Development and Performance Evaluation of Dissolvable Balls for Large Borehole Bridge Plug Fracturing

In China, conventional dissolvable balls are not adaptable to large borehole bridge plug fracturing. To solve this problem, a large diameter and high strength dissolvable ball was developed. It is a multi-component system with magnesium alloy as matrix as well as Zn, Cu and other elements in a net structure. The Zn and Cu content was optimized to improve the system’s compressive strength, yield strength and dissolution rate. Some tests showed that the compressive strength and yield strength of the system were over 430 MPa and 330 MPa, respectively. Pressure resistence capacity was over 70 MPa for the 89.027 mm diameter dissolvable ball made with the system. After coating the ball, pressures were stable for 6 hours, and 90% of the ball dissolved in a 3% KCl solution at 93℃ in about 92 hours. In gel, the ball would dissolve more slowly than in 1% KCl solution, and 90% of the ball was dissolved within 200 hours. We have concluded that the large diameter dissolvable ball can meet the requirement of high strength and rapid dissolution in large borehole bridge plug fracturing.