RU2585297C2 - Design of multi-hole well with two horizontal bores - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas industry, namely to designs of multi-hole wells with two horizontal bores. Structure includes cased bore vertical and inclined part of main shaft and inclined part of offshoot, shanks, tubing string lowered into well, opening arranged in joint of main shaft with inclined part of offshoot, assembly of miniature window, packer and flexible tube. Main and side shafts end with horizontal shafts. Assembly of miniature window used fixed opposite to window of casing of main shaft by means of hydraulic packer and attachment of nozzle assembly with small window and internal guides with through and deflecting slots. Inside borehole assembly is flexible insulating sleeve-adapter with external lugs corresponding grooves of borehole assembly, which connects tubing string with shank of main shaft and has possibility to provide tight connection with tail of another shaft. In horizontal part of main and lateral barrel assembly for multistage hydraulic fracturing - HFT. Said assembly consist of opening under effect of discharged balls couplings, swelling packers for annulus insulation of hydraulic fracturing steps and expandable shank fastening.

EFFECT: higher reliability for multistage fracturing in horizontal boreholes.

1 cl, 7 dwg

Description

The invention relates to the oil and gas industry, in particular to the construction of double-hole wells with two horizontal shafts revealing an ultralow-permeable reservoir, including carbonate-clay-siliceous strata of the Bazhenov and Abalak formations, which allow for processing of the bottom-hole formation zone, including multi-stage hydraulic fracturing, in each horizontal trunk.

The well-known design of a multilateral well, including the main and lateral shafts, an elevator string equipped with an operational packer (Oganov A.S. and others. Multilateral well drilling - development, problems, successes. - M.: VNIIOENG OJSC. 2001. - S. 43]. The disadvantage of this design is the lack of reliability and efficiency when processing under high pressure to stimulate the flow, which is especially important when conducting multi-stage hydraulic fracturing on each wellbore.

A well-known design of a multilateral well, including cased vertical and inclined parts of the main trunk and the inclined part of the side trunk, equipped with shanks, an elevator string lowered into the well, a window located at the junction of the main trunk with the inclined part of the side trunk, a miniature window assembly that is compatible with the aforementioned window (RU 79935 Ul, Е21В 43/25, published January 20, 2009). The disadvantages of this design are the lack of the ability to tightly isolate the connection of one liner with an elevator column, which is necessary when processing under high pressure to stimulate the flow, which is especially important when conducting multi-stage hydraulic fracturing on each well, for example, in ultra-low permeability reservoirs, including carbonate-clay -Silicon strata of the Bazhenov and Abalak formations.

The task is to create a reliable double-well design, which allows for multi-stage hydraulic fracturing in a fixed wellbore with isolation of another wellbore.

The problem is solved by the construction of a borehole with two horizontal shafts, including cased vertical and inclined parts of the main trunk and the inclined part of the side trunk, liners, an elevator string lowered into the well, a window located at the junction of the main trunk with the inclined part of the side trunk, and a miniature window assembly, a packer and a flexible sleeve, in which, according to the invention, the main and lateral trunks end with horizontal faces, as a miniature window unit contains a fixed head after opening the casing window of the main trunk with the help of a hydraulic packer and mounting the barrel-unit with a miniature window and internal guides through and deflecting grooves, a flexible insulating sleeve-nozzle with external protrusions corresponding to the grooves of the barrel-node that connects the elevator is placed inside the barrel-node with the shank of the main trunk and has the ability to provide a tight connection with the shank of the other barrel, in addition, in the horizontal part of the main and side trunks installed ki for multistage hydraulic fracturing, consisting of couplings opening under the action of discharged balls, swellable packers for annular isolation of hydraulic fracturing stages and expandable liner fastening

The proposed design differs from the known one in that it contains a trunk-node with a miniature window, a hydraulic packer and a fastening of the miniature window assembly as a miniature window unit. The barrel-assembly has guide grooves from the inside; in addition, the design contains a flexible insulating sleeve-nozzle, configured to provide access to the shank in the desired horizontal barrel due to guides made outside the sleeve-nozzle corresponding to the grooves of the barrel-assembly. In this case, the elevator column is connected to the desired shank with a flexible insulating sleeve-nozzle. Additionally, in the horizontal part of the main wellbore and in the horizontal part of the lateral wellbore, layouts for multistage hydraulic fracturing are located. The trunk unit with a miniature window is fixed at a certain depth using a hydraulic packer.

The invention is illustrated in FIG. 1-7:

FIG. 1- construction of a double-well borehole with two horizontal boreholes;

FIG. 2 - cross section of the trunk-node;

FIG. 3 is a cross section of a flexible insulating sleeve-nozzle;

FIG. 4 - a miniature window unit with an installed nozzle pipe for access to the main wellbore;

FIG. 5 - trunk-unit with installed pipe-nozzle for access to the side wellbore;

FIG. 6 - view of the trunk-node from the side of a miniature window;

FIG. 7 is a view of the trunk node from the side of the side of the miniature window.

The design of a double-well borehole with two horizontal boreholes (Fig. 1) includes:

1- horizontal part of the main trunk (open-cased);

2 - the horizontal part of the lateral trunk (uncased);

3 - vertical part of the well (cased);

4 - the inclined part of the main trunk (cased);

5 - the inclined part of the lateral trunk (uncased);

6 - shank located in the horizontal part of the main trunk 1;

7 - shank located in the horizontal part of the side trunk 2;

8 - mounting shanks 6 and 7;

9 - flexible insulating sleeve-nozzle with external guide protrusions to ensure a tight connection with the shanks 6 or 7;

10 - hydraulic packer;

11 - trunk node with a miniature window 12 and internal grooves;

18 is a window in the casing located at the junction of the vertical part 3 of the main trunk with the inclined part 5 of the side trunk;

13 - mount node miniature window;

14 - elevator column.

