Trends in offshore exploration continually push the definition of high pressure and high temperature in regards to oil and gas well completions. Recent discoveries in the Gulf of Mexico (GOM) are opening up vast reserves of natural gas and these discoveries are again challenging that definition. To meet the need of high-pressure, high-temperature (HPHT) applications in general and for an operator in one such HPHT field, an ultra high-pressure and high-temperature rated wellhead plug and downhole plugging system has been developed to provide wellbore integrity in extreme conditions. This paper addresses the challenges associated with development of slickline-retrievable equipment rated to 25,000 psi at temperature extremes from 32°F to 450°F and the approaches used to overcome those challenges. A review of design considerations, sealing technology, design verification, and validation testing that exceeds industry standards, is also provided.

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The concept of using natural gas as an energy source has increased to such an extent that there has been a notable worldwide increase in its usage. Supplying this growing demand has been an industry challenge. To this end, many operators have implemented the use of large-bore, high-rate gas wells for effective development of gas fields. One of the key components in this type of completion is the subsurface safety valve (SSSV) because of its primary role of containing the hydrocarbon in the event a well loss should occur. The SSSV is critical to the protection of the lives, assets, as well as the environment in the surrounding vicinity. During normal operations or after a well shut-in event, pressure must be equalized across the SSSV closure device, typically with a flapper, to reopen the valve. Because of the relatively high volumes of gas carried in the production tubing of a large-bore completion, non-self-equalizing SSSVs have been the product of choice. Traditional wisdom was that passing the large volume of gas through a self-equalizing feature would be detrimental to valve long-term reliability. The use of a non-self-equalizing SSSV requires the capability to supply tubing pressure above the SSSV closure device, which may not be operationally efficient or economical. Conversely, if a self-equalizing-type SSSV could be installed in large-bore gas completions, there would be significant benefits, which include:•Reduction in capital expenditure for surface pressure equipment•Operational simplicity•HSE benefits This paper will discuss the collaboration between a Middle East operator and the SSSV supplier to qualify a large-bore subsurface safety valve with a self-equalizing feature for use in high-rate gas-well applications. It will also review field implementation and resulting benefits with the use of these valves. Introduction The world economy is becoming increasingly reliant on natural gas as a vital component of the energy supply equation. In 2000, global natural gas consumption was 88 trillion ft3. Usage is predicted to exceed 125 trillion ft3 by 2015, which is an overall increase of 42%. From an oil-and-gas industry perspective, this growing demand places a premium on efficient natural gas extraction. To meet this challenge, the use of large-bore completion architecture in prolific gas reservoir applications is being employed to effectively exploit a reservoir's potential. To protect the people, environment, and investments in these developments, a tubing retrievable safety valve (TRSV) is placed in the production tubing to automatically shut in the well below the surface in the event that well control is lost. For these high-rate, large-bore wells, conventional wisdom suggested the use of a TRSV with no built-in feature for equalizing shut-in pressure across the closure device when the tool was to be reopened. This paper will highlight the efforts of a safety-valve manufacturer and Middle East operator in the qualification and installation of large-bore safety valves containing a self-equalizing feature in high-rate, large-bore natural gas wells. Self-equalizing features in TRSVs have been available for many years. With improvements in technology and the inherent reliability of these devices, the percentage of TRSVs employing an equalizing feature has steadily increased to where over 95% of TRSVs installed in general completions with 4½-in. production tubing size or less use this feature. The selfequalizing feature is much less often employed in deepwater offshore and large-bore, high-rate gas applications.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractMonobore completion techniques have been noted for their capability to provide operators with a high degree of maintenance flexibility. This enhanced flexibility is made possible by the fact that there are no restrictions on any tool that may be deployed in the liner as often happens when completions have tapered production strings. While this can result in substantial economic benefit, the advantages often are not realized until later in the life of the well.Although maintenance is always an important consideration, the general volatility of oil prices has forced the industry to target operational strategies that can offer quicker returns on investment. Therefore, innovations to the traditional monobore concepts have been needed. The completion system discussed in this paper employs large-diameter production tubing, and therefore, it can provide not only the maintenance benefits of a monobore system but also the added advantages of an increased flow area. The increased flow area 1) allows the number of wells to produce a given reservoir to be reduced and 2) enables production rates to be increased, which in turn, reduces long-term operating expense since the reservoir can be depleted in a shorter period of time.The specific benefits of the large-bore monobore completion are as follows:• No restrictions are imposed on production • Production rates are maximized • Gas turbulence areas are eliminated • No restrictions on any service/intervention tools • Tubing retrieval to the liner top is allowed • Full access to the liner for squeezing or mechanical isolation of the perforations is allowed• Ancillary equipment requirements are minimized.

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