Excellent video explaining fracking
Let’s take a look at the horizontal drilling and stimulation processes that have made shale exploration so successful.
Below is the transcript from the video...
A drill bit is mounted on the end of the drill pipe. As the bit grinds away a mixture a mixture of water and additives called mud is pumped into the hole to cool the bit and flush the cuttings to the surface.
The mud also cakes on the walls of the wellbore keeping it tacked. Similar to a vertical well, the hole is drilled to just under the deepest fresh water near the surface. The drill pipe and bit are then removed.
Surface casing is inserted into the drilled hole to the fresh water zone and also serves as a foundation for the blowout preventer: a safety device that connects the rig to the wellbore. Then cement is pumped down the casing and out through the opening of the shoe at the bottom of the casing. It is then forced up between the casing and the hole. Sealing off the well bore from the fresh water. The cementing process prevents any contamination of the fresh water aquifers.
The pipe and bit are lowered back down the hole to drill through the plug and cement and continue the vertical section of the well to approximately five hundred feet above the planned horizontal leg. This depth is called the kick off point, where the curve will begin so the horizontal section can be drilled. Up to this point the process is the same as the drilling a vertical well. Again the pipe and bit are pulled out of the hole and a down hole drilling motor with measurement while drilling instruments is lowered back into the hole to begin the angled building process. The distance to make the curve from the kickoff point to where the wellbore becomes horizontal is just under a quarter of a mile.
Once the curve is completed drilling begins on the wells horizontal section called the lateral. The pipe used to drill the well measures 30 feet in length and weighs approximately 495 pounds each. It takes over 350 pieces of pipe weighing nearly 87 tons to drill a 10,500 foot well.
At various stages of drilling the pipe it taken out of the hole for tool and bit changes and put back in. This process is called tripping pipe. When the targeted distance is reached the drill pipe and bit are removed from the wellbore one last time. Production casing is now inserted into the full length of the well bore. Cement is again pumped down the casing and out through the hole in the casing shoe. Forcing the cement up between the casing and the wall of the hole filling the open space known as the annulus. Casing the well is a very important process because it permanently secures the well bore and it prevents hydrocarbons and other fluids from seeping out into the
formation as they are brought to the surface.
As this point the drilling rig is no longer needed. A temporary well head is installed and the location is prepared for the service crew who will perf, frack, and prepare the well for production.
The first of these steps is to perf, or perforate the casing. A perforating gun is lowered by wireline into the casing to the targeting section of the horizontal leg. An electrical current is sent down the wireline to the perf gun and sets off a charge that shoots small holes through the casing and cement. And out a short distance into the shale formation. The perf gun is then pulled out of
Next because the shale is tight and compressed the well will have to be fracked. Known as hydrolic fracturing this is a process where water, sand and additives are pumped into the well bore and down the casing under extremely high pressure. As this mixture is forced out through the perforations and into the surrounding rock, the pressure causes the shale to fracture. This creates a fairway connecting the reservoir to the well and allows the released oil to flow to the well bore.
Next a temporary plugged is placed at the heal or left side of the first stage frack. The plug closes off or isolates the perforated frack section of the wellbore so that the second stage section of the horizontal leg can be perforated and fracked.
Tight reservoirs do not contain natural fractures and therefore cannot be produced economically without hydrolic fracturing. The permeability is increased by providing pathways through which the oil can flow more easily. With advancements in technology multi-stage fracking has becoming effective for recovering oil from shale reservoirs.
This process of perfing and fracking can be repeated several times to cover the entire horizontal distance of the wellbore. Once fracking is completed the plugs are drilled out. Allowing the oil to flow up the well bore.
The next step is to install a permanent well head and other necessary surface equipment. Sometimes a pump jack is used to help bring the oil to the surface. A pipeline is then built to transport the oil to the pipeline network. As field development expands additional infrastructure is built. Thanks to the vision and persistence of those who have perfected these new technologies shale plays across the U.S. Have become an innovative and highly productive source of new energy for our country.
At www.oilandgasequipmentsales.com we have all your new and used oil and gas exploration equipment.