Conventional high-pressure/high-temperature (HP/HT) packer and bridge-plug technology is generally limited to long-term operation at 15,000 psi and 450°F. A great deal of research-and-development effort has been put into extending performance beyond these limits. Recently, an innovative approach was applied to this problem, with the objectives of increasing these limits and enabling long-term isolation in ultra-HP/HT wells. This approach resulted in the development of an ultra-HP/HT permanent bridge plug for long-term exposure at 25,000‑psi pressure and temperatures of 500°F.

Introduction

The process of completing an ultra-HP/HT well with temperatures approaching 500°F and hydrostatic pressures approaching 35,000 psi is evolving at a rapid pace, and the industry has identified a need for a standalone barrier to isolate the shoe track in these wells. This barrier is required in these applications to mitigate uncertainties related to shoe-track integrity. Historically, bridge plugs for use in ultra-HP/HT applications (greater than 20,000-psi differential pressure and 450°F) have not been available in the marketplace, but the demand for competent, long-term isolation has led to the development of new HP/HT technologies—specifically, ultra-HP/HT bridge plugs.

Recently, an operator of an ultra-HP/HT well identified the need for a bridge plug capable of operation at a 25,000‑psi pressure differential (from above and below) and at 500°F. This bridge plug was required to function in a 6⅝-in. outer diameter (OD) casing over the weight range of 57.58 to 60.1 lbm/ft. Furthermore, the bridge plug had to meet validation and International Organization of Standardization requirements and possess an estimated service life equal to that of the 6⅝-in. casing.

A materials-screening and qualification program was used in the design of the bridge plug. The result was a list of three perfluoroelastomer compounds that were evaluated for various seal configurations. Three metallic alloys were also identified for use in the pressure-containing, structural, gripping, and sealing components in the bridge plug. A surface-treatment-qualification program also identified two coatings for use in combating friction and galling. This effort required 18 months.