Experimental and Numerical Study of the Explosive Forming of Slotted Metal Pipes for Energy-Gathered Nesting Plugging

At present, there is still no effective solution to the cavity-type lost circulation in the drilling and completion of oil, gas and geothermal resources. In the light of this, a energy-gathered nesting plugging technique was proposed, and experiments for explosive forming and the optimization of metal bridge strings were also conducted. The technique and its theory were first introduced, a numerical model for the explosive forming of slotted metal pipes was then established, the shapes of metal pipes slotted in different types and in different materials were analyzed. Finally, ground experimental device was designed, the experimental methods were determined, and according to the simulation results, ground experiments were conducted in air, submerged water, and submerged confining environments respectively. The numerical results show that the series 5 aluminum alloy pipe with straight slotting patterns, exhibits a suitable tensile deformation without failure after explosion, and can be utilized as the material for nesting bridge. The experimental device can effectively simulate the real downhole environment, providing conditions for further study on the the amount of explosives of different nesting tools. The research results show that the energy-gathered nesting plugging technology could be expected to better solve the technical problems that the plugging materials are difficult to retain and not easy to form the artificial well wall. By using it, the success rate of plugging of cavity-type lost circulation could be improved and the cost of drilling and completion could be reduced.