Abstract
Oilfield downhole operations including drilling, logging, completion and workover require equipment that utilizes materials capable of performing in a high-temperature and highly corrosive environment. Glass-fiber reinforced plastics (GRP) and other fiber-reinforced polymer composite products have been used in downhole operations since the 1970s and have advantages over traditional metals. These advantages include high strength-to-weight ratio, good corrosion resistance, longer fatigue life and electromagnetic transmission. However, these applications are still very limited in temperature rating (mostly below 93° C) and long-term performance reliability. In many cases of downhole operations in deep wells, the service tools are required to perform at a temperature from 150° C to 232° C and under a pressure from 5,000 (34.5) to 20,000 psi (138 MPa) and commonly in a wet environment. This presents a big challenge to polymer-matrix composites for downhole uses, especially when the service temperature approaches 204° C.
In this paper, the authors will give a brief overview on composite downhole applications and the HPHT downhole environmental challenges, and also present some results of current R&D on HPHT composite system development and characterizations with Baker Oil Tools. It is found that the HPHT hot-wet environmental/ hygrothermal effects to most fiber-reinforced polymeric composites are significant, and the mechanisms involve resin, fiber and fiber/resin interface property degradations and the hygrothermal cracking of the laminated structure. Experimental results and related mechanisms on HPHT hygrothermal degradation of the selected high-temperature polymer composite systems will be presented and addressed based on an ongoing composite downhole environmental resistance test program.
