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HTHP Elastic Carbon Composite Dart Valve Seal for Downhole Chemical Injection Application 400°F+

IP.com Disclosure Number: IPCOM000248094D
Publication Date: 2016-Oct-25
Document File: 2 page(s) / 134K

Publishing Venue

The IP.com Prior Art Database

Abstract

Abstract As offshore operators get into deeper waters and develop more mature oil & gas fields using more complex well architectures, downhole injection of chemicals is increasingly required to manage challenges such as scale formation or asphaltene precipitation within the wellbore. This operation relies on chemical injection system that includes an injection check valve installed downhole in high temperature (>400°F) and pressure (>6KSI). This harsh working conditions could easily cause leakage or total failure of seal that is commonly made of polymeric materials, e.g., elastomers, plastics, composites, etc., because these material lose their mechanical strength at elevated temperature, has low wear/impact resistance and poor chemical stability to injection fluids. This invention discloses new composition and microstructure of elastic carbon composite, and also claims the design, manufacture, and use of elastic carbon composite material for dart seal in downhole chemical injections valves. Compared with broadly utilized elastomer material, well-reserved mechanical strength at elevated temperature enable Elastic carbon composite seal to address extrusion and impaction issues, and its chemical inertness prevents potential chemical erosion from injected fluids, which could dramatically increase the liability and lifetime of downhole chemical injection valves in HTHP deep sea wells. Description of the invention As shown in Fig. a, dart seal design is commonly utilized in injection valve, and an extra high load from spring (>2KI) is usually applied to the seal in addition to high downhole pressure to prevent back flow of production fluids into injection lines. Since several chemical injection valves are usually installed onto on downhole production tubing string to inject chemicals of totally different chemical and physical characteristics (i.e., address scale, wax, asphaltene issues respectively), composition and microstructure of each valve seal will be customized just according to these chemicals. For example, ordinary binders, e.g., CuNi alloy, stainless steels, Inconel alloy, etc., will be used for less corrosive water based chemical solution, including phosphonates, surfactants, polyacrylamides, etc., and highly corrosion resistant metals (e.g., Ni alloy, Ti alloy, Mo alloy, Ag, Au, etc.), ceramics (e.g., BN, BC, SiC, SiO2, etc.) and HT plastics (e.g., PTFE, PEEK) will be selected or utilized in combination to address highly corrosive chemicals, including HCl, polycarboxylic acid, etc. For organic solvent, such as xylene, toluene, etc., non-polymeric binder should suffice. Due to large pressure differential requirement in downhole conditions, content of binder will be higher than typical Elastic carbon composite formulation to achieve improved mechanical strength while reserving its flexibility and elasticity to an acceptable level. Besides, gradient elastic carbon composite structure and wear-resistance surface enhancement will also be applied to dart seal design when high impaction or wear are encountered. Due to its excellent performance as face seal, elastic carbon composite material does not requirement design change on typical dart seal configuration. Conventional designs, such as Fig. b and Fig. c are acceptable, and designs that offer more face seal interface, e.g., Fig. d and Fig. e, will provide a higher sealing rate and improved reliability. Thanks to its metallic component, Elastic carbon composite seal can be joined easily to metal base via welding or brazing or directly manufactured together through hot press.

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Title of Invention: HTHP Elastic Carbon Composite Dart Valve Seal for Downhole Chemical Injection Application 400°F+

Abstract

As offshore operators get into deeper waters and develop more mature oil & gas fields using more complex well architectures, downhole injection of chemicals is increasingly required to manage challenges such as scale formation or asphaltene precipitation within the wellbore. This operation relies on chemical injection system that includes an injection check valve installed downhole in high temperature (>400°F) and pressure (>6KSI). This harsh working conditions could easily cause leakage or total failure of seal that is commonly made of polymeric materials, e.g., elastomers, plastics, composites, etc., because these material lose their mechanical strength at elevated temperature, has low wear/impact resistance and poor chemical stability to injection fluids. This invention discloses new composition and microstructure of elastic carbon composite, and also claims the design, manufacture, and use of elastic carbon composite material for dart seal in downhole chemical injections valves. Compared with broadly utilized elastomer material, well-reserved mechanical strength at elevated temperature enable Elastic carbon composite seal to address extrusion and impaction issues, and its chemical inertness prevents potential chemical erosion from injected fluids, which could dramatically increase the liability and lifetime of downhole chemical injection valves in HTHP deep sea wells.         

Description of the invention

As shown in Fig. a, dart seal design is commonly utilized in injection valve, and an extra high load from spring (>2KI) is usually applied to the seal in addition to high downhole pressure to prevent back flow of production fluids into injection lines. Since several chemical injection valves are usually installed onto on downhole production tubing string to inject chemicals of totally different chemical and physical characteristics (i.e., address scale, wax, asphaltene issues r...