? is 3.3325 g m-2 h-1. Electrochemical and surface morphology analysis show that DTEBTAC can form a protective layer on the surface of N80 steel, and is a hybrid corrosion inhibitor that can inhibit the main anode. Quantum chemical parameter calculation shows that DTEBTAC has a better corrosion inhibition effect than DTP. The molecular dynamics simulation results show that DTEBTAC has stronger binding energy than DTP, and forms a network packing structure through hydrogen bonding, and the adsorption stability is enhanced.Originality/valueA novel cationic mercaptopyrimidine derivative quaternium-ammonium salt corrosion inhibitor was designed and provided. Compared with the prior art, the preparation method of the synthesized mercaptopyrimidine derivative quaternary ammonium salt corrosion inhibitor is simple, and the presence of nitrogen-positive ions, sulfur atoms and nitrogen-rich atoms has an obvious corrosion inhibition effect, which can be used to inhibit metal corrosion during oil and gas field exploitation. It not only expands the application field of new materials but also provides a new idea for the research and development of new corrosion inhibitors.

The Mechanism of Air Blocking in the Impeller of Multiphase Pump

The exploitation and transportation of deep-sea and remote oil and gas fields have risen to become important components of national energy strategies. The gas–liquid separation and gas blocking caused by the large density difference between the gas and liquid phases are the primary influencing factors for the safe and reliable operation of gas–liquid mixed transportation pump systems. This paper takes the independently designed single-stage helical axial-flow mixed transportation pump compression unit as the research object. Through numerical simulation, the internal flow of the mixed transportation pump is numerically calculated to study the aggregation and conglomeration of small gas clusters in the flow passage hub caused by gas–liquid phase separation, influenced by the shear flow of phase separation, forming axial vortices at the outlet where gas clusters gather in the flow passage. The work performed by the impeller on the gas clusters is insufficient to overcome the adverse pressure gradient formed at the outlet of the flow passage due to the gathering of the liquid phase in adjacent flow passages, resulting in the phenomenon of gas blocking, with vortex gas clusters lingering near the hub wall of the flow passage.

Study on the Influencing Factors on the Effectiveness of Liquid Nitrogen Fracturing Technology

Liquid nitrogen fracturing technology is a new fracturing and permeability enhancement technology for reservoirs unsuitable for hydraulic fracturing, and its ultralow temperature, high compression ratio, high freezing and expansion force, and low viscosity characteristics are expected to provide a program for fracturing and permeability enhancement in low-permeability reservoirs. The paper systematically analyzes the influencing factors restricting the effect of liquid nitrogen fracturing, aiming to provide theoretical basis and technical support for the efficient and environmentally friendly exploitation of low-permeability oil and gas fields.

Study on the Mechanism of Coal Fracturing by Liquid Nitrogen

As a fracturing medium with excellent properties, liquid nitrogen has multiple fracturing effects on coal, and its potential application in coalbed methane mining has become a hot spot in current research. In this paper, the key scientific problems of fracturing and penetration enhancement by liquid nitrogen in low-permeability coals are discussed in depth, and the pore fracturing process and its fracturing mechanism of low-temperature fracturing coal are analyzed. It is found that the ultra-low-temperature fluid fracturing process has the effect of high-energy fluid fracturing to break the rock, and also has the coupled fracturing effect of low-temperature fracturing and phase-change fracturing to increase the energy-driven replacement. It aims to provide theoretical basis and technical support for the efficient and environmentally friendly exploitation of low-permeability oil and gas fields.

EVALUATION OF THE ENERGY EFFICIENCY OF THE NEW CONSTRUCTIVE SOLUTION OF SUCKER-ROD PUMP

As is known, in our country, oil production is carried out both in the Caspian Sea and in oil fields on land. For the mechanized exploitation of oil fields on land, in most cases used different type of sucker-rod pumps. The main object of the study of the article is a new constructive solution of the pumping unit, the novelty of which is approved by the ownership certificates of the Eurasian Patent Organization and the Intellectual Property Organization of the Republic of Azerbaijan. The main factor characterizing the operation of pumping units is its quality indicators such as metal consumption, reliability, efficiency and energy consumption. When switching from a balanced sucker-rod pumping unit to an unbalanced the efficiency factor decreases from 0.834 to 0.65 and decreases from 0.605 to 0.312. In this case, power losses increase sharply not only in transmissions, but also in energy distribution networks. If the engine is not fully loaded or is not selected correctly, then these energy coefficients decrease even more. The selection of engine power is performed according to the worst conditions, i.e. the cyclic mode of operation of an unbalanced pumping unit. Despite this, it can be said that in almost all oil fields, the power of asynchronous motors is greatly exaggerated, which causes additional losses. In article proposed expressions for determining the optimal power of the electric motor were proposed, taking into account the efficiency factor of the balancing device during the balancing of the proposed new constructive solution of the beamless pumping unit with a combined, movable counter weights and rotary counter weights. This allows to prevent excess energy consumption and reduce energy costs. Which is very important in the era of globalization, when energy prices are rising sharply.

