A Method for Optimizing the Perforation Scheme of Staged Fracturing Clusters in Horizontal Wells

Abstract

The invention discloses a method for optimizing perforation schemes of staged fracturing clusters of horizontal wells. The method comprises the following steps of: establishing a comprehensive compressibility index model which considers geological dessert and engineering dessert of a reservoir at the same time; determining a dessert position and brittle-plasticity of the reservoir by utilizing the model; and comprehensively determining an optimum cluster length and an optimum cluster number by combining an induced stress and a hole friction resistance according to a major fracture randomness extension principle. According to the method, the risk of causing ineffective and low-efficiency fractures can be reduced, accurate guidance can be provided for setting perforation schemes of staged fracturing clusters of horizontal wells, and the optimization result can greatly increase the reformation volume and remarkably improve the construction effect so as to obtain maximum economic benefit.

Description

technical field [0001] The invention relates to the technical field of petroleum exploitation, in particular to a method for optimizing a horizontal well staged fracturing cluster perforation scheme. Background technique [0002] The cluster perforation scheme design is very important in the staged fracturing design of horizontal wells. It is not only related to the judgment of the location of fracture initiation and the number of fractures, but also the judgment of whether there is seepage interference and stress interference in adjacent fractures, and ultimately affects the volume of fracture reconstruction and post-compression effect. [0003] Typical foreign shale gas horizontal wells have a cluster perforation length of 0.3-0.6 m, a cluster spacing of 5-30 m, and 3-10 clusters / section. With the popularization and application of well factory fracturing technology, the well spacing has been reduced from 500-600m to 80-150m, and the number of clusters in each stage of fra...

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Problems solved by technology

[0007] 2. The cluster spacing is generally too large

Although theoretically 20-30m can produce the induced stress interference effect (the induced stress difference is higher than the original horizontal stress difference), this calculated distance is the upper limit of the optimal cluster spacing. In fact, the smaller the cluster spacing, the easier it is for the cracks to turn

Moreover, the current calculation model of induced stress is generally based on linear elastic mechanics. For clastic rock or shale with high clay content, the calculated induced stress transmission distance is too large, but this error cannot be effectively eliminated at present.

[0009] 3. The perforation length of a single cluster (referred to as the cluster length) is generally too large

In the end, the following result may be formed: the total number of perforations in each section is the same, and the total number of fractures initiated is the same, but in foreign countries, each cluster has one fracture, and the distribution distance between them is similar, and the fracture reconstruction volume is large; Each cluster has more than one fracture, the fractures in the cluster are too small to interfere with each other and affect the yield, and the fractures between the clusters are too far apart, so there are areas between the clusters that are not affected by fracture seepage

Therefore, the volume of fracture stimulation is greatly reduced, which seriously affects the post-fracture effect.

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