A method for staged fracturing of horizontal wells

Abstract

The invention provides a horizontal well staged fracturing method. The horizontal well staged fracturing method comprises the step that N sand-carrying fluid injection stages are sequentially carriedout, wherein the volume density of a supporting agent used in the N sand-carrying fluid injection stage is smaller than the volume densities of supporting agents used in the (N-1) sand-carrying fluid injection stages before, and N is a natural number larger than one. Furthermore, fracturing fluid with the energy-storing modulus and the energy-consuming modulus being (2.0-5.0):1 is selected andused for the N sand-carrying fluid injection stage. According to the horizontal well staged fracturing method, by improving the suspension performance of the supporting agents and / or the fracturing fluid, the even replacement effect of each cluster of cracks is ensured, even fluid inlet and sand inlet of each cluster of cracks are ensured, thus synchronous gel-breaking back-displacement of the fracturing fluid in all the clusters of cracks is achieved, the replacement phenomenon occurring in the horizontal well staged fracturing process is reduced accordingly, the effect after fracturingis improved, and maximization of the stable production period is achieved.

Description

technical field [0001] The invention relates to the technical field of staged fracturing of horizontal wells, in particular to a method for staged fracturing of horizontal wells with reduced over-displacement, especially to the field of horizontal well fracturing of low-permeability and tight sandstone, carbonate rock, shale and coal rock A staged fracturing method for horizontal wells to reduce over-displacement. Background technique [0002] At present, the staged fracturing technology of horizontal wells has become the main development technology of low-permeability and tight sandstone, carbonate rock, shale and even coal rock, and has exerted huge economic and social benefits in production practice. During the construction of this technology, high-viscosity fluid must be used for displacement. However, unlike vertical well fracturing, horizontal well staged fracturing techniques all have over-displacement phenomenon, and some over-displacement volumes can reach more than...

AI Technical Summary

Problems solved by technology

[0004] The adverse effects of over-displacement on the fracturing effect mainly include: 1) severe reduction of the conductivity of near-wellbore fractures at the initial stage after fracturing, resulting in complete loss of the conductivity of near-wellbore fractures, resulting in the so-called "dumpling-making" effect; 2) if The synchronous gel breaking control is not good, the fracturing fluid in the first fracturing stage hydrates and breaks the gel in advance, and the large filtration loss causes the fracture to close prematurely, which has a fatal impact on the remedial measures of the fracture conductivity near the wellbore; The method of uniform perforation for each cluster leads to different over-displacement effects of fractures in different clusters during fracturing in the same section. The closer to the wellbore, the more over-displacement volume, and the contribution of each cluster of perforations to production is not balanced.