CN115961887A - A wellhead casing centering method - Google Patents

Abstract

The invention belongs to the field of petroleum drilling, and in particular relates to a wellhead casing centering method, which comprises running an inner casing into the outer casing and injecting cement for well cementing. Cut the outer casing. Calibrate the center point of the wellhead. Screw holes are formed on the wall surface of the outer casing. A screw is screwed into the screw hole, and the screw is in contact with the wall surface of the inner casing. By adjusting the screw rods, the horizontal distances from the contact points of each of the screw rods with the wall surface of the inner casing to the central point of the drilling rig base are equal. The invention is not only simple to operate, but also low in cost. The parts used therein are all existing and are convenient for large-scale popularization and use.

Description

A wellhead casing centering method

technical field

The invention relates to the field of oil drilling, in particular to a wellhead casing centering method.

Background technique

In the process of oil drilling, the cementing operation generally adopts the method of running a casing in the well for cementing. However, the size of the wellbore is usually larger than the size of the casing. In this way, it is inevitable that the centerline of the casing will not be consistent with the centerline of the wellhead of the drilling platform after the casing is run. If the drilling operation continues under such conditions, the drill pipe and the casing or the drill pipe and the rotary table on the drilling platform will be eccentrically worn, causing the drill string to vibrate, thereby affecting the efficiency of the drilling operation, and even deriving Lots of security issues.

Contents of the invention

The object of the present invention is to provide a wellhead casing centering method, which can center the inner layer casing with the center point of the wellhead. The invention is not only simple to operate, but also low in cost. The parts used therein are all existing and are convenient for large-scale popularization and use.

According to the present invention, a wellhead casing centering method is provided, comprising:

S1. After the drill bit drills to the middle completion depth, run the inner casing into the outer casing to the target well depth, and inject cement for cementing;

S2. Remove the landing joint of the inner casing, and cut the outer casing until its height is lower than the inner casing;

S3, calibrate the center point of the wellhead;

S4, forming several evenly spaced screw holes on the wall surface of the outer casing;

S5. Screw a screw into each screw hole, so that the screw passes through the outer casing until it contacts the wall of the inner casing;

S6. Adjusting the screw rods to make the horizontal distances from the contact points of each of the screw rods with the wall surface of the inner casing to the central point of the drilling rig base equal.

In one embodiment, four screw holes at the same height are formed in step S4.

In one embodiment, the distance between two adjacent screw holes is 90 degrees.

In one embodiment, step S3 includes: marking the midpoint on the crossbeam and longitudinal beam of the drilling rig base at the wellhead, forming a transverse positioning line and a longitudinal positioning line by connecting the midpoints on the crossbeam and longitudinal beam, and using The intersection of the horizontal positioning line and the longitudinal positioning line is used as the center point of the wellhead.

In one embodiment, the midpoints on the beams and stringers are connected by guy wires to form transverse and longitudinal positioning lines.

In one embodiment, in step S5, one end of each screw is located outside the outer sleeve, and the other end abuts against the outer wall of the inner sleeve.

In one embodiment, step S5 further includes: setting a first nut on the outer wall of the outer casing, and setting a second nut on the inner wall of the outer casing, wherein the screws respectively pass through the first nut and second nut.

In one embodiment, the diameter of the screw is in the range of 30mm to 60mm.

In one embodiment, steps S2 to S6 are performed before the cement slurry is solidified.

In one embodiment, step S7 is also included, wherein after the cement slurry is solidified, the screw and the mandrel are removed.

Description of drawings

The present invention will be described in detail below in conjunction with accompanying drawing, in the figure:

Fig. 1 schematically shows a top view using the wellhead casing centering method according to the present invention;

Figure 2 schematically shows a side view using the method of wellhead casing centering according to the present invention.

In the figures, the same parts are given the same reference numerals. The figures are not drawn to scale.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing.

Fig. 1 schematically shows a top view using the wellhead casing centering method according to the present invention. Figure 2 schematically shows a side view using the method of wellhead casing centering according to the present invention. As shown in Figures 1 and 2, the wellhead casing alignment method according to the present invention comprises seven basic steps in sequence:

Step S1: After the drill bit reaches the middle completion depth, run the inner casing 30 into the outer casing 20 to the target well depth, and inject cement for cementing.

Step S2: remove the landing joint of the inner casing 30 before the cement solidifies, and cut the outer casing 20 until its height is lower than the inner casing 30 .

Step S3: Calibrate the center point 13 of the wellhead.

Step S4: Forming several evenly spaced screw holes 21 on the wall surface of the outer casing 20 .

