CN111852411A - A kind of wellhead stabilization device and method for horizontal well in shallow soft hydrate reservoir in sea area - Google Patents

Abstract

The invention relates to the technical field of sea area natural gas hydrate development and exploitation, in particular to a sea area shallow soft water hydrate reservoir horizontal well wellhead stabilizing device and method, which comprises the following steps: determining the descending length of a guide pipe capable of maintaining the stability of a wellhead by combining geological data and sea condition, installing an internal supporting mechanism on the guide pipe corresponding to the depth of a deflecting point, and realizing the purpose of directional deflecting of a shallow soft stratum by matching the guide pipe with the internal supporting mechanism; the method is suitable for the process of building the horizontal well of the natural gas hydrate reservoir stratum in the sea area with shallow burial depth, and the purpose of shallow deflection is realized by using the method of opening the window at the side of the guide pipe on the premise of ensuring that the guide pipe has enough bearing capacity on the well mouth.

Description

A kind of wellhead stabilization device and method for horizontal well in shallow soft hydrate reservoir in sea area

technical field

The invention relates to the technical field of development and exploitation of natural gas hydrates in sea areas, in particular to a wellhead stabilization device and method for horizontal wells in shallow soft hydrate reservoirs in sea areas.

Background technique

In the process of marine gas hydrate exploitation, in order to achieve higher productivity, extended-reach wells or horizontal wells can be selected. Since the natural gas hydrates in the sea area are mostly buried in relatively shallow strata, in order to realize the smooth construction of extended-reach wells and horizontal wells, it is necessary to start deflection in shallow strata, which has a great impact on the running depth of the pipeline. At the same time, the mining process will involve relatively heavy wellhead equipment such as blowout preventers and underwater Christmas trees, which puts forward higher requirements for wellhead stability. Conventional offshore oil and gas wells can run surface conduits and technical casings of sufficient length to provide sufficient support for blowout preventers and subsea Christmas trees, so there is no problem of wellhead stability. However, the natural gas hydrate reservoir is shallow. In order to meet the requirements of shallow deflecting, the running depth of the conduit is greatly limited, and the wellhead stability is faced with great challenges.

Therefore, there is an urgent need to propose a wellhead device that can provide sufficient support for wellhead equipment in the process of marine natural gas exploitation to solve the above problems.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned technical problems, the present invention provides a wellhead stabilization device and method for horizontal wells in shallow soft hydrate reservoirs in the sea area to solve the problem that the wellhead equipment cannot be stably supported in the case of shallow deflection during the development of natural gas hydrate in the sea area.

The invention relates to a wellhead stabilization device for a horizontal well in a shallow soft hydrate reservoir in the sea area, which mainly includes a guide tube structure. A guide tube inner wall support ring is arranged at the lower part of the guide tube structure. The upper part and the lower part of the support ring adopt a conventional guide tube structure. The internal support mechanism is provided with an internal support mechanism C-ring, the support mechanism is provided with a bevel guide surface, and the lower part of the bevel guide surface adopts a columnar structure.

According to the wellhead stabilization device for a horizontal well in a shallow soft hydrate reservoir in the sea area of the present invention, the running length of the duct of the duct structure is determined according to the characteristics of the reservoir, the size of the duct, and the maximum weight of the wellhead equipment in the later stage multiplied by the safety factor. Parameters After the maximum load that the duct structure needs to carry, the length of the duct that needs to be run is calculated.

The invention relates to a wellhead stabilization device for a horizontal well in a shallow soft hydrate reservoir in the sea area. In the process of drilling natural gas hydrate in the sea area, an inner pipe string is installed inside the guide pipe, and a drill bit is installed at the bottom of the pipe string. The jet drilling method is used to drill down to the designed well depth.

According to the wellhead stabilization device for a horizontal well in a shallow soft hydrate reservoir in the sea area of the present invention, the position of the support ring on the inner wall of the conduit is determined according to the deflection depth of the extended reach well and the horizontal well. An internal support ring is installed at the bottom of the device, and the shape of the support ring must be consistent with the shape of the C-shaped ring of the internal support mechanism in claim 1, and can achieve mechanical sitting and hanging.

