Time-controlled sidetrack drilling method for Ordovician limestone stratum

Abstract

The invention discloses a time-controlled sidetrack drilling method for an Ordovician limestone stratum, and belongs to the technical field of coal mine water disaster area treatment. The method comprises the following steps: confirming a sidetrack drilling point in a drill hole; plugging cement at the sidetrack drilling point; the drill hole is swept to a sidetrack drilling point through a drilling tool; the drilled hole is subjected to redressing; and performing time-controlled sidetrack drilling at the sidetrack drilling point. The process is simplified, the steps are clear, and the construction difficulty is reduced; the sidetrack drilling time is short, the success rate is high, and economic benefits are improved; the method is suitable for all Ordovician limestone stratum horizontal branch wells, and the utilization range is wide.

Description

Technical Field

[0001] The invention relates to the technical field of regional governance of water hazards in coal mines, and in particular to a time-controlled sidetracking method for Ordovician limestone strata. Background Art

[0002] Mine water hazard problem is one of the main threats to coal mine production. In recent years, advanced coal mine water hazard regional control projects have been widely carried out in North China coalfields and achieved good results. This technology has become one of the main methods of coal mine water hazard control.

[0003] The horizontal branch well technology has multiple branches in one hole. By drilling horizontally in the target layer and reinforcing it with grouting, multiple branch boreholes are used to explore and cover the aquifer from point to surface, thus achieving water hazard management in coal mines. With the continuous in-depth application of regional management technology in coal mines, the owner of the mine has put forward higher requirements. By increasing the number of branches and expanding the management area, the economic benefits have become more obvious. Multiple branches mean repeated side drilling in a limited space. How to efficiently and quickly successfully side drilling has become a technical challenge.

[0004] In the past, the commonly used side drilling method for side drilling in the Ordovician limestone formation of horizontal branch wells was to use the open hole suspended side drilling technology in the oil and gas field industry, that is, using a large-bend screw with a curvature of more than 1.75° and a PDC drill bit to form a drill bit support surface in the empty wellbore chute and nest, and then increase the drill bit drilling pressure to complete the side drilling. However, the side drilling in the oil and gas field industry is mostly carried out in relatively loose sandstone formations, which is difficult to achieve in the dense and hard Ordovician limestone layer. Conventional chute and nest modes are difficult to form effective steps, and the success rate of side drilling cannot be guaranteed. Summary of the invention

[0005] The purpose of the present invention is to provide a time-controlled side drilling method for Ordovician limestone, which can not only effectively improve the side drilling success rate, but also save construction time. It is a set of side drilling method technology with simple construction and easy operation, and can be widely used in the side drilling of Ordovician limestone in North China coalfields.

[0006] In order to solve the above technical problems, the present invention provides a time-controlled sidetracking method for Ordovician limestone formations, comprising the following steps:

[0007] Confirm the sidetracking point in the borehole;

[0008] Seal cement at sidetrack points;

[0009] Use the drilling tool to sweep the borehole to the side drilling point;

[0010] Ream the drilled holes;

[0011] Side drilling during side drilling point control.

[0012] Preferably, plugging cement at the side drilling point specifically includes the following steps:

[0013] The cement is sealed 50m before and after the side drilling point; the specific gravity of the cement is 1.5g / cm 3 above.

[0014] Preferably, after plugging the side drilling point with cement, the method further comprises the following steps:

[0015] The cement was allowed to set for 72 hours.

[0016] Preferably, the drilling tool is used to sweep the borehole to the side drilling point, which specifically includes the following steps:

[0017] The borehole is swept by drilling tools to 10m before the side drilling point.

[0018] Preferably, the drilling tool adopts a 1.5 degree bent screw.

[0019] Preferably, side drilling during side drilling point control specifically includes the following steps:

[0020] The initial drilling time of sidetracking is the first drilling time;

[0021] When rock powder appears in the side drilling, adjust the drilling time to the second drilling time and continue the side drilling with time control;

[0022] When the mass proportion of rock dust in the drill dust of the side drilling reaches 50%, the drilling time is adjusted to the third drilling time to continue the side drilling with time control; when the mass proportion of rock dust in the drill dust of the side drilling reaches 100%, it is adjusted to drilling without time control.

