Seal Element Research Articles

Gene expression and trace elements in Greenlandic ringed seals (Pusa hispida)

Marine top predators such as ringed seals biomagnify environmental contaminants; and with the increasing human activities in the Arctic, ringed seals are exposed to biologically significant concentrations of trace elements resulting in reproductive impairment, immunosuppression, and neurological damages. Little is known about the molecular effects of heavy metals on these vulnerable apex predators suffering from a rapidly changing Arctic with significant loss of sea-ice. In the present study, concentrations of cadmium (Cd), mercury (Hg) and selenium (Se) were measured in liver of sixteen Greenlandic ringed seals (nine adults and seven subadults) together with molecular biomarkers involved in bio-transformation, oxidative stress, endocrine disruption and immune activity in blood and blubber. The concentrations of trace elements increased in the following order: Hg > Se > Cd with levels of mercury and selenium being highest in adults. Aryl hydrocarbon receptor nuclear translocator (ARNT), peroxisome proliferator activated receptor alpha (PPARα, estrogen receptor alpha (ESR1), thyroid hormone receptor alpha (TRα) and interleukin – 2 (IL-2) mRNA transcript levels were highest in blubber, while heat shock protein 70 (HSP70) and interleukin – 10 (IL-10) were significantly higher in blood. There were no significant correlations between the concentrations of trace elements and mRNA transcript levels suggesting that stressors other than the trace elements investigated are responsible for the changes in gene expression levels. Since Hg seems to increase in Greenlandic ringed seals, there is a need to re-enforce health monitoring of this ringed seal population.

Impact of artificial ageing on the performance of acrylic self-adhesive tapes

The use of sealing tapes in creating a continuous envelope to ensure the airtightness of the building is an essential factor. The study aims to investigate the performance properties of single-sided self-adhesive tapes for building applications and to obtain the changes in these properties due to the effects of environmental factors. The tapes were glued to the different substrates. Peel adhesion, tack of the tapes, and the air permeability of sealed elements were determined. The adhesive tape were aged in the laboratory using two different methods, standard (EN 12024) and a new one, during which the test samples were exposed to the cyclic impact of the temperature and humidity of multiple levels. Analysis of the results showed that the substrate has influence on the adhesive behaviour of the self-adhesive tapes. After artificial aging, in most cases, the performance properties of the tapes do not change significantly. The novel approach allowed the comparison of the influence of different aging factors on the change in the performance properties of the tape and contributed to the development of a methodology for testing the durability of sealing tapes. The effect of substrate on tape adhesion was also investigated, which is useful from both a practical and a methodological point of view.

Radial shaft seal with different relative velocities and on a 3D printed counter surface

PurposeThe purpose of this study is asking for a methodologically representable relation between different relative velocity approaches, counter surfaces and the tribological behavior of the radial shaft seal (RSS).Design/methodology/approachThe tribological behavior between the seal and the counterpart is examined experimentally to submit significant measured values. The correlations among seal elements, relative velocity approaches and counter surfaces with more aspects are searched.FindingsA basis for future research regarding optimization options for service life extension of the RSS under different operation environments has been set. New insights for the performance of 3D-printed counter surface are gained as well as the application possibility of that is searched.Originality/valueThe applied measuring procedure in investigation part especially the usage of different approaches in relative velocity approaches is designed with originality. In particularly, the usage of a 3D-printed counter surface comes for the first time in a scientific work.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2022-0325/

Analysis of Sealing Characteristics of Lip Seal Rings for Deep-Sea Separable Pressure Vessels

