Novel Expanding Metal Alloy for Non-Elastomeric Sealing and Anchoring

Abstract

A new class of expanding isolation systems has been enabled by the creation of a uniquely engineered expanding metal alloy. The engineered metal alloy expands downhole and chemically transforms from a metal alloy into a rock-like seal. This novel metal alloy results in a sealing system that combines the operational simplicity of swellable elastomers with the robustness of non-elastomeric seals and includes an anchoring capability to the seal. Swellable elastomers have provided effective zonal isolation since their introduction in the early 2000s. Swellable elastomers expand by absorbing fluids within the matrix of the elastomer. This absorption causes the swellable elastomer to expand in size and results in a high-pressure seal for zonal isolation. Despite the widespread success of swellable packers, for some applications a non-elastomeric seal for zonal isolation is preferred and more reliable. Applications benefit from non-elastomeric seals for zonal isolation due to temperature, pressure, or chemical compatibility reasons. Other applications, such as fluid injection operations, require anchoring capabilities which can be challenging with swellable elastomers. The new engineered metal alloy chemically reacts with the downhole water-based fluids and expands into a strong rock-like material that provides non-elastomeric zonal isolation with pressure and anchoring capabilities exceeding swellable technology at higher expansion ratios. In addition, water swellable elastomers are not suitable for applications which have a high salinity brine or produced water as the setting fluid. By contrast the expanding metal alloy chemical reaction is enhanced by increasing salinity. The expanding metal alloy bonds with the water-based fluid in the wellbore and this chemical reaction causes the metal to expand into a rock-like material. The chemical reaction results in a new material that is larger than the original alloy. Unlike a swellable elastomer which absorbs fluids (a purely physical process governed by thermodynamics and osmosis), the metal alloy's molecular structure chemically transforms, incorporating the water molecules to create a new material. The metal alloy can expand over 80% as it transforms into its final state as a rock-like seal. Extensive small-scale and full-scale tests were conducted to reliably and consistently map the metamorphosis from the engineered metal alloy into the rock-like material. These tests required developing new methods for testing the material including designing new test fixtures and new test procedures. Testing proved seals were created in smooth cylinders as well as in irregular shapes and with a wide range of brine types and brine concentrations. The result is an expanding engineered alloy that creates a robust and durable seal with anchoring capabilities across a wide range of downhole conditions. A novel non-elastomeric zonal isolation system is composed of a new expanding metal alloy that expands in water-based wellbore fluid, completion fluid, or formation fluid. The performance of this new material has been demonstrated through experimental testing. This paper discusses the development and initial testing of this new expanding metal and the process of forming a robust and reliable downhole seal with anchoring capabilities.