Rubber or elastomeric seals are flexible polymers used in a variety of applications in many industries, and as polymer technology has advanced, they have become more widely used in oilfield equipment. One significant problem, however, has concerned the fact that they can be damaged during a rapid decrease of pressure after being exposed to environments containing gas. This phenomenon is known as explosive decompression (ED) or rapid gas decompression (RGD).
RGD damage can be manifested as splits, cracks, or bubbles in the seals (depending on the rubber type), length of exposure to the gas, and the rate of pressure decrease. Damage caused to a seal by RGD can range in severity from a slight weakening of the physical properties of the rubber to a catastrophic failure of the integrity of the seal. RGD can be caused by both surface operations and downhole conditions and can result in failure of the equipment in which the seals are used.
This paper discusses tests performed on various elastomeric samples, including swellable rubber, to determine the effects that RGD will have on the seals under varying conditions. The tests exposed each sample to a range of pressure drops and gas exposure times. The samples were analyzed after each test for physical changes and signs of RGD damage. The purpose of mapping the effects of RGD on multiple samples and the various conditions to which the seals were subjected was to 1) develop a better understanding of the conditions leading to RGD damage, and 2), to identify operations at risk for causing RGD damage to elastomeric seals. The testing and results are discussed in this paper.