JPH0483083A - Long oblique hole rectilinear drilling method and drilling assembly - Google Patents

Abstract

PURPOSE:To enable a long hole to be drilled by guiding a down-hole drill so that the drill advance direction coincides with an oblique hole drilled by the drill, and rotating the drill and drill string with a specified rotational frequency to set a load at a specified value for drilling. CONSTITUTION:A down hole drill 2 is guided so that the drilling advance direction coincides with the direction of an oblique hole drilled by the drill 2, the rotational frequency of the down hole drill 2 is set to 200-350rpm, a load is set at 2t per 1 inch of bit 3 diameter or less and if necessary a drill string is rotated with 30-100rpm of low speed to drill a rectilinear oblique hole. Next, the inclination and orientation of the drilling direction are detected, and when the detecting value deviates over an allowable value from a predetermined oblique hole direction line 11, correction declination is given to the drilling direction of the down hole drill 2 to hold the drilling center within a predetermined displacement. The existing oblique hole is used for a guide hole so that the outer periphery is drilled expandedly by a hole expanding bit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a straight oblique hole drilling method and a drilling assembly thereof.

[Prior Art 1] 11H, when drilling underground using a drill, bending of the hole occurs due to the directionality of the strata, disturbance of the strata, gravity, etc., especially in oblique holes.

There is no known technology to drill a straight oblique hole into the ground without entering the hole. For example, if a long hole with an inclination of several degrees or more with respect to the vertical direction, a diameter of about 400 mm to 2000 mm, and an oblique hole length of up to 1000 m is drilled substantially straight, Conventionally, there is no technology that allows the deviation of the center of the drill hole to be within the permissible value in all directions with respect to the straight line.

2. Description of the Related Art Techniques for correcting hole curvature in a drilled hole when a hole curvature occurs in drilling using a drill are known. for example,
JP-A-62-107197 describes a method for correcting the bend in an excavated hole by fixing a portion of an air hammer to a direction correction guide and rotating the tip bit and rod to drill the hole.

This technology directs an air hammer and bit in a desired direction using a correction guide provided on an outer correction tube, and is related to short-distance excavation in the horizontal direction.
(Horizontal 10 m in the example) The side bottom cannot be applied to the straight drilling method for long oblique holes with an excavation length of 1000 m.

[Problem to be solved by the invention]

The present invention enables a straight oblique hole with a diameter of about 400 to 2000 mm and an inclination angle of 10" to 80" with respect to the vertical direction to be formed underground over a length of about 1000 m or more, in a substantially straight line. The goal is to excavate while keeping the deviation of the center within a certain value.

[Means for Solving the Problems] The method of the present invention for solving the above-mentioned problems is to guide the downhole drill so that the forward direction of drilling matches the direction of the diagonal hole drilled by the downhole drill, and to move the downhole drill at high speed and low speed. This is a long oblique hole straight drilling method that is characterized by driving a load and rotating a drill string at low speed as necessary to drill a straight oblique hole.

In this case, the rotation speed of the downhole drill should be set to 200 to 3
50 rpm, which is significantly faster than the normal 1100 rpm, and the load is set to 1 inch (25
, 4 mm) from about 3 to 4 per 2 t or less, for example 0.5
It is preferable to drill by pulling the drill string down to a certain degree, and if necessary, it is preferable to rotate the drill string at a low speed of 30 to 1100 rpm to ensure straightness even if there is disturbance of the strata.

In addition, the inclination and direction of the drilling direction are detected, and when the detected value has a deviation exceeding a tolerance value from the planned diagonal hole direction line, a corrected deviation angle is given to the drilling direction of the downhole drill, and the The corrected length calculated from the detected value is excavated, and the hole is pulled back to match the planned diagonal hole direction line, and the center of the hole is kept within a certain displacement range and excavated.

Furthermore, in the case of constructing a large diameter diagonal hole, the present invention uses the existing diagonal hole drilled by the above method as a guide hole, and uses a hole expanding bit larger than the diameter of the existing diagonal hole to expand the outer periphery of the existing diagonal hole.

