JPH0658071A - Well-head device and cementing method - Google Patents

Abstract

PURPOSE:To certainly perform the alignment of a casing pipe and cementing in a well which are different in type. CONSTITUTION:A centering jig 6 is equipped with a jig body 9 having a center hole 10 of a larger inner dia. than the outer dia. of a casing pipe to be inserted in an excavation hole 1 and a plurality of threaded holes piercing from the peripheral surface to the bore of the center hole 10 and with centering screws which are fitted in the threaded holes and push the peripheral surface of the casing pipe inserted in the center hole 10. At the time of excavating, a tool is sunk to perform excavation through this centering jig 6 in the condition that the centering screws are replaced with seal screws not protruding from the bore of the center hole 10. After excavation, the casing pipe is installed in the excavation hole 1 through the centering jig 6, and the seal screws are replaced with the centering screws, and alignment is made by pressing fast the casing pipe from the periphery. The gap formed between the excavation hole 1 and the casing pipe is filled with a filler such as cement.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a geothermal well, a hot spring well,
The present invention relates to a wellhead device and a cementing method for surely centering and cementing a casing pipe when making a water well or an oil or gas well.

[0002]

2. Description of the Related Art Wells for various wells such as geothermal wells are formed by excavating the ground to form excavation holes.
By inserting a casing pipe made of steel pipe or the like, and then filling a gap formed between the hole wall of the excavation hole and the casing pipe with a filler such as cement (hereinafter referred to as cementing). Be seen.

In this case, when the drill hole is shallow, cementing is performed by directly flowing the filler from the ground into the gap. In this method, as the depth of the drill hole increases, the filler is filled. It becomes difficult for the agent to reach the lower part of the gap. Therefore, when the excavation hole is equal to or more than a predetermined depth, after separating the excavation hole lower end and the casing pipe lower end in advance,

(1) The filler is flowed into the casing pipe, and then the inside of the casing pipe is pressurized to allow the filler in the casing pipe to flow into the gap.

(2) A pipe having a diameter slightly smaller than that of the casing pipe is dropped into the casing pipe, and the filler is press-fitted into a gap formed between the pipe and the casing pipe to obtain the filler. From this gap into the gap formed between the wall of the excavation hole and the casing pipe.

(3) A thin tube is inserted into a gap formed between the excavation hole and the casing pipe, and the filler is pressed into the thin tube while the thin tube reaches the lower end of the casing pipe. According to the method, cementing is performed from underground to above ground.

However, in this case, if the axis line of the drill hole and the axis line of the casing pipe are deviated from each other, it becomes difficult to attach the wellhead device thereafter, and in addition, it is formed between the drill hole and the casing pipe. The gap may be unevenly filled with the filler. And, if the filler is unevenly filled in the gap, the casing pipe may be tilted in the excavation hole, or the casing pipe may be unevenly expanded and contracted, and as a result, the wellbore. There is a problem that the aboveground structure formed on the slope inclines, which not only hinders the subsequent work but also deteriorates the performance of the well itself.

Therefore, in order to prevent this problem, it is necessary to align the axis of the excavation hole with the axis of the casing pipe (hereinafter referred to as centering). And
As a centering method,

(A) As shown in FIG. 5, in the gap formed between the casing pipe 2a that has already been cemented and the casing pipe 2 inserted into the new excavation hole 1,
After inserting the annular support member 3 from the ground and performing centering in advance using the support member 3, the method (1) or (2) described above is used with the support member 3 still attached. Do cementing

(B) As shown in FIG. 6, an annular support member 3 is mounted on a rig floor 4 for excavation, and a casing pipe 2 is inserted through the center of the support member 3 to perform centering. The casing pipe 2 is lowered. Then, after the lowering of the casing pipe 2 is completed, cementing is performed using the same method as the above (a).

(C) Various methods such as directly moving the casing pipe 2 in the excavation hole 1 for centering are used after the cementing and before the filler is hardened.

