Coal bed methane horizontal well nitrogen foam fracturing mining technology

Abstract

The invention relates to the technical field of coal bed methane exploration and development, in particular to a coal bed methane horizontal well nitrogen foam fracturing mining technology. The technology comprises the steps that three times of well completion and horizontal section well fixation are adopted for a coal bed methane horizontal well, namely, firstly, a surface of a horizontal well is drilled, and a surface layer sleeve is placed in to seal and fix earth surface easy-leaking stratum; then, a coil layer is drilled to, and a sleeve is placed in to seal and fix stratum above the coal layer section; finally, the horizontal well is drilled, and a sleeve is used for fixing the well. When nitrogen foam fracturing is conducted, two sets of equipment are combined for the operation, one set of equipment is in charge of pumping and injecting fracturing fluid and propping agents, and the other set of equipment pumps and injects nitrogen. The fracturing fluid, the propping agents and nitrogen converge in a high-pressure pipeline at the front end of a wellhead and enter a well barrel through fracturing the well head. The technology achieves the purposes that the horizontal well can be communicated with more cleat and cracks, a single well is large in control area, nitrogen foam greatly reduces the speed of the fracturing liquid filtered into stratum, filter loss is reduced, the harm of the fracturing liquid to the stratum is reduced, the foam fracturing liquid is good in sand carrying performance, flowback effect is good, and coal bed methane yield and recovery efficiency are improved.

Description

Technical field: [0001] The invention relates to the technical field of coalbed methane exploration and development, in particular to a coalbed methane horizontal well nitrogen foam fracturing mining technology. Background technique: [0002] Coal reservoirs in China are characterized by low pressure, low permeability, and low saturation. In the development of coalbed methane, the most prominent problem is that the permeability of coalbeds is generally low. At present, most domestic coalbed methane wells are exploited by vertical wells. The most commonly used stimulation measures It's hydraulic sand fracturing. The goal of hydraulic sand fracturing is to form a support fracture with high conductivity in the formation to improve the permeability of the coal seam. Due to the "three lows" characteristics of coal seams, the following problems exist when conventional water-based fracturing fluids are used to fracturing coal seams: (1) The proppant has a short migration distance ...

AI Technical Summary

Problems solved by technology

It overcomes the shortcomings of the existing vertical wells such as small control area and water-based fracturing fluid for limited reservoir stimulation, serious fracturing fluid leakage, low flowback rate, great damage to coal seams, and poor sand-carrying capacity