The drilling assembly of the present invention, which can suitably carry out the above method, includes a downhole drill, a downhole drill with a length of 7 m or more, which is fixed to the outside of the downhole drill, and guides the downhole drill along an oblique hole drilled by itself. A long oblique hole straight drilling assembly is used which includes a guide sleeve and a measuring device for detecting the inclination and orientation of the guide sleeve. The bit size of this downhole drill is preferably 8% inch to 26 inches (445 mmφ to 660 mmφ).

The guide sleeve may have a cylindrical outer diameter with no unevenness, and the diameter may be 1.6 to 3.2 mm smaller than that of the drill.Also, a large number of rollers may be provided protruding from the outer diameter, and these rollers may be inserted into the oblique hole. It is preferable to have the inner diameter in close contact with the inner diameter, and the close contact may be achieved by protruding from the outer diameter a large number of flat springs that are biased in the direction of expansion of the diameter. In this case, a large clearance is provided in areas other than the close contact areas.

The guide sleeve is composed of an outer tube and a guide sleeve support that is interposed radially between the inner diameter of the outer tube and the outer diameter of the downhole motor. A straight-travel type with a uniform height along the hole or a correction type with a tail end at a different height in the elongated direction are provided.Usually, the straight-travel type is used, and when a hole bend is detected, the latter is used. Used for correction.

In addition, as a drilling assembly for expanding a drilled oblique hole, a hole expansion bit and an opener having a plurality of rotary blades are connected, and a ring stabilizer, nose and two
Provided is a device equipped with a heavy pipe section. This hole-expanding drilling assembly can enlarge an oblique hole with a diameter of about 2 m.

[Function] The method of the present invention is a method of drilling a substantially linear long diagonal hole, and includes: (1) regulating the direction of excavation progress of the downhole drill using the diagonal hole drilled by itself as a guide;

■ By driving the downhole drill at high speed and with a low load depending on the strata conditions, etc., it is possible to advance without bending even if there is disturbance of the strata.

■ If necessary, rotate the drill string slowly to ensure coaxiality and prevent bending.

■ In addition, the inclination and orientation of the excavation progress direction are detected, and if a deviation exceeding the allowable value is detected from the planned diagonal hole direction line despite the above ■ to ■, the correction deviation in the excavation direction is detected. Modify by adding corners.

By the comprehensive action of the above, it is possible to construct a substantially straight diagonal hole.

In the above method, in order to constrain and guide the drilling direction of the downhole drill using the oblique hole dug by the user as a guide,
A guide sleeve having a length of 7 m or more and having an outer diameter approximately equal to the inner diameter of the oblique hole, that is, the bit diameter of the downhole drill, is externally fitted and fixed to the downhole drill. The upper limit of the length of this guide sleeve depends on handling, and is preferably up to about 12 m.

The outer diameter of this guide sleeve is 1.6 mm from the bit outer diameter.
(1/16 inch) ~ 3.2mm (1/8 inch)
If the diameter is made small and it is made to slide on the inner diameter of the drilled oblique hole, theoretically, a direction error of less than 1/2000 will occur. In this case, a recess, a hole, or the like may be appropriately provided as a relief to reduce the sliding resistance of the sliding surface.

Furthermore, it is also effective to provide close contact with the excavated hole by providing a large number of rotatable rollers protruding from the outer diameter of the guide sleeve or by providing a flat spring biased in the direction of diameter expansion.

The downhole drill is driven by high speed rotation and low load.
The rotation speed is preferably 200 to 350 rpm.

The speed should be selected within this range depending on the geological formation, but the conventional and commonly used speed of about 1100 rp is not acceptable.

Although the bit load (bit thrust) depends on the slope and the geological formation, it should be a low load of 2 tons or less per inch (25.4 mm) of bit diameter. Incidentally, 3 to 4 per inch of bit diameter is a normal value, although it depends on the geology and bit diameter. This bit load is primarily determined by the weight adjustment of the drill string.