The invention provides a wellhead stabilization device for a horizontal well in a shallow soft hydrate reservoir in the sea area. After the inner support mechanism is placed in place by the catheter structure and allowed to stand for adsorption, the inner support mechanism is fed into a tool through the inner support mechanism to run the inner support mechanism into the catheter. The location of the support ring inside the structure.

The invention is a wellhead stabilization device for a horizontal well in a shallow soft hydrate reservoir in the sea area. The C-shaped ring of the internal support mechanism is matched with the inner support ring of the conduit structure. When the internal support mechanism is sent in place, the C-shaped ring sits and hangs in the conduit , and the C-ring is made of high-strength materials to ensure that it can withstand the internal support mechanism and the drilling pressure during the subsequent drilling process.

The invention provides a wellhead stabilization device for a horizontal well in a shallow soft hydrate reservoir in the sea area. The deflecting guide surface determines the orientation of the guide surface through the feeding tool, and the C-shaped ring and the inner support ring are matched to orient the guide surface to the wellbore track. The extension direction of the deflecting can meet the requirements of shallow deflecting.

A method for stabilizing a horizontal wellhead of a shallow soft hydrate reservoir in the sea area of the present invention comprises the following steps:

Step 1. Using the catheter injection method, the catheter structure is lowered into the designed well depth by the injection method, and the adsorption is allowed to stand;

Step 2. Use the internal support mechanism to feed the tool, and send the internal support mechanism to about 5m above the support ring on the inner wall of the conduit, and use the inner support mechanism to feed the tool to determine the direction of the deflection guide surface of the internal support mechanism toward the wellbore trajectory for deflection extension direction.

Compared with the prior art, the present invention has the following beneficial effects: in the process of natural gas exploitation in the sea area, under the condition of ensuring the build-up rate in the shallow space, the supporting force for the wellhead equipment can be realized, and the stability of the wellhead can be improved. Ensure underground safety.

Description of drawings

1 is a schematic structural diagram of a horizontal wellhead stabilization device for a shallow soft hydrate reservoir in the sea area according to the present invention;

Fig. 2 is the sectional view of the conduit structure in Fig. 1;

Figure 3 is a front view of the internal support mechanism in Figure 1;

Symbols in the drawings: 1: catheter; 1-1: catheter inner wall; 1-2: catheter inner wall support ring; 2: inner support mechanism; 2-1: inner support mechanism outer wall; 2-2: inner support mechanism C-ring ; 2-3: Bevel guide surface.

Detailed ways

The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments. The following examples are intended to illustrate the present invention, but not to limit the scope of the present invention.

The invention relates to a wellhead stabilization device for a horizontal well in a shallow soft hydrate reservoir in the sea area, which mainly includes a guide tube structure. A guide tube inner wall support ring is arranged at the lower part of the guide tube structure. The upper part and the lower part of the support ring adopt a conventional guide tube structure. Internal support mechanism, the internal support mechanism is provided with an internal support mechanism C-ring, the support mechanism is provided with a deflecting guide surface, and the lower part of the deflecting guide surface adopts a columnar structure; in the process of natural gas exploitation in the sea area, it can provide sufficient wellhead equipment. Support force and improve the stability of wellhead equipment.

As a preferred technical solution, a wellhead stabilization device for a horizontal well in a shallow soft hydrate reservoir in the sea area of the present invention mainly includes a conduit structure, the lower part of the conduit structure is provided with a support ring for the inner wall of the conduit, and the upper and lower parts of the support ring adopt conventional Conduit structure, an internal support mechanism is installed inside the conduit, the internal support mechanism is provided with a C-shaped ring of an internal support mechanism, the support mechanism is provided with a bevel guide surface, and the lower part of the bevel guide surface adopts a columnar structure; The running-in length of the conduit is determined according to the characteristics of the reservoir, the size of the conduit and the maximum weight of the wellhead equipment in the later stage multiplied by the safety factor. After the maximum load that the conduit structure needs to bear is determined, the length of the conduit that needs to be run is calculated according to the reservoir parameters.