Deep-sea pressure vessels are specialized pressure vessels designed for automatic deployment from underwater to the surface. These vessels find extensive applications in underwater life-saving and transportation. Their interiors are furnished with a pair of sealing rings, one of which is lip-shaped, and the other is a convex shape, to ensure a dependable seal. With increasing water depth, the sealing rings experience augmented pressure, resulting in a gradual pressing of the rings into the sealing groove. Using ANSYS workbench finite element software, a two-dimensional axisymmetric lip seal finite element model using forces for overall constraint was established, the complete process of progressive pressing into the sealing groove was simulated, and the deformation, contact stress, maximum shear stress, and von Mises stress distribution was also simulated. We also conducted a comparative analysis of lip seals under low and high-water pressure sealing conditions. The findings of the study indicate that when subjected to a combined effect of the installation pre-tightening force and the working water pressure, the lip seal experiences complete compression into the sealing groove at a specific water depth. When subjected to the simultaneous influence of water pressure on the sealing ring material and friction force on the contact surface, two extremes of contact stress manifest in the primary sealing zone of the lip seal. These extremes have the capacity to elevate the contact stress and the effective sealing width, ultimately leading to an improvement in the sealing performance. Concurrently, as the water pressure gradually increases, the inner concave circle of the sealing ring experiences stretching, leading to a reduction in stress concentration, equivalent stress, and shear stress to a considerable extent. This mechanism ensures that the lip-shaped sealing ring retains sufficient strength. This study offers a viable solution for conducting sealing studies on deep-sea separable pressure vessels.

SYNERGETIC EFFECT OF STRENGTHENING POLYMER NANOCOMPOSITES

According to the cluster model of glassy polymers, in the amorphous state they are natural nanocomposites of two components of a loosely packed matrix and nanoclusters immersed in it, respectively playing the role of a matrix and filler in a natural composite. In this interpretation of the polymer, an important role is played by the dimensional effect of nanoclusters, identical to the specified effect of a nanofiller in an artificial nanocomposite, namely, a decrease in the size of both nanoclusters and dispersed particles leads to a sharp increase in the degree of amplification (modulus of elasticity) of the nanocomposite. In this paper, using parallel and sequential microcomposite models, upper and lower fractal estimates for the elastic modulus of the matrix are obtained and the synergistic effect of strengthening the elastic modulus of the nanocomposite as a whole as a superposition of the amplification effects from inorganic filler and from nanoclusters playing the role of filler of the loosely packed matrix is quantified. The object of research in this work is a packer - a device designed to disconnect two zones of the borehole and isolate the internal space of the production column from the impact of the borehole environment. The tightness of the packages is achieved thanks to sealing elements (SE), for the manufacture of which a composite with the composition is used: a mixture of synthetic butadiene nitrile and hydrogenated butadiene nitrile rubber (BNC + HBNC), vulcanizer, stabilizer, technological additives and copper nanoparticles. For the class of polymers under consideration, a rule has been developed for choosing the most preferred model from the above two micromechanical models at a given temperature. Keywords: oilfield equipment, synergetic effect, cluster model, natural nanocomposite, interfacial region, inter-component adhesion, loosely packed matrix.

Assessing the sealing quality of submarine mass transport complexes and deposits

Mass transport complexes and their associated mass transport deposits—both referred to here as submarine failure deposits—are virtually ubiquitous in the modern and ancient sedimentary record of many deepwater basins. As exploration expands to new frontiers, submarine failure deposits are being identified as components of the petroleum system in numerous prospects. Although such deposits were historically considered facies to avoid from a viewpoint of petroleum exploration, it is now recognized that they can act as source, reservoir, or seal elements. In this paper, we set out to investigate the role of submarine failure deposits as effective seals in the petroleum system using published data and propose a methodology to risk some first-order factors at a macro-, meso-, and micro-scale that influence the seal quality of these submarine failure deposits. We accomplish this by discussing the properties intrinsic to submarine failure deposits that affect the seal quality at different scales. Based on published literature, at least six offshore fields from the Gulf of Mexico and NW Borneo are reported to have a submarine failure deposit as an effective seal. These fields combined account for ∼0.9 billion barrels of oil equivalent of cumulative discovered reserves globally and prove the potential of submarine failure deposits as effective seals and a future undervalued play concept. We use three case studies to illustrate our methodology. Our methodology can be further customized using datasets from industry and public records. The seal risk matrix presented here is based on more than a decade of research and has been already used by several exploration companies with encouraging feedback. We acknowledge the limitations of the methodology, but future interdisciplinary research and integration of new datasets and results will improve the de-risking of submarine failure deposits in exploration. Additionally, this methodology can potentially be applied to assessing seal potential of submarine failure deposits for carbon capture sequestration and storage projects.