The drill string is rotated at a slow speed of 30 to 1100 rpm, more preferably 50 to 70 rpm. Rotation of the drill string corrects the tendency of the bit to bend. This effect is small below 30 rpm, and 110
If it exceeds 0rp, the effect will be saturated and it will be wasted.

The direction of excavation progress is determined by a tilt direction measuring device (MWDMeasu).
(rement While Drilling).

According to the method of the present invention, the deviation of the center of an underground oblique hole up to 1000 m in length from a straight line can be adjusted to a permissible value, for example, by 1.
It is possible to excavate within m. Therefore, for example, when opening a straight inclined shaft with a diameter of several meters and a length of several hundred meters, the method of the present invention can be used to first drill a diagonal hole for extracting (crushed rock) (excavating within the cross section of the inclined shaft). It becomes possible.

[Example 1] Hereinafter, as an example of the present invention, a diameter of 1500 mm and a diagonal hole length of 600 m with an inclination angle of 35 degrees with respect to the vertical are set. 1
The drilling of a diagonal hole within m.

In this case, the underground geology to be excavated has -axial compressive strength of 3
00-2000kg/crn', average about 1000
kg/crri'' rocks such as slate and sandstone, and gravel layers.

First, FIGS. 1 and 2 show a drilling assembly 1 used for carrying out the method of the present invention. This drilling assembly 1 includes a bit 3 and a downhole motor 5 that drives the bit.

A guide sleeve 4 is fitted around the outer diameter of the downhole motor 5. The sleeve 4 on the guy has an outer diameter 7 that is 1/16 inch (1.6 mm) smaller than the diameter of the bit 3 and is 8 to 12 m long. The guide sleeve 4 is externally fitted and fixed to the outer diameter of the downhole motor 5 via a support 6.

As shown in Fig. 1(b), the support 6 has a uniform height (constant radial dimension) along the length of the guide sleeve 4 (for coaxial guide sleeves), and as shown in Fig. 2 (
As shown in b), the tail end side (D-D cross section) is eccentric and has a constant slope, e.g. 1/600, with respect to the front end (CC cross section).
．． There is one with a slope of 1/300 (for side shaft guide sleeves).

The guide sleeve 4 regulates the direction of excavation progress of the downhole drill by using the oblique hole drilled by itself by the excavation assembly as a guide, so its outer diameter is made approximately equal to the inner diameter of the excavation hole. In this case, the sliding resistance becomes large and the problem arises that the excavation assembly is restrained by the formation. 3 to 5 show modified examples of the guide sleeve 4, which are examples in which these problems are solved.

The guide sleeve 4 in FIG. 3 has a large number of rollers 4 on its outer diameter.
1 with a protrusion. This roller 41 has an axis in the circumferential direction of the outer diameter of the guide sleeve, and the outer diameter is an envelope of a part of the circumference of the guide sleeve, and the roller 41 closely contacts the diagonal hole and allows the guide sleeve to move along the diagonal hole. Makes it extremely easy to move forward.

The guide sleeve shown in FIG. 14 has a large number of rollers 42t having coaxial axes disposed on its outer circumferential surface. In this case, rotation of the drill string becomes extremely easy.

FIG. 5 shows an example in which a large number of flat springs 43 biased in the direction of diameter expansion are arranged on the outer peripheral surface. Although the shape of the flat spring 43 does not matter, it is guided in close contact with the oblique hole.

The embodiments shown in FIGS. 3 to 5 have a portion that is in close contact with the inner diameter of the diagonal hole and a relief portion that maintains a gap, so that no confinement occurs. Furthermore, it is optional to make a through hole in the guide sleeve and supply muddy water as a lubricant to the outer diameter surface of the guide sleeve.

The downhole motor 5 is connected to a drill collar 8 having several joints to more than ten joints via an inclination direction measuring device 7. The drill collar 8 is a heavy hollow tube that is added as drilling progresses, and provides thrust to the bit 3 underground. Stabilizers to further stabilize the behavior of the drilling assembly and jars to prevent detention are inserted between the drill collars. The upper end of the drill collar is connected to the drill pipe, and sends muddy water that has the function of powering the downhole drill motor and discharging drilling debris.

