CN1052292C - Cutting device for making grooves in underground rock formations - Google Patents

Abstract

A cutting device for cutting a slot alongside a well traversing subterranean formations, comprising a saw arm (15) over which is fitted an endless chain (24), drive means for rotating the chain about the saw arm, and spring means, the chain carrying a cutting member (25), the spring means causing the saw arm to rotate to a first position in the absence of hydraulic pressure; characterised in that the drive means comprises a hydraulic motor (27) slidable in the housing (11), the motor and hinge mechanism (17) causing the saw arm to be pivoted to the second position when hydraulic pressure is applied. With this cutting device, grooves of greater area and depth can be made, thereby improving the communication between the wellbore and the surrounding formation.

Description

Cutting device for making grooves in underground rock formations

The present invention relates to a cutting device for slotting alongside a well that traverses a subterranean formation (subterranean formation).

In the drilling technology of oil and gas wells, it is often necessary to perforate the rock formation (formation) and/or the well wall and the surrounding cement sleeve in order to introduce the fluid in the rock formation into the well hole.

It is common practice to perform this type of perforation with a shaped charge perforating gun, which ejects high-velocity metal particles through the borehole wall and cement casing and into the surrounding rock formation.

Attempts have been made to devise means for drilling grooves alongside subterranean wellbores without deforming and compacting the surrounding rock formation as would be the case with the use of perforating guns.

US Patent Specification No. 3225828 discloses a downhole grooving device comprising a circular grooving cutting wheel. When using this existing device, the cutting wheel partially stretches out of the device housing, rotates to open a groove in the surrounding well wall or well hole, then the cutting wheel retreats into the housing, and the device is removed from the well. pull out. Other arrangements using circular grooved cutting wheels are described in US Patent Specification Nos. 4,106,561 and 4,220,201.

A disadvantage of existing grooving devices is that, since the maximum dimension of the cutting wheel is less than 50% of the borehole diameter, the depth of the grooves cut in the subterranean formation is relatively small.

UK Patent Specification No. 842,549 and US Patent Specifications Nos. 1,406,351 and 2,178,554 disclose chainsaw downhole cutting devices which include complex mechanisms for rotating the saw arm between its longitudinal and transverse positions.

SUMMARY OF THE INVENTION It is an object of the present invention to provide means for increasing the area and depth of grooves drilled alongside a well penetrating subterranean formations, thereby increasing the fluidity between the wellbore and the surrounding formation.

To accomplish this object, the present invention provides a cutting device for grooving alongside a well traversing a subterranean formation, the device comprising a casing hinged so as to be able to rotate in a first direction parallel to the longitudinal axis of the casing. position and its second position deviated from the longitudinal axis, a set of endless chains on the saw arm with cutting members, drive means to rotate the chain around the saw arm, and a spring mechanism, the spring mechanism is used to return the saw arm to the first position when there is no hydraulic pressure, characterized in that the drive device includes a hydraulic motor that can slide in the housing, so that when hydraulic pressure is applied to the motor, the The motor moves along the housing with a hinge mechanism to pivot the saw arm to the second position.

Moreover, the drive means includes a hydraulic motor slidably mounted in the housing so that when hydraulic pressure is applied to the motor, the motor moves along the housing with a hinge mechanism to turn the saw arm toward the second position; the cutting device also includes a spring mechanism that turns the saw arm back to the first position when there is no hydraulic pressure on the motor.

Preferably, the saw arm consists of an oval blade and the drive means for rotating the endless chain about the saw arm comprises a drive shaft driven by a Moineau type positive displacement hydraulic motor.

The hinge mechanism preferably includes a spur gear secured to the supported end of the saw arm, and the piston assembly includes a rack with teeth meshing with the spur gear.

The present invention is described in detail below in conjunction with the accompanying drawings, in the accompanying drawings:

Fig. 1 is a not-to-scale partial cross-sectional view of a vertical well in which the cutting device of the present invention is arranged; and

FIG. 2 is a partial cross-sectional view of the cutting device drawn on a scale different from that of FIG. 1 .

In Figure 1 there is shown a well 1 penetrating a subterranean formation 2, the well 1 comprising a borehole 3 in which a casing 5 is fitted. The annular space between the casing 5 and the wall of the borehole 3 is filled with cement 7 .

The cutting device 10 of the present invention includes a housing 11 and a saw arm 15 hinged on the housing 11 . The saw arm 15 is covered with an endless chain 24 on which a cutting element 25 is mounted. The cutting device 10 also includes a device 17 for hingedly connecting the saw arm 15 to the housing 11 , a motor (not shown) and a transmission 20 for rotating the endless chain 24 around the saw arm 15 .

