A refracturing process design method to improve the complexity of shale fracture network

Abstract

The invention belongs to the technical field of unconventional oil and gas output increasing transformation, and particularly relates to a re-fracturing process design method for improving the shale seamed web complexity. The method includes the steps that re-fracturing well sections are selected according to basic data of all the well sections as well as gas-bearing data and primary fracturing output increasing transformation volume ratio data; as for the candidate well sections, a stress balancing equation of discrete fractures is established, normal stresses of a fracture unit are calculated, and steering pressure of new fractured shale stratum fractures is obtained; the strength and dosage of a temporary plugging agent are determined according to the fracture height, particle sedimentation rate, fracture width and temporary plugging agent particle density as well as the number of primary fracturing seamed webs; and steering extension construction displacement of the re-fractured seams is calculated and designed. The re-fracturing process design method provided by the invention covers the basic procedures of shale re-fracturing design, the shale re-fracturing process design canbe achieved conveniently, rapidly and effectively, and a technical design method is provided for re-fracturing process mine field implementation.

Description

technical field [0001] The invention relates to a design method of a repeated fracturing process for increasing the complexity of a shale fracture network, and belongs to the technical field of unconventional oil and gas stimulation and transformation. Background technique [0002] Shale gas is widely distributed and has great development potential. In 2013, the U.S. Energy Information Administration’s statistics on global unconventional oil and gas resources showed that the technically recoverable reserves of shale gas in the world were about 207.0×10 12 m 3 . Among them, the technically recoverable resources of shale gas to be discovered in China are about 31.6×10 12 m 3 . However, due to the characteristics of low porosity, extremely low permeability and strong heterogeneity, shale reservoirs are more difficult to exploit than conventional oil and gas resources. Volume fracturing is an effective technical means to realize industrial exploitation, especially in the d...

AI Technical Summary

Problems solved by technology

The practice of shale gas development in recent years shows that during the production process of shale gas wells, the reservoir pressure will continue to decline, and the effective closure stress on the fracture system of the reservoir will increase, resulting in a continuous decrease in its conductivity, and the production of shale gas wells will increase sharply. decline, resulting in low production and low efficiency

In addition, mine production logging shows that only about 30% of the fracturing sections of shale horizontal wells are effective gas-producing sections after the initial fracturing, and a large number of fracturing sections cannot contribute to production due to insufficient stimulation. Insufficient stimulation and stimulation is also an important engineering factor causing low shale gas single well production

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