Profile prepared by G.W. McLellan, (509) 376-2260; additional contact: Jerry Bultena (509) 376-2956
Westinghouse Hanford Company
Drilling
This is a baseline technology.
This is a baseline technology
What are the objectives of this technology?
The objectives of this technology are to limit public and worker exposure to hazards, obtain representative geologic samples, and minimize the amount of secondary waste generated. A secondary objective both during drilling and after the completion of a boring or well is to place instruments, sensors, and other devices underground to be used in characterization, remediation, and monitoring.Cable tool drills operate by repeatedly lifting and dropping a heavy string of drilling tools into the borehole. There are five components on a full string of cable tool drilling equipment: a drill bit or shoe, a drill stem, drilling jars, a swivel socket, and a cable. The drill bit transmits the force to the earth. The drill stem is the longest section, and it connects the bit to the drilling jars. The drilling jars are like a pair of links in a chain and are used to jar the drill bit free of the formation. The swivel socket connects the rest of the drill tools to the cable. And the cable is strung up over a pulley on the mast to the drill motor. A drill casing is often used in unconsolidated formations to keep the walls of the well from collapsing.
To take core samples, a split-spoon sampler with a drill shoe can be added to the drill stem in place of the drill bit. A core catcher is placed at the bottom of the sampler to keep the core from falling out before it is retrieved at the surface. After the sampler is driven into the formation by the cable tool drill, it is removed from the hole and the sampler is split in half lengthwise to extract the core sample.
Two types of cable tool drilling methods are used at Hanford: hard tooling or percussion drilling and drive barrel or dry drilling. Hard tooling or percussion drilling is the most common form of cable tool drilling and can be used in any formation including basalt. The percussive action of the drill bit crushes the formation. Water is used to create a slurry (an average of 10 to 20 gallons of water are added, if no water is present in the formation). A device called a bailer removes the slurry from the hole before drilling continues. Samples obtained using hard tooling are low in quality because liquids are added and because the cuttings are pulverized; therefore, the samples are not useful for geological analysis. In addition, since water has flushed the sample, identifying contaminants will be difficult.
The other type of cable tool drilling used at Hanford is the drive barrel technique, also called dry drilling. This method is much like pile driving in that a drill casing is driven into the soil by the cable tool rig. The soil goes up the inside of the casing and can be collected in a split spoon sampler or core barrel. Sample quality using this technique is far superior to that of the hard tooling method because no water is added to the borehole.
When the core barrel is removed, it can be easily contained using plastic sleeves taped over both ends. The core barrel is then knocked with a hammer so that the soil drops into the plastic sleeve. When the barrel is empty the sleeve can be closed and placed in a drum if the soil is suspected to be contaminated. Thus public and worker exposure to contaminants is minimized.
This technique does not use any fluid to soften the formation or remove drill cuttings. It is a completely dry method, which prevents the spreading of contamination and improves sample quality.
The drive barrel technique is best used in relatively dry, unconsolidated soils such as the sands and gravels often found in the unsaturated zone (the soil above the water table) of the Hanford formation. At Hanford, hard tooling must be used below the water table, in areas where unsaturated zone soils become consolidated, or in areas where there are large boulders.
What is the technology that is currently used for this application?
This is a baseline technology
Two types of cable tool drilling methods are used at Hanford: hard tooling or percussion drilling and drive barrel or dry drilling. Hard tooling or percussion drilling is the most common form of cable tool drilling and can be used in any formation including basalt. The percussive action of the drill bit crushes the formation. Water is used to create a slurry (an average of 10 to 20 gallons of water are added, if no water is present in the formation). A device called a bailer removes the slurry from the hole before drilling continues. Samples obtained using hard tooling are low in quality because liquids are added and because the cuttings are pulverized; therefore, the samples are not useful for geological analysis. In addition, since water has flushed the sample, identifying contaminants will be difficult.
