Well body structure of offshore ultra-deep extended reach well

Abstract

The utility model discloses a well body structure of an offshore ultra-deep extended reach well. The well body structure comprises a phi 762 mm guide pipe, a phi 660.4 mm well hole, a phi 508 mm surface casing pipe, a phi 444.5 mm well hole, a phi 339.7 mm technical casing pipe, a phi 311.2 mm well hole, a phi 244.5 mm production casing pipe and a phi 215.9 mm well hole. Compared with a traditional phi152.4 mm well section structure, the offshore ultra-deep extended reach well bore structure has the advantages that the oil drainage area of an oil reservoir can be effectively increased, and the yield of a marginal oil field is increased.

Description

Technical Field

[0001] The utility model relates to the field of offshore oil and gas drilling, in particular to a wellbore structure for an ultra-deep extended reach well in the sea. Background Art

[0002] The reserves of offshore marginal oilfields are small. If the conventional development methods such as building new production platforms or underwater production systems are adopted, the economic benefits are often poor. The extended reach well technology can rely on existing offshore facilities to develop marginal oilfields within a certain distance around, and can realize the economic and effective development and utilization of offshore marginal oilfield reserves. However, for extended reach wells with a high difficulty level where the horizontal displacement exceeds 7000m, the conventional wellbore structure (usually completed drilling in the Ф152.4mm section) design cannot meet the requirements of safe well construction and efficient reservoir development at the same time. Summary of the Utility Model

[0003] The technical problem to be solved by the utility model is to provide a wellbore structure for an ultra-deep extended reach well in the sea.

[0004] The technical solution adopted by the utility model to solve its technical problem is to construct a wellbore structure for an ultra-deep extended reach well in the sea, including a Ф762mm conductor, and a Ф660.4mm wellbore formed inside the Ф762mm conductor, and a Ф508mm surface casing installed in the Ф660.4mm wellbore, and a Ф444.5mm wellbore formed inside the Ф508mm surface casing, and a Ф339.7mm technical casing installed in the Ф444.5mm wellbore, and a Ф311.2mm wellbore formed inside the Ф339.7mm technical casing, and a Ф244.5mm production casing installed in the Ф311.2mm wellbore, and a Ф215.9mm wellbore formed inside the Ф244.5mm production casing.

[0005] In some embodiments, the well inclination angle of the Ф762mm conductor is 3° - 7°.

[0006] In some embodiments, the well inclination angle of the Ф508mm surface casing is 40° - 60°.

[0007] In some embodiments, the well inclination angle of the Ф339.7mm technical casing is greater than 80°.

[0008] In some embodiments, the length of the horizontal extension section of the Ф244.5mm production casing is greater than 7000 meters.

[0009] Implementing the present utility model has the following beneficial effects: The wellbore structure of the offshore ultra-deep extended reach well includes a Ф762mm conductor, a Ф660.4mm wellbore formed inside the Ф762mm conductor, a Ф508mm surface casing installed in the Ф660.4mm wellbore, a Ф444.5mm wellbore formed inside the Ф508mm surface casing, a Ф339.7mm technical casing installed in the Ф444.5mm wellbore, a Ф311.2mm wellbore formed inside the Ф339.7mm technical casing, a Ф244.5mm production casing installed in the Ф311.2mm wellbore, and a Ф215.9mm wellbore formed inside the Ф244.5mm production casing. Compared with the traditional Ф152.4mm well section, the wellbore structure of the offshore ultra-deep extended reach well can effectively increase the oil reservoir drainage area and improve the production of marginal oilfields. Description of the Drawings

[0010] In order to more clearly illustrate the technical solutions of the present utility model, the present utility model will be further described below in conjunction with the drawings and embodiments. It should be understood that the following drawings only show some embodiments of the present utility model, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings. In the drawings:

[0011] Figure 1 is a schematic structural diagram of the wellbore structure of the offshore ultra-deep extended reach well in some embodiments of the present utility model. Detailed Embodiments

[0012] In order to have a clearer understanding of the technical features, objectives, and effects of the present utility model, the detailed embodiments of the present utility model will now be described in detail with reference to the drawings. In the following description, it should be understood that the orientation or positional relationships indicated by "front", "rear", "upper", "lower", "left", "right", "longitudinal", "transverse", "vertical", "horizontal", "top", "bottom", "inner", "outer", "head", "tail", etc. are based on the orientation or positional relationships shown in the drawings and are constructed and operated in a specific orientation, only for the convenience of describing the present technical solution, rather than indicating that the device or element referred to must have a specific orientation, and therefore should not be construed as a limitation to the present utility model.

