A direction-finding method for use in the case of magnetic interference during surface orientation at sea

Abstract

The present invention is used in the field of offshore oil and gas drilling, and relates to a directional method for offshore surface orientation under magnetic interference. The offshore well layout is very dense, and the distance between wells is 1.6×1.8 m. The MWD instrument while drilling is affected by the riser or the casing of adjacent wells, resulting in inaccurate magnetic tool face. This method is beneficial to determine the direction of the tool face, avoid the well trajectory of this well occupying the space of subsequent wells and reduce the risk of collision between this well and adjacent wells. The technical solution of the invention mainly consists of two parts. The first part is to mark the directional orientation of construction at the circular wellhead in the empty well state; the second part is to accurately extend the bend point mark of the downhole motor to the uppermost drill pipe. After the drill pipe reaches the bottom of the well, the bend point mark on the drill pipe is rotated to the mark of the directional orientation through the top drive, and then directional drilling can be started.

Description

Technical Field

[0001] The present invention relates to the technical field of oil drilling, and particularly to a directional method for offshore surface orientation in the presence of magnetic interference. Background Art

[0002] At present, in offshore oil exploration and development, due to platform conditions, well layout is very dense, and the distance between wells is 1.6×1.8 m. Therefore, anti-collision is an extremely important task.

[0003] Therefore, the vast majority of offshore drilling operations require surface orientation for obstacle avoidance to increase the minimum distance between two wells as much as possible.

[0004] However, since the magnetic tool face provided by the current downhole drilling instrument is calculated from the magnetic field, when there are risers or casings around, the magnetic field is interfered, and the magnetic tool face will be inaccurate. When constructing under an inaccurate tool face, the trajectory will be inaccurate, resulting in the actual trajectory occupying the space of the lower well or even colliding with adjacent wells, thus causing greater economic losses. Summary of the Invention

[0005] The object of the present invention is to provide a directional method for offshore surface orientation in the presence of magnetic interference in view of the deficiencies in the prior art.

[0006] The technical solution is as follows: A directional method for offshore surface orientation in the presence of magnetic interference, and the implementation process is as follows: Step 1, in the empty well state before drilling, at the ramp on the drill floor, use a square, with the intersection edge of the ramp and the drill floor as one side, and draw a perpendicular line towards the center of the wellhead; Step 2, irradiate a laser straight line along the perpendicular line direction, and the direction of the laser straight line towards the ramp is the first direction azimuth of the drilling platform; Step 3, at the near and far intersections of the laser straight line and the circular wellhead, respectively drill short lines towards the drill floor outside the circular wellhead along the laser straight line direction; Step 4, coincide the center of the bit gauge with the center of the wellhead, place it on the drill floor, divide the wellhead into several parts by using the marks on the bit gauge, and set the angle between every two marked points; Find the directional azimuth (1) according to the first direction azimuth of the drilling platform and the divided circle; Step 5, after assembling the bottom hole assembly, find the bend point mark of the downhole motor; Step 6, coincide the laser straight line with the bend point mark, irradiate towards the upper drill string direction, and according to the position of the laser straight line, the derrickman on the monkey board makes a short line mark on the upper drill string, which is consistent with the lower bend point in the vertical direction; Step 7, after lowering the current stand of drill pipe, use the previously made marked point as a mark to make a mark (2) on the upper part of the next stand of drill pipe; Step 8, repeat Step 6 until all drill pipes are lowered to the bottom of the well; Step 9, when the drill pipe reaches the bottom and starts drilling, when the marked point is rotated to the designed directional azimuth by using the top drive, sliding drilling can be started.

[0007] Further, in step 4, the wellhead is evenly divided into 12 or 24 parts by using the marks on the drill gauge.

[0008] Further, in step 4, after the wellhead is evenly divided, the included angle between every two marking points is 30 or 15 degrees.

[0009] Further, the laser straight line is emitted by irradiating with a laser flashlight or a laser pen.

[0010] Further, in step 3, short line marks are made on the drill floor outside the circular wellhead along the laser straight line direction at the near and far intersections of the laser straight line and the circular wellhead respectively with chalk.

[0011] Further, in step 3, short line marks are made on the drill floor outside the circular wellhead along the laser straight line direction at the near and far intersections of the laser straight line and the circular wellhead respectively with paint.

[0012] The beneficial effects of the present invention are as follows: 1. By using the method of determining the tool face by making marks, the problem that the tool face provided by the measurement-while-drilling instrument is inaccurate under the condition of magnetic interference is solved, the risk of collision with adjacent wells is effectively reduced, and the drilling risk is reduced.

[0013] 2. By using the method of determining the tool face by making marks, the construction is simple, economical and practical, and the drilling accuracy is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] None. DETAILED DESCRIPTION OF THE INVENTION

[0015] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concepts of the present invention.

