Method for obtaining surface contact ratio of acid etching fracture by experiment measure

Abstract

The invention discloses a method for obtaining the surface contact ratio of an acid etching fracture by an experiment measure. The method comprises the following steps of: (A) respectively cutting white paper and carbon paper which have the same surface shape and size as an original rock plate; (B) sequentially putting the white paper, the carbon paper and the rock plate subjected to acid etching on a smooth steel plate; then putting a rigid press head onto the rock plate; exerting preset pressure on the rigid press head; and performing stabilization for one minute; (C) unloading the pressure (a mark of the contact area between the rough surface of the rock plate and the steel plate is left on the white paper by carbon paper); (D) dividing the total pixel of the whole paper by the pixel of the mark part to obtain the contact ratio between the rock plate and the steel plate; and (E) multiplying the contact ratio by 20.25 to obtain the contact ratio of the two rock plate surfaces corresponding to the rock plate under the mutual contact condition. The method has the advantages that the principle is reliable; the operation is simple and convenient; and the accurate contact ratio data can be provided for the study of the acid etching crack flow guide capability.

Description

technical field [0001] The invention relates to the field of petroleum, in particular to a method for obtaining the surface contact ratio of acid-etched fractures by using experimental means in the field of acid fracturing. Background technique [0002] Acid fracturing (acid fracturing for short) is the main measure for oil and gas stimulation, which is mainly to inject acid liquid (or pre-fluid) into the reservoir under the condition of higher than the fracture pressure of oil and gas reservoirs or the closure pressure of natural fractures. New artificial fractures are formed in the reservoir or natural fractures are opened, and the injected acid solution causes non-uniform etching on the surface of the fractures. After the acid flowback, due to the rough surface of the fracture, the convex part of the surface keeps the fracture open to a certain extent under the closing pressure, thereby forming a fracture that provides a flow space for the fluid and has a certain flow con...

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Problems solved by technology

[0021] Although the Hertz contact formula provides a calculation method for the contact ratio of the acid-etched fracture surface under a certain closing pressure, it can be seen from the above parameters that the calculation process is relatively complicated, especially when calculating the root mean square roughness and the curvature of the rough surface , it is necessary to use a 3D laser scanner to scan the rough surface of the rock slab to obtain 3D data of the rough surface

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