RU2714397C1 - Unstable rocks driving method during drilling of offshoot with horizontal end - Google Patents

Abstract

FIELD: soil or rock drilling.

SUBSTANCE: invention relates to drilling of oil and gas wells, namely to methods of prevention of destruction and collapse of well walls at drilling intervals with unstable rocks. Unsustainable rocks driving method during drilling of offshoot with horizontal end, including window cutting in production string, drilling of the offshoot, attachment of the offshoot of the string with the shoe installed on the lower end, drilling of the offshoot to the projecting face. Method includes preliminary determining zone of unstable rocks of formation, after window cutting in production string, drilling of side bar bit with diameter of 1.3–2.5 % less than diameter of cut window with opening of zone of unstable rocks of formation, lower-string column-fly is lowered to the working face on the drilling string, equipped with a mounting device from above, and from below with a drilled working shoe, hydraulic pressure in the drilling pipe string is increased, the landing device is detached and removed from the drill string, at that, the diameter of the winding-free column is 7–8 % less than the diameter of the drilled offshoot, the drilling of the offshoot from the flush-joint column-volost to the design face is performed with chisel by 1.5–3 % less than the inner diameter of the flats-without winding column.

EFFECT: providing stability of process of driving and development of unstable hard-to-reach rocks of formation with diameter of well passage channel, drilling of well to project face with maximum possible diameter, direct flushing of well for removal of sludge, higher reliability of method, reduced labor input and duration of method implementation.

1 cl, 2 dwg, 1 tbl

Description

The invention relates to the field of drilling oil and gas wells, and in particular to methods of preventing destruction and collapse of the walls of the well when drilling intervals with unstable rocks.

A known method of drilling an additional wellbore from the production casing of a well (patent RU No. 2172384, IPC ЕВВ 7/06, published on 08/20/2001 in bull. No. 23), including drilling an additional wellbore with a smaller diameter compared to the main one, using a diverter, drilling additional trunk and its fastening with expansible profile pipes. In this case, the additional wellbore is drilled to the top of the reservoir, after which insulating material is pumped into the well and the drilled part of the additional wellbore is fastened with expandable profile pipes, and then the productive stratum is opened while maintaining pressure at the bottom, which is equilibrium with the in-situ or depressive to it.

The closest in technical essence and the achieved result is a method of sinking of unstable rocks while drilling a sidetrack with horizontal ending (patent RU No. 2344263, IPC ЕВВ 7/10, published on January 20, 2009 in Bull. No. 23), including cutting a window in the production casing , sidetrack drilling, sidetrack fastening with a string of pipes with a shoe mounted on the lower end, sidetrack drilling to the project face. The sidetracking in unstable rocks and the borehole wall are fixed in successive sections, the length of the section being chosen so that there is no collapse of unstable rocks during the raising of the bit and the installation of a profile overlap. In this case, the installation of profile shutoffs is performed with overlapping overlapping with a sequential decrease in the internal diameter of the installed profile shutoffs in the working position when drilling with the expansion of the wellbore in the first section of the interval of the formation or end-to-end during sequential drilling with the expansion of all sections of the wellbore.

The disadvantages of the methods are:

- the inability to develop difficult terrain with unstable formation rocks with a profile overlap, because of the low mechanical properties of the profile pipes do not absorb torque from the development tool, in addition, it is impossible to flush the well, as this expands the profile pipes;

- low reliability of the implementation of the method, due to the inability to expand the profile cutter by the supplied pressure to the design geometric dimensions after lowering into the well, since the collapsed unstable formation rock prevents uniform expansion;

- the complexity and duration of the method associated with additional tripping operations for expanding underexposed areas when installing a profile overlap;

- the high cost of applying the method associated with the high cost of the profile pipes (profile overlap), as well as the insufficient strength of the profile overlap after installation, since the profile pipes are pre-deformed and repeatedly annealed.

The technical objectives of the invention are to increase the efficiency of the method of sinking unstable rocks while drilling a sidetrack with horizontal completion by providing sinking and development of unstable rock formations with a diameter of the borehole channel, allowing to drill a well to the project bottom with the maximum possible diameter, ensuring direct washing of the well for sludge removal, improving the reliability of the implementation of the method, reducing the complexity and duration of implementation way, reducing financial costs for the implementation of the method.

Technical problems are solved by the method of penetrating unstable rocks while drilling a sidetrack with a horizontal end, including cutting a window in the production casing, drilling a sidetrack, attaching a sidetrack to a column of pipes with a shoe mounted on the lower end, and drilling the sidetrack to the project face.

