Deformation and Fracture of Polymers used in Oil & Gas Seal Systems
Buc Slay (Weatherford)
Engineering Mechanics and Materials in the Oilfield
Wed 10:45 - 12:15
CIT 227
Most sealing system polymers are useful in the recovery of Oil and Gas reserves. Lower performance materials can be effectively used if risk and replacement costs are minimal. Higher performance materials are often used to increase tool lifetimes, survive aggressive fluids, resist high temperature degradation, or improve reliability. Successful sealing solutions require compliance to conform to metal sealing surfaces, stiffness to resist extrusion, and toughness to resist fracture. This combination of properties is often achieved by stacking various rubber and plastic seal components. Standard laboratory tests are used to compare materials and generate modeling data but are less useful for predicting sealing performance, long term deformation, and fracture. Performance predictions are often times based on seal component and seal system testing in simulated service conditions. In the field, surface temperatures often drop below -40°C and downhole steam injection temperatures can top 300°C. Hydrostatic reservoir pressures can reach 276 MPa (40,000 psi) and differential pressures across a seal often exceed 172 MPa (25,000 psi). During the tool and seal development stages, the performance in benign fluid and gas environments is determined. One must then consider the effects of chemically aggressive media that might exist in the reservoir or are introduced from the surface. This presentation will explore the deformation and fracture of Oil & Gas sealing materials and how they are characterized with laboratory and part testing.