High-viscosity Oil Research Articles

ENGINE PERFORMANCE TEST EVALUATION OF BIODIESEL BLENDS FROM CASTOR SEED OIL AT VARYING MIXTURE RATIOS AND ENGINE SPEED

The growing global demand for energy with expected fossil fuel shortages stresses the search for alternative energy sources. Moreover, the high fossil energy consumption with its adverse impact on environment and climate changes calls for cleaner fuels. One of the most alternative fuel sources is the extraction of biofuels from Castor oil by acid-based catalysed trans- esterification process. In this study, experimental analysis was carried out to produce biodiesel from castor oil using trans- esterification process. The trans- esterification process occurs between castor oil and methanol in the presence of potassium hydroxide (KOH) as a catalyst. The biodiesel fuel produced was varied at different mixture ratios with diesel. The high viscosity and acid value of the castor oil was further reduced by two-three stage trans-esterification process to within the American Society for Testing and Materials (ASTM) D6751 – 0.2 limits for biodiesel. The biodiesel was tested in a single cylinder diesel engine and results of gas emission, load analysis, fuel consumption rate and engine efficiency were all obtained which are close to those of diesel fuel thus confirming that it can be used as alternative fuel for diesel engines. The Brake thermal efficiency was 96% at B-20 biodiesel blend which is close to the conventional diesel engine efficiency of 95.5%.

Influence of Oil Viscosity on the Tribological Behavior of a Laser-Textured Ti6Al4V Alloy.

Laser texturing with a dimple pattern was applied to modify a Ti6Al4V alloy at the micro level, aiming to improve its friction and wear resistance in combination with oil lubrication to optimize the performance in demanding industrial environments. The tribological analysis was performed on four different dimple-textured surfaces with varying dimple size and dimple-to-dimple distance and under lubrication with three different oils, i.e., T9, VG46, and VG100, to reflect the oil viscosity's influence on the friction/wear of the laser-textured Ti6Al4V alloy. The results show that the surfaces with the highest texture density showed the most significant COF reduction of around 10% in a low-viscosity oil (T9). However, in high-viscosity oils (VG46 and VG100), the influence of the laser texturing on the COF was less pronounced. A wear analysis revealed that the laser texturing intensified the abrasive wear, especially on surfaces with a higher texture density. For low-texturing-density surfaces, less wear was observed for low- and medium-viscosity oils (T9 and VG46). For medium-to-high-texturing densities, the high-viscosity oil (VG100) provided the best contact conditions and wear results. Overall, reduced wear, even below the non-texturing case, was observed for sample 50-200 in VG100 lubrication, indicating the combined effect of oil reservoirs and increased oil-film thickness within the dimples due to the high viscosity.

Super-hydrophobic graphene-based high elastic sponge with superior photothermal effect for efficient cleaning of oil contamination

Oil spills are frequent and often accompanied by chemically corrosive and complex operating environments, so there is an urgent need for new absorbent materials that can absorb oil efficiently and with stable performance. Herein, we reported a reduced graphene oxide coated melamine sponge (F-rGO@MF) modified by silane grafting, which had excellent superhydrophobic/superoleophilic surface properties (WCA up to 157.7°), high absorption capacity (58.7–147.8 g/g) for a variety of oils, and could perform multiple absorption cycles. The separation efficiency of the oil/water mixture was as high as 99.32%, and the separation efficiency could still reach 97.48% after 80 separation cycles. The absorbent could also separate oil and water continuously by peristaltic pump. Besides, F-rGO@MF still retained floating and chemical stability under strong corrosive environment. More importantly, due to the photothermal property of rGO, the surface temperature of F-rGO@MF could rapidly rise to 101 °C under 1.0 kw/m2 light intensity for 225 s, which was contribute to the viscosity reduction of crude oil and absorbed 14.75 g of crude oil in 7 min, providing the possibility of absorbing high viscosity oil spills.

