An adjustable downhole supercritical carbon dioxide jet sand mixing device

Abstract

An adjustable downhole supercritical carbon dioxide jet sand mixing device comprises a sand conveying pipe connected with a concentric pipe column in a wellbore. 2 to 4 suction ports are evenly distributed circumferentially at the middle and lower portion of the sand conveying pipe. The conveying sand pipe is internally provided with a jet device. A valve cover is arranged at the uppermost part ofthe jet device. The valve cover is provided with a through hole therein. A valve ball is arranged below the through hole. 2 to 4 suction ports are evenly distributed circumferentially at the centralportion of the jet device. According to the invention, with the use of the jet principle, the downhole fracturing liquid sand concentration can be controlled in real time by changing the pressure andflow rate of the injected carbon dioxide. At the same time, the sand mixing device in which the mixing of ground liquid-phase carbon dioxide and a proppant requires high pressure and low temperature is completed changed, the defect of failure to control the downhole sand concentration by the ground sand mixing process is overcome, and the reliability and economical efficiency are improved.

Description

technical field [0001] The invention belongs to a jet sand mixing device in the field of petroleum and natural gas exploitation, in particular to an adjustable underground supercritical carbon dioxide jet sand mixing device. Background technique [0002] The supercritical carbon dioxide fracturing process is a promising fracturing technology, which uses supercritical carbon dioxide as the fracturing fluid instead of the traditional water-based fracturing fluid. The supercritical state is a fluid form different from the gaseous state and the liquid state. The intermolecular force of carbon dioxide in the supercritical state is very small, and the surface tension is zero; the fluidity is extremely strong, the viscosity is low, similar to gas; the density is high, close to liquid, and has With strong dissolving capacity and high diffusion coefficient, supercritical carbon dioxide is one of the best working fluids for communicating reservoir micro-fractures and forming fracture ...

AI Technical Summary

Problems solved by technology

At the same time, the existing control method of ground fracturing sand concentration is to use the ground sand mixing device to press the fracturing fluid with a certain sand concentration into the formation through the fracturing pump truck and the pipe string; when the sand concentration needs to be adjusted, The newly prepared fracturing fluid with a certain sand concentration can only be transported to the formation through the fracturing pump truck and pipe string through the ground sand mixing device; therefore, it takes a certain time before and after the adjustment of the sand concentration, and at the same time Low viscosity characteristics, resulting in poor sand-carrying ability, making it impossible to control the sand concentration of the fracturing fluid reaching the formation in real time

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