[0013] It should also be noted that, unless otherwise clearly specified and defined, terms such as "installation", "connection", "linkage", "fixation", "setting" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. When a component is referred to as being "on" or "under" another component, the component can be "directly" or "indirectly" located above the other component, or there may also be one or more intermediate components. Terms such as "first", "second", "third", etc. are only for the convenience of describing the present technical solution and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", "third", etc. can explicitly or implicitly include one or more of such features. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0014] In the following description, specific details such as specific system structures, technologies, etc. are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present utility model. However, those skilled in the art should clearly understand that the present utility model can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present utility model.

[0015] Please refer to Figure 1 , the present utility model shows a wellbore structure of an offshore ultra-deep extended reach well. Compared with the traditional Ф152.4mm well section structure, the wellbore structure of the offshore ultra-deep extended reach well increases the oil reservoir drainage area by 42% and improves the production of marginal oilfields.

[0016] The wellbore structure of the offshore ultra-deep extended reach well includes a Ф762mm conductor 10, and a Ф660.4mm wellbore formed inside the Ф762mm conductor 10, and a Ф508mm surface casing 20 installed in the Ф660.4mm wellbore, and a Ф444.5mm wellbore formed inside the Ф508mm surface casing 20, and a Ф339.7mm technical casing 30 installed in the Ф444.5mm wellbore, and a Ф311.2mm wellbore formed inside the Ф339.7mm technical casing 30, and a Ф244.5mm production casing 40 installed in the Ф311.2mm wellbore, and a Ф215.9mm wellbore 50 formed inside the Ф244.5mm production casing 40. Among them, an offshore platform 100 is located above the wellhead of the wellbore structure of the offshore ultra-deep extended reach well, and the part labeled 200 is the seabed.

[0017] In this embodiment, the Ф762mm conduit 10 is used to establish a connection channel between the seabed and the production platform. Preferably, the well deviation angle of the Ф762mm conduit 10 is 3°-7°. For example, the well deviation angle of the Ф762mm conduit 10 is 4°, the well deviation angle of the Ф762mm conduit 10 is 5°, and the well deviation angle of the Ф762mm conduit 10 is 6°.

[0018] In this embodiment, the Ф508mm surface casing 20 is used to seal the unconsolidated formation in the shallow seabed formation. Preferably, the well deviation angle of the Ф508mm surface casing 20 is 40°-60°. For example, the well deviation angle of the Ф508mm surface casing 20 is 50°.

[0019] In this embodiment, the Ф339.7mm technical casing is used to seal the geological must-seal points in the upper well section and ensure the operation window for the subsequent well sections. Preferably, the well deviation angle of the Ф339.7mm technical casing 30 is greater than 80°. For example, it can be a well deviation angle of 85° or a well deviation angle of 90°.

[0020] In this embodiment, the Ф244.5mm production casing is used for the extended operation of the ultra-long horizontal well section and connects to the oil and gas reservoir. Preferably, the length of the horizontal extension section of the Ф244.5mm production casing 40 is greater than 7000 meters.

[0021] In this embodiment, the Ф215.9mm wellbore is used in the horizontal well section of the oil and gas reservoir to meet the requirements of well completion operations and realize oil and gas production.

[0022] In this embodiment, the drilling method for the wellbore structure of the offshore ultra-deep extended-reach well is as follows:

[0023] (1) For the first spud, the Ф762mm conduit 10 is used to establish a connection channel between the seabed and the production platform. The Ф762mm conduit 10 is pre-inclined and run in by directional pile driving (this is a mature industrial method), which can achieve a certain well deviation angle (the well deviation angle is 3°-7°) and relieve the build-up pressure in the subsequent well sections.

