A zero-discharge fracturing flowback fluid treatment system and its adjustment method

Abstract

A zero-discharge fracturing flowback liquid treatment system and an adjustment method thereof belong to the technical field of shale gas wastewater treatment and self-control adjustment. According to the salinity of the fracturing flowback fluid, the system adjusts the flow rate of the forward osmosis membrane draw liquid and the heating steam volume of the distillation crystallization device by adjusting the control unit. When the salinity of the fracturing flowback fluid on the raw material side increases, the water flux of the membrane decreases due to the concentration polarization in the membrane, the concentration of the draw solution outlet on the draw solution side decreases, and the treatment efficiency of the membrane decreases. In order to effectively reduce the influence of concentration polarization on water flux, increase the inlet flow rate of the draw liquid, increase the disturbance of the fluid between the membrane surface and the draw liquid, reduce the concentration polarization on the side of the membrane support layer, and increase the water flux of the membrane , to partially offset the water flux reduction effect caused by the increase in the salinity of the flowback liquid, realize the optimization of the flowback liquid treatment capacity between the two draw liquid forward osmosis membrane methods, and improve the treatment efficiency when the working condition deviates from the design, the maximum To a certain extent, the flowback fluid can be directly reused as fracturing fluid.

Description

technical field [0001] The invention relates to a zero-discharge fracturing flowback fluid treatment system and an adjustment method thereof, belonging to the technical field of shale gas wastewater treatment and self-control adjustment. Background technique [0002] As an unconventional clean energy, shale gas will play an important role in stabilizing my country's energy supply and economic development. The hydraulic fracturing technology for developing shale gas increases the production of shale gas, but it also brings about the problem of dealing with a large amount of fracturing flowback fluid. The main technical obstacle to the reuse of flowback fluid is that the flowback fluid contains chemical substances such as drag reducers, antiscalants, and fungicides, as well as chloride ions and metal ions. The treatment and reuse of flowback fluid has become an obstacle to shale gas exploitation. key factor. [0003] The difficulty in the treatment of high-salinity fracturin...

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Problems solved by technology

[0005] The existing technology is only applicable to the salinity of the flowback liquid under the design conditions, and the actual water quality of the flowback liquid changes greatly with the change of the mining cycle. When the salinity of the flowback liquid increases, the water quality of the forward osmosis membrane method The flux will be reduced, which in turn will reduce the outlet concentration of the draw liquid and the outlet concentration of the flowback liquid. As a result, the medium-pressure steam consumed by the distillation of the concentrated flowback liquid will increase significantly, and the draw liquid cannot be recycled.

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