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.

In 1919 the world record for the deepest well was broken by the Hope natural gas company with a total depth (TD) of 7,579 ft. Although it took over 3 years to reach TD, only 325 days were spent actually drilling. Today in deepwater operations, the water depth alone can exceed this record, and operators have drilled past 30,000 ft in just 4 or 5 months. Technology and procedures have evolved extensively as operations that appeared impossible a decade ago are now considered routine. Today, operators are being pushed more than before, not just to explore deeper prospects, but also to get there efficiently. The future of the industry depends on it. Now there are new questions the industry is asking about deep water: What is different about drilling deep in deepwater operations? What does it actually take to drill the deepest wells in the world today? Currently, there are only a handful of personnel with the knowledge and experience to execute these wells. This paper will discuss the challenges of planning and drilling directional wells in excess of 30,000 ft true vertical depth (TVD) and will also look at lessons from some of the major deepwater Gulf of Mexico (GoM) operations that have successfully drilled wells beyond this mark and are continuing to push the envelope further. These wells have held, at one time or another, records for deepest wells drilled in many categories in recent years. IntroductionMany of the deepest wells in the world have been drilled in the GoM, and many have been in deep water. Fig. 1 illustrates the trends in total TVD of the wells for the GoM. Fig. 2 illustrates the trend in increasing water depths with time for wells in the GoM. The direction that the industry is heading in is deeper: deeper water and deeper wells. The technology exists to take us there. However, there are critical factors to consider when planning these wells.

When planning dual gradient wells, it is important to understand the details of dual gradient drilling (DGD) operations and the resulting loads exerted on the casing strings in the wellbore. Standard casing design loads for conventionally drilled wells must be modified so that they apply to dual gradient drilling, and there are additional load cases specific to DGD that must be considered. This paper outlines those factors that should be accounted for in dual gradient casing design as compared to conventional deepwater casing design, including: Internal and external pressure profiles for typical deepwater casing design load cases for drilling and production strings. Additional load cases that should be considered for dual gradient drilling, such as running/cementing casing with an air gap in the string and tension/collapse combined loading when running in the hole. Application of dual gradient pressure profiles to worst-case discharge load cases. Annular pressure buildup analysis for dual gradient wells. Negative test magnitudes and procedures. While the dual gradient casing design loads are generally less severe than the corresponding load cases considered in conventional deepwater casing design, there are instances in which this does not hold true. Additionally, the collapse loads can be much greater than conventional due to the u-tube that exists during dual gradient operations. A thorough understanding of dual gradient operations is required to conduct a proper, diligent casing design that ensures a safe and efficient well plan and execution.

With all the emphasis today on the economics of improving well costs, the industry is faced with finding a way to provide marketable technology to drill more challenging wells even cheaper. The top drive stands out as one of a few key pieces of equipment in the critical path. As a result Top Drive failures have accounted for a large portion of down time, thereby increasing costs to drill a well, and the top drive is in essence "the drill" needed to reach reservoirs that are farther and deeper than once thought possible.ExxonMobil needed to upgrade its drilling platform in the Yastreb field in order to reach reservoirs with very long, extended reach. Drilling these wells necessitated a need for more torque and speed. Typically these parameters are supplemented with downhole motors. However, in extended reach wells, failure 5,000 -6,000 feet downhole costs up to a full day to retrieve the equipment and another full day to re-deploy the tool. With performance improvements to today's modern top drive, we have been able to increase torque and speed on the top drive and move that associated risk to the rig floor.Today's ultra-deepwater drilling necessitates durable, maintenance friendly top drives to off-set the high day rate and spread costs associated with these wells. For that, top drives in this environment have taken a step-change to increase durability with larger main thrust bearings, larger main shaft connections, heavy-duty link tilt function, etc. In addition to this increased focus on durability, these machines also need to be repaired quickly to get them running again. This has created a new generation focused on maintainability, and modularity.