Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B12/00—Accessories for drilling tools
  • E21B12/04—Drill bit protectors
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
  • E21B49/003—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells by analysing drilling variables or conditions
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
  • E21B49/006—Measuring wall stresses in the borehole

Definitions

• the object of the invention is a method of drilling for the purpose of exploring the soil, according to which method the drilling is started as penetration testing and subsequently continued, if necessary, as percussive drilling.
• the composition of the soil can be examined in several ways. One of them is to make the examination by penetration testing in cases where the soil is soft. Percussive drilling is used primarily to find out the location of the rock surface.
• Penetration testing and percussive drilling cannot be carried out with the same equipment due to the difference between the methods.
• One of the reasons is that in percussive drilling either water or air flushing is used, which means that the drill bit must comprise flushing ducts. Since flushing is not, however, used in penetration testing, the ducts become clogged during this work stage and once they are clogged, the work cannot be continued by percussive drilling.
• a counter-valve is located inside the drill bit, which valve closes the flushing ducts in the drill bit while the penetration testing takes place. Once percussive drilling is started after the penetration testing, the flushing pressure opens functioning of the drill bit is uncertain. Furthermore, it follows from the wearing out of the drill bit that the measurement results obtained are not comparable with each other.
• the aim of this invention is to eliminate the above- mentioned problems and to achieve a new method and new equipment which do not have the above disadvantages.
• the drilling is started as penetration testing with the type of drill bit equipment which comprises a drill bit and a protective cover placed over it, that when the drill bit equipment meets, in penetration testing, a rock or a layer of soil so hard that it is undesirable or impossible to continue penetration testing, the penetration testing is discontinued, and that the changeover to percussive drilling is effected using the same drill bit equipment, whereupon in commencing the percussive drilling, the impact force exerted on the drill bit equipment breaks the protective cover on the drill bit so that it .is detached from the drill bit.
• the invention combines two methods known as such, that is, penetration testing and percussive drilling.
• the drilling is started by penetration testing so that the drill bit is covered with a disposable drill bit cover, which is.similar in form to the penetration testing bit.
• Penetration testing is continued until a rock or a layer of soil so hard is reached that it is undesirable or impossible to continue penetration testing.
• the drill bit cover breaks and the drilling can be continued as percussive drilling.
• An object of the invention is also the drill bit equipment intended for soil exploration, comprising a drill bit and a disposable protective cover placed over it, which can be removed from the drill bit at a desired stage, for example, so that the protective cover breaks when percussive drilling is started.
• Protective covers on drill bits are known as such. They are described, for example, in US- patents 2 644 672 and 2 723 836 and in GB-patent 1 384 272. These types of protective covers for drill bits are not, however, suitable for carrying out the method relating to the present invention.
• the head of the protective cover placed on the drill bit is designed to suit penetration testing, and - that the strength of the protective cover has been designed to be such that in pene r .-ation testing the strength of the protective cover is sufficient, but once percussive drilling is started, the impact force breaks the protective cover.
• Figure 1 shows diagrammatically a vertical section of the soil and the penetration testing stage relating to the invention.
• Figure 2 corresponds to figure 1 and shows diagrammatically the percussive drilling stage relating to the invention.
• Figure 3 shows diagrammatically curves obtained from the measuring sensors.
• Figure 4 shows a drill bit on which is placed a cover relating to the invention.
• Figure 5 shows a drill bit at the percussive drilling stage without cover.
• Figure 1 shows diagrammatically a vertical section of the soil 10 and the penetration testing stage for exploring soil relating to the invention.
• the figure illustrates a carrier 20 on the surface of the earth, which is carrying out the penetration testing.
• a drill rod 21 which is pressed into the ground vertically, that is, in the direction of the z axis at compression speed v, the corresponding compressive force being F.
• Drill rod 21 is rotated at the speed of rotationC ⁇ , the corresponding torque being y .
• the parameters relating to the drilling are measured continuously and the results are recorded by means of a recording device 30 connected to the carrier.
• the plotter curves are shown in greater detail in figure 3.
• topmost on the surface of the earth is the dry crust layer 11, under which are soft clay 12 and silt 13.
• the layer of gravel 14 under these is already markedly harder than the previous layers.
• the penetration testing has been done through these so-called soft layers of soil, through distance a, using the drill bit equipment 22 relating to the invention. It comprises the drill bit required for percussive drilling, covered with a disposable protective cover. This construction is shown in greater detail in figure 4.
• the strength of the disposable protective cover of the drill bit has been dimensioned so that the protective cover breaks when the impact of the percussive drilling starts.
• the flushing ducts of the drilling machine will then open and drilling can be continued as percussive drilling down to the required depth.
• Figure 2 shows a situation in which percussive drilling has been continued for distance b without the drill bit protective cover.
• the pressure p of the flushing water is also recorded in addition to the earlier parameters.