Enhanced Reservoir Description via Areal Data Integration and Reservoir Fluid Geodynamics: A Case Study From Deepwater Gulf of Mexico

Accurate reservoir characterization is vital for effective decisions made throughout the life cycle of an oilfield reservoir, including management and development. Of all the components of reservoir description, hydraulic connectivity carries the highest amount of uncertainty, where inaccurate connectivity evaluation often results in production underperformance. Shortcomings are faced when applying conventional approaches of connectivity assessment. Seismic surveys are not always sufficient to evaluate lateral connectivity as detected faults can be transmissive or partially transmissive, while some faults are below the detection limits of seismic amplitude measurements. Vertical connectivity represents another uncertainty, where pressure measurements and well logs are often either unable to detect the baffles along oil columns or cannot assess whether detected baffles are relevant seals or flow diverters. Although conventional downhole fluid analysis (DFA) workflows have proven effective in delineating reservoir connectivity, enough DFA data are not always available, and with added complexity, uncertainties arise. Additionally, while equilibrated asphaltene gradients, measured through DFA probes, imply connectivity, ongoing reservoir fluid geodynamics (RFG) processes, such as current hydrocarbon charging, can preclude equilibration in a connected reservoir. Thus, a comprehensive assessment approach, that utilizes all available data streams, is needed to overcome the significant spatial complexity associated with moderately and heavily faulted reservoirs. In this paper, we employed our recently introduced interpretation workflow to evaluate the connectivity of a heavily faulted reservoir in the deepwater Gulf of Mexico. The field was divided into five investigation areas penetrated by 12 wells. Areal downhole fluid analysis (ADFA) was applied to assess local connectivity leading to reservoir-scale connectivity. Through integrating fluid/dynamic and rock/static data, each data type provided insights that were pieced together to enhance consistency and reduce uncertainty. Analyzed data included pressure-volume-temperature (PVT) reports, pressure surveys, well logs, and geochemistry. The study resulted in a verifiable connectivity description where faults, previously regarded as sealing, were classified into sealing or partially transmissive faults; unresolved faults were detected. Fault-block migration was detected, and fault throw was estimated; asphaltenes behavior was used to deduce original field structures prior to faulting. We also examined RFG processes to investigate oil biodegradation, where an asphaltene clustering trend was observed, causing high oil viscosities toward the bottom of one sandstone. A correlation was then derived and successfully implemented to estimate oil viscosity.

Investigation of anaerobic digested pyrolysis oil and waste derived biodiesel blends as sustainable fuel for marine engine application

In anaerobic digestion (AD) plants around 40% of the feed waste is utilised for biogas generation while the remainder is used as a fertiliser that is rich in oil that could be further utilised through pyrolysis. Dry AD waste, subjected to intermediate pyrolysis, generated a digested pyrolysis oil (DPO) of high viscosity (473 mm2/s) and low energy content (26 MJ/kg). To improve its fuel characteristics, we blended DPO with either used cooking oils (high in unsaturated fatty acids) or lamb fat (high in saturated fatty acids) using solvents of differing polarity including alcohols varying in chain length and hence aqueous miscibility from C1(methanol) to C5 (pentanol) and diethylether (DEE, a non-polar solvent). Five blends were prepared, typically consisting of 10–20% DPO, 20% solvent (alcohol or DEE) and 60–70% cooking oil or lamb fat. Physical properties of DPO blends e.g., viscosity, density, heating value, total acid number and flash point were found to be lower than neat DPO but increased about 25–40% over a storage period of 8 months. The blends were more stable than neat biodiesel as assessed by FT-IR spectroscopy. The elemental analysis (C, H, N, S and O) showed that atomic ratio of DPO blends; H:C, H:O, H:N and C:N were found to be lower than biodiesel and DPO fuels, respectively. Overall, the properties of DPO blends met the Marine Fuel Standard (Marine ISO 8217) and hence could be considered as a suitable replacement for bunker oil to protect marine environments following further testing and scale up studies.