[0023] Preferably, the first drilling time is 180 min / m;

[0024] The second drilling time is 90min / m;

[0025] The third drilling time is 60 min / m.

[0026] Preferably, the method further comprises the following steps:

[0027] Verify the accuracy of side drilling;

[0028] After verification is completed, directional composite drilling will proceed normally.

[0029] Preferably, verifying the accuracy of the sidetracking includes the following steps:

[0030] Obtain inclinometer data, drilling time and rock powder percentage data and verify them.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1) Simplify the process, make the steps clear, and reduce the difficulty of construction;

[0033] 2) Short side drilling time, high success rate and improved economic benefits;

[0034] 3) It is suitable for use in all horizontal branch wells in Ordovician limestone formations and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0036] Figure 1 It is a schematic flow chart of a time-controlled sidetracking method for an Ordovician limestone formation according to the present invention;

[0037] Figure 2 It is a schematic diagram of a multi-horizontal branch well;

[0038] Figure 3 It is a cross-section diagram of a horizontal branch well. DETAILED DESCRIPTION

[0039] Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention, so the present invention is not limited to the specific implementation disclosed below.

[0040] The terms used in one or more embodiments of this specification are only for the purpose of describing specific embodiments, and are not intended to limit one or more embodiments of this specification. The singular forms of "a", "said" and "the" used in one or more embodiments of this specification and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used in one or more embodiments of this specification refers to and includes any or all possible combinations of one or more associated listed items.

[0041] It should be understood that although the terms first, second, etc. may be used to describe various information in one or more embodiments of this specification, this information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of one or more embodiments of this specification, the first may also be referred to as the second, and similarly, the second may also be referred to as the first. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0042] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0043] like Figure 1 As shown, the present invention provides a time-controlled sidetracking method for Ordovician limestone formations, comprising the following steps:

[0044] Confirm the sidetracking point in the borehole;

[0045] Seal cement at sidetrack points;

[0046] Use the drilling tool to sweep the borehole to the side drilling point;

[0047] Ream the drilled holes;

[0048] Side drilling during side drilling point control.

[0049] Preferably, plugging cement at the side drilling point specifically includes the following steps:

[0050] The cement is sealed 50m before and after the side drilling point; the specific gravity of the cement is 1.5g / cm 3 above.

[0051] Preferably, after plugging the side drilling point with cement, the method further comprises the following steps:

[0052] The cement was allowed to set for 72 hours.

[0053] Preferably, the drilling tool is used to sweep the borehole to the side drilling point, which specifically includes the following steps:

[0054] The borehole is swept by drilling tools to 10m before the side drilling point.

[0055] Preferably, the drilling tool adopts a 1.5 degree bent screw.

[0056] Preferably, side drilling during side drilling point control specifically includes the following steps:

[0057] The initial drilling time of sidetracking is the first drilling time;

[0058] When rock powder appears in the side drilling, adjust the drilling time to the second drilling time and continue the side drilling with time control;

[0059] When the mass proportion of rock dust in the drill dust of the side drilling reaches 50%, the drilling time is adjusted to the third drilling time to continue the side drilling with time control;

[0060] When the mass proportion of rock powder in the drill powder of the side drilling reaches 100%, the drilling is adjusted to uncontrolled drilling.

[0061] Preferably, the first drilling time is 180 min / m;

[0062] The second drilling time is 90min / m;

[0063] The third drilling time is 60 min / m.

[0064] Preferably, the method further comprises the following steps:

[0065] Verify the accuracy of side drilling;

[0066] After verification is completed, directional composite drilling will proceed normally.

[0067] Preferably, verifying the accuracy of the sidetracking includes the following steps:

[0068] Obtain inclinometer data, drilling time and rock powder percentage data and verify them.

