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 leading to the requirement for downhole equipment to withstand temperatures 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 operate reliably in the challenging environments. The problem of high pressure is solved using seals to isolate the inner equipment from the wellbore fluid, protecting it from variations in material properties and geometrical dimensions. The greater challenge to electronic components is in the high-temperature environment. Conventional electronic components are generally rated to 158°F, 185°F and 257°F (70°C, 85°C and 125°C), respectively, which is far below the rating required to build a high-temperature MWD and rotary steerable system (RSS). New techniques were required in the design of MWD and RSS tools for high-temperature wells. The paper describes 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 authors utilize case histories to demonstrate how the system provides a performance change in the challenging 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, requiring downhole equipment to withstand temperatures in excess of 302°F (150°C) and pressures in excess of 30,000 psi. Directional wells require measurement while drilling (MWD) and a suitable drive system, such as a positive displacement mud motor or rotary steerable system (RSS), which can operate reliably in these challenging environments. High-pressure environmental challenges are successfully addressed using seals to isolate the inner equipment from the wellbore fluid, protecting it from variations in material properties and geometrical dimensions. High-temperature environments present a greater challenge due to the design and manufacturing constraints associated with electronic components. Conventional electronic components are generally rated to 158°F, 185°F and 257°F (70°C, 85°C and 125°C), respectively, which is far below the rating required to build a high-temperature MWD and RSS. As a result, new techniques were required in the design and manufacturing of MWD and RSS tools for high-temperature wells. This paper describes the development of high-temperature drilling equipment that can be used in environments up to 350°F (175°C) operating temperature and at pressures of 30,000 psi.The authors utilize case histories to demonstrate how the system provides a performance change in the challenging environment.
High-pressure oxy-fired direct contact steam generation (HiPrOx/DCSG) can be achieved by the oxy-combustion of fuels in the presence of water. This process is capable of producing flue gas streams containing approximately 90% steam with a balance of primarily CO 2 . The product flue gas is suitable for processes where the purity of the steam is less important, such as the steam-assisted gravity drainage process used for in situ production of bitumen within the Canadian oil sands. This study had three primary objectives: (1) To show that high-moisture HiPrOx/DCSG can be achieved with hydrocarbon fuels. For this purpose, n-butanol was used because of its high volatility and ease of handling.(2) To see if this technology could be applied to fuels with lower volatilities. This was studied by attempting to combust a graphite−water slurry as well as mixtures of graphite− water slurry and butanol. (3) To determine the effects of different fuel mixtures, oxygen-to-fuel ratios, and water inputs on process stability and H 2 O partial pressure in the product gas. This paper describes pilot-scale combustion testing and process modeling of n-butanol, graphite−water slurry, and their mixtures in an atmosphere consisting of oxygen and water at a pressure of 1.5 MPa(g). Graphite/butanol mixtures were selected because certain combinations could represent the range of fixed carbon/ volatiles ratios of waste fuels and indicate whether low-volatile fuels will ignite in the high-water moderator environment. Over the butanol test periods, a steam content of around 90 mol % at saturation was achievable; the O 2 in the combustion products was between 0.08 and 3.57 mol % (wet) with an average of 1.13 mol % (wet). The CO emissions were low (<25 ppmv wet, 3% O 2 ) in the combustor. The CO levels indicated that high fuel conversion was achieved with low excess O 2 content in the combustion products. The testing also indicated that operation with extremely low O 2 is possible for specific fuels, which will minimize downstream corrosion issues and reduce the energy consumption and costs associated with oxygen production requirements. Low CO emissions (<25 ppmv wet, 3% O 2 ) and relatively good process stability were experienced for the butanol/ graphite−water slurry mixtures containing ∼40% butanol. CO emissions increased and process stability decreased as the graphite content in the fuel mixture was increased. Unassisted combustion of the graphite−water slurry was achieved for a period of 20 minutes until operational problems were encountered, due to burner plugging by the slurry, requiring that the burner be shut off. It was found that the maximum attainable H 2 O content in the product gas increased with increasing hydrogen-to-carbon ratio in the fuel. H 2 O content was around 80 mol % with 100% graphite−water slurry, 81 mol % with a 25% butanol in graphite−water slurry mixture, and around 86.5% in a 40% butanol in graphite−water slurry mixture. It was also found that the fuel H/C ratio, excess O 2 , heat loss, O 2 purity, and fuel volatil...
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