Soil column-experimental research on the migration pattern of petroleum pollutant in the soil

In the process of oilfield exploitation and production, harmful pollutants, such as Crude oil that falls to the ground (generally refers to crude oil that leaks to the ground during oil production or transportation), production wastewater and oil-bearing mud are produced. In this contribution, the soil and crude oil from Daqing area are adopted as experimental materials to make a soil column-experimental device. The results show that the maximum migration depth of petroleum pollutants is 25 cm, most of the pollutants exist above 10 cm. The components of pollutants in disturbed soil column are complex, and the peak area of each component is large, mainly distributed in C12–C28, while in undisturbed soil column, the content of pollutants is small, and the peak area of each component is also small, mainly distributed in C12–C22. With the increase of depth, the relative content of aromatic hydrocarbons increases. The migration ability of low carbon component is weaker than the other components in crude oil. The components with high carbon number are significantly higher in shallow part. The relative contents of each component from high to low are saturates, aromatic hydrocarbons, resin and asphaltene in the soil. Compared with disturbed soil columns, the structure of undisturbed soil is complex, and the migration rate of pollutants in undisturbed soil is slower than that in disturbed soil. With the increase of depth, the light components of disturbed soil columns gradually decrease, and the relative content of heavy components changes little. The light components of the undisturbed soil column also gradually decreased, and the heavy components greater than C22 did not migrate to the depth of the soil column.

Zvezda Shipyard Project: Global Implications and Its Influence on the Russian Economy

This article expands upon the author's previous work regarding the Vostok Oil project, initially discussed in the Gubkin University journal. It focuses on the establishment and development of the Zvezda Shipyard project, arguing its critical role in the potential development of the Vostok Oil and Gas province. The paper posits that without the Zvezda Shipyard, it would not be feasible to exploit the Vostok Oil and Gas province or significantly enhance the transportation and logistics capabilities of the Northern Sea Route (NSR). The development of Zvezda's new production facilities is presented as essential for the advancement of the Russian Arctic, facilitating a pivotal eastward shift in the Russian economy. The significance of the Zvezda project and the strategic decisions leading up to it are discussed in detail, demonstrating how they integrate the development of the NSR, the exploitation of Vostok Oil fields, and the establishment of investment and technological foundations for Russia's long-term strategy. This strategy addresses both socio-economic goals and defense and security challenges. Additionally, the paper provides quantitative analyses of the multiplicative effects generated by the Zvezda Shipyard project's realization.

Time-dependent model for two-phase flow in ultra-high water-cut reservoirs: Time-varying permeability and relative permeability

For the ultra-high water-cut reservoirs, after long-term water injection exploitation, the physical properties of the reservoir change and the heterogeneity of the reservoir becomes increasingly severe, which further aggravates the spatial difference of the flow field. In this study, the displacement experiments were employed to investigate the variations in core permeability, porosity, and relative permeability after a large amount of water injection. A relative permeability endpoint model was proposed by utilizing the alternating conditional expectation (ACE) transformation to describe the variation in relative permeability based on the experimental data. Based on the time dependent models for permeability and relative permeability, the traditional oil-water two-phase model was improved and discretized using the mimetic finite difference method (MFD). The two cases were launched to confirm the validation of the proposed model. The impact of time-varying physical features on reservoir production performance was studied in a real water flooding reservoir. The experimental results indicate that the overall relative permeability curve shifts to the right as water injection increases. This shift corresponds to a transition towards a more hydrophilic wettability and a decrease in residual oil saturation. The endpoint model demonstrates excellent accuracy and can be applied to time-varying simulations of reservoir physics. The impact of variations in permeability and relative permeability on the reservoir production performance yields two distinct outcomes. The time-varying permeability of the reservoir results in intensified water channeling and poor development effects. On the other hand, the time-varying relative permeability enhances the oil phase seepage capacity, facilitating oil displacement. The comprehensive time-varying behavior is the result of the combined influence of these two parameters, which closely resemble the actual conditions observed in oil field exploitation. The time-varying simulation technique of reservoir physical properties proposed in this paper can continuously and stably characterize the dynamic changes of reservoir physical properties during water drive development. This approach ensures the reliability of the simulation results regarding residual oil distribution.

