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Elastomers are being increasingly used for sealing and other applications in the oil and gas industry. Specifically developed elastomers possess durable properties and have the ability to withstand detrimental effects of heat, chemicals, and harsh environments. For successful modeling and simulation of various downhole processes, it is very important to determine the behavior of elastomer materials under realistic well conditions. Of special interest is the class known as swelling elastomers. This article reports some results from experiments conducted on mechanical testing and characterization of an inert (nonswelling) and a water-swelling elastomer (both belonging to the EPDM family) used for sealing purposes by a local petroleum development firm. Experiments were designed and conducted in accordance with standard ASTM test methods. Apart from regularly available testing equipment, some simple test rigs and fixtures were designed and fabricated. Elastomer behavior was tested for hardness, compression set (at different temperatures and for different periods of time), tensile set (for different periods of time), tensile properties (fracture strength and percent elongation), and swelling. In the swelling test, different sample geometries (unconfined samples and samples mounted on steel plate) were tested for a total duration of 1000 h (roughly 45 days) in salt solutions of different concentrations and at different temperatures. Results show that compression set increases with increasing temperature and testing time, while room temperature tensile set also increases with longer testing time. Compared to the inert elastomer (exhibiting nonlinear elastic behavior like normal rubbers), swelling elastomer surprisingly showed linear stress—strain response. As expected, the inert elastomer did not exhibit any change in volume, while the swelling elastomer showed significant volume/thickness increase with increasing test temperature and decreasing salt concentration.

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Belonging to the class of chromium tool steels, AISI H11 possesses very good toughness and hardness, and is therefore suitable for hot metalforming jobs performed at very high loads. Mostly used in fabrication of helicopter rotor blades, H11 also has great potential as a die steel in hot-work forging and extrusion. This alloy steel can be heat treated to increase the service life and dimensional accuracy of the die and tooling. Main aim of the current investigation was to formulate an optimum heat treatment strategy for H11 steel, especially for hot work applications. High-speed milling and electric discharge machining were used to fabricate samples for tensile and impact testing. After various types of heat treatment (annealing, austenitizing, air cooling or oil quenching, single and double tempering), these samples were tested for hardness, toughness (impact), yield strength, tensile strength, and ductility. Microstructural analysis was also performed to analyze the effect of heat treatment on mechanical properties. As tempering temperature increases, hardness initially increases and then starts to gradually decrease; impact strength first decreases and then increases; and yield strength exhibits a fluctuating pattern of initial decline followed by an increase and another decrease. Even though H11 steel is highly suitable for both hot and cold-work, it is surprisingly not a common choice for metalworking dies and tools. Results presented here can encourage die designers and hot-work practitioners to explore the versatility of this tool steel, and to adopt appropriate heat treatment strategies for different applications.

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Swelling elastomers are special polymers that increase in volume when exposed to water or oil. They have been successfully deployed in oil and gas wells for isolation of water-producing zones, partial replacement of cementing, slimming down of wells, and so on. Performance appraisal and design modifications cannot be attempted without knowledge of material response under specific field conditions. Results from an experimental investigation are presented here about the behavior of two commercial elastomers, one water swelling and one oil swelling. Of the one-month total testing time, one set of samples (for each elastomer type) was tested under acid for one day, and the other set without any acid exposure. Readings were taken at different stages of swelling to record the variation in volume, thickness, and hardness of elastomer samples. Test parameters were set to match existing conditions in a regional oil well. These results can be used to assess performance of elastomers under given well conditions and for modeling and simulation of seal behavior.

Last decade has seen growing use of swelling elastomers in various applications by the oil and gas industry. Elastomers with special properties have been developed to sustain the specific downhole conditions of temperature, pressure, and chemical environment in different wells. Apart from targeted short-term tests conducted by rubber developers and drilling application companies, little is known about material characterization of such elastomers. Even these test results are not generally available in the public domain due to proprietary rights. In particular, an important factor that has not been previously explored is the effect of exposure on material response of swelling elastomers. Zonal isolation packers and other forms of elastomer-mounted tubulars are often stacked in open yards for a long time before their deployment in wells. Properties of elastomers may significantly change due to their exposure to air, sunlight, and humidity. Some results from a comparative study of the behavior of fresh and exposed samples of an ethylene propylene diene monomer (EPDM)-type water-swelling elastomers are reported here. Methodology of the swelling test was developed in consultation with petroleum engineers and rubber manufacturers. Other experiments were designed and performed in line with standard ASTM test methods. Properties of elastomers that are investigated are hardness, compression set, tensile set, tensile properties, and swelling behavior. Elastomer samples were allowed to swell for a total test duration of 1000 h. Two specimen geometries were tested for swelling: unconfined disc samples to study the behavior of free elastomer and plate samples (elastomer vulcanized on steel plate) to emulate the actual seal performance. Swelling was carried out in salt solutions of different concentrations and at different temperatures. Hardness of exposed elastomer samples (EPDM1) was generally higher than that of fresh samples (EPDM2). Similarly, exposed elastomer showed significantly higher amount of compression set when compared with fresh elastomer. Short-duration tensile set values (10 min test) were almost the same for both sample types. However, tensile set results for the longer-duration tests (10 h and 20 h) were higher for exposed samples. Surprisingly, stress–strain graphs for both fresh and exposed elastomers were almost linear, while rubber-type materials typically show a highly nonlinear behavior. Values of modulus of elasticity and stress at fracture were considerably higher for exposed samples. In contrast, percentage elongation results were higher for fresh samples. Amount of swelling against swelling time showed an up-and-down trend for both the sample types. At the same temperature and under brine solution of the same concentration, fresh elastomer generally swelled far more than the exposed one. The overall observation from the variety of experimental results is that exposure to sun and moisture for extended periods of time reduces the flexibility and swelling capacity of these elastomers.