[0024] (2) For the second spud, a Ф660.4mm wellbore is drilled, the Ф508mm surface casing 20 is run in and cemented to seal the unconsolidated formation in the shallow seabed formation. The surface build-up can be achieved by using a motorized directional method to reduce the dogleg severity in the third spud section and lower the difficulty of directional build-up. Among them, since the surface well deviation angle is usually less than 60°, the Ф508mm surface casing 20 is run in with grouting (this is a mature industrial method), and an insert cementing process is used for the cementing operation to seal the Ф508mm surface casing.

[0025] (3) Drill a triple-opening Ф444.5 mm wellbore, run in a Ф339.7 mm technical casing for 30 m, and cement it to seal the geological must-seal points in the upper well section, ensuring the operation window for the subsequent well section. At the same time, use directional drilling technology to increase the well inclination angle to more than 80° to meet the horizontal directional operation requirements of the quadruple-opening well section. The Ф339.7 mm technical casing is run in using a partial floating + partial grouting method (a mature industrial method), and a single-stage cementing process is used for cementing operations to seal the Ф339.7 mm technical casing, which can improve the runnability of the casing in highly deviated well sections.

[0026] (4) Drill a quadruple-opening Ф311.2 mm wellbore, run in a Ф244.5 mm production casing for 40 m, and cement it for the extended operation of the ultra-long horizontal well section and to connect the oil and gas reservoir. This well section is the key to achieving ultra-long horizontal extension and can perform horizontal extension directional operations according to design requirements. The Ф244.5 mm production casing is run in using a full floating + rotation method (a mature industrial method), and a single-stage cementing process can be used for cementing operations to seal the Ф244.5 mm production casing, which can effectively reduce the friction between the Ф244.5 mm production casing and the ultra-long horizontal section wellbore.

[0027] (5) Drill a quintuple-opening Ф215.9 mm wellbore 50 and complete the well for the horizontal well section in the oil and gas reservoir to meet the well completion operation requirements and achieve oil and gas production. After the Ф215.9 mm wellbore is drilled, a well completion string is run in to meet the oilfield production requirements. Compared with the traditional Ф152.4 mm well section structure, this well section increases the oil reservoir drainage area by 42% and improves the production of marginal oilfields.

[0028] It can be understood that the above embodiments only represent the preferred embodiments of the present utility model, and the description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present utility model, the above technical features can be freely combined, and several deformations and improvements can also be made, which all belong to the protection scope of the present utility model. Therefore, all equivalent transformations and modifications made to the scope of the claims of the present utility model shall fall within the scope covered by the claims of the present utility model.

Claims

1. An offshore ultra-deep extended reach wellbore structure, characterized in that: It comprises a Ф762mm conduit (10), a Ф660.4mm wellbore formed inside the Ф762mm conduit (10), a Ф508mm surface casing (20) installed in the Ф660.4mm wellbore, a Ф444.5mm wellbore formed in the Ф508mm surface casing (20), a Ф339.7mm technical casing (30) installed in the Ф444.5mm wellbore, a Ф311.2mm wellbore formed in the Ф339.7mm technical casing (30), a Ф244.5mm production casing (40) installed in the Ф311.2mm wellbore, and a Ф215.9mm wellbore (50) formed in the Ф244.5mm production casing (40).

2. The offshore ultra-deep extended reach wellbore structure according to claim 1, characterized in that: The well inclination angle of the Φ762 mm conduit (10) is 3°-7°.

3. The offshore ultra-deep extended reach wellbore structure according to claim 1, characterized in that: The well inclination angle of the Ф508mm surface casing (20) is 40°-60°.

4. The offshore ultra-deep extended reach wellbore structure according to claim 1, characterized in that: The well inclination angle of the Ф339.7 mm technical casing (30) is greater than 80°.

5. The offshore ultra-deep extended reach wellbore structure according to claim 1, characterized in that: The horizontal extension section of the Ф244.5 mm production casing (40) is greater than 7000 meters in length.

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