In FIG. 2 on the cross-section of the barrel-node 11 shows through grooves 15 made on its inner surface, providing, when the axis “C” (Fig. 3) is aligned with the axis “A”, the through passage of the sleeve-nozzle to the main barrel and deflecting grooves 16 extending into miniature 12, providing the deviation of the sleeve-nozzle and getting into the side barrel when combining the axis "C" with the axis "B".

On the cross section of the flexible insulating sleeve-nozzle (Fig. 3) shows the protrusions 17, made on the outer surface of the sleeve-nozzle 9, included in the grooves 15 or 16 and providing a through passage of the flexible insulating sleeve-nozzle 9 into the main barrel or getting into the side barrel .

In FIG. 4 shows the appearance of the site of a miniature window with a flexible sleeve-nozzle 9 when it passes through the main trunk. The situation arises when the protrusions of the flexible sleeve-nozzles 9 coincide with the through grooves 15 of the barrel-node 11.

In FIG. 5 shows the appearance of the site of the miniature window with a flexible sleeve-nozzle 9 when it is deflected into the side barrel 5 through the miniature window 12. The situation occurs when the protrusions of the flexible sleeve-nozzle 9 coincide with the slots 16 of the barrel-assembly 11 deflecting into the miniature window.

In FIG. 6 and 7 show views of the barrel-assembly 11 from the side of the miniature window 12 and from the side lateral of the miniature window, allowing to specify the location of the through grooves 15 and the deflecting grooves 16.

The construction of a multilateral well with two horizontal shafts, the design of which allows for separate processing of the shafts, including multi-stage hydraulic fracturing, is carried out in the following sequence:

1) drilling the vertical part of the well 3, the inclined part 4 of the main wellbore with the installation of the casing string;

2) drilling of the horizontal part 1 of the main trunk;

3) installation of the layout for multi-stage hydraulic fracturing, consisting of couplings opening under the action of discharged balls, swellable packers for annular isolation of hydraulic fracturing stages in the horizontal part 1 of the main trunk and securing with the expandable shank attachment 6;

4) the installation of a hydraulic packer 10 for controlling the depth where the exit window 18 will be cut into the side barrel 5, which is also used as a seat for the trunk unit 11;

5) descent of the deflector of the trunk path (not shown in the figures) and fixing on the packer 10;

6) the cutout of the window 12 in the necessary direction, confirmed by the value of the gyroscope;

7) drilling the inclined part of the side shaft 5 without installing a casing string;

8) setting the layout for hydraulic fracturing in the horizontal part 2 of the side trunk and securing with the expandable shank mount 7;

9) installation of a miniature window assembly: the barrel assembly 11 is mounted on the hydraulic packer 10 by means of a fastener 13.

Separate processing of boreholes with two horizontal boreholes, in particular multi-stage hydraulic fracturing in both boreholes, is performed in the following sequence:

1) using a flexible tubing (CT), an insulating sleeve-nozzle 9 is installed in the miniature window assembly, oriented at an angle so that the guide protrusions 17 fall into the through guide grooves 15, providing access to the main wellbore 1;

2) the elevator column 14 is connected to the mount 13;

3) treatment of the bottomhole formation zone in the horizontal part of the main wellbore 1;

4) the elevator column 14 is disconnected from the mount 13;

5) the insulating sleeve-nozzle 9 is removed from the miniature window assembly;

6) with the help of a coiled tubing, an insulating sleeve-nozzle 9 is installed in the miniature window assembly, oriented at an angle so that its guide protrusions 17 fall into the deflecting grooves 16, providing access to the side wellbore 5 and 2;

7) the elevator column 14 is connected to the mount 13;

8) treatment of the bottom-hole zone of the formation is carried out in the horizontal part of the side wellbore 2;

9) the elevator column 14 is disconnected from the mount 13;

10) the insulating sleeve-nozzle 9 is removed from the miniature window assembly.

The operation of processing the bottom-hole zone of the formation in the horizontal part of the main and lateral layers can be carried out repeatedly and in any sequence.

The inventive design of the well provides the possibility of hermetic isolation of the connection between the liner and the lift string, which is necessary when processing under high pressure to stimulate the flow, for example, when conducting multistage hydraulic fracturing on each fixed wellbore with isolation of the other wellbore. This is especially important in conditions of ultra-low permeability reservoirs, including carbonate-clay-siliceous strata of the Bazhenov and Abalak formations.

Claims (1)

The design of a double-well borehole with two horizontal shafts, including cased vertical and inclined parts of the main shaft and the inclined part of the side trunk, liners, an elevator string lowered into the well, a window located at the junction of the main barrel with the inclined part of the side shaft, a miniature window assembly, a packer and a flexible sleeve, characterized in that the main and lateral trunks end with horizontal trunks, a main window fixed in front of the casing window is used as a miniature window unit using a hydraulic packer and mounting the barrel-assembly with a miniature window and internal guides through and deflecting grooves, a flexible insulating sleeve-nozzle with external protrusions corresponding to the grooves of the barrel assembly that connects the lift column to the shank of the main trunk and is placed inside the barrel assembly has the ability to provide a tight connection with the shank of another barrel, in addition, in the horizontal part of the main and side shafts are installed layouts for multi-stage The hydraulic fracturing - EMG consisting of opening under the action of the discharged balls clutches annulus swellable packers for isolation and fracturing stages expandable shank attachment.

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