Review Paper on The Research and Development of Corrosion Inhibitors

Corrosion problems are widely found in various industries, and corrosion inhibitors also play an important role in various corrosion environments, especially in oil exploration. However, as China's oilfield exploitation enters a high water injection period, the mining environment is becoming more and more harsh, and the requirements for oilfield corrosion inhibitors are getting higher and higher. At the same time, various scaling phenomena have emerged one after another in the process of oilfield exploitation. The corrosion and scale inhibitor with good scale inhibition reflects its advantages, and the integration of corrosion and scale inhibition has become a major tendency in the development of corrosion inhibitors. This review introduces different corrosion inhibitors, and focuses on the research on corrosion inhibitors at home and abroad. At the end of the review, it puts forward views on the future development direction of corrosion inhibitors.

An enhanced oil recovery technology applicable to kazakhstan reserves with highly viscous oils

The subject of discussion of the article below is polymer flooding as an EOR (enhanced oil recovery) technique considered here within the context of Kazakhstan’s depleted oil-fields exploitation. The underlying factor for considerable residual hydrocarbon saturation observed in the productive reservoirs of the majority of Kazakhstan’s oil fields connected with their stratified heterogeneous structures. Such kind of Oil Reservoirs require additional developments comprising new technologies promoting enhanced oil-recovery. Keywords: viscosity; inhomogeneity; polymer flooding; polyacrylamide; degree of inhomogeneity; permeability; catholyte; trim.

Measurement of steam dryness using one-dimensional acoustic waves in pipelines

Heavy oil, extra-heavy oil and bitumen exceed 6 trillion barrels, roughly three times the world total Conventional oil and gas reserves. Thermal-chemical flooding (TCF) is an effective alternative to enhance heavy oil recovery after steam injection. In the steam injection and extraction process of oil, the accurate measurement of water steam dryness can provide a strong guarantee for the efficient exploitation of oil fields. The traditional steam dryness measurement device is affected by the steam flow state, and the error generated will affect the enthalpy calculation of the injected steam, which affects the judgment of energy efficiency of oil well injection in the field. Firstly, this paper proposes a mathematical model for calculating water steam dryness using mixed sound velocity and operating temperature, which is based on the mathematical relationship between water steam dryness and gaseous volume fraction, combined with Wood's formula and the density and sound velocity calculation formula for each region in the IAPWS-IF97 model to derive the monotonic correspondence function of sound velocity and dryness. Secondly, the one-dimensional acoustic wave model of the pipeline is applied to establish a set of sound velocity equations for the frequency-domain data of the array sensors, and the traversal iteration method is used to solve the mixed sound velocity of water steam. Finally, the dryness of steam injection under the operating condition of 270°C∼290°C at the wellhead was measured in the experimental area H33 in Xinfanguan of Liaohe Oilfield, and compared with the standard dryness value, the relative error of the experiment was -3.33% and the repeatability was 1.24%, the accuracy met the requirements of energy efficiency calculation, which verified the feasibility of the sound velocity method to measure the dryness of water steam. Therefore, it is of great engineering guiding significance to utilize sound velocity method to realize the measurement of dryness in the thick oil steam injection process.

Optimization of Horizontal Well Location and Completion to Improve Oil Recovery for an Iraqi Field

Exploitation of mature oil fields around the world has forced researchers to develop new ways to optimize reservoir performance from such reservoirs. To achieve that, drilling horizontal wells is an effective method. The effectiveness of this kind of wells is to increase oil withdrawal. The objective of this study is to optimize the location, design, and completion of a new horizontal well as an oil producer to improve oil recovery in a real field located in Iraq. “A” is an oil and gas condensate field located in the Northeast of Iraq. From field production history, it is realized the difficulty to control gas and water production in this kind of complex carbonate reservoir with vertical producer wells. In this study, a horizontal well design with multi-stage completion is studied and proposed to find optimal oil recovery in the southeast region of the selected field. A bulk oil well sector model is used to simulate the fluid flow of a single-porosity/single-permeability model. Then, a sensitivity analysis has been run to optimize; the well trajectory path, different scenarios on well oil and water production potential, and well completion design. The result of the well sector simulation indicates that the well trajectory with an Azimuth of 89 degrees and with a multi-stage completion design has better production performance under water production constraints. Optimum oil production rates of 1000 to 2000 STB/day, as delaying and controlling early gas and water production challenges is achieved.