Maternal offloading of arsenic and other trace elements in Peruvian fur seals

AbstractThe maternal transfer of 15 elements was examined in Peruvian fur seal (Arctocephalus australis) dam and pup paired vibrissae (whiskers), serum, and milk samples collected from 2009 to 2019. Pup vibrissae, grown in utero, represented gestational transfer, while milk represented lactational transfer. Element concentrations, except arsenic, were highest in vibrissae compared to serum and milk for both dams and pups. Mean arsenic concentrations in pup vibrissae (0.44 μg/g) and milk (0.41 μg/g) were twice as high as dam vibrissae concentrations (0.19 μg/g) and nearly ten times higher than dam (0.06 μg/g) and pup serum (0.04 μg/g) concentrations. Mean arsenic concentrations from 2011 to 2019 increased in dam vibrissae (0.026 μg/g to 0.262 μg/g) and milk (0.361 μg/g to 0.484 μg/g). Pup vibrissae had significantly higher concentrations for 11 of the 15 elements analyzed compared to dam vibrissae, suggesting that element transfer is occurring through recent exposure and remobilization of elements from dam body stores. Potentially high concentrations of aluminum, arsenic, copper, and lead in pup tissues may impact their survival and population health. The impact of regional mining activities can contribute to elevated trace elements through runoff and pose a possible threat to local marine environments.

Age-specific trace element bioaccumulation in grey seals from the Gulf of St. Lawrence

We measured concentrations of 19 trace elements and mercury speciation in grey seals (Halichoerus grypus) from the Gulf of St. Lawrence (GSL), Canada. With interest growing in commercializing grey seal products for human consumption in this region, our goal was to measure essential and non-essential trace elements in grey seals to evaluate health concerns and nutritional benefits. From 2015 to 2019, 120 grey seals were sampled by hunters and researchers at 4 sites in the GSL. Muscle, liver, heart and kidney samples were analyzed for 10 non-essential elements (Sb, As, Be, B, Cd, Pb, Hg, Ni, Tl, Sn) and 9 essential elements (Co, Cr, Cu, Fe, Mg, Mn, Mo, Se, Zn). Both total mercury (THg) and methylmercury (MeHg) were analyzed for a subset of samples. Results showed a two-step bioaccumulation pattern with lower element concentrations in the muscle (Fe, Mg, Se) and livers (Cd, Cr, Hg, Mn, Mo, Se) of young-of-the-year harvested in the winter (<6 wks old) compared to older animals feeding at sea. We did not observe progressive age-dependent bioaccumulation for older seals (∼5 mos–29 yrs). Sex-specific differences were not very pronounced, but a few elements were 30–70% higher in the muscle (THg, MeHg) and liver (Mn, Zn) of male seals. Comparison to Canadian dietary reference intakes shows that a weekly portion of liver from young-of-the-year (<6 wks old) is a good source of essential elements (Cu, Fe) and that muscle and liver from this age category do not exceed reference values for toxic elements (As, Cd, Pb, MeHg). Discussions with regional public health professionals are on-going to develop dietary recommendations for the consumption of older grey seals.

A new marine mammal assemblage from central Chile reveals the Pliocene survival of true seals in South America

ABSTRACT The fossil record of marine mammals from the upper Pliocene of the western coast of South America is poorly known, hindering our knowledge about how and when marine mammal faunas attained their modern distribution in the area. Here, we describe a new marine mammal assemblage from the Horcón Formation (upper Pliocene), located in the Valparaíso Region of central Chile. The material reported comprises postcranial remains of an indeterminate seal (Phocidae), Delphinoidea vertebrae, and mysticete elements (still in the field). The Phocidae remains constitute the youngest pre-Pleistocene record of this family in South America, providing new information regarding the timing for the establishment of the modern diversity and distribution of pinnipeds in the Southern Hemisphere. Furthermore, the pinniped and cetacean remains reported indicate that the marine mammal assemblage from the upper Pliocene along central Chile was composed of a mixture of modern and extinct taxa.

