Broken and soft low-permeability coal bed horizontal well staged fracturing technology

Abstract

The invention belongs to the coal-bed gas well fracturing motivation technology, and particularly relates to a broken and soft low-permeability coal bed horizontal well staged fracturing technology. The broken and soft low-permeability coal bed horizontal well staged fracturing technology aims at improving the broken and soft low-permeability coal bed mining benefits and adopts the fracturing technology mode that sealing and fracturing are carried out section by section. The previous sealed section produces induction stress for the fracture initiation of the rear fracturing section. By optimizing the sectioning distance, the maximum horizontal principal stress difference caused by coal reservoir burial depth, heterogeneity and aeolotropism is improved, the manual fracture initiation direction and natural fracture initiation included angle are enlarged, coal bodies can form joint nets more easily, natural fractures are communicated, and the fracture complexity degree is improved; different kinds of pressure are distributed for different sections, the contact area between the fracture wall face and the coal matrix face is enlarged, a complex crossed fracture network system is built finally, the seepage distance from the coal matrix in any direction to the fracture is the shortest, and the low-permeability coal reservoir can achieve economic output.

Description

technical field [0001] The invention belongs to the fracturing excitation technology of coalbed gas wells, and in particular relates to a staged fracturing technology for horizontal wells in broken soft low-permeability coal seams. Background technique [0002] my country's coal reservoirs are affected by geological structures to a large extent. Taking the gas-enriched area in the southern Qinshui Basin as an example, the degree of influence by geological structures gradually increases from south to north, and the characteristics of coal bodies are buried from south to north. The proportion of deep and crushed coal gradually increases, and the physical properties of coal reservoirs show that the matrix porosity, permeability and complexity gradually deteriorate, and the characteristics of heterogeneity and anisotropy are significant. The geological factors affecting coal seam production mainly include: coal reservoir physical properties (reservoir porosity, permeability, wate...

AI Technical Summary

Problems solved by technology

The geological factors affecting coal seam production mainly include: coal reservoir physical properties (reservoir porosity, permeability, water saturation), structural stress conditions, and coal bed methane resources (coal seam gas content, coal seam thickness), if the traditional The mining of soft and low-permeability coal seams by fracturing in horizontal wells has a low economic output value, which seriously affects the mining efficiency

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