New Technology Allows for Hands-Off Intervention During Cementing Operations Increasing Safety and Operational Efficiency

The culture of safety within the oil and gas industry has undergone an evolution since the advent of significant E&P operations in the late 1800s. The initial focus on safety was to protect property, not people. This mentality has shifted over time to include a greater focus on the safety of personnel, in parallel with technology developments that have pushed the limits of operators’ and service providers’ abilities to drill and complete more complicated wells. The safety efforts introduced to date have yielded results in every major HS&E category; however, falls and dropped objects continue to be areas in need of improvement. During cementing rig up and operations there are still many manual activities that require working at heights in the derrick. New technological advances have allowed the industry to reduce the number of hands-on activities on the rig and operators have moved to eliminate these activities by automating operations. Man lifting operations are recognized as a high-risk activity and, as such, many rigs require special permitting. During cementing operations, not only are personnel lifted into hazardous positions, but they are usually equipped with potential dropped objects. Some of these objects, if dropped, reach an impact force that could seriously injure or, in worst cases, result in a fatality. During these operations, personnel are also hoisted along with a heavy cement line in very close proximity. This introduces other dangers such as tangling, pinch points, and blunt force trauma. These risks are heavily increased when working in adverse conditions, such as high winds or rough seas. By utilizing a wireless cement line make up device, along with wireless features on a cement head to release the darts/plugs/balls and operate the isolation valves, an operator can eliminate the need for hands-on intervention. This paper will discuss current cement head technologies available to the operator that allow them to improve safety and efficiencies in operational rig time. Three field studies will be presented that detail running cement jobs with all functions related to the wireless attributes of the cement head. The field studies will present the operational efficiencies achieved by utilizing the wireless features compared to the standard manual method. Before the recent introduction of a wireless cementing line make-up device, a wireless cement head still required hands-on intervention to rig up the tools, putting people in high-risk situations.

THEORETICAL ANALYSIS OF THE LEAKAGE THROUGH THE CEMENT LINE OF A SINGLE OSTEON

This work focuses on the Lacunar–Canalicular Porosity (PLC) of cortical bone which includes the osteons. Osteons are semicylindrical porous structures saturated with fluid within the bone and are approximately 250[Formula: see text][Formula: see text]m in diameter. The outer boundary of the osteon is called the cement line. Some studies suggested that the cement line is less highly mineralized and produced evidence that it has less calcium and phosphorus and more sulfur than the neighboring bone lamellae. Most authors assume that the cement line is impermeable, while others assume that some canaliculi are crossing the cement line which will make it permeable to certain degree. The objective of this work is to develop a theoretical analysis to study the leakage through the cement line and its relationship with the pore pressure distribution. The theoretical analysis is developed using our previous analysis for osteon under harmonic loading with addition of leakage parameter. The leakage parameter varies from 0 to 1, where a value of 0 indicates free flow through the cement line and a value of 1 indicates no flow through the cement line. Experimental results could be compared to this developed theoretical solution to get in depth understanding of the effect of leakage on osteon poroelastic properties. Additionally, the developed theoretical solution will give insight into sensitivity of osteon pore pressure to leakage through the cement line.

Effects of Microstructure Characteristics of Cortical Bone on its Microcrack Propagation

Scanning electron microscope (SEM) was used to observe and analyze the microstructure of the cross section of cortical bone. The observation results illustrated that the cortical bone is composed of cylindrical osteons and interstitial bone between osteons, and the osteon are unevenly distributed. Based on the microstructure characteristics of cortical bone, three types of cortical bone mesoscopic analysis models were established. Then, the extended finite element method (X-FEM) was used to simulate the microcrack propagation process in bone. The simulate results show that the crack initiation strain of the two-phase model is 19.1% larger than that of the single-phase model, and the three-phase model is 57.8% larger than that of the two-phase model, which demonstrated that the osteons and cement line can significantly enhance the crack initiation strain of bone. In addition, under the same boundary conditions, the model with cement line can effectively change the propagation path of microcrack and prevent the propagation of crack. Therefore, the cement lines in cortical bone can effectively increase the fracture resistance of bone and enhance the fracture toughness of cortical bone.

Stress Cracking Behavior of Interstitial Matrix and Cement Line Interface Deflection

Bone can be noticed as a complex hierarchically organized structures at several length scales, which has both metabolic and mechanical functions. One of the major type of bone is known as cortical bone as it comprises of distinct microstructures including osteons, interstitial bone, and cement line which play an important role in examining the fracture behavior in cortical bone. Microcracking of these unique features may lead to bone fracture. To date, there are a few of studies have been done regarding to its special microstructures. However, the mechanical properties of cement line is absently described to predict the cracking behavior at micro-scale level. This study aims to determine the stress distribution of cement line deflection in single osteon using finite element (FE) method. A FE analysis were performed to simulate the secondary osteon model under mode I, mode II and mixed-mode loading. The finding of this study propose the stress is accumulated near to the cement line. The maximum stress may be found to be high at the longest crack. The study concluded that the stress cracking behavior of cement line deflection is influenced by different mode of loading.

