Method for acquiring opening timing of natural fracture under in-slit temporary plugging condition

Abstract

A method for acquiring an opening timing of natural fracture under an in-slit temporary plugging condition and a device thereof are provided. The method includes steps of: acquiring physical parameters of stratum according to site geological data, and measuring a slit length L of a hydraulic fracture; dividing the hydraulic fracture into N unit bodies of equal length and numbering them sequentially; and dividing a total calculation time t into in time nodes with equal interval; calculating a width of each unit body in the hydraulic fracture at the initial time; calculating a fluid pressure in the hydraulic fracture at the k-th time node; calculating a closed pressure at an entrance of the natural fracture on an upper side and a lower side of the hydraulic fracture at the k-th time node; and determining whether the natural fracture is opened by a determining criteria based on the above calculation results.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a method for acquiring an opening timing of natural fracture under an in-slit temporary plugging condition and a device thereof, which belongs to the field of oil and gas exploration and development.BACKGROUND OF THE INVENTION[0002]Hydraulic fracturing technology is an important means for increased production of low permeability oil and gas reservoirs. Hydraulic fracturing means that a set of ground high-pressure pumps is used to pump the fracturing fluid into the stratum with a displacement exceeding the absorption capacity of the stratum to produce hydraulic fracture, and then a fracturing fluid with proppant (sand particles) is continued to be injected to allow the fracture to continue to extend and be further filled with the proppant. When the fracturing fluid is discharged to return, the proppant acts as a support in the fracture for preventing the fracture from closing due to the pressure of the stratum, so that a sa...

AI Technical Summary

Benefits of technology

The present invention provides a method for accurately calculating the opening timing of a natural fracture during a temporary plugging turnaround fracturing process, which helps to provide effective guidance for fracturing design. This method is reliable and high in calculation accuracy, allowing for accurate results even in complex situations.

Problems solved by technology

Temporary plugging failure refers to the phenomenon that the fracturing fluid inside the hydraulic fracture breaks through temporary plugging regions at the tip during the fracturing process, causing the temporary plugging section to lose its plugging effect, and then the hydraulic fracture continues to extend forward along the original path.

For hydraulic fracturing, the length and width of hydraulic fracture increase continuously during the fracturing process, resulting in a continuously increased extrusion on the surrounding rocks, so that the induced stress generated inside the rock increases continuously, which may also indirectly affect the opening process of the natural fracture.

However, most of conventional studies only aim at determining the opening time when the hydraulic fracture tip meets the natural fracture, but without specifically analyzing the opening timing of the natural fracture in the case of also applying in-slit temporary plugging onto the tip after the hydraulic fracture passes through the natural fracture.

Therefore, these conventional methods may not reflect or predict well the actual opening process of natural fracture under the in-slit temporary plugging condition.

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