The oilfield employs many people as many are needed in oil well drilling.
Personnel from truck drivers to engineers and geologists find employment in the oilfield.
The first ones to be employed are geologists, because, to find an oil reservoir, a geologist is needed.
Geologists have many resources available to them for use.
The geologist interprets surface rock and terrain using satellite images. Once a possible location is found, core samples of the formation of interest may be taken.
Gravity sensors can also be used. Gravity sensors detect small changes in the earth's gravitational field that may indicate flowing oil.
Sniffers may also be used. Sniffers are electronic devices that "smell" for hydrocarbons.
Seismology is also commonly used. Seismograph crews are sent out to measure electronic shock waves that bounce through the formations of the earth. These waves are measured via a computer printout. The printout is then analyzed by a geologist, must like an X-ray is read by a radiologist.
Once a prospective oil field is found, the location is marked by GPS.
Before drilling can begin, legal issues need to be taken care of. Issues such as permits, landowner rights, leases, and environmental impact surveys have to all be resolved prior to any drilling operations.
Once all the legal stuff has been settled, it's time to prep the location.
Crews are brought in to clear and level the land. Roads to the location are built. A reservoir, or mud pit, to store the cuttings has to be dug and lined with environmental plastic.
Since water is required for oil well drilling, a source has to be nearby. If there is no source, a water well may need to be drilled.
Once the operation is ready to commence, a "rat hole" rig may come in to drill surface. A rat hole rig is a small, mobile drilling rig. Oftentimes, these types of operations are small, local companies with one or two rigs. The only job a rat hole company may do is drill surface holes for large companies.
The rat hole, or surface hole is a large hole that is cemented with conductor pipe. The size and depth of the rat hole depends on several things.
For instance, state regulations may dictate the depth and size of the surface hole along with any cementing requirements. Once the surface hole is drilled, state inspectors have to inspect the surface hole and give the go ahead before any other drilling may commence.
Groundwater contamination is the primary reason for all the red tape.
Drilling the Well
It's now time to bring in the rig and drill the well.
|WELLBORE - the drilled hole, including the open and uncased portions of the hole.|
Rigging up is the process of bringing in all the necessary equipment onto location and "rigging up" the drilling rig.
The process usually takes at least 24 hours, and the location is extremely busy with trucks going everywhere!
In addition to the drilling rig, large diesel pumps have to be brought in. On large locations, housing for the company man, pusher, geologists, and any other needed personnel is brought in and set up.
Once the crew is through rigging up, the well is ready to be spudded. The exact date and time of spudding is recorded in the drilling log and the show is finally on the road.
Prior to all of this flurry of activity, engineers have had to make many decisions about HOW to drill the well.
Decisions Made Prior To Oil Well DrillingSize of hole - hole size may be one size from spud to td or may begin with a larger sized bit and taper down smaller and smaller as the well gets deeper. Each section is cased with casing and the cement allowed to set before drilling operations commence.
Type of Bit - PDC bit or button bit (See also Atlas Copco Drill Bits)
TD - total depth of the well
Kickoff Point - the point in the well when the directional drilling company will begin to deviate the well. Only used in directional drilling applications.
Downhole tools - includes which bit to run and what mud motor, if any, will be used.
|ANNULUS - the space between the wellbore and casing|
One pre-drilling decision prior to oil well drilling is whether to circulate the drilling fluid conventionally or whether to reverse circulate.
Reverse circulation pumps the drilling mud down the annulus of the drill string and back up through the center of the pipe - opposite of conventional circulation methods.
The reason for reverse circulating is that volume in the center of the pipe is much less that the volume of the annulus. For this reason, cuttings and larger particles can be brought out of the hole much more quickly. Reverse circulation also enables the removal of large cuttings that may not be able to be removed using conventional circulation methods.
As is obvious, oil well drilling takes many qualified personnel.
Bakken Shale: The Bakken Shale was at one time considered to be a marginal find because the oil was trapped in such low permeable shale.
Deepwater Horizon: Transocean's Deepwater Horizon burned for two days and then sank - an equipment loss of over $200 million.
Directional Drilling: Directional drilling is common practice in shale gas plays such as the Bakken and Barnett Shale, and the selection of drilling tools is critical.
Drilling Mud: Drilling mud can be oil, air, or water based. It cools and cleans the bit, stabilizes the well bore, and creates wallcake.
Exxon Valdez: The effects of the Exxon Valdez oil spill are still being felt almost 30 years later.
Natural Gas Drilling: Natural gas drilling looks to continue because the natural gas reserves of the United States are large enough to fuel our needs for many years to come.
Oil Well Drilling: Oil well drilling requires many pre-drilling decisions, such as whether to reverse circulate and which type of drilling mud to use.
Shale Oil: Shell Oil Company's in-situ conversion process requires a "freeze wall" around the outside perimeter of the shale oil extraction zone to prevent groundwater contamination.
Spindletop: The oil revolution began when Spindletop gushed black gold 150 feet in the air for nine days in 1901, and Howard Hughes invented the roller cone bit.
Tar Sands: Tar sands are a black, tar-like combination of clay, sand, water, and bitumen. They are sometimes called "oil sands" to make them seem more appealing.