A method for increasing speed and efficiency of a well by synchronous head point change

Abstract

This invention relates to the field of oilfield downhole workover technology, and particularly to a method for accelerating and improving the efficiency of simultaneous workover operations with a "fish head" (or "fish head" point) with varying depths. The method includes: determining the depth of the stuck point using methods such as pulling and a locator; positioning and cutting: selecting a suitable cutting spring based on the size of the stuck tubing in the well, positioning and cutting to remove all tubing above the stuck point in one operation; simultaneously milling deformed casing and removing debris: using a milling shoe with a pointed tip to mill the entire casing, repairing the lower casing while milling the "fish head"; and repairing the lower casing by milling with a pen tip milling cone: milling the lower casing with a pen tip milling cone and scattering debris to prevent it from being stuck due to the deformed casing during retrieval, thus ensuring it can be pulled out or scattered after being retrieved. The method for accelerating and improving the efficiency of simultaneous workover operations with a "fish head" point with varying depths provided by this invention effectively solves the problem of simultaneous workover operations with varying "fish head" points, thereby achieving rapid and efficient construction of such wells.

Description

Technical Field

[0001] This invention relates to the field of oilfield downhole operation and workover technology, specifically to a method for accelerating and improving the efficiency of synchronous workover wells with a fish-head-shaped workover point. Background Technology

[0002] Currently, during major well repairs, situations frequently arise where objects stuck in the well's gripping point cannot be removed. This situation easily leads to damage to the "fishhead" (the casing head) and the well where the change in gripping point occurs simultaneously. For such wells, the current common practice is to use a positioning milling sleeve to mill the lower casing and the "fishhead." However, this method has two main problems: first, it severely damages the "fishhead," causing significant breakage. Even if the issue of synchronized change in gripping point is resolved, the reshaping and retrieval of the lower casing remains extremely complex; second, the casing is prone to opening during milling, often failing to effectively remove the "fishhead" and the deformed lower casing, with the milling sleeve worn off to the outside of the casing, resulting in lost access, high uncertainty, low success rate, and long construction period. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] This invention provides a method for accelerating and improving the efficiency of synchronous workover of fish-head changing points, in order to overcome the problems of damaged fish-head and the damage to the fish-head by milling during synchronous workover of changing points, and the easy opening of the casing in the existing technology.

[0005] (II) Technical Solution

[0006] To address the aforementioned problems, this invention provides a method for accelerating and improving the efficiency of synchronized major well workover using a fish-head-shaped workover point:

[0007] Step S1: Determine the depth of the jamming point inside the well;

[0008] Step S2: Select the corresponding size cutting bullet according to the size of the stuck tubing in the well, position and cut, and remove all tubing above the stuck point in one go;

[0009] Step S3: Simultaneous milling of deformed sleeve and falling objects, including using a mortar and milling shoe to lift the entire process, reducing the milling drill pressure to 1-2 kN, and simultaneously milling the fish head and lower sleeve for 0.3-0.5 m;

[0010] Step S4: Repair the lower sleeve by milling with a pen tip conical mill.

[0011] Preferably, in step S1, the initial value of the checkpoint depth is obtained by using the lifting method and the checkpoint measuring instrument, and the accurate checkpoint depth is determined by combining the well construction experience of the same block.

[0012] Preferably, if the stuck tubing in the well is 3-1 / 2 ordinary tubing, a Φ64mm incendiary cutting bullet is used for cable positioning and cutting.

[0013] Preferably, step S3 includes: lowering the collar eye grinding shoe, inserting the collar rod into the fish cavity, and grinding and milling to the preset size throughout the process. When it is determined that it is no longer possible to grind and mill to the lower break, the grinding and milling is stopped and the drill is lifted.

[0014] Preferably, step S4 specifically includes:

[0015] Using a pen-tip milling taper, the lower sleeve and the object are simultaneously milled inside the fish cavity. While the lower sleeve is being expanded, the object below is tilted away. Once the object is caught, it cannot be pulled out or tilted away. A suitable retrieval tool is then selected to retrieve the portion of the object below the tilt point.