On the other hand, when cementing is performed, the drill hole 1
When the depth is increased, the weight of the filled filler causes a crack on the side surface of the drill hole 1, and the filler may leak into the ground through the crack to reduce the filling amount.

In the above case, after cementing, the filling amount of the filler in the gap formed between the excavation hole 1 and the casing pipe 2 becomes insufficient.
It is necessary to refill the above-mentioned filler from the ground again by the shortage amount.

Here, when water remains on the upper surface of the previously filled filler, the filler is refilled from the ground to refill the upper surface of the previously filled filler. Water is sealed at the interface with the agent, and as a result, this water expands as the temperature around the drill hole 1 increases,
The casing pipe 2 may be damaged. Therefore, in order to prevent this problem, after the water remaining on the upper surface of the filler is removed in advance, the filler is again filled from the ground.

[0015]

However, in the above-mentioned conventional centering method (a), the gap formed between the casing pipes 2 and 2a is substantially closed by the support member 3. Therefore, neither removal of water remaining on the interface nor refilling of the filler was possible. Further, there is a problem that it is difficult to carry out cementing due to bad air escape in the gap, and it is difficult to grasp the cementing state after centering.

In the method (b), since the casing pipe 2 is lowered into the excavation hole 1 after centering at a relatively high position, the casing pipe 2 is moved to the left and right during the descending process. There is a problem that it may shake, resulting in a decrease in centering accuracy.

Further, the method (c) has a problem that the centering accuracy is low and that the centering must be completed before the filler is cured.

[0018]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. First, the wellhead device of the present invention is provided at the opening portion of a borehole and is inserted into the borehole. A support structure for supporting the pipe is provided, and a centering jig for coaxially supporting the casing pipe is provided on the support structure, and the centering jig has a center having an inner diameter larger than the outer diameter of the casing pipe. A jig body having a plurality of screw holes penetrating from the hole and the outer peripheral surface toward the inner peripheral surface of the central hole; and an outer peripheral surface of a casing pipe screwed into each of the screw holes and inserted into the central hole. And a centering screw for pressing.

Further, the cementing method of the present invention is provided with a wellhead device having a support structure at the opening of the excavation hole, and the support structure has an inner diameter larger than the outer diameter of the casing pipe to be inserted into the excavation hole. A jig main body having a large central hole and a plurality of screw holes penetrating from the outer peripheral surface toward the inner peripheral surface of the central hole, and an outer periphery of a casing pipe screwed into each of the screw holes and inserted into the central hole. Provide a centering jig that has a centering screw that presses the surface,

When forming the excavation hole, excavation is performed by lowering the excavation tool through the centering jig with the centering screw of the centering jig being replaced with a sealing screw that does not protrude from the inner peripheral surface of the center hole. on the other hand,

After forming the excavation hole, the casing pipe is placed in the excavation hole through the centering jig, the sealing screw is replaced with a centering screw, and the casing pipe is pressed and fixed from the surroundings to perform centering. And further filling a filler such as cement in a gap formed between the excavation hole and the casing pipe.

[0022]

In the wellhead device and the cementing method of the present invention, after the wellhead device is installed on the excavation hole, the amount of protrusion of the screw is adjusted for centering, so that the amount of protrusion of the screw is finely adjusted. By doing so, accurate centering is possible. Further, during centering, since a gap is formed between the inner periphery of the wellhead device and the outer periphery of the casing pipe, after cementing, removal of water remaining on the interface of the filler and removal of the filler. Refilling can be performed easily and the situation of cementing can be always grasped.

[0023]

Embodiments of the present invention will now be described in more detail with reference to the drawings. FIG. 1 shows an example of a wellhead device 5 of the present invention. This wellhead device comprises one end of a centering jig 6 having a cylindrical center hole 10, a valve device 7 having a straight tubular openable / closable passage 7a, and a tubular excavating pipe 8 connected in series. And as a result,
The central hole 10, the passage 7a, and the excavating pipe 8 are all coaxial.