The cutting device 10 is suspended at the bottom end of a pipe 21 in the well 1 . When lowering the cutting device 10 into the well 1 , the saw arm 15 maintains its first position parallel to the longitudinal axis I of the housing 11 . When the cutting device reaches the position to be cut in the casing 5 and the surrounding formation 2 , the motor is activated to drive the endless chain 24 . At the same time the saw arm 15 is slowly turned to its second position offset from the longitudinal axis I of the housing 11. In the second position, as shown in FIG. 1 , the saw arm 15 is perpendicular to the longitudinal axis I of the housing 11 . The cutting device 10 is then moved upwards through the well 1 and the cutting extension 25 on the endless chain 24 cuts an elongated slot 23 through the casing 5, the cement sleeve 7 and the surrounding formation 2. When the elongated slot 23 has reached the desired length, the saw arm 15 is turned back to the first position, and the cutting device 10 is withdrawn from the well 1 . The surface area of each side of the slit 23 is equal to the length of the slit 23 multiplied by the depth of the slit 23 perpendicular to the well 1 .

The length of the saw arm 15 is selected as: the depth of the elongated slot 23 is equal to or more than 0.25-3.0 times the diameter of the borehole 2, preferably 0.5-1.50 times the diameter of the borehole 2.

The cutting device 10 shown in FIG. 1 will be described in detail below with reference to FIG. 2 . The cutting device 10 includes a housing 11 and a saw arm 15 hinged to the housing 11 . As shown in FIG. 2 , saw arm 15 is rotatable between its first position parallel to the longitudinal axis of housing 11 and its second position offset from the longitudinal axis of housing 11 .

This cutting device also comprises a saw arm 15 and the device 17 that shell 11 is hinged and a motor 27, and motor 27 is provided with spline telescopic output shaft 28 and transmission device 20, thereby the endless chain 24 that cutting member 25 is housed on it surrounds The saw arm 15 rotates.

The endless chain 24 is looped over a sprocket 29 on the supported end of the saw arm 15 . The sprocket 29 is connected to a drive shaft 30 which is rotatably connected to the housing 11 by a bearing assembly (not shown). The drive shaft 30 is oriented perpendicular to the longitudinal axis I of the housing 11 and the saw arm 15 is articulated to the drive shaft 30 .

The drive shaft 30 is in turn driven by the transmission 20 . The transmission device includes a linear or spiral bevel gear consisting of a passive gear 31 sleeved on the drive shaft 30 and a driving gear 32 mounted on the bottom end of the telescopic output shaft 28 of the motor 27 . The telescopic output shaft 28 is supported by a support (not shown) near the drive gear 32 to prevent the end of the telescopic output shaft 28 from moving axially or laterally.

The means 17 for articulating the saw arm 15 comprise a means 35 for translating the bar 37 in the longitudinal direction of the housing 11 and a means 39 for converting the translation of the bar 37 into a rotation of the saw arm 15 . The device 39 includes a spur gear 40 which meshes with a tooth 41 on the bar 37 . The spur gear 40 has an arm 42 connected to the saw arm 15 to transmit the rotation of the spur gear 40 to the saw arm 15 .

The means 35 for translating the bar 37 in the longitudinal direction of the housing 11 comprises a piston 45 having an opening 46 therein and a tubular drive assembly 48 comprising a housing 49 and an inner tube 50 . The top end of the outer shell 49 is connected to the piston 45 , while the strip 37 is connected to the bottom end of the inner tube 50 .

There is an inwardly protruding ring 52 on the housing 11, and a shoulder 53 is arranged on the outer tube 49, so that the device 35 can only abut against the first position where the shoulder 53 and the inwardly protruding ring 52 and the piston 45 and the The inwardly raised ring 52 moves between the second abutment position. Therefore, the rack 37 and the spur gear 40 are designed such that: in the first position, the saw arm 15 is in the same direction as the housing 11 ; and in the second position, the saw arm 15 is perpendicular to the housing 11 .

There is also an inwardly protruding support ring 55 on the outer shell, and an outwardly protruding ring 56 is arranged on the inner tube 50 . Two springs are housed in the annular space 60 between the inner tube 50 and the shell 11: a return spring 62 between the inwardly protruding support ring 35 and the outwardly protruding ring 52 and a return spring 62 between the outwardly protruding support ring 35 and the outwardly protruding ring 52. The compression spring 64 between the raised ring 56 and the bottom end of the housing 49. These two springs 62 and 64 provide a slight floating suspension for the saw arm 15 to accommodate the rigid construction of the casing and/or surrounding cement sleeve and rock formation.

The motor 27 is secured to the inner tube 50 by means of supports 67 and 68 , while the telescoping output shaft 28 of the motor 27 passes through a hole 70 in a plate 71 .

The motor 27 is a Moineau type positive displacement hydraulic motor. The motor 27 is coaxial with the longitudinal axis I of the housing 11 . The upper support 67 is a collar that prevents fluid leakage from the drive motor 27 .

In normal operation, the cutting device 10 is lowered into the well 1 (see FIG. 1 ) to the bottom end of the tube 21 . When the cutting device 10 is lowered, the saw arm 15 is in a first position coaxial with the longitudinal axis I. Motor 27 is then actuated by driving fluid through tube 21 , which fluid flows into displacement motor 27 through opening 46 . A telescoping output shaft 28 of a motor 27 drives an endless chain 24 on which a cutting element 25 is provided via a transmission 20 .