Study on sealing performance of packer rubber based on stress relaxation experiment

In the last few decades, rubber seal elements have been extensively used in the oil and gas industry. However, mechanical properties of rubber decrease at high temperatures, and stress relaxation can lead to sealing performance degradation, even sealing element failure. Therefore, how high temperature and stress relaxation affect the sealing performance of rubber is an important issue in oil and gas production. According to the oilfield feedback information, hydrogenated nitrile butadiene rubber (HNBR) was chosen for sample tension test at different temperature (20 °C and 120 °C) and the stress relaxation tests at 120 °C. The constitutive model of rubber was fitted by the test data. At the setting pressure of 14 MPa, the influence of temperature and stress relaxation on the packer rubber seal system was investigated by finite element analysis (FEA) software. The results indicated that temperature and stress relaxation had an appreciable impact on the sealing performance of packer rubber seal system. The average contact stress at 120 °C between the rubber and the borehole wall, compared with the calculation results at 20 °C, decreased by more than 15% and the maximum contact stress decreased by 20%. Similarly, the average contact stress before the relaxation decreased by more than 35% after stress relaxation behavior at 120 °C. In addition, the maximum contact stress decreased by 50% due to the stress relaxation. Our experimental results and discussion enable us to provide some advice to improve the sealing performance of a packer seal system, and present a basic experimental and theoretical foundation for future research into the optimum design of a packer sealing system.

Hydrocarbon Columns of Oil and Gas Fields in the South Sumatra Basin

The South Sumatra Basin is a prolific basin with a long history of oil and gas exploration that started in early 1900s. It is located in the southern part of Sumatra Island, Indonesia, where more than 300 oil and gas fields have been discovered. The basin contains multiple hydrocarbon reservoir horizons, from Pre-tertiary Basement to Miocene age. The kitchen areas also have various depths, with different levels of maturity. This petroleum system variation is reflected by the field size distribution and the heights of the hydrocarbon columns.Many authors have discussed the petroleum system of this basin and they are useful for providing regional geological perspectives. The oil and gas fields in South Sumatra are usually discussed independently by the operators. Different seismic vintages, density and quality make seismic correlations across the basin challenging. Apart from that, the data restriction is another hurdle in making correlation of the fields. Therefore, statistical studies of the fields and play level understanding become challenging.This study utilizes the Indonesian Petroleum Association Atlas of South Sumatra oil and gas fields, which was published in 1990. Several new fields, especially in fractured basement reservoirs, were added, based on recent publications. Additional information from the IHSE fields database was used to support the study. These data allow a statistical study on hydrocarbon column heights in the South Sumatra Basin. The result of this study could explain more about the charge and seal elements in the basin.

Design and Safety Considerations for Coiled Tubing Operations in Geothermal Wells