On the other hand, the other end of the centering jig 6 is installed on the opening of the casing pipe 2a formed in the excavation hole 1 so that the center hole 10 and the casing pipe 2a are coaxial with each other. An excavating tool (not shown) having a bit for excavating at the tip is installed in the excavating pipe 8 so that the excavating tool can pass through the wellhead device 5 and the casing pipe 2a. After passing, it is possible to descend to the bottom of the excavation hole 1.

The structure of the centering jig 6 is shown in FIGS. The jig body 9 has a short tubular shape, and a central hole 10 penetrates through the central portion thereof.

A plurality of screw holes 11 (8 in FIG. 2) are formed on the side surface of the jig body 9 so as to be perpendicular to the axis of the centering jig 6 and penetrate in the radial direction of the jig body 9. . In each of these screw holes 11, a screw is formed only in an arbitrary range a from the outer peripheral side of the jig body 9, and the inner peripheral side thereof is a simple round hole. Furthermore, each screw hole 1
1 are arranged on the same plane parallel to the end surface of the jig body 9 so that the distances between the adjacent screw holes 11 are equal.

A centering screw 12 is screwed into the screw hole 11 from the outer peripheral side of the jig body 9. Here, as shown in FIGS. 2 to 4, the centering screw 12 is formed with a screw over a range b shorter than the range a at the base end portion thereof, and the tip side thereof has a simple round bar shape. Further, the length of the centering screw 12 is such that when the centering screw 12 is tightened most, the tip of the centering screw 12 is within the above range b from the inner peripheral surface of the jig body 9.
The length is such that it can protrude by a slightly shorter length.
Therefore, the centering screw 12 can move back and forth within the screw hole 11 by the same width as the above range b, and when the centering screw 12 is loosened most, the centering screw 1 can be moved.
The tip end surface of 2 retreats slightly from the inner peripheral surface of the opening.

As shown in FIG. 4, the reduced diameter portion 12 is provided at each of the base end of the centering screw 12 and the position retracted from the tip of the centering screw 12 by the width of the range b.
a and 12b are formed, and O is formed in each of the reduced diameter portions 12a and 12b.
A ring (not shown) is fitted. This is to improve the airtightness between the centering screw 12 and the screw hole 11. In addition, a mounting hole 13a and a recess 13b for connecting to the valve device 7 or the casing pipe 2a are formed on the upper and lower surfaces of the jig body 9.

On the other hand, if necessary, instead of the centering screw 12, the screw hole 11 has a length such that its tip does not protrude from the inner peripheral surface of the jig body 9 (hereinafter referred to as a sealing screw) even when tightened most. (Referred to as)) can be inserted.
Also in the sealing screw, a reduced diameter portion is formed similarly to the centering screw 12, and an O ring is fitted in the reduced diameter portion.

Next, an excavation and cementing method using the wellhead device 5 of the present invention will be described.

First, in the state of FIG. 1, after the sealing screw (not shown) is screwed into the screw hole 11, the valve device 7 is opened and the tip of the excavating tool is the hole of the excavating hole 1. Excavation is performed by lowering the excavation tool until it contacts the bottom. Here, since the sealing screw is screwed into the screw hole 11, the presence of the centering jig 5 hinders the lowering and excavation of the excavating tool, and the screw hole 11 is clogged with earth and sand. There is no such thing.

After the end of the excavation, the tip of the excavation tool is pulled up into the excavation pipe 11, and the valve device 7 is once closed and then gradually opened to prevent a rapid injection of gas from the excavation hole 1 before excavation The pipe 11 and the valve device 10 are removed, then a new casing pipe 2b is inserted into the center hole 10, the casing pipe 2b is installed at a predetermined position in the excavation hole 1, and then screwed into the screw hole 11. The sealing screw is replaced with the centering screw 12.

Then, as shown in FIGS. 2 and 3, the centering screw 12 is projected from the inner peripheral surface of the jig body 9 so that the centering screw 12 surely presses and fixes the casing pipe 2b from the surroundings and performs centering. To do. In this case, accurate centering is possible by finely adjusting the amount of protrusion of the centering screw 12.

