Device for observing transportation of propping agent in fracturing process of coal reservoir

Abstract

A device for observing transportation of a propping agent in a fracturing process of a coal reservoir comprises a coal reservoir simulating system, a confining pressure loading system, a fracturing fluid pumping-in system, a data acquiring and analyzing system and a waste treatment system, wherein the fracturing fluid pumping-in system is connected with a liquid inlet of the coal reservoir simulating system; and the waste treatment system is connected with a liquid outlet of the coal reservoir simulating system. For solving the problems that distribution conditions of a fractured propping agent in fracture channels of coal beds are unclear under different fracturing operational discharge capacity, propping agent concentration, liquid levels and fracture development of the coal reservoir, and field fracturing design cannot be guided effectively, a visualized device which simulates transportation and laying of the propping agent in a fracturing process under different fracture development degrees of the coal reservoir and different pumping-in diameters is designed. By the device, the laying condition of the propping agent fractured under different conditions can be observed clearly, so that experimental basis can be provided for field fracturing design.

Description

technical field [0001] The invention belongs to the technical field of coal reservoir development and production, and in particular relates to a proppant migration device for observing coal reservoir fracturing process. Background technique [0002] Coalbed methane mainly exists in the coal seam in the state of adsorption. Coal reservoirs are double-porous fractured rock formations composed of matrix pores and fissures. The shape, size and connectivity of pores and fissures determine the storage and migration of coalbed methane. Because the original fractures of my country's coal reservoirs are not well developed, it is necessary to reform the coal reservoirs in order to develop the coalbed methane that exists in the coal seams. In order to prevent fracture closure after reconstruction, a certain amount of proppant needs to be added to support the fracture. Differences in the stress state of the coal seam, the development of fractures in the coal seam itself, the mechanica...

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Problems solved by technology

[0003] In order to study the migration of proppant in the coal reservoir during the fracturing process, some researchers at home and abroad made a box-shaped container, drilled several holes on one side of the container to simulate the holes in the fracturing coal seam, and pumped The liquid and proppant are injected into the box-shaped container to see the migration law of the proppant. Since the coal reservoir fractures and the stress state cannot be simulated more realistically, there is a certain discrepancy between the simulation results and the actual situation.

Some researchers simulate a single fracture in a slab, and test its conductivity by changing the concentration of the proppant and the size of the proppant particles, which cannot realistically simulate the placement of the proppant during the fracturing process and guide the on-site Fracturing has certain limitations

Some researchers change the fracture width through a flat plate, inject proppant into the flat mold through a pump, and test the change of permeability before and after injection, which has certain guiding significance for fracturing design, but this device does not consider the frictional resistance of fractures during fracturing and local resistance, when the site friction is large, the result of proppant laying and the actual difference will be large, which will affect the fracturing design results

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