Calculating method for fracturing pressure of each perforation cluster of horizontal well sectioned multi-cluster fracturing

Abstract

The invention relates to a calculating method for fracturing pressure of each perforation cluster of horizontal well sectioned multi-cluster fracturing. The calculating method comprises the steps that firstly, needed basic parameters comprising the Poisson ratio, in-situ stress, crack height, original net pressure and the like are calculated and collected; secondly, the effective net pressure of the last perforation cluster crack of a N fracturing section relative to a (N+1) fracturing section stratum is calculated; thirdly, the total induced stress borne by the (N+1) fracturing section stratum is calculated; and fourthly, the fracturing pressure of each perforation cluster of a (N+1) fracturing section is calculated, specifically, when the perforation orientation is along the vertical ground stress, the fracturing pressure of each perforation cluster is calculated, when the perforation orientation is along the maximum horizontal ground stress, the fracturing pressure of each perforation cluster is calculated, and the fracturing pressure of each perforation cluster of the (N+1) fracturing section is the minimum value between the two fracturing pressure values. The stress barrier effect and the stress interference effect between cracks when the multiple cracks in horizontal well sectioned multi-cluster fracturing sections are synchronously expanded are considered, and the calculating method more accords with the actual working condition of sectioned multi-cluster fracturing.

Description

technical field [0001] The invention relates to a horizontal well staged multi-cluster fracturing reservoir transformation technology, in particular to a method for calculating the rupture pressure of each perforation cluster in the horizontal well staged multi-cluster fracturing. Background technique [0002] Horizontal well staged multi-cluster fracturing technology is an effective means to develop unconventional low-permeability reservoirs. This technology can not only realize the communication between artificial fractures and natural fractures, but also use induced stress to promote stress diversion to generate diverted branch fractures. A complex fracture network is formed in the formation, which makes the seepage distance of oil and gas in the matrix in any direction "shortest" to the fractures, and greatly improves the overall permeability of the reservoir and the productivity and ultimate recovery of oil and gas wells. [0003] In the multi-stage multi-cluster fractu...

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Problems solved by technology

[0008] 2. There is a stress interference effect when multiple fractures in the staged multi-cluster fracturing stage expand synchronously

[0010] Due to the stress barrier effect and stress interference effect when the fractures at multiple perforation clusters in the staged multi-cluster fracturing section of a horizontal well are extended simultaneously, the induced stress at each perforation cluster in the stage to be fractured is not Due to the superposition of induced stress generated at this point, the existing method for calculating the fracture pressure of each perforation cluster in multi-stage horizontal well fracturing is not suitable for the working conditions of multi-stage fracturing

So far, no one has proposed a method for calculating the fracture pressure of perforation clusters that meets the multi-stage multi-cluster fracturing conditions of horizontal wells and considers the effects of stress barrier and stress interference when multiple fractures expand synchronously, as well as the resulting change in effective net pressure in the fractures.

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