The other type of cable tool drilling used at Hanford is the drive barrel technique, also called dry drilling. This method is much like pile driving in that a drill casing is driven into the soil by the cable tool rig. The soil goes up the inside of the casing and can be collected in a split spoon sampler or core barrel. Sample quality using this technique is far superior to that of the hard tooling method because no water is added to the borehole.
When the core barrel is removed, it can be easily contained using plastic sleeves taped over both ends. The core barrel is then knocked with a hammer so that the soil drops into the plastic sleeve. When the barrel is empty the sleeve can be closed and placed in a drum if the soil is suspected to be contaminated. Thus public and worker exposure to contaminants is minimized.
This technique does not use any fluid to soften the formation or remove drill cuttings. It is a completely dry method, which prevents the spreading of contamination and improves sample quality.
The drive barrel technique is best used in relatively dry, unconsolidated soils such as the sands and gravels often found in the unsaturated zone (the soil above the water table) of the Hanford formation. At Hanford, hard tooling must be used below the water table, in areas where unsaturated zone soils become consolidated, or in areas where there are large boulders
Where (in-situ/ex-situ): This technology operates in situ
Media: This technology is used in the vadose zone and groundwater
Targeted Contaminants: Drilling is required for retrieval and treatment of chemical and radioactive waste at Hanford.
This is a baseline technology
Not applicable to a baseline technology
Not applicable to a baseline technology
The major technical challenge of cable tool drilling is its slow penetration rate. Its slowness limits the use of cable tool drilling to shallow wells of less than 800 feet for practical reasons. Though the ancient Chinese used this method to drill wells as deep as 3000 feet, they took generations to complete. Other limitations of cable tool rigs are that they can only drill vertical, not angled or horizontal, wells and that long strings of casing may be difficult to pull back in some geologic conditions unless special equipment is used.
Performance Criteria:
What contamination will remain after the technology is applied?
Cable tool drilling often requires the addition of water (10-20 gallons) to the borehole in cemented and hard formations.
Adding water may spread contamination and create more waste because the slurry must be bailed out of the hole and disposed of. For example, if 10 gallons of water per foot were used for hard tool drilling of an 8-inch-diameter borehole in a 35% porosity formation, the water would only migrate about 21 inches from the center of the borehole into the soil. Also, under difficult drilling conditions when water is added, approximately 6 times more waste could be generated than if dry drilling were used.
Process Waste:
What process waste (secondary waste) does the technology produce?
Wells and borings result from drilling.
Drill cuttings are in the form of dry soil or, in the case of hard tooling, slurry.
If it is contaminated, this waste is drummed. When drilling an 8-inch-diameter hole, one 55-gallon drum of cuttings is produced for every 10 feet of hard tool drilling and one drum of cuttings is produced for every 60 feet of drive barrel drilling.
Describe the treatment or storage needed for the secondary waste and its availability:
The treatment and handling of secondary waste depend on the waste type: radiological, chemical, or mixed. But management by treatment or storage is available.
Describe the requirements for decontamination or decommissioning of equipment:
In contaminated sites any equipment or tools that go down the hole will be decontaminated (core tubes/samplers, drill bits, core barrels, and drill rods).
The entire drill rig must be decontaminated before work begins. The shoe, liner, and core catcher of the split spoon sampler must be chemically decontaminated before each sample is taken. In contaminated sites, samples are taken every 5 feet or continuously. When drilling proceeds 5 feet beyond the area of contamination, all the drilling tools are decontaminated. It is not usually necessary to decommission any equipment.
How must the secondary waste be disposed of? Is disposal available?
For the small quantities of drilling waste, disposal depends on the type of contamination. Hard tooling creates greater amounts of waste.
Practicality:
What future cleanup options are precluded by this technology?
This technology is very practical, and it does not foreclose future cleanup options.
How reliable is the technology?
This method is one of the most reliable drilling techniques. There are very few equipment failures.
Failure in casing and drill tools occurs 4% to 8% of the time the drill is in use.
If the technology fails, how are the effects of the failure controlled?
This question is not applicable to drilling technology.
How easy is the technology to use?
