Oilfield seals

A REVIEW OF ELASTOMERS USED FOR OILFIELD SEALING ENVIRONMENTS... 

These standard inhibitor solutions have been used over the last two or three years to evaluate the performance of some oilfield seal elastomers and some of these data will be reviewed here. 

Parts made from fluoroelastomers ate used ia appHcations that justify their high cost, usually where the maintenance and replacement costs are high enough to offset the initial cost of the part. These include automotive appHcations such as valve stem seals, fuel injector components, radiator, crankcase and transmission seals, and carburetor needle tips. Numerous seals and gaskets in the marine, oilfield, and chemical processing industries employ fluoroelastomers. In addition, many hoses in the automotive and chemical industry are made entirely of fluoroelastomer compounds or have a veneer of the fluoroelastomer as a barrier exposed to the harsh environment. Seals and gaskets in military appHcations and the binder for flares and missile appHcations ate made with fluoroelastomers. 

Vluorosilicone. By fluorinating the siHcone polymer molecule it is possible to improve the solvent, fuel, and oil resistance of this already heat-resistant class of elastomers. The resulting polymers are especially useful in select automotive seals and gaskets as weU as military and downhole oilfield parts. 

Sahnas, J.L., Miller, C.A., Yoo, K.H.K., Puerto, M., Hirasaki, G.A., 2009. Viscometer for opaque, sealed microemulsion samples. Paper presented at the SPE International Symposium on Oilfield Chemistry, Woodlands, 20-22 April. 

It is used for down-hole packers and seals in oil exploration and production. Oilfield equipment seals are exposed to short-term temperatures from 302 to 482°F (150 to 250°C) and pressures above 10,000 Ib/in (68.7 MPa) in the presence of aggressive hydrocarbons H2S, CH4, CO2, amine-containing corrosion inhibitors, and steam and water. 

Seals and gaskets in the marine, oilfield, and chemical processing industries employ fluoroelastomers. In addition, many hoses in the automotive and chemical industry are made entirely of fluoroelastomer compoimds or have a veneer of the fluoroelastomer as a barrier exposed to the harsh environment. 

The following standards have been developed for testing nonmetallic seal materials used in oilfield equipment ... 

NACE Standard Worksheet for the Selection of Oilfield NonmetaUic Seal Systems (RP0491) provides information on test conditions, test media, test procedures, equipment, and reports for CO2 environment testing under pressures greater than atmospheric. 

Worksheet for the Selection of Oilfield Non-metallic Seal Systems... 

Carboxylated nitrile rubbers are now increasingly seen as versatile, easy-to-process abrasion-resistant elastomers which can be used in seals, valve linings, military and industrial footwear, hoses, pump components and conveyor belts, and perhaps more significantly in all aspects of oilfield applications." ... 

The elastomeric seal is required to have the best resistance to the range of organic chemicals which are used in oilfield exploration and production. In addition to the obvious necessity for resistance to crude oil, the elastomer must not be affected by aromatic and alcohol fluids. 

The more specific property requirements relevant to oilfield usage would then be defined by separate sufiixes. The tests envisaged would address the problem areas for seals discussed already in this chapter. 

Studies of chemical attack on nitrile rubber by fluids encountered in sealing applications in the oil industry are reported. The results showed that excessive hardening of nitrile rubber in the downhole oilfield environment occurs at the acrylonitrile sites, and that it could be due to either hydrolysis or reduction of the cyano group. Hydrolysis is driven by Bronsted acids (proton donors) and reduction by Lewis acids (electron donors). Catalysis by metal ions could possibly cause these reactions to occur at a greatly reduced activation energy. Oxidative attack at the butadiene sites is the primary cause of hardening in aboveground applications of nitrile rubber. 12 refs. 

Eight papers, presented at this one-day seminar, are published examining aspects of elastomer component use in the oil recovery industry. Topics under discussion include an evaluation of HNBR in severe oilfield environments hose failure and the implications for design, manufacture and service conditions elastomeric seal life prediction and polymer coated fabrics in the oil industry. EUROPEAN COMMUNITY UK WESTERN EUROPE... 

The problem of explosive decompression damage to oilfield flowline equipment prompted the development of James Walker s FR58/90 fluoroelastomer. The research, development and field testing of Union seals made of this material is described. The Anson Superseal has now been approved and accepted by major operators for sour gas explosive decompression service. 2 refs. 

K.J. Kennelley, P.J. Abrams, J.C. Vicic, and D. Cain, Failure Life Determination of Oilfield Elastomer Seals in Sour Gas/Dimethyl Disulfide Environments, Paper 212 Presented at Corrosion 89, NACE, New Orleans, April 17-21, 1989. 

D. Janoff, J. Vicic, and D. Cain, Thermoplastic Elastomer Alloy, TPA, Sub sea Hydraulic Seal Development for Service Including Water-Based Fluids, Conference Papers, International Conference on Oilfield Engineering with Polymers, October 28-29, 1996, London, UK. 

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