[0069] In order to better illustrate the technical effect of the present invention, the present invention provides the following specific embodiments to illustrate the above technical process:

[0070] Example 1: A time-controlled sidetracking method for Ordovician limestone formations. First, cement slurry is used to plug the completed wellbore (50m before and after the sidetracking point, cement density is above 1.5g / cm3). After the cement plug has a certain strength after the cement plug is cured, a 1.5° small bend screw guide drill assembly is inserted, and the cement plug is used as a drill bit support. The time-controlled sidetracking method (such as Figure 3 After the side drilling is successful, normal directional composite drilling can be continued directly.

[0071] The specific steps include:

[0072] (1) Select appropriate side drilling points according to the design; Figure 2 As shown;

[0073] (2) Seal cement to 50m before and after the side drilling point (specific gravity 1.5g / cm 3 above);

[0074] (3) Wait for 72 hours;

[0075] (4) Run a conventional drilling tool assembly (1.5 degree screw) to sweep the hole to 10 m before the side drilling point;

[0076] (5) Place the appropriate tool face to ream the eye (drilling time is controlled at 60 min / m) to the side drilling point;

[0077] (6) Time-controlled side drilling: When the drilling time is controlled at 180 min / m for 1-3 m, the drilling time is adjusted to 90 min / m after rock powder is seen, and the time-controlled side drilling is continued. When the rock powder mass ratio reaches 50%, the drilling time is adjusted to 60 min / m. When the rock powder ratio reaches 100%, drilling is continued without time control;

[0078] (7) Normal directional composite drilling is carried out after deviation from the original wellbore based on inclination data, drilling time, and rock powder ratio.

[0079] Aiming at the low success rate and high cost of suspended sidetracking in Ordovician limestone, the invention proposes a time-controlled sidetracking method for Ordovician limestone formations, which is suitable for sidetracking construction of horizontal branch wells in Ordovician limestone.

[0080] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A time-controlled sidetracking method for Ordovician limestone formations, characterized in that: The following steps are involved: Confirm the sidetracking point in the borehole; Seal cement at sidetrack points; Use the drilling tool to sweep the borehole to the side drilling point; Ream the drilled holes; Side drilling during side drilling point control.

2. The time-controlled sidetracking method for the Ordovician limestone formation according to claim 1, characterized in that: The cement plugging at the side drilling point specifically includes the following steps: The cement is sealed 50m before and after the side drilling point; the specific gravity of the cement is 1.5g / cm 3 above.

3. The time-controlled sidetracking method for the Ordovician limestone formation according to claim 2, characterized in that: After the side drilling point is sealed with cement, the following steps are also included: The cement was allowed to set for 72 hours.

4. The time-controlled sidetracking method for the Ordovician limestone formation according to claim 3, characterized in that: The borehole is swept to the side drilling point by the drilling tool, which specifically includes the following steps: The borehole is swept by drilling tools to 10m before the side drilling point.

5. The time-controlled sidetracking method for the Ordovician limestone formation according to claim 4, characterized in that: The drilling tool adopts a 1.5 degree bent screw.

6. The time-controlled sidetracking method for the Ordovician limestone formation according to claim 5, characterized in that: When side drilling is performed in side drilling point control, the following steps are specifically included: The initial drilling time of sidetracking is the first drilling time; When rock powder appears in the side drilling, adjust the drilling time to the second drilling time and continue the side drilling with time control; When the mass proportion of rock dust in the drill dust of the side drilling reaches 50%, the drilling time is adjusted to the third drilling time to continue the side drilling with time control; When the mass proportion of rock powder in the drill powder of the side drilling reaches 100%, the drilling is adjusted to uncontrolled drilling.

7. The time-controlled sidetracking method for the Ordovician limestone formation according to claim 6, characterized in that: The first drilling time is 180min / m; The second drilling time is 90min / m; The third drilling time is 60 min / m.

8. The time-controlled sidetracking method for the Ordovician limestone formation according to claim 7, characterized in that: The following steps are also included: Verify the accuracy of side drilling; After verification is completed, directional composite drilling will proceed normally.

9. The time-controlled sidetracking method for the Ordovician limestone formation according to claim 8, characterized in that: Verify the accuracy of the sidetracking, including the following steps: Obtain inclinometer data, drilling time and rock powder percentage data and verify them.

Images