The technology is easy to use.
Rigs are simple in design and require little sophisticated maintenance. Though a cable tool rig can be operated by one person, at Hanford a helper is required for safety reasons.
What infrastructure is needed to support the technology?
One person is required to operate the rig. Cable tool drills are powered by engines that run on gasoline, diesel, or propane.
How versatile is the technology?
Cable tool drilling can be used in any kind of formation and can be operated in rugged inaccessible terrain.
Because of its small size, cable tool drilling can be used in areas where space is limited.
Describe the technology's compatibility with other elements of the system?
Cable tool drilling is compatible with other elements of the system. 14.3.8. Can the technology be procured "off-the-shelf"? (Is it an innovative use of an existing technology?) Which components are available and which must be developed?
Cable tool drilling is an off-the-shelf technology.
How difficult is the technology equipment to maintain?
The technology is known for its simple design and easy maintenance.
What equipment safety measures are needed and in place to protect workers and the public?
Cable tool drilling has an outstanding safety record at Hanford. Standard mechanical and chemical safety measures are required.
What are the scale-up issues and how are they being addressed?
Describe the technology's ability to function as intended.
Cable tool drilling is a common method of well drilling and works consistently.
What is the start-up cost of the technology?
Rigs are common and relatively inexpensive.
What are the operations and maintenance costs of the technology?
Maintenance is simple and inexpensive.
Drilling costs range from $250/ft in areas of low contamination to $1600/ft in high contamination. Also the costs of energy and maintenance are relatively low because of the machine's simplicity.
What are the life cycle costs of the technology?
Drilling costs range from $250/ft in areas of low contamination to $1600/ft in high contamination.
When will the technology be available for commercial use or use at other sites?
This baseline technology is available now.
What is the speed or rate of the technology?
Cable tool drilling is relatively slow and varies from 20 ft/day in areas of low contamination to 10 ft/day and less in areas of high contamination.
At the speed or rate identified above, what is the total time required for the technology to achieve its objectives?
Not applicable to drilling technologies.
Worker Safety:
What potential is there for workers to be exposed to hazardous materials and/or other hazards? Describe those materials and hazards:
The cable tool method has no circulation system and controls waste at the collar of the hole, minimizing personnel exposure.
When the core barrel is removed, it can be easily contained using plastic sleeves taped over both ends. The core barrel is then knocked with a hammer so that the soil drops into the plastic sleeve. When the barrel is empty the sleeve can be closed and placed in a drum if contamination is suspected. In a similar way, slurry can be contained when hard tooling is being used. Thus public and worker exposure to contaminants is minimized.
In contaminated areas slower drilling rates improve contamination control. Though other technologies drill wells faster, in contaminated areas the need to control and limit public and worker exposure to contaminants is of the utmost importance. For this reason drilling using any method should be slowed to allow for greater control of the hazardous material being extracted from the hole.
What are the physical requirements for workers?
The noise level is 53 to 115 dBa [decibels adjusted], so hearing protection is required. Standard protective gear is adequate at non-contaminated sites. Workers must be able to handle heavy equipment.
Standard protective gear is adequate at non-contaminated sites. Workers must be able to handle heavy equipment.
How many people are required to operate the technology?
Though a cable tool rig can be operated by one person, at Hanford a helper is required for safety reasons and to handle tooling.
A geologist is also employed at most Hanford drilling sites to log samples. In areas of medium to high contamination a Health Physics Technician (HPT) and a Site Safety Officer are needed to monitor contamination levels. In areas of high contamination, an additional laborer is needed for contamination control and to decontaminate equipment.
Public Health and Safety:
What is the technology's history of accidents?
No accident hazard to the public exists from operating this technology.
If drilling in hazardous areas, use of proper containment techniques can eliminate hazardous releases. Infrequent releases of VOC vapor may occur at sites where the cable tool technique is used to drill through VOC-contaminated soil.Infrequent releases of VOC vapor may occur at sites where the cable tool technique is used to drill through VOC-contaminated soil.
