Land Drilling
Preparation on Land
Land must be prepared for drilling and these are the first steps for preparation:
1. The land must be cleared and levelled, access roads may need to be built
2. There must be a water source nearby as water is used in drilling. If there is no nearby water source, a water well may be dug
3. A reserve pit must then be dug; the pit is to dispose of bits of rock and mud dug up during the drilling process. The pit has to be lined with plastic to avoid mixing of different types of soil. If the site is an ecologically sensitive area, then the rock bits and mud dug up have to be trucked away instead of dumped in the pit.
Several holes must then be dug to make way for the rig and the main hole. A rectangular pit called a cellar is dug around the main hole; this provides a work space for the crew. The crew must then start drilling the first hole in the main hole with a small drill truck, not the main rig. The first hole is dug with a truck instead of the main rig in order to make is larger yet shallower. It is then lined with conductor pipe. Additional hole are dug off to the side to hold equipment. After these holes are finished, the rig equipment are brought in and set up. Equipment may be brought in by helicopter, ship or truck depending on the location of the site and the accessibility via road.
Oil Drilling Process
First the crew must drill and pre-set depth which is where they think the oil trap is. There are a few steps involved in the first drilling process.
The casing crew puts the casing pipe in the hole. The cement crew pumps cement down the casing pipe using a bottom plug, a cement slurry, a top plug and drill mud. The cement slurry moves through the casing, filling the space between the outside of the casing and the hole because of the pressure from the drill mud. The cement is allowed to harden and then tested for properties such as hardness, alignment and a proper seal.
Testing for Oil
Drilling becomes repetitive, the crew drills, then runs and cements the new casings, then drills again. When the rock cuttings come up as oil sand, the crew may have reached the well’s final depth. The drilling apparatus is removed and several tests are performed to confirm the finding.
· Well logging - lowering electrical and gas sensors into the hole to take measurements of the rock formations
· Drill-stem testing - lowering a device into the hole to measure the pressures, which will reveal whether reservoir rock has been reached
· Core samples - taking samples of rock to look for characteristics of reservoir rock
Once the final depth has been reached, the well is completed to allow oil to flow into the casing in a controlled manner. First, perforating gun is lowered into the well to the production depth. The gun creates holes in the casing with explosive charges through which oil can flow. After the casing has been perforated, a small-diameter pipe (tubing) is run into the hole as a conduct for oil and gas to flow up through the well. A device called a packer is run down the outside of the tubing. When the packer is set at the production level, it's expanded to form a seal around the outside of the tubing. Finally, they connect a multi-valved structure called a Christmas tree to the top of the tubing and cement it to the top of the casing. The Christmas tree allows them to control the flow of oil from the well.
After the well is completed, the crew must start the flow of oil into the well. For limestone reservoir rock, acid is pumped down the well and out the perforations. The acid dissolves channels in the limestone that lead oil into the well. For sandstone reservoir rock, a blended fluid containing proppants (sand, walnut shells, aluminum pellets) is pumped down the well and out the perforations. The pressure from this fluid makes small fractures in the sandstone that allow oil to flow into the well, while the proppants hold these fractures open. Once the oil is flowing, the oil rig is removed from the site and production equipment is set up to extract the oil from the well.
Land must be prepared for drilling and these are the first steps for preparation:
1. The land must be cleared and levelled, access roads may need to be built
2. There must be a water source nearby as water is used in drilling. If there is no nearby water source, a water well may be dug
3. A reserve pit must then be dug; the pit is to dispose of bits of rock and mud dug up during the drilling process. The pit has to be lined with plastic to avoid mixing of different types of soil. If the site is an ecologically sensitive area, then the rock bits and mud dug up have to be trucked away instead of dumped in the pit.
Several holes must then be dug to make way for the rig and the main hole. A rectangular pit called a cellar is dug around the main hole; this provides a work space for the crew. The crew must then start drilling the first hole in the main hole with a small drill truck, not the main rig. The first hole is dug with a truck instead of the main rig in order to make is larger yet shallower. It is then lined with conductor pipe. Additional hole are dug off to the side to hold equipment. After these holes are finished, the rig equipment are brought in and set up. Equipment may be brought in by helicopter, ship or truck depending on the location of the site and the accessibility via road.
Oil Drilling Process
First the crew must drill and pre-set depth which is where they think the oil trap is. There are a few steps involved in the first drilling process.
- Place the drill pipe, drill bit and collar in the hole
- Attach the Kelly and turntable, start drilling
- Circulate mud through the pipe and out of the bit to float the rock cuttings out of the hole as drilling progresses
- Add new sections of drill pipes as the hole gets deeper
- Remove the drill pipe, collar and bit when the pre-set depth is reached, this can be anywhere from a few hundred to a couple of thousand feet.
The casing crew puts the casing pipe in the hole. The cement crew pumps cement down the casing pipe using a bottom plug, a cement slurry, a top plug and drill mud. The cement slurry moves through the casing, filling the space between the outside of the casing and the hole because of the pressure from the drill mud. The cement is allowed to harden and then tested for properties such as hardness, alignment and a proper seal.
Testing for Oil
Drilling becomes repetitive, the crew drills, then runs and cements the new casings, then drills again. When the rock cuttings come up as oil sand, the crew may have reached the well’s final depth. The drilling apparatus is removed and several tests are performed to confirm the finding.
· Well logging - lowering electrical and gas sensors into the hole to take measurements of the rock formations
· Drill-stem testing - lowering a device into the hole to measure the pressures, which will reveal whether reservoir rock has been reached
· Core samples - taking samples of rock to look for characteristics of reservoir rock
Once the final depth has been reached, the well is completed to allow oil to flow into the casing in a controlled manner. First, perforating gun is lowered into the well to the production depth. The gun creates holes in the casing with explosive charges through which oil can flow. After the casing has been perforated, a small-diameter pipe (tubing) is run into the hole as a conduct for oil and gas to flow up through the well. A device called a packer is run down the outside of the tubing. When the packer is set at the production level, it's expanded to form a seal around the outside of the tubing. Finally, they connect a multi-valved structure called a Christmas tree to the top of the tubing and cement it to the top of the casing. The Christmas tree allows them to control the flow of oil from the well.
After the well is completed, the crew must start the flow of oil into the well. For limestone reservoir rock, acid is pumped down the well and out the perforations. The acid dissolves channels in the limestone that lead oil into the well. For sandstone reservoir rock, a blended fluid containing proppants (sand, walnut shells, aluminum pellets) is pumped down the well and out the perforations. The pressure from this fluid makes small fractures in the sandstone that allow oil to flow into the well, while the proppants hold these fractures open. Once the oil is flowing, the oil rig is removed from the site and production equipment is set up to extract the oil from the well.