Practical experience of heat treatment of an oil carbonate reservoir

The majority of reserves of small oil companies of the Republic of Tatarstan are represented by carbonate reservoirs with low filtration and capacitance properties, low reservoir pressures and high oil viscosity. All this leads to a rapid decrease and a low level of current oil flows. The Akan oil field of Predpriyatie Kara Altyn CJSC is one of the examples. Thermal methods are considered as the most effective technologies for deposits with high-viscosity oil. According to the results of laboratory study of various variants of thermal methods and geological and hydrodynamic modeling, the steam-cyclic method of development was determined as the most effective at the Akan field. Two producing directional wells and two horizontal wells have been selected for experimental work on steam injection. The article considers the downhole equipment used for injection heat carrier, describes the process of steam injection with the dynamics of controlled parameters, production indicators and efficiency after heat treatment of wells. Conclusions are presented for the completed works on wells.

Анализ зависимости проницаемости от открытой пористости карбонатных пород коллектора в районах Астраханского газоконденсатного месторождения

At the present moment the fields reserves containing viscous and high-viscosity oil account for more than half of all the explored reserves of oil and gas fields. Carbonate deposits, in which oil and gas fluids are concentrated, are characterized by a complex structure of void space containing hydrocarbons. Due to the higher content of part of the oil in unrelated shallow cracks, the development of such reserves is difficult. For this reason, the main task of this study was to establish the dependence of the core-core permeability index on the porosity of carbonate reservoir rocks composing the Astrakhan Gas Condensate field (AGCM). Based on the characteristics of the Astrakhan arch and deposits in the AGCM areas, the paper presents the results of research work to determine the porosity of the rock by hydrostatic weighing based on the available information about the carbonate deposits of the formation, the physical properties of the rocks composing the formation, the characteristics of the geophysical values of porosity and permeability. The obtained values of the mass samples are given by weighing in various saturation states and calculating the permeability of the core samples. The linear dependence of the open porosity of carbonate rocks on permeability is revealed. The analysis of the results of studies on core samples obtained at the wells of the AGCM was carried out. The values of porosity and permeability coefficients are given. Based on the conclusion about the filtration-capacitance properties of the deposit the dependence of the permeability of the rock on the open porosity on the reservoir properties of the deposit was cocluded. The graph obtained on the basis of the calculated data is given, the equation of the “core-core” dependence or a linear regression equation is compiled.

Superhydrophobic and robust photothermal/electrothermal PVDF-a/CNT-s@PDMS membrane for crude oil removal and dye adsorption

Recently, the crude oil spill has brought inevitable harm to the global ecological environment. Due to the high-viscosity crude oil, it is wise to take advantage of the photothermal/electrothermal effects of the membrane to separate the crude oil from the water. However, the functional separation membrane always suffers from low photothermal/electrothermal effects and poor stability. Herein, the vinyl polyvinylidene fluoride/mercapto carbon nanotubes@vinyl-terminated polydimethylsiloxane (PVDF-a/CNT-s@PDMS) membrane with fast photothermal/electrothermal effects and organic absorption property was successfully prepared by electrospinning and multi-layer loading method. The prepared PVDF-a/CNT-s@PDMS membrane resisted a variety of liquids and had stable superhydrophobicity (WCA = 156°). Furthermore, the membrane maintained superhydrophobicity even suffer from water and milk under the applied voltage condition. After 100 wear resistance tests, the membrane maintained stable superhydrophobicity and the separation rate remained unchanged. The surface temperature of the membrane rapidly approached to the maximum temperature in 30 s, showing a rapid photothermal/electrothermal effects, and the average separation rate of crude oil was 1185 kg m−2 h−1·bar−1. Meanwhile, the membrane exhibited outstanding efficiency for separate immiscible oil-water mixtures. Importantly, the incorporation of the sulfhydryl group enhanced the special ability of the composite membrane to adsorb organic dyes from oil phase. Therefore, the PVDF-a/CNT-s@PDMS membrane has a wide range of potential application in the domain of oil-water separation.