Does this technology produce routine releases of contaminants?
If drilling in hazardous areas, use of proper containment techniques can eliminate hazardous releases.
Are there potential impacts from transportation of equipment, samples, waste, or other materials associated with the technology?
There are no impacts from transporting the drill rig. Contaminated cuttings and samples will be put in drums and may need to be transported for disposal or treatment.
What impact will this technology have on the ecology of the area?
As with all drilling technologies, an area must be cleared for a drill pad, but no permanent effects will result from using this technology.
What aesthetic impacts does the technology have?
The cable tool rig is approximately the same height as other drill rigs, but less massive. The percussion of the tool is loud (53-115 dBa) and vibrates the soil.
What natural resources are used in the technology's development, manufacture, or operation?
No natural resources are used for this technology, other than those required to manufacture the equipment.
What are the technology's energy requirements?
Cable tool drills are powered by engines that run on gasoline, diesel, or propane.
Public Perception:
What is the reputation of the technology's developer and/or user?
Not applicable.
How familiar is the technology to the public?
As the oldest drilling technology, cable tool drilling is the simplest to understand and until the past century, the most common.
How easy is the technology to explain to the public?
Tribal Rights/Future Land Use:
What is the reputation of the technology's developer and/or user?
A pad must be graded for the drill rig, but grading does not preclude revegetation.
What are the potential economic impacts of this technology?
A cable tool rig requires the least capital investment and the least maintenance but has the slowest drilling rates.
Cable tool drilling will have no major economic impact on the area in which it is used.
How will the technology affect labor force demands?
At Hanford, union workers are employed in cable tool drilling, and it creates no unusual demands on the labor force.
Describe the technology's compatibility with cleanup milestones:
Cable tool drilling is compatible with cleanup milestones and is the basis for many of the existing milestones.
How familiar are regulators with this or a similar technology?
What is the technology's regulatory track record?
Cable tool drilling has an extensive track record and has been accepted by regulators.
How does the technology comply with applicable regulations?
This system complies with all regulations.
What is the name of the industrial partner?
This section is not applicable; cable tool drilling is a baseline technology.
What is the rationale for this partnership?
What is the contract mechanism?
Are there other potential partners?
Are there potential international partners?
Who owns the patent for this technology?
Are there other patent owners?
Is there a patent number for this technology?
Cost Sharing:
Developed in China about 4000 years ago, cable tool drilling is the oldest drilling method. Until the twentieth century it was also one of few drilling methods, and it is still in common use today. The drive barrel method of cable tool drilling is a relatively new development. It first appeared in the early 1940s in southeastern Washington state where many areas of unconsolidated soil exist above the unsaturated zone (the soil above the water table). In the Hanford formation, the unsaturated zone is composed mostly of unconsolidated soils such as sands and gravels, ideally suited for drive barreling.
This method has been further developed at Hanford. In the early 1970s, heavy 5-inch- outside-diameter split spoon samplers were first developed to improve the quality (representativeness) of geologic samples. After Hanford changed its mission to focus on environmental cleanup, the drive barrel method of cable tool drilling was further adapted for use in contaminated zones. This method is especially well suited for contaminated areas because it is one of the few drilling methods that does not use any circulation fluids which would spread contamination. The only other such methods are auger drilling and sonic drilling. Of these two, only sonic is able to contain the contaminants as effectively as cable tool does. Cable tool drilling is also being used at other DOE sites such as Fernald, Idaho National Engineering Laboratory, and Rocky Flats, but nowhere is it being used to the extent that it is used at Hanford.
Driscoll, F. G., Groundwater and Wells, 2nd Edition, St. Paul, Minnesota: Johnson Filtration Systems Inc., 1986, pp. 268-277.
Vogel, H. U., "The Great Well of China," Scientific American, June, 1993, pp. 116-121.
WHC-SD-EN-TRP-002, "Results of Testing the Sonic Drilling System at the Hanford Site (September 1991 to May 1992)," Revision 0, dated October 26, 1992.