INTRODUCTION
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 strengthto- 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 hightemperature polymer composite systems will be presented and addressed based on an ongoing composite downhole environmental resistance test program.
It is commonly known that oilfield downhole operations including drilling, logging, completion, production and workover require equipment to perform in an extremely harsh environment in a deep well involving high-pressure, high-temperature (HPHT), and various corrosive fluids and gases. This requires the aterials for downhole equipment to possess high strength with heat- and corrosion-resistant capabilities. Many completion and workover tools are set temporarily in a well bore, and must be removed immediately after the operation. This requires easy drilling or milling of the tool materials. Recently developed new technologies in oil and gas E&P, involving offshore deepwater extended reach drilling and completion, further require the materials for downhole tubular components and equipment to possess light-weight and fatigue-resistance. Traditional metals are inherently heavy and difficult to drill. Carbon steel products are susceptible to corrosion, and have relatively low fatigue life. These limit the efficiency of the operations substantially in oil-field exploration and production.
Advanced fiber-reinforced composite materials, with recent advances in high-temperature, highperformance matrix resins, enable work at elevated temperatures in well bore, offering various advantages such as high strength, light weight, good corrosion resistance, long fatigue life and easy removal. Non-conductive and non-magnetic polymer composites have been long ideal materials for housing structures of the electrical and electromagnetic devices in resistivity and induction logging tools.
Glass-fiber-reinforced plastics (GRP) and other polymer-matrix composite products have been used in certain downhole operations since 1970s, such as sucker rods, downhole tubing, drill pipes, coiled tubing and well screens1. However, these applications are still very limited in temperat