Experimental investigation of viscous oil–water–sand flow in horizontal pipes: Flow patterns and pressure gradient

Fluid production from unconsolidated reservoirs often leads in sand production, which poses a number of issues. Sand deposition in flowlines can result in significant pressure dips, pipe and facility damage, and obstructions that decrease productivity. More research is needed to understand the movement and deposition of sand in oil–water–sand (O–W–S) fluxes. This article focuses on O–W–S flows in a 6-meter-long horizontal pipe with an inner diameter of 0.0381 m. The study looks at the flow behavior of high viscosity oil–water (O–W), water–sand (W–S), and oil–water–sand (O–W–S) flows. Experiments were carried out at 250 psig pressure in a laboratory flow test facility using various heavy synthetic oils (viscosities ranging from 3500 cP to 7500 cP at 25°C) and tap water. The sand concentration varied from 1% to 10%, with an average sand particle diameter of 145 μm and material density of 2630 kg/m3. Water cuts ranged from 0.0 to 1.0. The experimental results revealed a minor change in pressure gradient between (O–W) and (O–W–S) flows. However, increasing the sand concentration in (O–W–S) flow resulted in higher pressure losses. The reduction factor of pressure gradient indicated that the highest decrease in pressure drop occurred at higher superficial oil velocities. Furthermore, a direct relationship was observed between the reduction factor and the decrease in water cut. The results also showed that the minimum required transportation velocity for sand slurry decreased with increasing superficial oil velocity, while the minimum transportation condition increased with higher sand concentration. The comparison between the expected pressure gradient from Bannwart and McKibben et al. and the actual experimental data demonstrated significant accuracy for the oil viscosities and superficial oil velocities used in the study.

Gravity-based focusing and size-dependent separation of metal microparticles in lubricating oil.

The separation of wear microparticles in lubricating oil is crucial for improving the accuracy and throughput of the subsequent detection. However, there are few kinds of research on the separation of high-density metallic microparticles in high-viscosity lubricating oil. In this paper, a passive method for separating the metallic microparticles in oil is proposed. Gravity sedimentation was adopted to realize three-dimensional (3D) focusing of the particle by using an inclined capillary. The gravity-based 3D focusing made the sheath flow no longer responsible for the particle focusing and effectively reduced the sheath flow. Then, the separation of different-sized metallic microparticles was achieved in a horizontal channel with the aid of a sheath flow based on the different driving forces. The present method solved the problem of nonsynchronous separation of the particle in comparison to the traditional methods. This device has a simple structure with high separation efficiency, and it is easy to integrate with the detection channel. The influence of numerous parameters on the gravity-based focusing and separation was systematically studied by the numerical simulation and the experiment. The design criteria were established, which is useful in designing and employing the device, expanding its application to other non-neutral buoyancy particle separation cases, and opening up more prospects for microfluidic technology.

Femtosecond laser constructed anti-pollution silica glass surfaces with high-viscosity-oil adhesion prevention

Transparent surfaces with anti-pollution and anti-adhesive properties show promise for optical windows. However, there is currently no effective way to create glass surfaces that are impervious to highly viscous and sticky oils, like crude oil. In this research, an electrical-heating silica glass with resistance to high viscosity oil was prepared using a femtosecond laser process. An inner micro-channel system was fabricated by the femtosecond laser wet etching method, and the surface was treated to be superhydrophilic/underwater superoleophobic through femtosecond laser irradiation. The prepared sample could be electrically heated by its internal heating unit, which could reduce the viscosity of the crude oil. Thus, the prepared sample is resistant not only to typically low-viscosity oils, but also prevents the adhesion of crude oil, which would be widely applied in anti-pollution optical windows.

Study on effect of viscosity on thickness of boundary layer in tight reservoir

It has become a consensus that viscosity has an important impact on boundary layer of tight reservoirs. However, there are few quantitative studies on the effect of viscosity on boundary layer by core experiments. NMR analysis based on high-speed centrifugal gas-water and gas-oil displacement and low-temperature adsorption experiment were implemented in this study on typical tight reservoir parallel cores of Ordos and Bohai Bay basins. Total bound water/oil saturation, specific surface area and ratio of micro pore of the reservoir quantitatively were finally obtained, which were used for calculating irreducible water/oil film thickness of reservoir and analyzing influence of viscosity on movable oil and boundary layer. Research show that, movable oil saturation of core saturated high viscosity oil is 23.92% and 18.61% lower than that of core saturated low viscosity oil and water respectively, and effective seepage space is greatly reduced. The lower permeability reservoir has, the greater reduction movable space with high viscosity oil of reservoir owns. The average bound water film thickness of Ordos and Bohai Bay basin cores is 17.74 nm and 16.99 nm, respectively. The average bound oil film boundary of core in Ordos Basin is 20.72 nm. The average thickness of high viscous oil film of core in Bohai Bay basin is 38.10 nm, and the thickness of low viscosity oil film is 18.80 nm. The oil-water viscosity ratio in Ordos Basin is small, and oil-water film thickness is close, indicating that fluid viscosity has little influence on boundary layer thickness of target reservoir. The low viscosity oil-water viscosity ratio in Bohai Bay basin is small, and oil-water film thickness is close. The thickness of high viscosity oil film is more than twice that of low viscosity oil film and water film. When the oil viscosity is higher than 8.9 mPa s, thickness of boundary layer will be greatly affected, leading to a significant reduction of effective seepage throat, a significant increase of seepage resistance and development difficulty.