The tilt direction measuring device 7 has a function of measuring the tilt and direction using measurement while drilling and transmitting the measured values to the ground surface as a mud water pressure pulse signal. measurement while drilling
t while drilling (M W
D) is a method of transmitting information about the bottom of a pit during excavation to the surface of the earth, and by instantly obtaining information about the bottom of a pit, it helps to carry out safe and efficient excavation. This system is
It consists of (1) bottom hole sensor, (2) transmission system, and (3) surface equipment. There are two types of transmission systems: the mud pulse method and the wire/line method. The main application fields of MWD are (1) slope measurement and control, (2) efficiency and safety of excavation, and (3) geological formation evaluation. Measurement items include inclination, orientation, tool face, bit load,
It is possible to measure torque, mud temperature, gamma ray, geological resistivity, etc.

Next, FIG. 4 shows the structure of a drilling assembly used for hole expansion, in which the bit 21 drills a first hole 31 following the guide hole drilled by the drilling assembly 1 shown in FIG. do. The nose 22 fits into this enlarged hole 31. The opener 23 for additionally drilling the second hole 32t is equipped with a hole-expanding roller cutter group 24 and a ring stabilizer 25 for maintaining its stability.

Water, air, etc. for driving the bit 21 and roller cutter group 24 and for removing cutting material are supplied from a double pipe 26. The double tube 26 also serves as the thrusting assembly for the hole reaming assembly.

Next, steps of an example of the method of the present invention will be explained. To create a straight oblique hole with a diameter of 1500 mm and an oblique hole length of 600 m under the above conditions, first drill a straight oblique hole with a 17 inch (445 mmφ) drilling assembly, and then use this as a guide hole to drill a 37 inch (953 mmφ) and a 59 inch ( 1500mm
The hole was expanded using a hole expansion drilling assembly of φ).

(I) Drilling a straight lead hole.

In order to meet the requirements for the deviation of the borehole core, the diameter 1
A 7V2 inch (445 mm $) lead hole was first drilled.

■ A 20 m long guide pipe will be accurately installed on the ground surface in order to launch the drilling assembly accurately in the planned diagonal hole direction.

■ Excavate underground following this guide tube, use the hole you drilled as a guide as a guide sleeve, and fix the downhole motor and bit to the guide sleeve. In addition, in order to eliminate hole bending due to strata, a downhole motor is used to operate the bit with low load and high speed rotation.

FIG. 6 shows this excavation state, in which the downhole drill 2 drives the bit 3, and the guide sleeve 4 follows the excavation hole that it has drilled itself, thereby regulating the excavation direction of the downhole drill.

The bit size was 17 inch (445 mmφ). The bit is Eastman Christensen's P.
DC bit 5P21D was used. The downhole motor is the company's Navi-Drill Matsuha 2.
l Mach2) Outer diameter 934 inches (241mmφ)
It was used.

The guide sleeve is a plain guide sleeve with an outer diameter of 17 inches (438 mmφ) because the geology to be drilled is relatively stable and there is no particular tendency for hole bending.
, 8m long.

■ In addition to rotating the bit at high speed with a downhole motor, the entire drill string can also be rotated from a drilling rig on the surface.
Rotate at 70 rpm to enhance coaxiality of the guide sleeve into the borehole.

■ At the transition point in the strata, the bit load (thrust) is reduced by about 5 tons and drilling takes about twice as long to carefully drill to prevent hole bending.

■ If a fractured layer or gravel-containing layer is encountered, excavate the required length, then lift the excavation assembly to the ground, inject cement, seal it, and excavate again after hardening.

■ If there is a tendency for the borehole centerline to exceed the permissible deviation based on the inclination/azimuth measurement using the inclination/azimuth measurement device, then the drilling assembly should be pulled to the surface and a sidewall installed instead of the coaxial guide sleeve. The correction assembly, in which the shaft guide sleeve is fitted onto the downhole motor, is lowered to perform corrections to overcome the tendency of hole bending.

