By exposing reinforced concrete samples to four common chloride-based deicers, the corrosive effect of chloride-based deicers on rebars and dowel bars was systematically investigated. The experiments were designed in such a way that the effect of deicers on reinforced concrete can be characterized in an accelerated manner, by either ponding the concrete samples with deicer solutions at room temperature, or incorporating pressurized ingress, wet-dry cycling and temperature cycling into the test regime. The chloride ingress over time was monitored using a custom-made chloride sensor embedded in each concrete sample. Also periodically measured were the open circuit potentials (OCPs) of the top bar in concrete. Once the chloride sensor detected the arrival of sufficient chlorides near the top bar and the OCP data indicated the possible initiation of top bar corrosion, the corrosion rates of rebars and dowel bars are characterized by macrocell current and corrosion current density derived from electrochemical impedance measurements. From a modeling perspective, artificial neural networks (ANNs) were used to achieve better understanding of the complex cause-and-effect relationships inherent in the deicer/concrete/bar systems and were successful in finding meaningful, logical results from the noisy data associated with the deicer ponding experiments. According to the ANN modeling, corrosion inhibitor (and possibly other additives in the inhibited CaCl 2 and MgCl 2 deicers) did slow down the ingress of chloride into concrete (indicated by more positive 105 Brought to you by | Purdue University Libraries Authenticated Download Date | 5/26/15 11:42 PM Volume 28, Nos. 3 & 4, 2010 Laboratory Investigation and Neural Networks Modeling chloride sensor potentials),, reduce the pitting risk of rebars and dowel bars in concrete (indicated by more positive OCP values) and reduce their corrosion rate in concrete (indicated by reduced macrocell current and corrosion current density of top bar). For both concrete mixes and both types of deicer ponding, the overall risk of deicers to reinforced concrete was in the order of: non-inhibited NaCl > inhibited NaCl > inhibited CaCl 2 deicer > inhibited MgCl2 deicer. While the corrosion inhibitors in deicer products provide some benefits in delaying the corrosion initiation of rebars and dowel bars in concrete, such benefits seem to diminish once the active corrosion of the bars is initiated. In other words, the inhibitors showed little benefits in repassivating the actively corroding bars in concrete or in stifling the corrosion propagation.

In a preliminary experiment in 12 healthy volunteers, one drop of thymoxamine 0.5% instilled into the conjunctival sac completely reversed the mydriasis produced by phenylephrine 2.5%, 5% and 10% after 20 minutes. In a second study in eight volunteers, thymoxamine 0.5% completely prevented the mydriasis produced by phenylephrine 2.5% and produced a miosis. It also completely reversed the mydriasis produced by tropicamide 0.5%. The mydriatic effect of tropicamide 0.5% plus phenylephrine 2.5%, however, was not completely reversed by thymoxamine 0.5% over a period of 180 minutes. Phenylephrine, tropicamide and thymoxamine are freely available for use by registered optometrists.

Qualification of landing strings has become a major concern for oil industry operators as longer and heavier casing, tie-back or liner sections are required in deepwater and ultra-deepwater wells. Total buoyed weights are currently approaching two million pounds, making it imperative that every component in the landing string assembly is properly qualified. Any process which qualifies a landing string assembly must be multi-faceted, consisting of both design verification and a subsequent "fit for purpose" inspection. Experience has proven this approach is absolutely necessary to confirm all design assumptions hold true. Over the past six years, a systematic, field-proven, and reliable qualification process has been developed which has allowed operators to successfully land assemblies with buoyed weights up to 1.6 million pounds in water depths from 2,850 feet to almost 9,000 feet on semi-submersible rigs and drillships. This process addresses critical design considerations such as verification of specialty tool ratings, the effect of makeup torque on connection capacity, appropriate usage of existing slip crushing calculation methods, heave-induced dynamic loading, and minimizing the probability of plugs becoming lodged in the assembly. Inspection issues addressed include coverage and scheduling, traceability to ensure accurate material properties are used in all design calculations, full-length ultrasonic testing of the drill string, and proper inspection of components which are routinely inspected incorrectly. This paper details the most relevant aspects of this field-proven process, and reviews the implementation of this process by an operator for use on a broad range of casing and liner landing operations. The paper provides a concise summary of the approach that will allow the reader to confidently design for ever heavier loads while preventing costly (yet avoidable) failures during landing operations. Introduction Qualification of any landing string assembly requires the following steps be taken for each component:The design of the component is verified to have sufficient capacity for the anticipated loads. This can be accomplished either via classical engineering analyses, load testing of design prototypes, or a properly conducted finite element analysis (FEA).Material properties must meet the specified minimums used in all design calculations. Of primary concern for a landing string component is yield strength, but ductility and impact toughness are also critical for components with stress concentrators.The component must be properly inspected to ensure that prior service has not rendered it unfit for use in the given landing operation, and that all critical dimensions match those used when the component's capacity was verified.When deployed, the tool must be properly assembled within the landing string assembly.

Nonproductive time (NPT) caused by preventable tool and equipment failures in offshore drilling and completion operations typically accounts for 5% of well delivery time, but can reach as high as 30%[1]. This equates to millions of dollars per year that could have been spent on other well delivery opportunities. Mutual benefit exists for both operators and vendors to dedicate the time and effort necessary to consistently perform comprehensive investigations and develop effective solutions to mitigate risk of repeat failures. A one-sided or inadequately supported approach to failure response can lead to incomplete analyses and insufficient solutions that treat symptoms rather than root causes, thereby sustaining or creating reliability gaps and allowing further NPT to be incurred. In recent years, Shell’s Gulf of Mexico (GOM) drilling operations formed a specialized, dedicated team to establish and facilitate an effective, sustainable approach to failure response. The team’s immediate goal was the reduction of NPT cost associated with drilling tool failures. Long term, the team’s objective was to promote a culture within both operator and vendor organizations for effective failure prevention and performance improvement. Via this team consistent representation, influence, and support is maintained during failure response activities. The team enforces vendor failure response expectations and ensures complete, unbiased analyses and solutions with appropriate local, regional and global communication within operator and vendor organizations, such that the chance of repeat failures anywhere in the industry is minimized. Since inception, the team’s efforts have facilitated a significant reduction in NPT, which translates to yearly multi-million- dollar savings. Given its evident success, the scope of this initiative has been expanded within the Americas and also in global operations. This paper reviews the approach and process, clarifies the roles, responsibilities and accountabilities for both operator and suppliers, highlights the mutual benefits for operators and vendors, and illustrates the effectiveness of the approach through its very positive impact on operational NPT reduction.