Step S5 : screw a screw 40 into each screw hole 21 , make the screw 40 pass through the outer sleeve 20 until it contacts the wall of the inner sleeve 30 .

Step S6: adjusting the screw rods 40 to make the horizontal distances from the contact points of each screw rod 40 with the wall surface of the inner casing 30 to the central point of the drilling rig base 10 equal.

Step S7: After the cement slurry is solidified, remove the screw rod 40 and the stretch wire.

Before step S1, it is found through a large number of tests that the wall of the inner casing 30 placed in the well is relatively thin. If the operation is carried out through the wall surface of the inner layer casing 30 to complete the centering effect on the wellhead casing, then the inner layer casing 30 will be deformed as a whole due to extrusion, so that the inner layer casing 30 The cross-section of the pipe wall is not uniform, which leads to errors in the measured data in step S6 and affects the centering effect of the wellhead casing.

Therefore, in order to make up for the above defects, the thicker outer sleeve 20 is selected as the main support wall, and the thinner inner sleeve 30 is selected as the secondary support wall. In this way, the screw 40 penetrates from the outside of the outer casing 20 to the inside of the outer casing 20 until one end of the screw 40 directly abuts against the outer wall of the inner casing 30, thereby restricting the inner casing. 30 positions. The other end of the screw 40 extends outside the outer casing 20 . By rotating the end of the screw 40 outside the outer casing 20 , the screw 40 can move in the radial direction, thereby adjusting the position of the inner casing 30 in real time, and realizing the centering effect on the inner casing 30 .

In step S1, specifically, after the drill bit has drilled to the middle completion depth, the outer casing 20 has been placed in the well to provide a running path for the subsequent running of the inner casing 30 . The inner casing 30 is put into the inner side of the outer casing 20 and reaches the depth of the target well, so that the inner casing 30 is initially positioned. After the inner casing 30 is lowered to the depth of the target well, cement is injected into the well for reinforcement to prevent collapse during drilling.

In step S2, the following two operations need to be performed before the cement solidifies. Step 1: remove the landing joint placed on the inner casing 30 . Step 2: Cut the top of the outer sleeve 20 so that the height of the outer sleeve 20 is lower than the height of the inner sleeve 30, so that the inner sleeve 30 will be partially exposed, which is conducive to observing the inner sleeve. The centering effect of the tube 30.

In step S3, including the drilling rig base 10 arranged at the wellhead. The drilling rig base 10 is a rectangular frame structure, including beams and longitudinal beams. According to the invention, the transverse positioning line 11 is formed by connecting the respective midpoints of two beams, while the longitudinal positioning line 12 is formed by connecting the respective midpoints of two longitudinal beams. Thus, the intersection of the transverse positioning line 11 and the longitudinal positioning line 12 forms the center point 13 of the wellhead.

In one embodiment of the present invention, the midpoints on the beams and longitudinal beams are connected by stretch wires, so as to form a transverse positioning line 11 and a longitudinal positioning line 12 . The setting of the mandrel is very simple, and it can be easily observed and measured.

As mentioned above, the walls of the outer sleeve 20 are thicker than the walls of the inner sleeve 30 . Therefore, in step S4 , the overall structure of the outer casing 20 will not be affected after the screw holes 21 are formed on the wall surface of the outer casing 20 . Preferably, there are four screw holes 21 in total, all of which are formed by drilling into the wall surface of the outer casing 20 . In addition, according to the present invention, the four screw holes 21 are all at the same height, so that the measurement of the horizontal distance in step S6 will be simpler and faster, and the accuracy of the wellhead casing alignment will be further improved.

In one embodiment of the present invention, the positions of the four screw holes 21 can be selected arbitrarily, as long as the distance between two adjacent screw rods 40 is 90°. Such a layout mode can make the data of the horizontal distance obtained by the wellhead casing centering method more accurate, and at the same time reduce the cost of forming screw holes.

In step S5, one end of the screw 40 is outside the outer casing 20, and the screw 40 is rotated to move it radially, while the other end is inside the outer casing 20 and abuts against the outer wall of the inner casing 30, Used to limit the position of the inner casing 30 .

In one embodiment of the present invention, a first nut 41 is disposed on the outer wall of the outer sleeve 20 , and a second nut 42 is disposed on the inner wall of the outer sleeve 20 . The screw rod 40 respectively passes through the first nut 41 and the second nut 42 until abutting against the outer wall of the inner casing 30 . Both the first nut 41 and the second nut 42 are used to limit the position of the screw rod 40 so that it can only move in the radial direction, so as to avoid deflection around and ensure the accuracy of the centering of the wellhead casing.