[0016] Preferably, step S4 further includes: ensuring that the pen tip is inserted into the lower part of the fish cavity during the pen tip milling process, and milling at a low idle speed.

[0017] (III) Beneficial Effects

[0018] The present invention provides a method for accelerating and improving the efficiency of synchronous workover wells with changing fish-head points. It can effectively solve problems such as casing windowing and fish-head damage during synchronous workover well construction with changing fish-head points. The construction process is highly controllable and has a high success rate, thereby achieving the goal of accelerating and improving the efficiency of synchronous workover wells with changing fish-head points. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method for accelerating and improving the efficiency of synchronous well repair by changing the fish head point according to an embodiment of the present invention. Detailed Implementation

[0020] The following detailed embodiments further illustrate the method for accelerating and improving the efficiency of synchronous well workover using the fish-head changing point method of the present invention, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention. It should be stated that the descriptions of the specific embodiments are exemplary and do not imply a limitation on the scope of protection of the present invention. The scope of the rights of the present invention is determined by the defined claims.

[0021] like Figure 1 As shown, the method for accelerating and improving the efficiency of synchronized major well workover using the fish-head changing point method provided by the present invention specifically includes the following steps:

[0022] Step S1: Determine the depth of the jamming point inside the well;

[0023] The depth of the checkpoint was calculated and measured using methods such as the pull-up method and the checkpoint measuring instrument. The depth of the checkpoint measured by several methods was compared, and the accurate depth of the checkpoint was determined by combining the well construction experience in the same block.

[0024] Step S2: Select the corresponding size cutting bullet according to the size of the stuck tubing in the well, position and cut, and remove all tubing above the stuck point in one go;

[0025] Based on the size of the stuck tubing in the well, select the corresponding cutting bullet, position and cut, and remove all tubing above the stuck point in one go, effectively preventing damage to the head of falling objects at the change point.

[0026] Step S3: Simultaneous milling of deformed sleeve and falling objects, including using a mortar and milling shoe to lift the entire process, reducing the milling drill pressure to 1-2 kN, and simultaneously milling the fish head and lower sleeve for 0.3-0.5 m;

[0027] Using a drill shoe with a raised eye throughout the entire process (changing traditional construction parameters to reduce the drilling pressure from 10-20kN to 1-2kN) prevents the casing from opening during the milling process, and simultaneously mills the fish head and the lower casing for 0.3-0.5m.

[0028] The milling process must be suspended throughout to ensure that the fish head and the deformed lower part of the casing can be repaired as much as possible before the casing is opened.

[0029] Step S4: Repair the lower sleeve by milling with a pen tip conical mill.

[0030] Using a pen-tip milling taper, the lower sleeve and the object are simultaneously milled inside the fish cavity. While the lower sleeve is being expanded, the object below is being tilted away to prevent it from being unable to be pulled out or tilted away after being caught due to the deformation of the sleeve during the retrieval process. A suitable retrieval tool is then selected to retrieve the part of the object below the change point, successfully solving the problem of synchronous fish head change point.

[0031] During the milling process of the pen tip, ensure that the pen tip is inserted into the lower part of the object's cavity, and use a low idle speed for milling to prevent the pen tip from breaking.

[0032] Example 1

[0033] The invention will be further explained in conjunction with the Daqing South 4-2-737 well.

[0034] Step S1: Determine the depth of the checkpoint.

[0035] The depth of the measuring card was determined to be 784.2m by repeatedly pulling the measuring card using the lifting method; the actual depth of the measuring card was 778.6m using a measuring instrument. Based on previous construction experience, the bottom of the second tender section of this block was discontinuous (depth of the second tender section: 780.5m), and the depth of the measuring card was determined to be 780.5m.

[0036] Step S2, Positioning and Cutting:

[0037] The stuck tubing in the well was 3-1 / 2 standard tubing. A Φ64mm incendiary cutting bomb from Northern Schlumberger was selected for cable-guided positioning and cutting. The cutting bomb encountered resistance at a depth of 780.2m, and the cut was successful at that point. 81 tubing strings were retrieved from the original well, with the last one being 9.2m long. According to the tubing string records, 0.3m of tubing body remained in the well.