Fracture analysis of cortical bone under the condition of cement line debonding and osteon pullout

Cortical bone consists of osteons embedded in interstitial bone tissue and there is a thin amorphous interface, named cement line, between osteon and interstitial bone. Due to fatigue and cyclic loading, the pullout or debonding phenomenon often occurs in osteonal and interstitial tissue bone. The study aims to construct a fiber-reinforced composite material debonding model for cortical bone, in which the bonding condition along the osteon, cement line and interstitial tissue bone are assumed to be imperfect. In the study, we used the complex variable method to obtain series representations for stress fields in the osteon, cement line and the interstitial tissue bone with a radial crack. The effects of material properties of osteon and cement line, crack position, and varying degrees of debonding on the fracture behavior were investigated by computing the stress intensity factor (SIF) in the vicinity of the microcrack tips. The investigation results indicated that the cement line was important for controlling the fracture toughening mechanisms and that the level of imperfect bonding among osteon, cement line and interstitial tissue bone had a pronounced effect on the crack behavior and should not be ignored.

Marginal Adaptation and Quality of Interfaces in Lithium Disilicate Crowns — Influence of Manufacturing and Cementation Techniques

SUMMARY Purpose: To evaluate the cement line thickness and the interface quality in milled or injected lithium disilicate ceramic restorations and their influence on marginal adaptation using different cement types and different adhesive cementation techniques. Methods and Materials: Sixty-four bovine teeth were prepared for full crown restoration (7.0±0.5 mm in height, 8.0 mm in cervical diameter, and 4.2 mm in incisal diameter) and were divided into two groups: CAD/CAM automation technology, IPS e.max CAD (CAD), and isostatic injection by heat technology, IPS e.max Press (PRESS). RelyX ARC (ARC) and RelyX U200 resin cements were used as luting agents in two activation methods: initial self-activation and light pre-activation for one second (tack-cure). Next, the specimens were stored in distilled water at 23°C ± 2°C for 72 hours. The cement line thickness was measured in micrometers, and the interface quality received scores according to the characteristics and sealing aspects. The evaluations were performed with an optical microscope, and scanning electron microscope images were presented to demonstrate the various features found in the cement line. For the cement line thickness, data were analyzed with three-way analysis of variance (ANOVA) and the Games-Howell test (α=0.05). For the variable interface quality, the data were analyzed with the Mann-Whitney U-test, the Kruskal-Wallis test, and multiple comparisons nonparametric Dunn test (α=0.05). Results: The ANOVA presented statistical differences among the ceramic restoration manufacturing methods as well as a significant interaction between the manufacturing methods and types of cement (p<0.05). The U200 presented lower cement line thickness values when compared to the ARC with both cementation techniques (p<0.05). With regard to the interface quality, the Mann-Whitney U-test and the Kruskal-Wallis test demonstrated statistical differences between the ceramic restoration manufacturing methods and cementation techniques. The PRESS ceramics obtained lower scores than did the CAD ceramics when using ARC cement (p<0.05). Conclusions: Milled restorations cemented with self-adhesive resin cement resulted in a thinner cement line that is statistically different from that of CAD or pressed ceramics cemented with resin cement with adhesive application. No difference between one-second tack-cure and self-activation was noted.

Finite Element Modeling of Microcrack Growth in Cortical Bone

Bone is similar to fiber-reinforced composite materials made up of distinct phases such as osteons (fiber), interstitial bone (matrix), and cement lines (matrix-fiber interface). Microstructural features including osteons and cement lines are considered to play an important role in determining the crack growth behavior in cortical bone. The aim of this study is to elucidate possible mechanisms that affect crack penetration into osteons or deflection into cement lines using fracture mechanics-based finite element modeling. Cohesive finite element simulations were performed on two-dimensional models of a single osteon surrounded by a cement line interface and interstitial bone to determine whether the crack propagated into osteons or deflected into cement lines. The simulations investigated the effect of (i) crack orientation with respect to the loading, (ii) fracture toughness and strength of the cement line, (iii) crack length, and (iv) elastic modulus and fracture properties of the osteon with respect to the interstitial bone. The results of the finite element simulations showed that low cement line strength facilitated crack deflection irrespective of the fracture toughness of the cement line. However, low cement line fracture toughness did not guarantee crack deflection if the cement line had high strength. Long cracks required lower cement line strength and fracture toughness to be deflected into cement lines compared with short cracks. The orientation of the crack affected the crack growth trajectory. Changing the fracture properties of the osteon influenced the crack propagation path whereas varying the elastic modulus of the osteon had almost no effect on crack trajectory. The findings of this study present a computational mechanics approach for evaluating microscale fracture mechanisms in bone and provide additional insight into the role of bone microstructure in controlling the microcrack growth trajectory.