Evidence of catastrophic choke failure in a few hours, when deployed downstream of wellhead, upstream of cyclonic sand traps, constrains operators on placement to protect mission critical expensive production equipment. This potentially leads to exposure of site personnel to high pressures and temperatures when dumping sand, and the frequent replacement of chokes due to high velocity sand erosion. To increase mean time between failures (MTBF) of the components discussed above, a multi prong approach is warranted with intelligent design changes to made to overcome these frequent failures. Design reviews with operators and end customers, including root cause failure analysis, have helped resolve part of underlying problems. With the advent of bulk nanomaterials, abrasion resistant nanocomposites with tailored properties: strength, modulus thus apposite hardness, abrasion aka erosion resistance, and fracture toughness surpassing properties of commercial cemented carbides have been proposed as a key alternate to help bridge this challenging technology gap.
For extreme wear, we have adapted a powder metallurgy approach. Here we present, the design of nanocomposites wherein the base material may be a combination of ultra-hard, heavy nanoparticulates having multi nanophase inclusions with grain size varying between 100 nm to submicron grains (800 nm), coated Polycrystalline Diamond (PCD) to prevent graphitization during consolidation abetted by high pressures and temperatures and Cubic Boron Nitride (CBN). Salient American Society for Testing and Materials (ASTM) G65 standard abrasion tests on bulk solids have shown superior performance up to ten fold (10X) improvement over High Velocity Oxygen Fuel (HVOF) Tungsten carbide (WC) coatings and overlays and a two- to five- fold (2 to 5X) improvement over traditional bulk WC*. The rationale for the predicted high erosion resistance of the abrasion resistant nanocomposite (ARn-C) sample in the ASTM G65 test is due to the defect free sintered carbide with proprietary High Entropy Alloy/Bulk Metallic Glass (HEA/BMG) binders at elevated consolidation temperatures, under pressure.
The first embodiment, a choke bean for high pressure gas well, was deployed and field trials performed in H2 2023, wherein venturi choke beans survived placement downstream of wellhead in aggressive field trials and outperformed commercial counterparts. 24/64 and 32/64 venturi choke beans were introduced alongside their commercial counterparts in the field. Our unique design intelligently places vena-contracta, where maximum velocity (and lowest pressure) is evident, away from metallic outer sleeve of choke bean, unlike the conventional design. This is one of the rationale, designed venturi choke bean survived days of flow in an extreme abrasive stream, while conventional bean failed in a few hours.
Multiple designs of choke beans are now matured, embodiments manufactured and awaiting final field trials before commercialization. ASTM G65 tests, Computational Fluid Dynamics (CFD) and field trials have allowed us calibrate erosion profile of ARn-C, optimize the design, include eddy breakers and deflector in the venturi exhaust to tailor flow. One of many designs is a superior, however economized offering to participate in current competitive landscape. The focus of our paper is detailing a structured engineering approach to develop a solution for choke beans while outlining other technology gaps to be bridged using ARn-C. Re-design choke beans offers significantly increased operating life and lower MTBF.
Nanocomposites stemming from a metal-matrix, polymeric or a combination thereof or an agglomeration of nanocrystalline particulates exhibiting novel properties are unique. Designed venturi choke bean allows 5 to 15% increase flow compared to conventional commercial choke bean due to its efficient venturi design. *Patents-Pending.
