The selection of gel breaker for clearing fracturing fluid in CBM well

To solve gel breaking problems in CBM well,through studying the influence of sort,temperature,dos-age and pH value on gel-breaking time,four new type of temperature-sensitive chemical gel breakers—PJJ-25,PJJ-30,PJJ-35 and PJJ-40 were screened for different depths of CBM well.The research showed that the dosage of such gel breakers is 0.02 %~0.03 %,gel-breaking time can be controlled between 0.5~5 h,after gel breaking the viscosity less than 3 mPa.s,surface tension less than 30 mN/m,residue content below 0.1 %.Practice has proved that the adopted gel breakers have satisfactory gel breaking results.The gel-breaking liquids have good compati-bility with the formation,and the damage to coal bed is small.