[0038] Step S3: Simultaneous milling and grinding of deformed sleeves and falling objects:

[0039] The Φ118mm leader drill bit encountered resistance at a depth of 780.35m, confirming that the leader rod had entered the fish cavity. The total milling depth was 0.42m. The amount of iron filings in the returned fluid decreased while the amount of mudstone particles increased. It was determined that it was impossible to mill to the lower fracture. Continuing to mill would cause the casing to open. Therefore, milling was not continued and the drill bit was pulled out.

[0040] Step S4: Repair the lower sleeve by milling and taper grinding with pen tip:

[0041] The Φ76mm inverted retrieval spear was lowered and caught, but the movable tubing was ineffective and could not be reversed, so the retrieval tool was withdrawn. The Φ114 pen-tip milling cone was lowered, but the obstruction depth was 781.15m, confirming that the pen tip had entered the lower fish cavity. The milling was carried out at idle speed for 0.36m (with inversion during the milling process), and the advance slowed down. The pen-tip milling cone was then removed. The Φ76mm inverted retrieval spear was lowered, but the upward movement did not show any indication. One oil pipe was then retrieved.

[0042] The original tubing string of well South 4-2-737 could not be pulled out. The bottom of the Nen 2 block suffered severe misalignment, leading to the conclusion that the original tubing was jammed by deformed casing. This was identified as a "fish-head" well with a variable-point synchronous design. The well was addressed using a faster, more efficient "fish-head" synchronous design method. Initially, by measuring the jamming point and locating the cutting, the depth of the jamming point was accurately determined, and the entire tubing string above the jamming point was pulled out. A cylindrical grinding shoe was used to repair the "fish-head" while simultaneously treating the deformed casing below, effectively preventing casing breakage. Later, a pen-tip milling cone was used to treat the fracture while simultaneously scattering the debris below, successfully retrieving one section of tubing below the fracture. The "fish-head" synchronous design problem was successfully resolved in just six days.

[0043] The above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention, and the patent protection scope of the present invention should be defined by the claims.

Claims

1. A method for accelerating and improving the efficiency of synchronized major well workover using a fish-head-shaped workover point, characterized in that: include: Step S1: Determine the depth of the jamming point inside the well; Step S2: Select the corresponding size cutting bullet according to the size of the stuck tubing in the well, position and cut, and remove all tubing above the stuck point in one go; Step S3: Simultaneous milling of deformed sleeve and falling objects, including using a mortar and milling shoe to lift the entire process, reducing the milling drill pressure to 1-2 kN, and simultaneously milling the fish head and lower sleeve for 0.3-0.5 m; Step S4: Repair the lower sleeve by milling with a pen tip milling cone. Specifically, this includes: using a pen tip milling cone to introduce the lower sleeve and the object into the fish cavity and milling them simultaneously. While expanding the diameter of the lower sleeve, the object is tilted open. Then, a suitable retrieval tool is selected to retrieve the part of the object below the change point.

2. The method for accelerating and improving efficiency of synchronized major well workover using the fish-head changing point method according to claim 1, characterized in that, In step S1, the initial value of the check point depth is obtained by using the lifting method and the check point measuring instrument, respectively. Combined with the well construction experience in the same block, the accurate check point depth is determined.

3. The method for accelerating and improving efficiency of synchronized major well workover using the fish-head changing point method according to claim 1, characterized in that, If the stuck tubing in the well is 3-1 / 2 ordinary tubing, use a Φ64mm incendiary cutting bullet for cable positioning and cutting.

4. The method for accelerating and improving efficiency of synchronized major well workover using the fish-head changing point method according to claim 1, characterized in that, Step S3 includes: lowering the collar eye grinding shoe, inserting the leader rod into the fish cavity, and grinding and milling to the preset size throughout the process. When it is determined that it is no longer possible to grind and mill to the lower break, stop grinding and milling and start drilling.

5. The method for accelerating and improving efficiency of synchronized major well workover using the fish-head changing point method according to claim 1, characterized in that, Step S4 also includes: During the pen tip milling process, ensure that the pen tip is inserted into the lower part of the object's cavity, and mill at a low idle speed.

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