Wellbore Isolation Intervention Devices Utilizing a Metal-to-Metal Rather Than an Elastomeric Sealing Methodology

Abstract

Abstract Metal-to-metal sealing technology is a medium-to high expansion, innovative type of seal that utilizes expanding metal to achieve a fully formed pressure barrier on a tubular wall. The presented material will highlight the evolution of common oil and gas industry wellbore isolation/intervention devices that take advantage of a sealing system with an expandable metal-to-metal approach rather than a more traditional/conventional elastomeric packing element style. The applications for the technology within our industry are wide ranging even reaching through areas such as completions, liner hangers, sand control, and flow control. Initially the development was centered around proving the technology from a predominantly live well intervention philosopy focusing on bridge plugs and straddles. The replacement of an elastomeric sealing element applies in many environments; however, the metal-to-metal seal is designed with an extraordinary seal performance envelope that cannot be achieved by conventional elastomeric seals and is perceived to be particularily desirable within the realms of hostile, high pressure, high temperature and geothermal markets. Many common failures in these type of environments leading to NPT issues will be shown to be mitigated with a technology step change in seal design. The results of the learning curve knowledge gained from both the design and implementation phase of the project will be compiled and introduced. Case histories to highlight the effectiveness and uniqueness of the technology will be disseminated in order to show the differentaiting technology between the use of a metal sealing methodology when compared with that of an elastomeric approach. Evaluation of the metal-to-metal sealing technology will offer a guide in order to help in the construction of a set of criteria to fully interpret the benefits and selection of a metal sealing technology over an elastomeric seal. The contributions to our industry will be shown through the features and benefits of the metal-to-metal sealing technology over an elastomeric sealing system. Description The first evolutionary step for bridging devices was launched in Prudhoe Bay, Alaska, in the mid 1980s with the introduction of the inflatable-type isolation device. The inflatable-type packers and bridge plugs had never before seen expansion characteristics dictated by the necessity of deploying through production tubing and setting in the casing below the completion while maintaining pressure holding capability. The 'inflatable' tool was born and would forever change the high expansion world for pressure isolation devices. As operations in bottleneck type completions were becoming more common practice in the workover arena, the applications for the through-tubing inflatable also began to evolve, including:Selective and zonal chemical treatments;Temporary and permanent plug back operations;Intermediate zone blank off;Production and injection flow profile modifications; andFormation fracturing. As applications began to increase, the development of high expansion tools followed closely with the evolution of permanent and temporary bridge plugs, permanent cement retainers, permanent and retrievable straddle systems, and reliable coiled tubing conveyed multi-set straddle systems for accurate placement of wellbore treatments such as acids, scale treatments and water shutoff polymer gels.