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 30408, “Design and Safety Considerations To Perform Coiled Tubing Operations in Large-Diameter, High-Temperature Geothermal Wells,” by Ishaan Singh, SPE, Danny Aryo Wijoseno, SPE, and Kellen Wolf, Schlumberger, et al., prepared for the 2020 Offshore Technology Conference Asia, originally scheduled to be held in Kuala Lumpur, 17–19 August. The paper has not been peer reviewed. Copyright 2020 Offshore Technology Conference. Reproduced by permission. The productive section in a high-pressure, high-temperature (HP/HT) geothermal Field A in the Philippines features shallow and deep reservoirs separated by a low-permeability formation. However, recent years have seen a reduction in production levels. To activate and enhance well production, coiled tubing (CT) nitrogen-lift operations were required. CT simulations were combined with simulations from the geothermal reservoir to overcome modeling limitations. The outcome helped the design of a new cooling-loop system and allowed optimization of the nitrogen-lift technique. As a result, two large-diameter geothermal wells were lifted safely with 2-in. CT. Introduction This study describes design and safety considerations in performing CT operations in high-temperature, large- diameter geothermal wells. The customized high-temperature-grade seal material was chosen to withstand high bottomhole temperatures (BHT) (600°F), and a heat exchanger riser system was designed and tested on the job to handle high-surface-temperature steam (350–400°F), thus mitigating potential well-control incidents. Challenges of Seal Damage Caused by High Surface Temperatures in Live Well Intervention The CT interventions in quenched HP/HT geothermal wells reduce the risk of surface equipment failure. The seal material readily available in the market is rated to 250°F, but, if quenching is not possible, the high-temperature steam (approximately 350–400°F) may flow into the pressure-control equipment, leading to seal damage and CT contingencies. At high temperatures (400°F), these seals are unusable. It becomes essential to use a surface heat exchange riser (HER) system to prevent this issue. Design and Execution of HER Systems in Field A To avoid any well contingency and to keep pressure-control equipment safe, HER systems can be used. Some basic designs for HERs are described in the complete paper. For this study, a customized 4.06-in. HER cooling system (Design 1, shown in Fig. 1) was designed to accommodate 2-in. CT pipe. Design 1 was chosen from an evaluation of three design candidates outlined in the complete paper. The wellhead stack featured seal elements rated to high temperatures (400°F). To prevent high- temperature steam from entering the wellhead stack, the blowout preventer, and other surface- equipment elements, an efficient HER system was designed wherein, while the CT is still in the well performing CT operations, the cold water can be pumped into the CT-stack annulus from the top flow cross through the cooling riser to the bottom flow cross and back to the return tank. The temperature of the cooling loop was continuously monitored to ensure that it was well below 212°F (the boiling point of water).

Performance evaluation of liner dual barrier system in CO2-rich geothermal wells

Geothermal well construction typically consists of a slotted production liner to support the wellbore and provide a conduit for produced reservoir fluids. To maintain the integrity of the well, the production liner is designed with a dual barrier system - a seal assembly at the top of the liner and a cement sheath between the formation and the liner. The integrity of barrier elements can compromise due to the degradation caused by acidic gases such as H2S and CO2 that usually exist in geothermal reservoirs. In this paper, experimental and numerical studies were conducted to evaluate dual barrier system's performance and identify its failure modes at various downhole conditions.In this study, an experimental setup was designed to replicate the production liner dual barrier system consisting of a cement sheath and elastomer O-rings. The hydraulic and mechanical integrity of the seal assembly and the cement sheath barriers were investigated by conducting pressure tests. EPDM elastomer and neat class H cement were used as the barrier materials. The performance of elastomer was investigated after aging in an autoclave at 1000 psi and 180°F under CO2 exposure. The performance of the cement was evaluated at different wait on cement (WOC) intervals. Verified finite element models (FEM) were developed to simulate the response of barrier elements under different conditions.Results indicated that exposure to CO2 compromised the hydraulic integrity of the seal element. The structural integrity of the elastomer was also jeopardized after CO2 aging, as evident by the blisters and cracks visually detected on elastomers’ surfaces. Verification by sealability test indicates that FEA modeling can be a reliable tool for estimating seal performance if elastomer material properties are known for the design conditions. Simulation results demonstrate that CO2 exposure can reduce the sealability of EPDM elastomer (measured in terms of contact stress) by up to 37%.For cement, the experimental results demonstrated insufficient interfacial bonding between cement and the inner pipe, as evidenced by the leak pathways observed during the hydraulic integrity tests. WOC time improves the hydraulic integrity of cement barrier element. Mechanical properties of cement cured at the elevated temperatures of up to 350°F were used in the FEA model to investigate the impact of temperature and wellbore pressure load on cement integrity. The results revealed that tensile hoop stress induced by the wellbore pressure loads is a likely failure mechanism that compromises the mechanical integrity of cement in geothermal wells. Results indicate that neat Class H cement may not serve as a reliable barrier in case of a defective seal assembly of a liner hanger. Overall, this paper identifies some of the barrier elements’ major limitations and provides recommendations for designing barriers and improving well integrity.