• the drill passes through the layers of soil shown in this example, that is, the gravel layer 14 and moraine 15. Drilling can be continued down to the rock 16, and its properties can be examined. In figure 2 drilling has been continued to a desired depth in the rock. Drilling has thus been continued e.g. through the fracture zone 17.
• Figure 3 shows the set of sample curves 31 obtained from plotter 30.
• the first on the left is compression speed v, the unit for which is metres per minute.
• the next curve to the right is the modified speed of penetration v f , which is a calculatory curve and filters off the irregularities of the previous curve.
• the third curve from the left is the speed of rotation Co, the unit for which is revolutions per minute.
• the fourth curve is torque M y , the unit for which is N .
• the torque value is obtained from the hydraulic pressures, and with it is measured the skin friction of the drill rod.
• the fifth curve is compressive force F, the unit for which is kN.
• the sixth curve is flushing water pressure p w , the unit for which is bar.
• the seventh curve represents the amount of flushing water Q w , the unit for which is litres per minute.
• the remaining two right-hand side curves B and K re1 are calculatory auxiliary parameters on the basis of which the properties of soil types are determined. From the plotter curves it is also possible to select the point at which the changeover from penetration testing to percussive drilling is made.
• Figure 4 shows the drill bit equipment 22 relating to the invention, which comprises a drill bit 23 used in percussive drilling, and a disposable protective cover 24 placed over it.
• the protective cover 24 is made of such material which breaks under the force of impact of the percussion drilling. Such materials are, for example, plastic or metal, preferably light metal.
• the head of protective cover 24 is designed to be conical. The shape corresponds mainly to the shape of known penetration testing heads. In the example of figure 4, the conical angle ⁇ is 60°.
• the protective cover 24 relating to figure 4 is designed to stay firmly in place during penetration testing.
• the edges 25 can be designed to press against drill bit 23.
• the protective cover 24 can also be provided with cogs which fit into the grooves 26 of the drill bit 23, and which prevent the protective cover 24 from rotating with the drill bit 23.
• Figure 5 shows the drill bit equipment 22 relating to figure 4 after the disposable protective cover 24 has broken and detached itself from the drill bit 23.
• the ordinary drill bit remains, with which the drilling is continued as percussive drilling once flushing has been started.
• the drilling method put forth is a combination of two existing drilling methods, the penetration testing method and the percussive drilling method. With the combined drilling method a new subsoil exploration method is achieved, by means of which the structure and geotechnical properties of the soil can be efficiently surveyed.
• the cover is designed taking the international standard recommendation into account.
• Essential features of the conical cover relating to the invention are that, during the penetration testing phase, the cover prevents the soil from penetrating into the flushing ducts, and that in performing penetration testing with the cover relating to the invention, sufficient comparability with common penetration tests is achieved.
• Automatic recording equipment is used to make possible more accurate and versatile informative recording, the said equipment being able, if necessary, to record as many as eight information channels at the same time.
• the type of drilling machine used is such that its power is dimensioned to achieve a sufficient capacity with it even in difficult conditions.
• the problems caused by the insufficient capacity of presently available equipment can be eliminated.
• the method relating to the invention can, however, also be utilized with equipment presently in use.
• the insufficient capacity of such equipment may, however, cause limitations.
• the drill rods used can be Georods, which are well suited for percussive drilling, and do not incorporate any problematic coupling sleeves.
• the recording equipment used can be any existing equipment, such as a Geoprinter, on the six channels of which six different kinds of information can be recorded as a function of depth.
• the data to be recorded are usually the following:
• the parameters can also be determined automatically by computer on the basis of the data collected, in which case the planner has the preliminary parameters immediately at his disposal.
• Drilling is started as penetration testing after the possible penetration through the dry crust or backfill layer.
• the disposable conical cover relating to the invention is installed on the head of the drill bit.
• the drill rods are pressed into the ground, for example, at a constant speed of 3 m/min, while rotating the drill rods at a speed of rotation of 25 rpm. Flushing is not used during penetration testing. In fact, this would not be possible since the conical cover covers the flushing openings on the drill bit head.
• the automatic recording device records all other parameters except those relating to flushing, such as the pressure of the flushing water.
• drilling can be continued down to the required depth.
• rock drilling the same parameters are recorded and on the basis of these e.g. the degree of fragmentation of the rock and the location of crushed zones can be determined.

Landscapes

• Engineering & Computer Science (AREA)
• Geology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Mining & Mineral Resources (AREA)
• Physics & Mathematics (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Earth Drilling (AREA)
• Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8530817

Family Applications (1)

Country Status (3)

Citations (3)

• 1990
  • 1990-07-18 FI FI903615A patent/FI87390C/fi not_active IP Right Cessation
• 1991
  • 1991-07-18 WO PCT/FI1991/000220 patent/WO1992001857A1/en unknown
  • 1991-07-18 AU AU82078/91A patent/AU8207891A/en not_active Abandoned

Patent Citations (3)

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