Step calibration method for rock plate surface scanning data in acid etching physical simulating experiment
A technology of physical simulation and scan step size, which is applied in acid fracturing and petroleum fields, and can solve problems such as the size effect of scan step size
Active Publication Date: 2015-11-18
SOUTHWEST PETROLEUM UNIV
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[0005] However, there is a serious problem in the calculation process of the parameters characterizing the roughness of the fracture surface (hereinafter collectively referred to as the characterization parameters)—the scanning step size effect
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[0039] The present invention will be further explained below based on the drawings.
[0040] First, the "size effect" is explained in detail with reference to the drawings. Such as figure 1 , figure 2 , image 3 As shown, between point A and point B is any curve on the rough surface of the rock slab, the black point is the point selected equidistantly between point A and point B, and the distance between two adjacent points is ΔL. The following approximate calculation of the curve segment length between A and B according to different scanning step lengths.
[0041] 1) When the scan step size is ΔL
[0042] Such as figure 1 As shown, take the scan step length as ΔL, and calculate the length of the curve segment between A and B as L 1 (That is, the length of the zigzag line between A and B in the figure).
[0043] 2) When the scan step size is 2ΔL
[0044] Such as figure 2 As shown, take the scan step length as 2ΔL, and calculate the length of the curve segment between A and B as L...
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The invention discloses a step calibration method for rock plate surface scanning data in an acid etching physical simulating experiment. The step calibration method comprises the steps of (A) setting the initial scanning step of a three-dimensional laser scanner to 0.01mm; (B) scanning a smooth and flat rock plate surface which is not etched by an acid by means of the three-dimensional scanner for acquiring three-dimensional data of the rock plate surface; (C) calculating the average deflection ratio epsilon<-> of the rock plate surface by means of three-dimensional data in the step (B); (D) calculating the relative error [the absolute value of epsilon<->-1] by means of the average defection ratio epsilon<-> which is obtained in the step (C); and (E) changing the scanning step in a manner of adding 0.1mm each time; and successively repeating the step (B), the step (C) and the step (D) until the value of the calculated [the absolute value of epsilon<->-1] is smaller than 0.0001, and the scanning step when the [the absolute value of epsilon<->-1] is just smaller than 0.0001 is an optimal scanning step. The step calibration method has an advantage of reliable principle and furthermore can supply an appropriate scanning step for calculation of a characterization parameter.
Description
Technical field [0001] The invention relates to the field of petroleum, in particular to a step length calibration method of scan data on the surface of a rock slab in an acid etching physical simulation experiment in the field of acid fracturing. Background technique [0002] Acid fracturing (abbreviated as acid fracturing) is the main measure of oil and gas production stimulation. It is mainly used to inject acid (or prefluid) into the reservoir under the condition of higher than the fracture pressure of the oil and gas reservoir or natural fracture closure pressure. New artificial fractures are formed in the reservoir or natural fractures are opened. At the same time, the injected acid will etch the surface of the fractures unevenly. After the acid fluid flows back, due to the roughness of the crack surface, the convex part of the surface keeps the crack open to a certain degree under the action of the closing pressure, thereby forming a crack with a certain conductivity and a...
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Login to View More IPC IPC(8): G01B11/30E21B43/27
Inventor 卢聪白翔郭建春苟兴豪罗波
Owner SOUTHWEST PETROLEUM UNIV