Melt-blown fiber felt for efficient all-weather recovery of viscous oil spills by Joule heating and photothermal effect

Adsorbents play a vital role in responding to marine oil spills, yet effectively cleaning up viscous oil spills remains a technical challenge. Herein, we present a superhydrophobic oil-adsorbing felt prepared using melt-blown technology and functionally enhanced with a photoelectric composite CNT/PANI coating for effectively cleaning up high-viscosity oil spills. By virtue of its superior solar/Joule heating ability and thermally conductive fiber network, p-CNT/PANI@PP notably reduced crude oil viscosity and enhanced the oil diffusion coefficient within pores. Leveraging primarily solar heating and supplemented by Joule heating, p-CNT/PANI@PP demonstrates an impressive in-situ adsorption rate of up to 560 g/h for ultra-high-viscosity crude oil (c.a. 138000 mPa·s), alongside an adsorption capacity of 15.57 g/g. This measure enables efficient viscosity reduction and continuous day-and-night recovery of viscous crude oil, addressing the challenges posed by seasonal fluctuations in seawater temperature and adverse weather conditions. Moreover, a conveyorized collector integrated with an oil-adsorbing felt realizes continuous recovery of viscous oil spills with speed control to tackle varying thicknesses of oil film. Given the top-down material design, superior functionality, and applicability to applications, this work provides a comprehensive and feasible solution to catastrophic large-area viscous oil spills.

Экологические аспекты промышленного освоения нефтегазовых месторождений арк­тических территорий Республики Коми

The paper considers the ecological aspects of the development of oil and gas fields in the Arctic zone of the Komi Republic. The authors inform about the state of the resource base, the dynamics of oil production, drilling of wells, and the increase in reserves. Oil and gas production dominates in the region’s economy, while at the same time impacts negatively on the environment. Field development, geological exploration, drilling of exploration and production wells, laying of pipelines, transportation of oil and other types of work are inevitably accompanied by harmful emissions into the atmosphere, pollution of water bodies and the earth surface. There is a thermal, mechanical and chemical impact on the environment. The situation is getting worse due to the increase in the share of hard-to-recover dense and high-viscosity oil in recoverable oil reserves. The development of hard-to-recover oil deposits is carried out via technologies that cause additional environmental damage. A large amount of oil enters the environment not during its extraction, but due to accidents at oil pipelines, especially inter-field and intra-field ones. The Arctic regions are ecologically very vulnerable due to the spread of permafrost. The technogenic thermal impact activates various negative processes, such as subsidence, swelling, erosion, landslides, flooding, waterlogging. Among the most polluted Arctic regions where oil production is carried out, is the Usinsky region with a number of large oil fields being developed, and extensive network of oil pipelines laid. The authors suggest a number of measures to minimize the negative impact on the environment during the construction and operation of oil production facilities. They outline the need to comply with the equipment technological operating modes, carry out preventive measures, including control of the technical condition of the basic equipment, to analyze the transported products (physical and chemical properties of the working environment), as well as to implement measures for the protection of surface and ground waters. It is expedient to upgrade the pipeline infrastructure in a timely manner with the use of the latest achievements in the field of pipe surface protection, and the elimination of decommissioned boreholes.