As a preferred technical solution, a wellhead stabilization device for a horizontal well in a shallow soft hydrate reservoir in the sea area of the present invention mainly includes a conduit structure, the lower part of the conduit structure is provided with a support ring for the inner wall of the conduit, and the upper and lower parts of the support ring adopt conventional The conduit structure is provided with an internal support mechanism inside the conduit, the internal support mechanism is provided with an internal support mechanism C-ring, the support mechanism is provided with a bevel guide surface, and the lower part of the bevel guide surface adopts a columnar structure; the conduit structure During the drilling of natural gas hydrate in the sea area, the inner pipe string is installed in the conduit, and the drill bit is installed at the bottom of the pipe string, and the jet drilling method is used to run down to the designed well depth.

As a preferred technical solution, a wellhead stabilization device for a horizontal well in a shallow soft hydrate reservoir in the sea area of the present invention mainly includes a conduit structure, the lower part of the conduit structure is provided with a support ring for the inner wall of the conduit, and the upper and lower parts of the support ring adopt conventional Conduit structure, an internal support mechanism is installed inside the conduit, the internal support mechanism is provided with an internal support mechanism C-ring, the support mechanism is provided with a bevel guide surface, and the lower part of the bevel guide surface adopts a columnar structure; the inner wall of the catheter supports The position of the ring is determined according to the deflection depth of the extended reach well and the horizontal well. After the deflection depth is determined, an internal support ring is installed at the bottom of the deflection point. The shape of the support ring must be the same as that of the internal support mechanism C in claim 1. The shape of the ring is the same, and the mechanical sitting and hanging are realized.

As a preferred technical solution, a wellhead stabilization device for a horizontal well in a shallow soft hydrate reservoir in the sea area of the present invention mainly includes a conduit structure, the lower part of the conduit structure is provided with a support ring for the inner wall of the conduit, and the upper and lower parts of the support ring adopt conventional The catheter structure, an internal support mechanism is installed inside the catheter, the internal support mechanism is provided with an internal support mechanism C-ring, the support mechanism is provided with a bevel guide surface, and the lower part of the bevel guide surface adopts a columnar structure; the internal support mechanism After the conduit structure is placed in place and left to stand for adsorption, the internal support mechanism is lowered to the position of the inner support ring of the conduit structure through the internal support mechanism feeding tool.

As a preferred technical solution, a wellhead stabilization device for a horizontal well in a shallow soft hydrate reservoir in the sea area of the present invention mainly includes a conduit structure, the lower part of the conduit structure is provided with a support ring for the inner wall of the conduit, and the upper and lower parts of the support ring adopt conventional The catheter structure, an internal support mechanism is installed inside the catheter, the internal support mechanism is provided with an internal support mechanism C-ring, the support mechanism is provided with a bevel guide surface, and the lower part of the bevel guide surface adopts a columnar structure; the internal support mechanism The C-shaped ring is matched with the inner support ring of the catheter structure. When the inner support mechanism is in place, the C-shaped ring opens and clips into the catheter. The C-shaped ring is made of high-strength materials to ensure that it can withstand the internal support mechanism and subsequent drilling. WOB during the process.

As a preferred technical solution, a wellhead stabilization device for a horizontal well in a shallow soft hydrate reservoir in the sea area of the present invention mainly includes a conduit structure, the lower part of the conduit structure is provided with a support ring for the inner wall of the conduit, and the upper and lower parts of the support ring adopt conventional The catheter structure, an internal support mechanism is installed inside the catheter, the internal support mechanism is provided with an internal support mechanism C-ring, the support mechanism is provided with a bevel guide surface, and the lower part of the bevel guide surface adopts a columnar structure; the internal support mechanism The C-ring cooperates with the inner support ring of the conduit structure. When the internal support mechanism is in place, the C-ring sits and hangs in the conduit, and the C-ring is made of high-strength materials to ensure that it can withstand the internal support mechanism and the subsequent drilling process. The deflection guide surface determines the direction of the guide surface by feeding the tool, and before the C-ring cooperates with the internal support ring, the guide surface is directed toward the extension direction of the wellbore trajectory deflection, so as to meet the requirements of shallow deflection.

