Abstract
The supercritical carbon dioxide (SC-CO2) jet offers many advantages over water jets in the field of oil and gas exploration and development. To take better advantage of the SC-CO2 jet, effects of nozzle configuration on rock erosion characteristics were experimentally investigated with respect to the erosion volume. A convergent nozzle and two Laval nozzles, as well as artificial cores were employed in the experiments. It was found that the Laval nozzle can enhance rock erosion ability, which largely depends on the pressure and temperature conditions. The enhancement increases with rising inlet pressure. Compared with the convergent nozzle, the Laval-1 nozzle maximally enhances the erosion volume by 10%, 21.2% and 30.3% at inlet pressures of 30, 40 and 50 MPa, respectively; while the Laval-2 nozzle maximally increases the erosion volume by 32.5%, 49.2% and 60%. Moreover, the enhancement decreases with increasing ambient pressure under constant inlet pressure or constant pressure drop. The growth of fluid temperature above the critical value can increase the enhancement. In addition, the jet from the Laval-2 nozzle with a smooth inner profile always has a greater erosion ability than that from the Laval-1 nozzle.
Highlights
The application of supercritical carbon dioxide (SC-CO2 ) has achieved obvious progress during the last few decades, stimulated by the demand of a wide range of industries that have recognized the incomparable advantages of SC-CO2 fluid [1]
Sci. 2017, 2017, 7, 606 likely to depend on the nozzle configuration and the ratio of the inlet pressure and the ambient depend onThis the nozzle and thepressure ratio of the inlet and effects the ambient pressure
To improve erosion ability of the SC-CO2 jet for better practical applications, effects of nozzle configuration on rock erosion were experimentally investigated with respect to the macroscopic appearances and erosion volumes of eroded specimens
Summary
The application of supercritical carbon dioxide (SC-CO2 ) has achieved obvious progress during the last few decades, stimulated by the demand of a wide range of industries that have recognized the incomparable advantages of SC-CO2 fluid [1]. SC-CO2 is an intermediate state between gas and liquid for carbon dioxide when the pressure and temperature are both above the critical point (Pc = 7.38 MPa and Tc = 304.13 K, respectively; the subscript “c” indicates the critical value.) [2]. It has many unique properties, such as high density, high diffusivity, low viscosity, high absorptive capacity by rock substances and so on, which make SC-CO2 very suitable for the exploitation of oil and gas reservoirs as a working fluid [3,4,5,6].
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