An experiment on refracturing with fuzzy-ball fluid for water control and stimulation of CBM Well Zheng 3X

In CBM Well Zheng 3X, hydraulic fractures connect water bearing sandstone formations, leading to high water production and low gas production.In this paper, fuzzy-ball fluid was used to plug water bearing sandstone formations and primary fractures, and then refracturing was carried out to create new fractures so as to decrease the water production rate of gas well while increasing its gas production rate.It was tested in laboratory.It is shown that after the application of fuzzy-ball fluid, pressure resistance of fractures in coal rocks is 21 MPa, water permeability of sandstones decreases by 52.67% and matrix permeability recovery rate of damaged coal rocks is 87%.It is demonstrated that fuzzy-ball fluid can satisfy the performance requirements for diverting fracturing and water plugging.80 m³ fuzzy-ball fluid was prepared on site, and its density and apparent viscosity were 0.85-0.95 g/cm³ and 40-60 mPa·s, respectively.After water bearing formations and primary fractures are plugged successfully by fuzzy-ball fluid, fracturing is performed by using active water.It is shown from production results that the water production rate after the refracturing drops by 79% in water drain-age period and 68% in gas production period, and gas production rate increases by 44%.Clearly, fuzzy-ball fluid is successfully applied in the experiment on the water control and stimulation of Well Zheng 3X.To sum up, fuzzy-ball fluid presents good plugging and water control properties, and it can be used for integrated water plugging and fracturing operation in watered CBM wells.