What is new is that the zone of unstable formation rocks is preliminarily determined, after cutting the window in the production casing, the sidetrack is drilled with a bit 1.3–2.5% smaller than the diameter of the cut-out window with the opening of the zone of unstable formation rocks, the clutchless column is lowered to the bottom the fly on the drill pipe string, equipped with a landing device on top, and on the bottom, a drillable, working shoe, increase the hydraulic pressure in the drill pipe string, disconnect and remove the landing device with a drill pipe string, at the same time, the diameter of the collarless fly-string is 7–8% less than the diameter of the drilled lateral shaft, the side trunk is drilled from the collar-free fly-string before the bottom hole with a bit 1.5–3% less than the inner diameter of the collar –– Flying.

In FIG. 1 schematically and sequentially shows the implementation of the proposed method.

In FIG. Figure 2 shows the assembly of the coupling sleeveless drill string with the drill pipe string.

The method is carried out in the following sequence.

Preliminarily, the zone of unstable rocks of formation 1 is determined by neighboring wells and by the materials of geophysical studies of the well.

In the production casing 2 (Fig. 1), a window 3 is cut out by any known method, for example, by installing a deflecting wedge 4, using a cutter to cut a window (not shown in Fig. 1, 2). The through diameter of the cut-out window 3 is equal to the diameter of the cutter used.

Then, a bit is lowered on the drill pipe string, for example, with PDC cutters (not shown in Fig. 1, 2), which has a diameter of 1.3–2.5% less than the diameter of the cut-out window 3 (Fig. 1) in production casing 2. This ratio of diameters provides unimpeded descent and passage through the cut out window 3 of the descent equipment and drilling of the side trunk 5 with the opening of the zone of unstable rocks of the formation 1, thereby increasing the reliability of the method. The diameter of the side trunk 5 is equal to the diameter of the bit. Next, the bit is removed at the wellhead.

Next, to fasten the zone of unstable rocks of the formation 1 of the lateral shaft 5 on the string of drill pipes 6 (Fig. 2), a couplingless flywheel string 7 is lowered into the well (Figs. 1 and 2). Preliminarily, at the manufacturing plant, a clutchless fly-off column 7 is equipped with a connection unit to the drill pipe string 6 from above, and a drillable, working shoe (bottom not shown in Figs. 1, 2) from the bottom.

Clutchless fly column 7 is a column of cylindrical pipes interconnected by welding, the diameter of which is 7-8% less than the diameter of the drilled side barrel 5 (Fig. 1), which corresponds to the conditions of patency of the launched equipment. To accelerate the descent process, the clutchless flying column 7 may consist of pre-prepared pipe lashes of two pipes (24 m).

A drillable, mining shoe is used of any known design, for example, equipped with spiral blades with PDC cutters or with a layer surfacing with tungsten carbide incorporation and having wash holes.

During the descent of the clutchless flying column 7, in the case of tacking and obstruction, it is rotated to the right up to 40 revolutions per minute while flushing with washing liquid. While being drilled, the working shoe drills the sludge cushion while ensuring the patency of the clutchless fly column 7 of unstable rock formations of formation 1.

The connection node of the clutchless fly-string 7 with the drill pipe string 6 is a landing device 8 (Fig. 2), fixed on the upper pipe of the flare fly-pipe string 7 using a sealed part 9 and having a sealing collar 10.

After working out and reaching the bottom hole 11 of the well (Fig. 1), a ball is thrown into the string of drill pipes 6 from the wellhead (not shown in Fig. 1, 2). In this case, the ball reaches the drillable, working shoe and closes the central hole, the circulation of the flushing fluid stops.

Next, the hydraulic pressure is raised inside the string of drill pipes 6 (Fig. 2) to the calculated value, which ensures the expansion of the sealed part 9 of the joint. In this case, the landing device 8 (Fig. 2) comes out of the sealed part 9 of the upper pipe of the clutchless fly column 7, while the bell 12, made in the form of a funnel, fixes the upper part of the clutchless fly column and ensures the entry of the descent bit for subsequent drilling.

The signaling device for uncoupling the landing device 8 from the clutchless flying column 7 is a drop in hydraulic pressure. The drill string 6 along with the lander 8 is removed from the well.

In the lower part of the lateral wellbore 5 (Fig. 1) of the well, a sleeveless fly-off column 7 is fixed from being moved by the bottom 11 of the well, and in the upper - by a bell 12 in the form of a funnel.

Next, the horizontal part 13 of the lateral shaft 5 of the well is drilled from the clutchless fly-string 7 to the design face with a drill bit (not shown in FIGS. 1, 2) having a diameter 1.5–3% less than the inner diameter of the fly-off clutch string 7. the ratio allows you to freely lower the bit through the sleeveless fly-off column for further drilling to the bottom hole and provides the diameter of the borehole channel with the maximum possible diameter for the subsequent unhindered lowering of the production casing or shank.