An equivalent NVH model of vehicle door seal strip and its application in door vibration problem

The vehicle door seal strip has complex dynamic characteristics and is a critical component in the vibration and sound transmission of the vehicle system. However, in noise, vibration, and harshness (NVH) analysis, the seal strip is commonly simulated as a linear spring model, which results in inaccurate vibration and sound prediction. Thus, it is necessary to propose an alternative model, which allows characterising the complex dynamic behaviour of the seal strip accurately. In the present study, an overlay material model of rubber was encoded and embedded in ABAQUS with the UMAT subroutine. The overlay model was used in a seal strip finite element model validated by the quasi-static and dynamic measurements. By analysing the effects of frequency, amplitude, and pre-compression on the dynamic stiffness of a seal strip, an equivalent NVH model consisting of spring and damping elements was proposed. The proposed model was validated by comparing the simulated mode and vibration transfer function results with experimental ones. Using the spring model, the deviations of vibration transfer function with the experimental results are 37% and 8.3% at the first and second peaks, respectively. The corresponding deviations are only 4.6% and 2.6% employing the proposed model, demonstrating that the proposed model provides higher accuracy than the spring model. With the assist of the proposed model for vibration transmission analysis, a typical door vibration problem was successfully addressed, which proved the effectiveness of the equivalent model in engineering practice.

COMPREHENSIVE FILTRATION SYSTEM FOR CLOSED HYDROSYSTEMS OF AGRICULTURAL EQUIPMENT

The article the issue of increasing the durability and reliability of units of closed hydraulic systems of agricultural equipment by ensuring the purity of the working fluid is considered. The analysis of existing systems of filtration of working liquid for the closed hydraulic systems of the agricultural equipment is resulted. It is noted that the basis of the created and implemented filtration systems are filtration installations in pressure mains, including with automatic washing, which provide filtration fineness up to 50 μm, filter elements which have high strength, reliability and are capable of countercurrent washing at working pressure of hydraulic system. The complex system of filtration of working liquid for the closed hydraulic systems of the agricultural equipment is offered. The filtration system of the working fluid provides for the use of filters with backwash and filtration elements with a slit-like brass wire of round cross section. The total length of the filtration gap of one filtration element with a width of 0.05 mm is 40 m The filter provides passive cleaning technology - countercurrent flushing, as the simplest in design, easy to manufacture and sufficiently efficient and cheap. Feature of the filtration installation is a possibility of washing of its filtration elements by a countercurrent of working liquid. The signal for flushing is the occurrence of a pressure drop on the filter, which can be used to judge the degree of contamination and the readings of manometers installed at the inlet and outlet of a closed hydraulic system of agricultural equipment. It is noted that the developed complex filtration system for closed hydraulic systems of agricultural equipment will increase the reliability of control hydraulics at least twice and reduce costly downtime of agricultural machinery due to failure of sealed elements of hydraulic equipment.

Chemiluminescence Biosensor for Non-invasive Crew Health Monitoring at the International Space Station

Long-duration manned space missions require that astronauts be equipped with analytical devices suitable for performing on-site clinical-chemistry analysis. In the frame of the ???IN SITU Bioanalysis??? project, an analytical device for measuring the steroid hormone cortisol (an indicator of chronic stress) in saliva has been developed. The device performed a Lateral Flow Immunoassay (LFIA) for cortisol employing disposable plastic cartridges produced by FDM (Fused Deposition Modeling) 3D printing technology, which encapsulated a sealed fluidic element containing the LFIA strip and the reagents required for the analysis. Detection was performed by chemiluminescence (CL) using a dedicated CL reader equipped with a cooled charge-coupled device (CCD) camera. The European Space Agency (ESA) astronaut Paolo Nespoli successfully used the ???IN SITU Bioanalysis??? analytical device during the mission ???VITA???, a 6-months space mission onboard the International Space Station (ISS) in the framework of a dated bilateral agreement between the Italian Space Agency (ASI???Agenzia Spaziale Italiana) and NASA. The experiments proved the feasibility of CL-LFIA ultrasensitive (i.e., at the sub-ng/mL level) quantitative bioassays in space. In perspective, the ???IN SITU Bioanalysis??? analytical device could be adapted to the measurement of other biomarkers of diagnostic and prognostic relevance, even in a multiplexed fashion (i.e., detection of multiple biomarkers in a single analysis) to develop panels tests for diagnosis and follow-up of pathologies or monitoring health status of astronauts.