Further, the excavation hole 1 and the casing tube 2b.
Cementing is performed by inserting a filler such as cement into the gap formed between them. Here, in the case of the present invention, centering and cementing may be performed simultaneously, or after centering, cementing may be performed again. Moreover, since a gap is formed between the jig body 9 and the casing pipe 2b during centering and cementing, it is easy to remove water remaining on the upper surface of the filler and refill the filler after cementing. Besides, it is possible to always grasp the situation of cementing.

Then, by adjusting the protrusion amount of the centering screw 12 from the inner peripheral surface of the jig body 9 according to the outer diameter of the casing pipe 2b, the centering of the casing pipes 2b having different outer diameters can be performed by the same centering treatment. It can be performed with the tool 5.

Moreover, as described above, the centering screw 1
By exchanging 2 with the above-mentioned sealing screw, excavation with the centering jig 6 installed is possible. Therefore, if the centering jig 6 is installed on the casing pipe 2a in advance before starting excavation. The centering jig 5 can perform centering and cementing over several orders.

[0037]

As described above, in the wellhead device and the cementing method of the present invention, after the wellhead device is installed on the excavation hole, the screw is projected from the inner peripheral surface of the wellhead device to perform centering. Accurate centering is possible by finely adjusting the protruding amount of the screw. Further, during centering, since a gap is formed between the wellhead device and the casing pipe, it is possible to easily remove water remaining on the interface of the filler and refill the filler after cementing. In addition to being able to do it, it became possible to always grasp the situation of cementing.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a wellhead device and an installation example thereof in the present invention.

FIG. 2 shows an example of a centering jig according to the present invention,
It is sectional drawing which followed the II-III line of a centering jig.

FIG. 3 shows an example of a centering jig according to the present invention,
It is sectional drawing which followed the III-III line of a centering jig.

FIG. 4 is a side view showing an example of a centering screw according to the present invention.

FIG. 5 is a cross-sectional view of a well that schematically shows an example of a conventional centering method.

FIG. 6 is a cross-sectional view of a well that schematically shows an example of a conventional centering method.

[Explanation of symbols]

 1 excavation pit 2, 2a, 2b casing pipe 3 support member 4 rig floor 5 wellhead device 6 centering jig 7 valve device 7a passage 8 excavation pipe 9 jig body 10 center hole 11 screw hole 12 centering screw 12a, 12b reduced diameter portion 13a Mounting hole 13b Recess a Screw forming range of screw hole b Screw forming range of centering screw

Claims (2)

[Claims] 1. A wellhead device having a support structure provided at an opening of a pit and supporting a casing pipe inserted inside the pit, wherein the casing pipe is coaxial with the support structure. A centering jig for supporting is provided, and the centering jig has a central hole having an inner diameter larger than the outer diameter of the casing pipe and a plurality of screw holes penetrating from the outer peripheral surface toward the inner peripheral surface of the central hole. A wellhead device comprising: a jig main body; and a centering screw that is screwed into each of the screw holes and presses an outer peripheral surface of the casing pipe inserted into the center hole. 2. A wellhead device having a support structure is provided at the opening of the drill hole, and the support structure includes a central hole and an outer peripheral surface having an inner diameter larger than an outer diameter of a casing pipe to be inserted into the drill hole. A jig body having a plurality of screw holes penetrating toward the inner peripheral surface of the center hole, and a centering screw that is screwed into each of the screw holes and presses the outer peripheral surface of the casing pipe inserted into the center hole. When a drilling hole is formed, the centering screw of the centering jig is replaced with a sealing screw that does not protrude from the inner peripheral surface of the center hole when the drilling hole is formed. While excavating by lowering the drill hole, after forming the drill hole, place the casing pipe in the drill hole through the centering jig and attach the sealing screw. A ring screw is exchanged, the casing pipe is pressed and fixed from the surroundings to perform centering, and a gap such as a cement formed between the excavation hole and the casing pipe is filled with a cementing agent. Method.