Eco-friendly calcium alginate microspheres enable enhanced profile control and oil displacement

Polymer microspheres (PMs), such as polyacrylamide, have been widely applied for enhanced oil recovery (EOR), yet with environmental concerns. Here, we report a microfluid displacement technology containing a bio-based eco-friendly material, i.e., calcium alginate (CaAlg) microspheres for EOR. Two dominant mechanisms responsible for EOR over CaAlg fluid have been verified, including the microscopic oil displacement efficacy augmented by regulating capillary force (determined by the joint action of interfacial tension and wettability between different phases) and macroscopic sweep volume increment through profile control and mobility ratio reduction. This comprehensive effectiveness can be further impacted when the CaAlg microsphere is embellished ulteriorly by using appropriate amount of sodium dodecyl sulfonate (SDS). The core flooding and nuclear magnetic resonance (NMR) tests demonstrate that CaAlg-SDS microsphere can balance the interphase property regulation (wettability alteration and IFT reduction) and rheology properties, enabling simultaneous profile control and oil displacement. Excessive introduction of SDS will have a negative impact on rheological properties, which is not favored for EOR. Our results show that the involvement of 4-mM SDS will provide the best behavior, with an EOR rate of 34.38%. This cost-effective and environmentally-friendly bio-microsphere-based microfluidic displacement technology is expected to achieve “green” oil recovery in future oilfield exploitation.

Биологические свойства почв Надеждинского и Северо-Камышанского нефтяных месторождений, расположенных на территории заказника «Меклетинский»

The most acute environmental problem in many regions of Russia and other countries is environmental pollution with oil and oil products. Soil pollution with oil products can occur in various emergencies in areas of oil production and processing, when oil pipelines break, which causes leakage and spills on the soil surface, as well as in places where oil products are distributed. The purpose of this study is to study the biological properties of soils in Kalmykia under conditions of oil and oil products pollution. The soils of the Nadezhdinskoye and Severo-Kamyshanskoye oilfields located on the territory of the Mekletinsky nature reserve were chosen as the objects of study. Laboratory and analytical studies, as well as sampling, were carried out using methods generally accepted in biology and soil science. The content of oil products in the soils of the oil field is in a wide range: from 0.4 to 12.5%. A negative correlation was established between the content of oil products in the soil and the activity of catalase and phosphatase. Oil products have a negative impact on the growth and development of radishes. The exploitation of oil fields in specially protected natural areas leads to the flow of oil and oil products into the environment. In the soils of Kalmykia on the territory of oil fields, under the influence of pollution with oil and oil products, the activity of soil enzymes is inhibited, in addition, the soils exhibit a high degree of phytotoxicity with respect to test plants.

Комплексный экологический мониторинг негативного воздействия нефтесодержащих отходов в районах нефтяных месторождений как объекта экологического риска

In this paper peculiarities of negative impact of oil-containing waste to humans and biosphere and approaches to its estimation are considered. For the estimation of ecological risks of negative impact of oil-containing waste in areas of oil and gas fields it is suggested to take into account not only its toxicological and quantitative characteristics, but also the degradation of the territories of fields, potential recultivating capacity of fields, suitability of wastes for utilization etc. Negative ecological impact not only from operation but also from mothballed oil well should be investigated. Results of complex experimental researches of negative impact of oil-containing waste in regions of development and exploitation of oil and gas fields are described. In number of cases increased values of oil containing waste and heavy metals were determined in soil and in water environment. For oil wells of Mogutovskoye field acute toxicity of soil samples near to the wells and excess over maximum permissible concentrations of methane were determined. Results of monitoring of toxicological impact of oil containing waste in areas of different oil fields of Samara region and in oil treatment plants by using of biological testing methods have showed that a number of samples have enlarged toxicity and are causing acute toxic effect to the test-organisms – green algae Chlorella vulgaris Beijer and Scenedesmus quadricauda (Turpin) Brébisson, crustaceans Daphnia magna Straus. In number of cases increased values of oil products was observed. Thus, it was determined that negative impact of oil-containing waste in areas of oil fields is complex in nature and may cause significant ecological risks for air, water and soil. Results of work allow us to carry out more efficient and high quality monitoring of negative impact of oil-containing waste and estimation of ecological risks as well as to develop the measures for reduction of negative impact of oil-containing waste.