Experimental Studies of Magnetic Fluid Seals and Their Influence on Rolling Bearings

There are many seals designed for rolling bearings. One interesting perspective is the application of magnetic fluid seals for this purpose, because they are an alternative to commonly-used solutions and combine the advantages of contactless seals (e.g. labyrinths) and contact seals (e.g. rubber lip seals), therefore they have low resistance moment and high tightness. This publication describes rolling bearings and a magnetic fluid seal system in terms of the maximum sealing pressure, which was compared to the results of numerical simulations, and the influence of the magnetic field on the bearing torque was also investigated. The tests were carried out for various types of seal stage shapes. Different magnetic circuit configurations have been considered i.e. the main magnetic flux passing through the seals or rolling bearings (steel or ceramic). Studies have shown that a magnetic field increases the torque in the bearing and magnetic fluid seals may reduce the torque because part of the magnetic flux passes through the seal elements. This result is important because it shows that it

Theoretical analysis and experimental studies on torque friction in magnetic fluid seals

Magnetic fluid seals are among the most common applications of ferrofluids. In such seals, the torque friction results only from the internal friction in the fluid and there is no direct contact between seal elements. Despite this, the heat generated during operation can be significant due to the low volume of the ferrofluid in the seal and high rotational speeds. The difficulty in calculating the torque friction is because the ferrofluid is a non-Newtonian fluid and changes its viscosity under the influence of a magnetic field. In order to measure torque friction in magnetic fluid seals, a special test stand was built. Tests were performed at different rotation speeds, different temperatures, and two seal stage geometries (rectangle and trapezoid). Numerical simulations were performed to determine the magnetic field distribution in the seal. Dynamic viscosity under the influence of the magnetic field was measured on a rotary rheometer. Mathematical models were compared with laboratory results. The results obtained from the calculations in some cases gave overstated values almost twice in value. An additional correction in the case of ferrofluid viscosity is proposed.

Experimental investigation of elastomers in downhole seal elements: Implications for safety

One of the multiple barriers that is installed in the downhole during drilling and completion is the liner hanger seal assembly. The liner hanger is used to engage the liner, connect it to the previous casing, and seal off with cement before a pressure test is performed. Verifying the sealability of the elastomeric element in a liner hanger is a critical factor for well integrity. In this study, the performance verification process and tests were conducted based on critical reviews of literature, current regulations, and applicable industry standards. The objectives of this experimental study are to develop testing protocols to investigate the performance of common elastomeric seals that are used in a liner hanger seal assembly. Ethylene propylene diene monomer (EPDM) and nitrile butadiene rubber (NBR) were selected for the tests because they are commonly used in downhole sealing systems. The results from the experiments revealed that the elastomeric seals did not exhibit any leakage when they were subjected to a pressure test of 40 psig (275.79 kPa) under normal conditions. The sealing performance of EPDM and NBR after surfactant degradation was not impaired for the test conditions used in this study. However, both elastomers failed the pressure tests and leaked when a mechanical defect was intentionally created and after exposure to carbon dioxide. The pressure cycling results showed that elastomers energization plays a critical role in maintaining their seal integrity. The results also showed that prolonging the pressure test duration from 30 to 60 min did not affect the elastomers performance.

Influence of Selected Parameters on the Reseal Instability Mechanism in Magnetic Fluid Seals

Magnetic fluid has many technical applications and many new ones are being developed. One of the applications is in magnetic fluid seals. This publication describes the new phenomenon of the magnetic fluid seal reseal mechanism, discovered while carrying out research. This phenomenon is manifested by the pressure oscillation medium being sealed, which results from the instability (cyclic destruction and rebuild of the liquid ring) in the magnetic fluid seal. It occurs in an inhomogeneous magnetic field and, in this case, is caused by the eccentricity of the seal components. In order to study this mechanism, magnetic fluid characterized by different physical properties was selected. Numerical simulations were performed to determine the magnetic field distribution in the seal. Research results showed the possibility of measuring the eccentricity of the magnetic fluid seal elements. Studies have shown that it is possible to determine the displacement of about 0.01 ㎜.