In a specific embodiment of the present invention, the selection range of the size of the screw 40 is between Φ30mm-Φ60mm. Preferably, the screw rod 40 should be compatible with the first nut 41 and the second nut 42 .

In step S6, the cement at this time is not solidified. By rotating the screw rod 40 , the screw rod 40 moves in the radial direction, thereby pushing the inner sleeve 30 and adjusting the position of the inner sleeve 30 . In this way, when the horizontal distances from the contact points of each screw rod 40 with the outer wall surface of the inner casing 30 to the center point of the drilling rig base 10 are equal, the centering of the wellhead casing is completed. At this time, the center position of the inner casing 30 is the same as the center point 13 of the wellhead.

Stand still after completing the above-mentioned centering work, and proceed to step S7 after the cement slurry is completely solidified. The screw rod 40 is removed from the outer casing 20 and the tension wire is removed from the rig base 10 respectively. So far, the work related to the wellhead casing alignment has been completed.

The present invention determines the center point 13 of the wellhead through the pre-arranged drilling rig base 10, and then uses the screw 40 to adjust the position of the inner casing 30 in real time, by measuring the contact between each screw 40 and the outer wall surface of the inner casing 30 The horizontal distance from the point to the center point of the drilling rig base 10, so as to realize the centering effect on the inner casing 30. The present invention realizes the centering effect of the inner casing 30 through a scientific and rational design. The present invention focuses on simplicity, quickness and low cost, that is, the existing tools at the well site are utilized. For example, the screw rod 40 can be the screw rod of a blowout preventer.

The above are only preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art can easily make changes or changes within the disclosed scope of the present invention, and such changes or changes should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (10)

1. A casing centering method, comprising the steps of:

s1, after a drill bit drills to the middle well completion depth, an inner casing (30) is put into an outer casing (20) to the target well depth, and cement is injected for well cementation;

s2, removing the joint of the inner layer sleeve (30), and cutting the outer layer sleeve (20) until the height of the outer layer sleeve is lower than that of the inner layer sleeve (30);

s3, calibrating a central point (13) of the wellhead;

s4, forming a plurality of uniformly spaced screw holes (21) on the wall surface of the outer sleeve (20);

s5, screwing a screw (40) into each screw hole (21), and enabling the screw (40) to penetrate through the outer-layer sleeve (20) until the screw is contacted with the wall surface of the inner-layer sleeve (30);

s6, adjusting the screws (40) to enable horizontal distances from contact points of the screws (40) and the wall surface of the inner-layer sleeve (30) to the center point of the drilling machine base (10) to be equal.

2. A wellhead casing centering method according to claim 1, characterized in that four screw holes (21) are formed at the same height position in step S4.

3. A wellhead casing centering method according to claim 2, characterized in that adjacent two bolt holes (21) are spaced 90 degrees apart.

4. A wellhead casing centering method according to claim 3, wherein step S3 comprises: the method comprises the steps of calibrating midpoints on a cross beam and a longitudinal beam of a drilling machine base (10) arranged at a wellhead, forming a transverse positioning line (11) and a longitudinal positioning line (12) by connecting the midpoints on the cross beam and the longitudinal beam, and using the intersection point of the transverse positioning line (11) and the longitudinal positioning line (12) as the central point (13) of the wellhead.

5. A wellhead casing centering method according to claim 4, characterized in that the midpoints on the cross beams and the longitudinal beams are connected by guy wires to form transverse positioning lines (11) and longitudinal positioning lines (12).

6. A wellhead casing centering method according to claim 5, characterized in that in step S5, one end of each screw (40) is located outside the outer casing (20) and the other end abuts against the outer wall of the inner sleeve (30).

7. A wellhead casing centering method according to claim 6, characterized in that step S5 further comprises: a first nut (41) is arranged on the outer wall of the outer sleeve (20), a second nut (42) is arranged on the inner wall of the outer sleeve (20), and the screw (40) penetrates through the first nut (41) and the second nut (42) respectively.

8. A wellhead casing centering method according to any of claims 1 to 7, characterized in that the diameter of the screw (40) is in the range of 30mm to 60 mm.

9. A wellhead casing centering method according to any of claims 1 to 7, characterized in that steps S2 to S6 are performed before the cement slurry is set.

10. A wellhead casing centering method according to claim 9, characterized by further comprising step S7, wherein the screw (40) and the guy wires are removed after the cement slurry is set.

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