Drilling Operations in HP/HT Environment

The development of oil and gas assets is becoming more complex, with reserves being found in more challenging environments. Wells are being drilled to greater depths and in areas where the temperature gradient is higher. This has led to requirement for downhole equipment that can withstand temperature in excess of 302° F (150°C) and pressures in excess of 30,000 psi. Directional wells require measurement while drilling (MWD) and drilling systems that are reliable in these challenging environments. The problem with pressure is solved by seals to isolate equipment from the wellbore fluid and variations in materials and dimensions to withstand the pressure. The greater challenge is with electronic components in a high-temperature environment. Conventional drilling assemblies are generally rated to 302°F (150°C), which is far below the rating required for a high-temperature MWD and rotary steerable systems (RSS). New techniques were required in the design of MWD and RSS tools for high-temperature wells. This paper covers the work of one service company in the development of high-temperature drilling equipment that can be used in environments up to 350°F (175°C) and at pressures of 30,000 psi. The paper will describe the development of a new system that included an MWD system and an RSS capable of drilling wells at 350°F (175°C) and up to 30,000 psi. The authors will use detailed case histories to show how this system was used to provide a true step-change in performance in this challenging environment.