Hydraulic Fracturing Process
Hydraulic fracturing happens in small sections called stages. It starts at the end of the wellbore and moves toward the beginning.
Step 1 – Perforating the Casing First, a perforating gun is lowered into a targeted position within the horizontal portion of the well. Then, an electrical current is sent down the well to set off a small explosive charge. This shoots tiny holes through the well casing and out a short, controlled distance into the shale formation. The holes created by the “perf” gun serve two purposes: they provide access for the fracturing fluid to enter the formation and subsequently allows natural gas to enter the wellbore.
Step 2 – Shale Fracturing The fracturing of a well creates a complex network of cracks in the shale formation. This is achieved by pumping water, sand and a small amount of additives down the wellbore under high pressure. After these cracks are created the sand will remain in the formation propping open the shale to create a pathway for the gas to enter the wellbore and flow up the well.
Step 3 – Repeat in Stages During each stage experts will monitor, adjust and record all of the stage parameters to ensure worker and public safety and to maximize the natural gas production from the shale. After each stage is completed, a plug will be set and new perforations created to direct the frac fluid to the next stage. By segmenting the well in stages, a greater amount of gas is produced from the lateral length of the well.
Step 4 – Safe Frac Fluid Removal After hydraulic fracturing is completed, all of the plugs placed between frac stages are drilled out to remove the restrictions in the wellbore. The completed well is then opened up to safely remove the fracturing fluid so that natural gas can be harvested. The frac fluid that is recovered from each well is treated and reused in future frac jobs through Cabot’s closed-loop water recycling system.
Step 5 – Flaring Toward the end of the frac fluid removal process, gas will start to travel up the well along with the fluid. Since the amount of gas increases as the water decreases, a flare is set up to make sure the gas is safely burned.
Step 6 – Harvesting the Natural Gas After safely removing the fracturing fluid from the formation, the sand will remain in the shale to provide a pathway for the gas to flow into the wellbore and to the surface. Once at the surface, the gas will be processed and delivered to nearly 70 million homes and businesses across the country
Credit to: Cabot Oil & Gas Corporation