Gelled fracturing fluid being applicable to coalbed methane reservoir

Abstract

The invention discloses a gelled fracturing fluid being applicable to coalbed methane reservoir, which consists of 0.3 to 0.5 percent of non-ionic polyacrylamide and 0.014 to 0.04 percent of zirconium oxychloride (ZrOCl12) which are used as cross-linking agent, 0.01 to 0.12 percent of hydrochloric acid which is used as pH adjusting agent, 0.06 to 0.12 percent of gelbreaker and surplus water, wherein the gelbreaker is of a redox system which is formed by ammonium persulfate and sodium sulfite according to the mass ratio of (1.0 to 3.0): 1. With the gelbreaker, the gel can be broken under the low-temperature condition. The gelation time and the gel-breaking time of the gelled fracturing fluid are adjustable. The gelled fracturing fluid has the advantages of fast low-temperature cross-linking sped, large viscosity, low filter loss, thorough breaking, no residual slag of gelled fracturing liquid and easy flowback, and can effectively improve the yield of the coalbed methane.

Description

Technical field: [0001] The invention relates to a jelly fracturing fluid, which is used as a working fluid for reservoir reconstruction in the development of coal bed methane. technical background: [0002] Coalbed methane is a kind of unconventional natural gas associated with coal and self-generated and stored in coal seams in the form of adsorption. It is different from oil, which exists in a liquid state, and from conventional natural gas, which mainly exists in the formation in a free state. The exploitation of coalbed methane is a process of decompression desorption, diffusion and seepage. Hydraulic fracturing of coal seams is one of the most common and important well completion stimulation measures. In coal seam fracturing construction, the performance of fracturing fluid is an important factor related to the success or failure of fracturing construction and the effect of post-fracturing stimulation. At present, active water fracturing fluid and vegetable gum frac...

AI Technical Summary

Problems solved by technology

The former is simple to prepare and has little damage to the coal seam, but due to its own rheological properties, the scale of use is limited; the latter has a wide range of sources, low cost, and high applicable temperature, but there are many water-insoluble substances and a high content of gel-breaking fluid residue, which is harmful to coal seams and coal seams. The fracture permeability is greatly damaged, which affects the fracturing effect