This modification assembly consists of a downhole drill and a shaft guide sleeve with the orientation of the bit at an angle relative to the central axis of the guide sleeve. Side axis guide sleeves with several types of eccentric axis gradients are prepared depending on the strength of the hole bending tendency. For example, the eccentric axis gradient is 1/600°1
/300, etc.

FIG. 7 shows a state in which the displacement is corrected using the side shaft guide sleeve. When the center line of the guide sleeve is biased with respect to the planned excavation center line 11 and the guide sleeve becomes flattened 12, A corrective action is given using the side shaft guide sleeve 4a as a sleeve to restore the displacement along the corrective line 13.

When using a side shaft guide sleeve, the slope between the shaft center line of the guide sleeve and the shaft center line of the downhole drill is △, and the length of the guide sleeve is determined! , where R is the radius of curvature of the excavation trajectory, Δ=β/R.

The displacement χ from the center when the excavation length is excavated is χ=R−Rcosθ=R(1−cosθ). At this time, L/2πR=θ/360. Therefore, θ=180L/πR=180L△/π! becomes. The length β of the guide sleeve is 8 m, the slope of the side shaft guide sleeve is Δ=1/600.1/300, and, for example, the excavation length L is 30 m.

A comparison of 60m and Zoom results as shown in Table 1. That is, it is possible to return to the center position within a deviation of 1 m from a straight line within an excavation length of 100 m.

■ The following measures are effective as measures against internment.

(a) Jarls (
A hammering device) is installed to make it easier to remove the vessel if it is detained.

(b) Better management of muddy water and shear (fractured rock)
Fried well.

(C) A roller is provided protruding from the outer diameter of the guide sleeve to provide clearance.

(d) Straight digging simultaneously rotates the entire string in addition to the downhole motor.

(II) Expansion drilling.

After drilling a pilot hole with a diagonal hole diameter of 17 inches (45 mmφ) as planned as described above, a 3-inch (953 mm
φ) and a 59 inch (1500 mmφ) hole expansion drilling assembly are used to perform hole expansion drilling.

Since the diameter of 1500mmφ is large, reverse circulation must be incorporated into the grinding process. Therefore, the same applies to 953 mmφ. An embodiment of the trench widening assembly near the bit is schematically shown in FIG.

In order to improve the excavation rate and stabilize the conditions inside the hole, the jet to the opener 23 is secured. Reverse circulation is by air lift. The macaroni pipe is lowered to an appropriate depth in the inner pipe of the double pipe 26, and air is introduced therethrough. The nose 22 and ring stabilizer 25 stabilize the entire opener 23 and allow it to accurately follow the leading hole. At this time,(
The ratio of air amount)/(pumped water amount) is approximately 2.3. If two 10P-130 pumps are operated at 80 spm (strokes per minute), the discharge amount will be 2.1 rn''/min. Therefore, the minimum required air amount is 5 rn'/min. However, This amount of air must be increased due to the presence of excavation debris and pressure loss within the inner pipe.

Assuming that the inner diameter of the inner tube of the double tube is 3 inches (76 mm), 2
．． The pressure loss for a flow rate of 1 rn'/min is 0.1 kg/min, assuming the specific gravity of muddy water is 1.1.
cr rr1''/m. This is a fairly large pressure drop, and for long excavations, the inner diameter of the inner tube must be increased (if this is not possible, the air placement premium must be increased considerably).

[Effects of the Invention] According to the present invention, it has become possible to drill an oblique hole with a diameter of 400 to 2000 mm with a hole bias within a certain limit up to a hole length of 1000 m.

Therefore, according to the present invention, for example, it is possible to construct in advance a slot guide hole for spacing a long-distance straight inclined shaft within the cross section of the inclined shaft to be opened. As a result, the construction methods, construction facilities, design, and construction process for straight-inclined shaft excavation work will be radically changed, and the contribution it will make to this industry will be an art university.

