Efficacy of Various Implant Abutment Screw Access Channel Sealing Materials in Preventing Microleakage: A Systematic Review

The aim of this systematic review is to evaluate the effectiveness of different materials used for sealing dental implant abutment screw access channel (ASAC), in preventing microleakage. As per the searched indexed English literature, this study is the first review of its kind. Indexed English literature published up to 20 th February 2021 was systematically searched on relevant electronic data bases. The recommendations specified by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) were applied for constructing framework, and reporting the current review. The focused PICO question was: “Which material (C) is more effective in sealing (I) implant ASAC (P) in terms of causing minimal microbial leakage (O)”. Quality of articles was assessed with modified CONSORT scale for in vitro studies. Five in vitro studies were selected for qualitative analysis after final stage screening. Modified CONSORT scale suggested that out of the five selected studies, one each was of low and high quality, whereas three studies were of moderate quality. Included studies had contrasting results related to the efficacy these materials as sealants in ASAC. Sealing capacity against microleakage should be considered as one of the important criteria while selecting the material to fill implant ASAC. Definitive conclusions asserting superiority of a single material over others are difficult to draw, due to non-homogeneity in study design of the included papers. More studies should be conducted in the near future to investigate the efficacy of various combination of materials in preventing micro leakage.

Study on a New Static Sealing Method and Sealing Performance Evaluation Model for PEMFC

The long-term stability and durability of seals are critical for various instruments and types of equipment. For static sealing, an important sealing state, there are currently two representative sealing methods, namely, pre-compressing static sealing and adhesive static sealing. In this paper, the characteristics and shortcomings of these sealing methods are summarized. At present, some static sealing requirements are urgent and difficult. For example, the deterioration of the sealing performance is an important factor which limits the service life of proton exchange membrane fuel cells and redox flow batteries. Therefore, a new method of static sealing whose sealing materials are rubber elastomers is proposed, named alterable static sealing. Then, its sealing processes are proposed. Furthermore, the actual contact area ratio r is used as the standard for sealability. Based on the mathematical model of pre-compressing static sealing, the influence of interface bonding was considered, and the mathematical model of alterable static sealing was established. Moreover, the compensatory effect of alterable static sealing on the static sealing capacity of rubber elastomers was proved.

A normalized method for determining the influence on the fixed joints tightness using the technology of the sealing surface job

The existing approaches for determining and evaluating the sealing properties of seals for fixed sealants, as well as methods of leakage monitoring are considered. The description of a normalized method for leak-tightness assessment is given, which allows solving a sufficiently large number of evaluation tasks, for example, technological task: assessment of the influence of the technology sealing surfaced job; design: assessment of the influence of the seals surface layer quality of sealants and geometric parameters of them on sealing capacity (service property).

Early Age Sealing Capacity of Structural Mortar with Integral Crystalline Waterproofing Admixture

Crystalline admixtures embedded in concrete may react in the presence of water and generate thin crystals able to fill pores, capillaries and micro-cracks. Once the concrete has dried, the crystalline chemicals sit dormant until another dose of water starts the crystallization again. The research aims to analyses the early age self-sealing effect of a crystalline admixture at a dosage rate of 1–3% of the cement mass. Specimens made with two types of gravel were pre-loaded with three-point bending to up to 90% of the ultimate capacity, and conditioned through wet–dry cycles. Micro-crack closure was measured with a microscope after pre-loading, and after 1 day, 4 days, 8 days, 14 days and 20 days of wet–dry exposure. The results show that an admixture content of 3% achieves the best early self-sealing performance. These results are also confirmed by probabilistic analyses, which also emphasize the self-sealing potential of lower ICW contents.

18 3/4" 15000 Psi Shear Anything KBOS for Subsea Well Applications

Kinetic Pressure Control has developed the 18 ¾" 15000 psi blowout stopper (KBOS) system for applications on all subsea well activities. The 18 ¾" 15000 psi systems builds upon the successful development of the 5-1/8" 15000 psi KBOS system for surface BOP applications[5]. The system can be configured within the existing subsea BOP, by replacing a casing shear ram or blind shear ram, or can be configured as a shut-in device below the BOP. The KBOS system provides a significant improvement over existing shear ram technology, providing the ability to shear/seal any items in the wellbore, which reduces the likelihood of a blowout, resulting in an improved risk profile. The KBOS is a proprietary design which uses a pyro-technical, electrically initiated process the actuate the shearing process. The system has been designed and tested to actuate and shear/seal in milliseconds, under full wellbore flowing conditions and meets NACE/ISO sour service requirements without exemptions. The control system includes real-time monitoring and function testing capabilities, and requires minimal in-service maintenance, as the working components are isolated from the wellbore fluids. A computational predictive model has been developed, with a test regime conducted to validate the model results. A full qualification program, with 3rd party certification, has been completed to industry standards. Shearing tests have been conducted for a large range of tubulars which have been challenging to shear with existing technology. These include: 9 ½" drill collars, combinations of large OD casing and inner strings, high strength drill pipe and tool joints, wireline, and production tubing. A subsea test of the system was successfully performed in 2019 to shear large OD casing and inner string. The KBOS system utilizes technology from other industries (ballistics, military, automotive) to provide improved shearing and sealing capabilities for all well activities (drilling, completion, intervention). The improved shearing/sealing capacity and reduced time enable a reduced likelihood of a blowout and improved risk profile

Joint Kinematics and Sealing Capacity Assessment of Ductile Iron Pipes under Abrupt Transverse Ground Movements

