Over the past decade, operators have been faced with an ever-increasing demand to reduce operational costs. One approach to effecting this reduction has been to maximize production tubing bores while reducing corresponding casing sizes. These new concepts have required many completion configurations and related equipment to undergo extensive change. An excellent example of how new requirements for design enhancement for one technology can impact the design of related equipment is shown in a review of the slimhole / monobore completion technique. This paper wiii discuss enhancements to subsurface safety valve equipment that have been required by the need to support the new requirements of siimhole monobore technology. The paper wiii present an overview of:The evolution of the flappers designThe constraints various flapper designs place on OD / ID ratios of the safety valve for slimhole monobore completions.The extensive testing that has been performed to verify performance capability. Comparison of OD/ID capabilities will be made between conventional "fiat plate" flappers, curved flappers, and bail vaive designs. Finaliy, the design of a proven flapper that uses a uniquely contoured configuration to 1) optimize OD / ID ratio, 2) provide enhanced metal-to-metal sealing capabilities, and 3)address the problems faced with other safety valve design options will be presented. INTRODUTION In designing a particular safety valve, the outside diameter (OD) or inside diameter (iD) is usually determined by the closure mechanism. Closure mechanisms typically used for subsurface safety valves have been poppet, ball or flapper designs. Since the poppet design does not lend it self to full-bore access, it wiii not be discussed in this paper. When designing a wireline retrievable safety valve, the OD would normality be the starting point and would be determined by the tubing or other tubing accessories; the ID becomes a by-product of design. When designing a tubing-retrievable valve, the ID is the starting point and is determined by the tubing or associated tubing accessories; the OD becomes a by-product of the design. When designing a wireline safety valve, the engineer?s goal during the design process is to maximize the valve?s bore ID to achieve the largest possible throughput for maximizing production rates and through bore access. Similarly, when designing a tubing retrievable subsurface safety valve, the goal is to minimize the valve?s OD. The OD of the tubing retrievable subsurface safety valves can have significant impact on the completion design. Typically, the tubing-retrievable safety valve is the component in the tubing string with the largest OD; therefore, it etermines the casing ID requirements. The term, "OD / ID ratio" will be used throughout the paper, and as such, its usage will always relate to the annular wall requirements to house the components of the TRSV. The thinner the annular wall requirement, the smaller the OD/ ID ratio will be. All examples discussed in this paper will relate to tubing-retrievable safety valve (TRSV) design; however, all technologies presented are equally applicable towireline safety valve design.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractTubing-retrievable safety valve (TRSV) performance has been improved drastically over the last decade as a result of simplified design concepts, increased use of non-elastomeric and metal-to-metal (M-t-M) sealing materials, and enhanced validation testing. Unfortunately, the demands imposed by deep-water applications have also increased, and in spite of continuing improvement in safety-valve technology, equipment continues to be pushed to its limits. Higher valveopening pressures associated with deep-set applications have emerged, and to address these needs, conventional solutions have focused on balancing the wellbore and its reaction to the hydraulic piston area using mechanisms that require additional seals and/or gas-charged chambers. These solutions are heavily dependent on elastomeric seals and/or the permanent, long-term containment of a dome charge or pressure counterbalance, to maintain reliability. Unfortunately, dynamic elastomeric seals have posed a major limitation when design intent tries to focus on equipment that will provide lifeof-the-well reliability. This paper will review a unique TRSV design that is a revolutionary new concept. This design incorporates a floating-magnetic-coupler mechanism that allows the hydraulic actuator to be positioned in a dedicated chamber isolated from contact with well fluids and pressure. Since the hydraulic actuator has been separated from the tubing wellbore, this new valve is the first in the industry to have 100% M-t-M sealing with no moving seals within the tubing wellbore. The low hydraulic operating pressure of the valve also simplifies the complexity of the pressure source equipment and completely eliminates the need for highpressure operating equipment. This is significant when considering both safety and cost; furthermore, it could completely eliminate use of high-pressure equipment and

Tubing-retrievable safety valve (TRSV) performance has been improveddrastically over the last decade as a result of simplified design concepts, increased use of non-elastomeric and metal-to-metal (M-t-M) sealing materials, and enhanced validation testing. At the same time, the demands imposed bydeep-water, high-pressure/high-temperature (HPHT) environments, high-flow-rategas reservoirs and remote subsea applications have also increased, and in spiteof continuing improvement in safety-valve technology, equipment has continuedto be pushed to its limits. As a result, higher valve-opening pressuresassociated with deep-set applications have emerged, and to address these needs, conventional solutions have focused on balancing the wellbore and its reactionto the hydraulic piston area using mechanisms that require additional sealsand/or gas-charged chambers. These solutions are heavily dependent onelastomeric seals and/or the permanent, long-term containment of a dome (gas)charge or pressure counterbalance, to maintain reliability. Unfortunately, dynamic elastomeric seals have posed a major limitation when design intentfocuses on equipment that will provide enhanced life-of-the-wellreliability. This paper will review a unique TRSV design that is a revolutionary newconcept. This design incorporates a floating magnetic coupler that allows thehydraulic actuator to be positioned in a dedicated chamber isolated fromcontact with well fluids and pressure. Since the hydraulic actuator has beenseparated from the tubing wellbore, this new valve is the first in the industryto have 100% M-t-M sealing with no moving seals within the tubing wellbore. The new intrinsically simple design:Increases environmental and personnel safetyReduces system costsReduces sealing requirementsProvides an extremely reliable tubing retrievable safety valveEnhances life-of-the-well. Introduction The development of hydrocarbon recovery methods has occurred in phases thatfor the most part have been driven by technological advancements. For example, shelf development in the US (GOM) began with the first producing well out ofthe sight of land being completed in 1947. This feat was enabled by thecapability to construct a well jacket to contain and protect the well. Thistechnology climaxed with large platforms that contained numerous well slots setin water depths up to 2000 feet. The advent of 3D seismic techniques led to further development anddevelopment of shelf properties. By using 3D seismic tools, developers wereable to identify greater depths in oil and gas prospects. Aided by this newtechnology, smaller companies identified a niche in sub-salt pay fields. In the mid-1990's, deeper fields were reached with subsea completions. Inaddition to the ever increasing depths made available by subsea completions, tension leg platforms (TLP) and new completion techniques wereintroduced.1,2 These advancements place ever deeper prospects withinreach of this new technology. These ongoing developments have resulted in deepwater prospects becoming theprimary driver of capital expenditures, and deepwater activity is now a majorpart of the oil and gas industry throughout the world. As a result of thistrend, completion equipment has been subjected to more corrosive and demandingHP/HT conditions.3,4 In addition to current deepwater development, 3D seismic analysis has turnedup other indicators that are of interest to the oil industry, and these arecurrently being investigated. While promising superior production capabilities, these deeper targets will further challenge technology. With reservoir depthsas deep as 40,000 feet, bottomhole temperatures above 400°F, and bottomholepressures approaching 30,000 psi, new equipment will be required to drill andcomplete these potential "super" wells. The demanding conditions of deep-water, HP/HT), high- flow-rate gasreservoirs and remote subsea applications challenge the integrity of allequipment in these environments. These conditions place a particularlystringent challenge on surface-controlled subsurface safety valve (SCSSV)designs and demands equipment that outperforms the capabilities of conventionalSCSSV designs.

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