Method for improving uniform extension and support of in-section multi-cluster cracks

Abstract

The invention discloses a method for improving uniform extension and support of in-section multi-cluster cracks. The method comprises the following steps that 1, ultralow-density proppants with different particle sizes are sequentially injected according to the particle sizes in a slug type sand adding mode; 2, mixed injection of mixed-density proppants with different particle sizes and linear fibers with different particle sizes is carried out in sequence according to the particle sizes in a slug type sand adding mode; and 3, conventional-density proppants with different particle sizes are sequentially injected according to the particle sizes by adopting a slug type sand adding mode. The characteristics that the flow following performance of the ultralow-density proppants and the fracturing fluid is good, the flow conductivity is greatly improved after the conventional-density proppants and the ultralow-density proppants are mixed, and the conventional-density proppants are large in density and flow inertia are utilized, so that the proppants easily enter a crack close to a target point B in the middle and later periods of construction; and the method has the advantages of being simple in process, low in cost and good in crack opening plugging effect, multi-cluster crack uniform extension and uniform sand adding are achieved, the crack complexity is increased, and the multi-cluster staged fracturing effect is greatly improved.

Description

technical field [0001] The invention belongs to the field of fracturing, in particular to the field of multi-cluster segmental fracturing of sandstone and shale horizontal wells, and more particularly relates to a method for improving the uniform extension and support of multi-cluster fractures in a segment. Background technique [0002] At present, the application of multi-cluster staged fracturing technology in horizontal wells is becoming more and more popular, especially in sandstone and shale, the casing completion method is generally adopted, and the application of multi-cluster fracturing technology in intervals is more common. Generally, the number of perforation clusters in the section is 2-3 clusters or even 3-5 clusters. However, the initiation and extension of multiple clusters of fractures is not as uniform as imagined. A large number of monitoring data at home and abroad show that the fractures near the heel (near the A target point) generally extend longer and...

AI Technical Summary

Problems solved by technology

[0005] 3) Due to the large density difference between the proppant and the fracturing fluid during injection, its followability is poor

[0006] 4) Except for the first section of fractures, when the other sections are fracturing, the fractures near the toe are interfered by the induced stress of the longer fractures near the upper section near the heel. Firstly, the fracture pressure is high, and secondly, the stress reversal occurs due to the induced stress phenomenon, the above-mentioned fractures near the toe may change direction to become longitudinal fractures parallel to the horizontal wellbore, which greatly reduces the overall stimulation volume of the fractures

The main innovation of this patent is to temporarily plug a certain position inside the main fracture. The main measure is to add sand continuously, using two kinds of proppant with smaller particle size of 140-230 mesh and 70-140 mesh to mix, in order to produce more The complex fracture system with small scale is more suitable for generating micro-fractures in deep shale gas, but cannot achieve the goal of balanced initiation of multi-cluster fractures

This patent mainly realizes multi-scale fracture propagation and full-scale fracture support in a single cluster of fractures, and does not mention how to achieve balanced expansion and support of multi-cluster fractures from the beginning to the end

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