Joint kinematic behaviour, i.e., joint rotation and axial translation, can partially help pipelines to accommodate abrupt ground movements, and cause leaking if joint service limit is exceeded, even without any structural failure. Kinematic behaviour of bell-spigot jointed ductile iron (DI) pipes and its influence on joint sealing capacity under abrupt transverse ground movements are investigated in this study. Firstly, a beam-on-spring finite element analysis on joint kinematics of DI pipes is conducted, in which different fault-pipe crossing positions are implemented. Based on simulated results, a modified joint kinematic solution incorporating pipe deflection and joint shear force under different fault-pipe crossing positions is proposed. Then, a Monte Carlo simulation (MCS)-based reliability assessment procedure for joint sealing capacity is developed. Sensitivity analysis is subsequently conducted to investigate the effects of uncertainties associated with initial axial translation, soil properties, and crossing positions on the joint sealing capacity, and the effects of different deterministic solutions are compared. The proposed method allows engineers to effectively evaluate how the joint sealing capacity of DI pipes changes with consideration of uncertainties when abrupt transverse ground movements are encountered.

Ureolytic MICP-Based Self-Healing Mortar under Artificial Seawater Incubation

Ureolytic microbial-induced calcium carbonate precipitation (MICP) is a promising green technique for addressing sustainable building concerns by promoting self-healing mortar development. This paper deals with bacteria-based self-healing mortar under artificial seawater incubation for the sake of fast crack sealing with sufficient calcium resource supply. The ureolytic MICP mechanism was explored by morphology characterization and compositional analysis. With polyvinyl alcohol fiber reinforcement, self-healing mortar beams were produced and bent to generate 0.4 mm width cracks at the bottom. The crack-sealing capacity was evaluated at an age of 7 days, 14 days, and 28 days, suggesting a 1-week and 2-week healing time for 7-day- and 14-day-old samples. However, the 28-day-old ones failed to heal the cracks completely. The precipitation crystals filling the crack gap were identified as mainly vaterite with cell imprints. Moreover, fiber surface was found to be adhered by bacterial precipitates indicating fiber–matrix interfacial bond repair.

Gas Migration Mechanisms and Their Effects on Caprock Seal Capacity: A Case Study in Depleted Gas Fields in the Sarawak Basin, Offshore Malaysia

This paper focuses on the gas characteristics in caprock interval and the gas migration mechanisms from the carbonate reservoir into the caprock and its effects on caprock seal capacity. The workflow mainly includes three methods:(1) Gas geochemistry analysis from the GWD (Gas While Drilling) data to understand the gas composition, their distribution and mechanism for gas migration; (2) Petrophysical analysis to understand the rock types, petrophysical properties and the pore-throat system; and (3) Pore pressure prediction to understand the pressure sealing capacity of the caprock. Integrating the results from these three aspects, the sealing capacity can be evaluated by capillary pressure sealing, pore pressure sealing and the effects on the sealing efficiency for CO2. There are two gas migration mechanisms in the area: gas diffusion and gas advection. The gas in the caprock of Field A shows decreasing molecular weight trend from deep to shallow depths implying migration from the underlying carbonate reservoir by gas diffusion. However, the gas in the caprock of Field B where there is a gas chimney visible in the seismic data, has composition similar to the gas in carbonate reservoir, suggesting that the gas came from carbonate reservoir below by gas advection through faults and induced fractures and occurred simultaneously with the gas accumulation in the reservoir. There is also gas in the caprock above the gas chimney with lighter molecular weight representing gas that migrated from the gas chimney by gas diffusion. The caprock seal capability in the two fields are different. The gas in the carbonate reservoir in Field A can be sealed and trapped by the high displacement/entry pressure of the capillary pore-throat system and the abnormally high pore pressure in the caprock. The gas chimney at Field B would be connected to the carbonate reservoir below over geological time and there is effective seal enough to contain hundreds ft of gas column in the carbonate reservoir. The understanding of the leaking mechanism in these two fields is helpful for understanding the leakage scale, the effects on the sealing capacity, the risk evaluation and mitigation amendment.

Activated Shale Creep and Potential Micro-Annulus Investigated in the Field

It has been demonstrated that creeping shales can form effective hydraulic well barriers. Shale barriers have been used for many years in P&A of wells in Norway. More recently, shale barriers for zonal isolation have also been used in new wells where shale creep was found to occur within days. In some cases, shale creep is activated by a reduction in annulus pressure, in other cases shale creep sets in without any active activation, possibly by time-dependent formation-pressure changes. However, the presence of thixotropic fluids (drilling muds) in the annulus may prevent full closure of the annulus as it requires large pressure differentials to squeeze the fluid out of a microannulus. Furthermore, elastic rebound of an actively activated shale barrier could result in a microannulus and hence a possible leakage pathway. Improved logging technology is needed for identifying shale barriers and the presence of micro-annuli in shale-barrier zones. We use cement bond log data and standard bond logging criteria to evaluate the quality of the shale well barriers (Williams et al., 2009). In addition, in order to detect microannuli on the outside of the casing, a new inversion algorithm for the bond logging data was developed and tested on field data. Later, we had the chance to apply the inversion algorithm to bond-log data obtained in the laboratory with a miniature bond-logging tool inside a cased hollow-cylinder shale-core sample place. It turned out that both the micro-annulus widths and shale velocities determined by the inversion technique were too high. By constraining the shale velocities to more realistic values, the updated microannulus widths were smaller and more consistent with the experimental results. Small microannuli may not cause any measurable leakage along the well, especially if filled with a thixotropic fluid. However, more studies are needed to quantify the impact of microannuli on the sealing capacity of shale barriers.