How does horizontal multistage fracing work?
Using mechanical means or fluid pressure, each segment of the horizontal wellbore is isolated and fractured individually. Frac fluid is pumped from the surface at a predetermined and constantly monitored rate to the “toe,” the farthest isolated segment in the horizontal section. When the fracture is created, proppant-laden fluid is pumped into the fracture to keep it open. Once complete, the process is repeated for each segment in the wellbore, working back towards the “heel.” After all segments have been fractured, hydraulic pressure is removed from the formation and the fracing equipment leaves the location. The wellbore pressure is then reduced to allow the frac fluid to be recovered at surface, known as flowback; often only a portion of the frac fluid and proppant is recovered, while the remainder is retained in the formation being fractured. Some of the flowback fluids can be recycled for use in fracing other wells. The storage, handling, and disposal of recovered frac fluids must
