Advances in drilling and completion technology are allowing high-pressure, high-temperature (HP/HT) applications to become more commercially viable. Whilethere is a minimum industry accepted designation of 15,000 psi as " highpressure" and 350°F as " high temperature," these are rapidly becoming the lowerlimits of the HP/HT category. The HP/HT designation serves to alert operatorsand manufacturers alike that equipment for such use requires a higher level ofattention to adhere to new regulatory requirements with respect to design, qualification, and testing.
While the HP/HT designation typically applies to all completion equipment ratedhigher than 15,000 psi or 350°F, it is particularly critical within thesubsurface safety valve suite of tools. As these tools serve as the emergencyfail-safe flow controlling safety device within the completion, they have asupreme requirement for both performance and reliability. These tools mustperform throughout the life of the well, which is extremely challenging whenoperating these tools in HP/HT environments. For such a development, everyfeature within the subsurface safety valve must be evaluated and scrutinizedand considered against regulatory requirements. As a result, additionalvalidation techniques must be employed to ensure robust, fit-for-purposeperformance of the product early in the development process.
This paper discusses key aspects in the design, development, and validation ofHP/HT subsurface safety valves. The paper will cover specific componentsincluding detailed stress analysis in addition to elastic displacements, metallic and nonmetallic materials, control fluids, and validationmethods.
Driven by increased energy demands and the search for hydrocarbons in deeperformations, the number of HP/HT projects has increased significantly over thepast couple of decades. Advances in drilling and completion technologies allowfor extreme HP/HT applications to be commercially viable. And increasedcustomer collaboration with key operators, combined with significant investmentby service companies in technology innovation, will commercialize products thatwill make ultra HP/HT a reality in the not-too-distant future.
While there is a minimum industry accepted designation of 15,000 psi as" high-pressure" and 350°F as " high temperature," these are rapidly becoming thelower limits of the HP/HT category. The industry has widely accepted a tierstructure to depict HP/HT applications which categorizes these tiers andprovides detail to the limitations of completion technology within each (Fig. 1).