A Proven Elastomer Compound for Extremely Hostile Geothermal and Oilfield Environments

Abstract

Abstract Since 1979 the Y267 EPDM elastomer has been independently tested by other organizations in a variety of field and laboratory applications. The following are some examples. The same &267 EPDM O-rings worked with no leaks as logging tool seals for multiple trips to 4600M (15k ft.) at 320C (608F) BHST. A packer element performed flawlessly for five months in a 204C (400F) continuous steam injection well and was retrieved at the end of the test in an as-new condition. A high-pressure Y267 EPDM packer test was performed with complete success at 232C (450F) for a 7.5 day test in sour crude with differential pressures to 138 MPa (20 ksi) and the seal condition was only very slightly changed by the test. Comprehensive compatibility testing of 34 compounds from 15 companies in geothermal brine, isobutene, and oil at 191C-266C (375-510F) showed that the Y267 EPDM was best of the 34 in all three fluids. Over 15 laboratory and over 20 field case histories of Y267 EPDM such as the above examples are reported. All strongly establish that Y267 EPDM is at the cutting edge of technology. Introduction During the period of 1976 to 1979 under the sponsorship of the U.S. Department of Energy - Division of Geothermal Energy, L'Garde, Inc. developed new elastomer compounds for the unusually histile 260C (500F) geothermal environments. Though compounds based on four different polymer systems exceeded the contract requirements, one compound (Y267 EPDM) was eminently successful for high-temperature geothermal, and oil and gas applications. Since completion of the compound development, widespread laboratory and downhole experience occurred. This paper summarizes over 15 laboratory and over 20 field tests of the Y267 EPDM under various extreme conditions. 95% of the tests were performed independent of L'Garde by other organizations. These and other substantiating data clearly show that Y267 EPDM can be classified as a technology breakthrough for high-temperature elastomers. EPDM Is Not EPDM Unfortunately, it is has been common in the industry to specify an elastomer by the polymer and its hardness, e.g. 70 durometer nitrile. This is adequate for benigh environments, however, in hostile environments which are becoming more and more commonplace today, this simple specification is grossly inadequate. Generally speaking an elastomer compound is made up of about 50% polymer, i.e. EPDM, and about 50% other ingredients. Hence, there is wide latitude to vary the characteristics with the other 50%, and it is not unusual for one of the very minor ingredients to markedly change the characteristics. In addition, with EPDMs there are about seven American manufacturers and each has about ten different EPDM polymers which have varying characteristics. It is true that a polymer will afford general characteristics virtually independent of the specific compound, however, when the requirements demand the ultimate capability to be yielded, the specific compound is critical and very probably specific tailoring for the application is required. Fortunately, the Y267 EPDM is showing superior performance in a wide variety of applications beyond the original intent, static geothermal seals. When Y267 EPDM works well outside the realm for which it was designed, the opportunity remains for even better performance with specific tailoring as was done for the geothermal static seals. Given this insight, it becomes obvious that specifying polymer and hardness is grossly inadequate for hostile environments, i.e. an EPDM is not an EPDM.