[0016] A directional method for offshore surface orientation under magnetic interference of the present invention is applicable to offshore oil and gas directional drilling. The initial directional azimuth is marked at the wellhead by using the first direction azimuth of the drilling platform provided by the drilling design, and marks are made on the upper part of the drill string according to the bend point mark of the downhole motor and the laser flashlight.

[0017] By using a right-angled ruler and a laser flashlight, the initial directional azimuth is marked at the circular wellhead in the empty well state, and the bend point mark of the downhole motor is accurately extended to the uppermost drill string by using the laser flashlight. After the drill string reaches the bottom of the well, the bend point mark on the drill string is rotated to the marked directional azimuth through the top drive, and then directional drilling can be started.

[0018] The specific steps are as follows: Step 1, in the empty well state before drilling, at the ramp on the drill floor, use a set square. Taking the intersection edge of the ramp and the drill floor as one side, draw a perpendicular line towards the center of the wellhead. Step 2, use a laser flashlight to irradiate along the direction of the drawn perpendicular line (the direction of this laser straight line towards the ramp is the heading azimuth of the drilling platform). Step 3, use chalk or paint to make short line marks on the drill floor outside the circular wellhead along the laser direction at the near and far intersections of the laser and the circular wellhead respectively. Step 4, align the center of the bit gauge with the center of the wellhead and place it on the drill floor for testing. Use the marks on the bit gauge to divide the wellhead into 12 or 24 equal parts, with an angle of 30 or 15 degrees between every two marked points; find the directional azimuth (1) according to the heading azimuth of the drilling platform and the divided circle. Step 5, after assembling the bottom hole assembly, find the bend point mark of the power drill. Step 6, align the laser flashlight with the bend point mark and irradiate towards the upper drill string. According to the position of the laser flashlight, the derrickman on the monkey board makes a short line mark on the upper drill string, keeping it consistent with the lower bend point in the vertical direction. Step 7, after running in this stand of drill pipe, use the previously made marked points as a reference to make a mark (2) on the upper part of the next stand of drill pipe. Step 8, repeat Step 6 until all the drill pipes are run to the bottom of the well. Step 9, when the drill pipe reaches the bottom and starts drilling, when using the top drive to turn the marked points to the designed directional azimuth, sliding drilling can be started.

[0019] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A directional method for surface orientation at sea in the presence of magnetic interference, characterized in that, the implementation process is as follows: Step 1, in the empty well state before drilling, at the ramp of the drill floor, use a right-angle ruler to draw a perpendicular line towards the center of the wellhead with the intersection edge of the ramp and the drill floor as one side; Step 2, irradiate a laser straight line along the perpendicular line direction, and the direction of the laser straight line towards the ramp is the heading azimuth of the drilling platform; Step 3, at the near and far intersections of the laser straight line and the circular wellhead, respectively, make short line marks on the drill floor outside the circular wellhead along the laser straight line direction; Step 4, coincide the center of the bit gauge with the center of the wellhead, place it on the drill floor, divide the wellhead into several equal parts using the marks on the bit gauge, and set the angle between every two mark points; Find the directional azimuth (1) according to the heading azimuth of the drilling platform and the divided circle; Step 5, after assembling the bottom hole assembly, find the bend point mark of the power drill; Step 6, coincide the laser straight line with the bend point mark, irradiate towards the upper drill string direction, and according to the position of the laser straight line, the derrickman on the monkey board makes a short line mark on the upper drill string, which is consistent with the lower bend point in the vertical direction; Step 7, after lowering this stand of drill pipe, use the previously made mark points as a reference to make a mark (2) on the upper part of the next stand of drill pipe; Step 8, repeat Step 6 until all the drill pipes are lowered to the bottom of the well; Step 9, when the drill pipe reaches the bottom and starts drilling, use the top drive to turn the mark point to the designed directional azimuth, and then sliding drilling can start.

2. A directional method for surface orientation at sea in the presence of magnetic interference according to claim 1, characterized in that, in the said Step 4, the wellhead is divided into 12 or 24 equal parts using the marks on the bit gauge.

3. A directional method for surface orientation at sea in the presence of magnetic interference according to claim 2, characterized in that, in the said Step 4, after the wellhead is evenly divided, the angle between every two mark points is 30 or 15 degrees.

4. A directional method for surface orientation at sea in the presence of magnetic interference according to claim 1, characterized in that, the said laser straight line is irradiated and emitted by a laser flashlight or a laser pen.

5. A directional method for surface orientation at sea in the presence of magnetic interference according to claim 1, characterized in that, in the said Step 3, use chalk to make short line marks on the drill floor outside the circular wellhead along the laser straight line direction at the near and far intersections of the laser straight line and the circular wellhead respectively.

6. A directional method for surface orientation at sea in the presence of magnetic interference according to claim 1, characterized in that, in the said Step 3, use paint to make short line marks on the drill floor outside the circular wellhead along the laser straight line direction at the near and far intersections of the laser straight line and the circular wellhead respectively.