The fluid flowing through the tube 21 also acts on the piston 45 , causing the means 35 for translating the bar 37 to move downwards, so that the saw arm 15 turns slowly to a position offset from the longitudinal axis I of the housing 11 . As the saw arm 15 rotates, the cutting member 25 cuts through the casing 5 (see FIG. 1 ), the cement layer 7 and the subterranean formation 2 . When the saw arm 15 is perpendicular to the longitudinal axis I, the cutting device 10 is raised to form an elongated slot 23 in the subterranean formation 2 .

When the elongated slot 23 reaches the desired length, the fluid supply is interrupted, and the return spring 62 pushes against the device 35 to move up the bar 37, so that the saw arm 15 returns to its first position. The cutting device 10 is then withdrawn from the well 1 .

The length of the saw arm 15 is not limited by the diameter of the housing or bore, so the depth of the slot can be much greater than with existing cutting devices using circular cutting knives. Moreover, the walls of the slots of the present invention are plane, so compared with the existing holes of the same depth drilled by perforating guns, the output of a slot can be increased by at least 25%. The narrow and long slots produced by the method of the present invention are also beneficial to further treatment of the well, such as pebble backfilling, hydraulic crushing and other treatment for increasing production. If the tanks of the present invention are used in combination with pebble backfill, a significant increase in production (up to 300%) can be expected due to the absence of a crunched zone where fines block the pores of the pebble filter layer drilled with existing perforating techniques.

The cutting device may be provided with piping and nozzles to flush the cut piece with fluid from the drive motor.

By properly choosing the density of the fluid in the well, the fluid pressure at the saw arm can be controlled. This pressure may be greater than the formation pressure to facilitate cutting the formation. The pressure may also be less than the formation pressure so that fluid flows from the formation into the well to flush the cuttings.

The motor of the device described in conjunction with Fig. 2 is a displacement hydraulic motor, but it can also be replaced by a hydraulic turbine or an electric motor. If the motor is driven by fluid, the cutting device is installed at the bottom of pipes such as drill rods or coiled pipes. If the motor is an electric motor, the cutting device is mounted on the bottom end of the wire or coil containing the wire. The cutting device may also be provided with transmission means to transmit the rotation of the pipe carrying the cutting device downhole to the endless chain.

The bar 37 can be replaced by a rotatable spindle driven by an electric motor, which cooperates with a spur gear.

The cutting device according to the invention can be equipped with more than one saw arm, for example two symmetrical saw arms. At this time, the second saw arm (not shown) can be hinged on the drive shaft 30 to rotate by a spur gear driven by a rack. The rack and spur gear may be arranged at the mirror images of the spur gear 40 and the rack 37 shown in FIG. 2 .

As described in connection with FIG. 1 , the cutting member cuts through the casing, cement and rock formation. It should be noted that if the well has a liner, the cutting member cuts through the liner; if the well is an open hole, only the rock formation is cut.

Additionally, if the well has a steel casing or liner, the device can be fitted with a circular saw blade that first cuts a slot in the steel casing or liner, and then turns the chainsaw through the slot to break the cement casing. Open a slot in the surrounding rock formation.

The well shown in Figure 1 is a vertical well, but the cutting device of the present invention is not limited to vertical wells. The well can also be a deviated well or a horizontal well, in which case the word "upward" refers to the direction toward the wellhead.

Endless chains can rotate in both directions depending on the motor and transmission.

Can upwards (as described in conjunction with accompanying drawing 1), also can leave the narrow and long groove downwards.

The cutting element 25 is made of wear-resistant material, such as tungsten carbide, natural or synthetic diamond.

It should be seen that the saw arm 15 is slowly rotated to the transverse position shown in FIG. 1 while the cutting piece is cutting, and the hinge mechanism that makes the saw arm return to the longitudinal position after slotting is various.

It should therefore be understood that the embodiments of the cutting device shown in the drawings are by way of illustration only.

Claims (3)

1. A cutting device for grooving beside a well passing through an underground formation, the device comprising a shaft hinged on a housing (11) so as to be able to move in its direction parallel to the longitudinal axis (I) of the housing (11) A saw arm (15) rotating between a first position and a second position offset from the longitudinal axis (I), an endless chain (24) mounted on the saw arm (15) with cutting elements (25) on it ), the drive to rotate the chain (24) around the saw arm (15), and a spring mechanism (62, 64) for turning the saw arm (15) back to the first position when there is no hydraulic pressure , it is characterized in that the driving device includes a hydraulic motor (27) that can slide in the housing (11), so that when hydraulic pressure is applied to the motor (27), the motor and a hinge mechanism (17) move along Moving the housing (11) causes the saw arm (15) to turn to the second position. 2. Cutting device according to claim 1, characterized in that the motor (27) is a positive displacement hydraulic motor mounted in the housing (11) coaxially to the longitudinal axis (I) of the housing. 3. Cutting device according to claim 1 or 2, characterized in that, the hinge mechanism (17) comprises a spur gear (40) and a piston assembly (35) fixed on the supported end of the saw arm (15) ), the piston assembly connects the motor and a rack (37) meshing with a spur gear (40).

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