CALCULATION OF THE BOTTOM-HOLE PARAMETERS OF THE HEAT CARRIER DURING ITS MOVEMENT ALONG THE WELLBORE OF A DIRECTIONAL WELL CONSIDERING THE FLOW STRUCTURE

Link for citation: Gilmanov A.Ya., Rodionova A.V., Shevelev A.P. Calculation of the bottom-hole parameters of the heat carrier during its movement along the wellbore of a directional well considering the flow structure. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 8, рр. 121-128. In Rus. The relevance of the research is caused by the need to involve fields with high viscosity oil in the development, since fields with low and medium viscosity oil are depleted. Oil viscosity directly depends on the temperature, therefore, thermal enhanced oil recovery methods are used to reduce the viscosity. From the point of view of using the heat injected into the formation, the most effective thermal method is the cyclic steam stimulation, i. e. cyclic steam injection into the well. However, when steam moves through the pipe, it condenses, that is why the production at the well bottom-hole are often has high water cut. Accurate calculation of the heat carrier parameters along the entire wellbore will help to avoid this problem. The main aim of the research is to determine the effect of the well inclination angle, steam quality at the wellhead, initial pressure and thermal conductivity of thermal insulation on the heat carrier characteristics in the wellbore, considering flow modes. Objects of the research are deposits with high-viscosity oil. Methods: physical and mathematical modeling of injection of a two-phase (steam-water) heat carrier into the reservoir based on the laws of conservation of mass, momentum and energy, considering the movement of the heat carrier along the wellbore of a directional well, heat loss through the walls of the well and fluid flow modes. Results. The calculation of the steam quality and heat carrier flow rate along the wellbore of a directional well was conducted. The influence of the well inclination angle on the parameters of the heat carrier at the well bottom-hole (steam quality, pressure and wellhead flow rate of the heat carrier) is analyzed. It is determined that the smaller the well inclination angle, the deeper the steam penetrates through the depth of the formation.

Durable LBL microcapsule-based sponges with superhydrophobic/super-oleophilic and photothermal behaviors for oil–water separation

Spills of marine oily pollutants and illegal discharges of industrial organic solvents have severely undermined the natural resources and ecological sustainability. Herein, a versatile and durable modified melamine sponge (MS) was fabricated by integrating with multilayered microcapsules (MCs) and chemical vapor deposition of 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES), namely PFDTES@MCs@MS. The combination of giant microcapsules on the sponge structure imparts the rough surface micro-construction, accompanied by the hydrophobic modification, which enabled PFDTES@MCs@MS to exhibit superhydrophobic/super-oleophilic and self-cleaning capabilities. PFDTES@MCs@MS displayed outstanding oil–water mixtures or emulsions separation capabilities with the separation efficiencies more than 99%. Impressively, PFDTES@MCs@MS preserved mechanical and chemical durability in 100 recycle tests or chronic processes under harsh conditions. In addition, PFDTES@MCs@MS exhibited the remarkable uptake capacity of organic solvents or oils, and the adsorption amount of light or heavy oil was barely impacted with squeezing after the 50 times of circulation. Furthermore, the PFDTES@MCs@MS displayed antibacterial performance. Significantly, the PFDTES@MCs@MS showed superior photothermal conversion capability, the temperature of it increased dramatically to approximately 80 °C within 180 s under simulated sunlight from room temperature (about 25 ℃), and the flux of separating high-viscosity oils was significantly increased. This study presents a novel oil sorption and separation materials with excellent durability and repeatability, which establishes the foundation for the judicious design of innovative weapons to combat the challenging oil spills.

Study of the Rheological Properties and Flow Process of High-Viscosity Oil Using Depressant Additives

This article analyzes the dependence of the choice of the method of transportation of high-viscosity oil on the rheological characteristics of the oil in question. An analysis of existing rheological models of high-viscosity oil was carried out, and it was found that a number of models have certain features (model coefficients, their purpose, quantity) that affect the choice of a rheological model of oil. The dependences for determining the coefficient of dynamic viscosity when pumping high-viscosity oil with the addition of pour-point depressants were studied, and the dependence of the hydraulic resistance coefficient when depressants are added to the oil was obtained. A method for choosing a rational oil heating temperature and diluent concentration to achieve the maximum pipeline performance is substantiated.