A method for stabilizing the wellhead of a horizontal well in a shallow soft hydrate reservoir in the sea area of the present invention is realized by the following steps: Step 1. Using a conduit jetting method, the conduit structure is lowered into the designed well depth by the jetting method, and it is allowed to stand for adsorption; Step 2 2. Use the internal support mechanism to send the tool, and send the internal support mechanism to the vicinity of 5m on the support ring of the inner wall of the conduit, and determine the direction of the deflection guide surface of the internal support mechanism toward the deflection extension direction of the wellbore trajectory by feeding the tool through the inner support mechanism. .

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the technical principles of the present invention, several improvements and modifications can also be made. These improvements and modifications It should also be regarded as the protection scope of the present invention.

Claims (8)

1. A horizontal wellhead stabilization device for shallow soft hydrate reservoirs in sea area, characterized in that the device comprises a conduit structure (1), and the lower part of the conduit structure is provided with a conduit inner wall support ring (1-2), and the The upper part and the lower part adopt a conventional conduit structure (1-1), an internal support mechanism (2) is installed inside the conduit, an internal support mechanism C-ring (2-2) is provided on the internal support mechanism, and the support mechanism is provided with a ramp The guide surface (2-3), the lower part of the bevel guide surface adopts a columnar structure (2-1). 2. The wellhead stabilization device for a horizontal well in shallow soft hydrate reservoirs in sea area as claimed in claim 1, characterized in that, the running length of the conduit of the conduit structure (1) is based on reservoir characteristics, conduit size and later wellhead The maximum weight of the equipment is determined by multiplying the safety factor. After the maximum load that the conduit structure needs to bear is determined, the length of the conduit that needs to be run is calculated according to the reservoir parameters. 3. The wellhead stabilization device for a horizontal well in a shallow soft hydrate reservoir in sea areas as claimed in claim 1, wherein the conduit structure (1) installs an inner pipe through the inside of the conduit during the drilling of natural gas hydrate in the sea area. The drill bit is installed at the bottom of the pipe string, and the jet drilling method is used to run down to the designed well depth. 4. The wellhead stabilization device for horizontal wells in shallow soft hydrate reservoirs in sea area according to claim 1, characterized in that, the position of the support ring (1-2) on the inner wall of the conduit is based on the construction of the extended-reach well and the horizontal well. The slope depth is determined, and after the build-up depth is clarified, an internal support ring is installed at the bottom of the build-up point. The shape of the support ring must be consistent with the shape of the C-ring (2-2) of the internal support mechanism in claim 1, and achieve Mechanical mount. 5 . The wellhead stabilization device for a horizontal well in shallow soft hydrate reservoirs in sea area according to claim 1 , wherein the internal support mechanism ( 2 ) is placed in place after the conduit structure ( 1 ) is placed in place and allowed to stand for adsorption. 6 . , run the internal support mechanism to the position of the inner support ring of the catheter structure through the internal support mechanism feeding tool. 6 . The wellhead stabilization device for horizontal wells in shallow soft hydrate reservoirs in sea area according to claim 1 , wherein the C-ring (2-2) of the internal support mechanism is the same as the internal support of the conduit structure in claim 4. 7 . When the internal support mechanism is in place, the C-shaped ring sits and hangs in the conduit, and the C-shaped ring is made of high-strength materials to ensure that it can withstand the internal support mechanism and the drilling pressure during the subsequent drilling process. 7. The wellhead stabilization device for a horizontal well in a shallow soft hydrate reservoir in sea area according to claim 6, wherein the deflecting guide surface (2-3) determines the orientation of the guide surface by means of a feeding tool, and the right In Requirement 6, before the C-shaped ring is matched with the inner support ring, the guide surface is directed towards the extension direction of the wellbore trajectory deflection, so as to achieve the requirement of shallow deflection. 8. A method for stabilizing a horizontal wellhead of a shallow soft hydrate reservoir in sea area, characterized in that, comprising the following steps: Step 1. Using the catheter injection method, the catheter structure (1) is lowered into the designed well depth by the injection method, and is allowed to stand for adsorption; Step 2. Use the internal support mechanism to feed the tool, and send the internal support mechanism (2) to the 5m vicinity of the support ring on the inner wall of the conduit, and feed the tool through the inner wall support mechanism to determine that the direction of the deflection guide surface of the internal support mechanism faces the wellbore Trajectory build-up extension direction.

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