[Brief explanation of the drawing]

FIG. 1 shows the structure of an excavation assembly according to an embodiment used in carrying out the present invention, in which (a) is an overall perspective view, (b) is a vertical cross-sectional view, (c) is a central cross-sectional view, and FIG. The figures show other embodiments; a) is an overall perspective view, (b) is a longitudinal sectional view, and (c) is a longitudinal sectional view.
) and (d) are respectively a CC arrow view and a D-D arrow view of (b), FIGS. 3 to 5 each show an example of the guide sleeve, and (a) is a perspective view, respectively. (b) is a cross-sectional view, FIG. 6 is a vertical cross-sectional view showing the state during diagonal hole drilling, FIG. 7 is an explanatory diagram of the deviation correction operation, and FIG. 8 is a schematic cross-sectional view of the drilling assembly for hole expansion. It is. 1... Drilling assembly 2... Downhole drill 3... Bit 4... Guide sleeve 5... Downhole motor 6... Support 7... Direction measuring device 8... Drill collar 11 ... Planned excavation center line 12 ... Deviation line (direction of guide sleeve, 11) 13
... Correction line applicant Japan Offshore Drilling Co., Ltd.

Claims (1)

[Scope of Claims] 1. A long straight hole characterized in that a downhole drill is guided so that the forward direction of excavation matches the oblique hole drilled by itself, and the downhole drill is driven at high speed and with a low load to drill a straight oblique hole. Straight oblique hole drilling method. 2. The long oblique hole straight drilling method according to claim 1, further comprising rotating the drill string at a low speed. 3. Increase the rotation speed of the downhole drill to 200 to 350 rpm.
3. The method for straight drilling a long oblique hole according to claim 1 or 2, wherein the load is 2 tons or less per inch (25.4 mm) of bit diameter. 4. The long oblique hole straight drilling method according to claim 2, wherein the rotation of the drill string is 30 to 100 rpm. 5) Detecting the inclination and orientation of the drilling direction, and when the detected value has a deviation exceeding a tolerance value from the planned diagonal hole direction line, giving a corrected deviation angle to the drilling direction of the downhole drill;
A long oblique hole straight drilling method, characterized in that the drilling is performed by a corrected length calculated based on the detected value, and the center of the drill hole is kept within a certain displacement range from the planned diagonal hole direction line. 6. A long diagonal hole straight drilling method characterized by using an existing diagonal hole as a guide hole and drilling the outer periphery of the existing diagonal hole with a hole expanding bit having a diameter larger than that of the existing diagonal hole. 7 A downhole drill, a guide sleeve with a length of 7 m or more that is fitted and fixed to the downhole drill and guides the downhole drill along the oblique hole drilled by itself, and measurement to detect the inclination and orientation of the guide sleeve. A long oblique hole straight drilling assembly comprising a device. 8. The long oblique hole straight drilling assembly according to claim 7, wherein the downhole drill has a bit size of 81/2 inches to 26 inches (445 mmφ to 660 mmφ). 9. The long oblique hole straight drilling assembly according to claim 7, wherein the guide sleeve has an outer diameter smaller than the bit outer diameter of the downhole drill by 1.6 to 3.2 mm. 10. The long oblique hole straight drilling assembly according to claim 7, wherein the guide sleeve has a plurality of rollers protruding from its outer diameter. 11. The elongated diagonal hole straight drilling assembly according to claim 7, wherein the guide sleeve has a plurality of flat springs projecting from the outer diameter thereof, which are biased in the direction of expanding the diameter. 12 The guide sleeve consists of an outer tube and a guide sleeve support that is radially interposed between the inner diameter of the outer tube and the outer diameter of the downhole motor, and the guide sleeve support is arranged uniformly along the longitudinal direction of the guide sleeve. An elongated oblique hole straight drilling assembly according to any of claims 7 to 10, wherein the heights or longitudinal tails are of different heights. 13. A hole-expanding drilling assembly characterized by connecting a hole-expanding bit and an opener having a plurality of rotary blades, and comprising a ring stabilizer, a nose, and a double pipe section.