Integrity Assessment of High-Performance PVC Pipes for Thermal Wells.

In wells with high-viscosity crude oil, steam injection is used to improve the fluidity of the heavy oil. Screens made of steel are employed for sand control, with corrosion being a serious problem. Non-metallic pipe materials, such as novel high-strength PVC, are therefore being tried out. This paper presents the results of an integrity assessment of large-diameter hard PVC pipes under compressive loading. Plain, built-up, and slotted pipes were subjected to a 3-month aging process in saline water. Strain gauge sets were used for dynamic testing of longitudinal and transverse deformations. Values of fracture strength, total deformation, and anisotropy (Poisson's ratio) were extracted from the stress-strain graphs and analyzed. Upon aging in saline water, the stiffness of all pipes increased and was the highest for slotted pipes. Maximum stress after soaking was reduced by 11-12%. The ductility was the highest for plain pipes and the lowest for built-up pipes. Poisson's ratio remained almost constant for all pipes and aging conditions. The good news for field applications is that overall, aging had only a minor impact on the major compressive properties. The main conclusion was that corrosion-prone steel pipes and sand screens can be successfully replaced by corrosion-free high-strength PVC pipes and screens for water transport applications in thermal wells. This work provides a scientific basis for the structural integrity assessment of this new PVC and helps field engineers in the proper pre-deployment selection of pipes for target oilfields.

An Investigation Into the Influence of Viscosity on Gear Churning Losses by Considering the Effective Immersion Depth

We present an experimental investigation into the influence of oil viscosity on gear churning losses in splash-lubricated transmission systems. The inertia rundown method was used to perform tests on a single gear within a cylindrical housing with several oils of different viscosities at several immersion depths. A complex and nonmonotonic relationship between churning torque and viscosity was observed that was highly influenced by the rotational speed, with higher viscosity oils resulting in lower churning torque at higher speeds in some cases. This was attributed to a reduction in effective immersion depth due to oil being centrifugally distributed around the casing by the rotating gear, an effect that was observed to be more pronounced with higher viscosity oils. An effective immersion depth parameter, dependent on the rotational speed of the gear and the lubricant viscosity, was defined to account for this phenomenon. Gear churning losses could be better predicted using an existing empirical model when this parameter was used instead of the nominal immersion depth as is usually done.

Chemicals-CO2 mechanisms of inhibiting steam heat transfer and enhancing oil film strip: Steam flow through the wall-adhering oil film surface in porous medium

The CO2 and Sodium Dodecyl Sulfate (SDS) assisted steam flooding technology was an effective approach addressed the persistent issues that have hindered the stable development of high-viscosity cold oil through steam injection. However, in the process of steam flow through porous media, the synergistic influence of the oil film adsorbed in near wellbore porous media, and the CO2-SDS on steam heat transfer has not been investigated. Steam heat transfer is the key factors affecting heavy oil recovery. The primary objective of this study was to research the effect of CO2-SDS on steam heat transfer and oil film stripping by designing experiments. The study results demonstrated that in the initial stage of displacement, the heat transfer resistance between the steam and the porous medium was increased by the oil film adsorbed in near wellbore area. In additional, the condensation mode of the steam was altered from bead condensing to film condensing by the composite thermal fluid flooding, preventing the steam heat dissipation near wellbore area and transferring more thermal to the long-distance area. At the later stage of displacement, the interfacial tension between oil-water and oil-gas was reduced by CO2-SDS, improving the fluidity of oil and providing the seepage channel for steam, and increasing the steam thermal sweep range. Compared to the sandpack experiment of steam flooding, the temperature at the output end of the sandpack model increased from 69.8 °C to 88.7 °C, indicating an expansion of the steam heat sweep range and successful long-distance heat transfer during composite thermal fluid flooding. In the process of composite thermal fluid flooding, the maximum displacement pressure difference increased from 2.28 MPa to 3.07 MPa, and the maximum oil recovery rate increased from 2.48 g/mL to 2.81 g/mL. The peak of the high production period was raised, resulting in a 40.97% to 51.86% increase in recovery rates.