Packer & Safety Valve Development for Ultra High Pressure High Temperature Test & Production Wells
Authors: Taylor Daniel Martin 
Published: April 2012

As operators continue to uncover new hydrocarbon reservoirs, they are findingthat there are a growing number of opportunities for new developments in ultrahigh-pressure, high-temperature (UHPHT) formations beyond 400ºF and up to30,000 psi. However, if these new areas are to be successfully exploited, newequipment must be developed that will maintain integrity for theseconditions.

This paper looks at issues surrounding the development of " fit-for-purpose" drill-stem-testing (DST) completion solutions as well as the development oflong-term UHPHT production packers and safety valves. This equipment requiresappropriate metallurgical and elastomeric selection, and this will include notonly conventional oilfield materials qualified to higher parameters forshort-term test applications, but qualification of new materials for long-termapplications that will require cyclic load testing for a 30-year well life. Inaddition, setting methods with the forces needed to affect a high-pressure sealand dynamic sealing systems will be required that can provide pressureintegrity and prevent tubing overloads. Consideration for design requirementssuch as maximized IDs through the packers will be needed as well.

The discussion will include:Completion equipment that is already available to the industry for theseconditionsEquipment being developed currently to meet the new requirementsTest methods and qualification requirements for validation of suchequipmentRequirements for environmental, personnel, and regulatory standards as wellas safety.

Introduction

With the ever increasing global demand for hydrocarbons, the oil and gasindustry is being challenged to explore and develop deeper and hotterreservoirs, pushing the boundaries of equipment capabilities ever further intothe extreme and ultra-extreme HPHT arenas from the traditional standard andHPHT environments. Figure 1 illustrates the evolution of this progress andprovides one definition of the various HPHT environments.

While there are many equipment components that will be needed in order toexplore and develop these horizons, two of the most critical safety componentsare the tubing retrievable safety valve (TRSV) and the packer. The design ofthese tools must balance two conflicting aspects of UHPHT completions. Thefirst concerns the fact that the exploitation of deep HPHT horizons involvesconsiderable investment, and therefore, maximization of production is requiredto justify this investment. With extreme temperatures limiting the period oftime perforating guns can be in the well prior to firing (Hahn et al., 2005), installation operations can dictate the use of wireline-conveyed perforatingguns, necessitating the maximization of the completion inside diameter (ID) torun and retrieve these guns. For relatively lower temperatures, perforatingguns can be run with the completion below the packer and fired once thecompletion is landed and tested. In this scenario, maximizing production flowrate will continue to require maximizing the IDs of the TRSV and packer.

The second aspect to the design of these tools (as well as all casings andtubulars) is that higher temperatures reduce material yield-strength ratings. Coupled with the need to contain the high pressures, these two factors drivethe need for increased wall thickness, which reduces the IDs.