After drilling, the production casing 2 is lowered to the design face and cemented in any known manner.

An example of the practical application of the method of driving unstable rocks while drilling a sidetrack with a horizontal end.

The zone of unstable rocks 1 is determined from neighboring wells and from the materials of geophysical studies of the well.

In the production casing 2 with a diameter of 168 mm (Fig. 1), a window 3 is cut with the installation of a deflector 4 using a window cutter with a diameter of 146 mm (not shown in Fig. 1, 2).

Next, a drill bit, for example, a PDC (not shown in Fig. 1, 2) having a diameter of 143 mm, which is 2.1% less than the diameter of the cut-out window 3 (Fig. 1) in production casing 2, is lowered on the drill pipe string 6 and is produced drilling a sidetrack 5 with opening the zone of unstable rocks 1 of the reservoir and lift the tool at the wellhead.

Then, to fasten the sidetrack 5 in the zone of unstable rocks 1 on the drill pipe string 6 (Fig. 2), a sleeveless fly-off string 7 with a diameter of 133 x 5 mm is lowered into the well, which is 7.5% less than the diameter of the drilled sidetrack 5 (FIG. 1). The clutchless fly column 7 (Figs. 1 and 2) is equipped on top with a connection unit to the drill pipe string 6, and on the bottom, a drillable, drill shoe equipped with spiral blades with PDC cutters (not shown in Figs. 1, 2).

During descent, the clutchless fly column 7 is rotated with a torque of up to 12 kN · m while flushing with flushing fluid to eliminate sticking and obstruction, while the working shoe drills the slurry cushion while ensuring the passage of the entire column.

Upon reaching the bottom hole 11 of the well (Fig. 1), a ball is thrown into the string of drill pipes 6 from the wellhead (not shown in Figs. 1 and 2). Then, inside the column, the hydraulic pressure is raised to 150 atm. At the same time, the landing device 8 of the connection node with the drill pipe string 6 (Fig. 2) leaves the sealed part 9 of the upper pipe of the clutchless fly string 7, while the bell 12 forms an inlet funnel. The signaling device of the landing device 8 is a drop in hydraulic pressure. The string of drill pipes 6 together with the landing device 8 of the connection node is removed to the surface. At the same time, a flyaway clutchless column 7 was fixed from displacement in the lateral shaft 5 in the lower part by the bottom 11 of the well, and in the upper - by the bell 12. The diameter of the bell 12 after the exit of the landing device 8 increased to a diameter equal to the inner diameter of the well - 143 mm.

Next, the horizontal part 13 of the side well 5 is drilled to the design bottom from the sleeveless fly-off column 7. Drilling is carried out with a PDC bit (not shown in FIGS. 1 and 2) having a diameter of 120 mm, which is 2.5% less than the internal the diameter of the sleeveless coupling column 7. Then, a liner with a diameter of 102 mm and couplings with a diameter of 110 mm are lowered into the horizontal wellbore, which freely pass through the sleeveless coupling string 7 and reach the design bottom.

Other examples were performed analogously to the application example described above. The results are shown in the table.

Table

Diameter of a window mill Sidetrack Drill Bit Diameter Diameter of the Flying Column Drill bit diameter for bottom hole drilling 146 144.7 134.6 122.7 143.5 132 120.3

Thus, the present invention allows to ensure the stability of the process of drilling and development of unstable difficult formations with a diameter of the borehole of the formation, allows to drill the well to the project bottom with the maximum possible diameter, to ensure direct washing of the borehole to remove sludge, to increase the reliability of the method, reduce the complexity and duration the implementation of the method, reduce financial costs for the implementation of the method.

Claims (1)

A method of driving unstable rocks while drilling a sidetrack with a horizontal end, including cutting a window in the production casing, drilling a sidetrack, securing the sidetrack with a pipe string with a shoe mounted on the lower end, drilling a sidetrack to the project bottom, characterized in that the zone of unstable formation rocks, after cutting a window in the production casing, a sidetrack is drilled with a bit with a diameter of 1.3-2.5% less than the diameter of the cut window with opening the zone of unstable rock of the formation, a clutchless fly-string on the drill pipe string is lowered to the bottom, equipped with a landing device from above and a drillable drill shoe at the bottom, hydraulic pressure in the drill pipe string is increased, the landing device with the drill pipe string is uncoupled and removed, while the diameter of the couplingless Flying columns are 7-8% less than the diameter of the drilled sidetrack; sidetracks are drilled from a collarless Flying column before the project bottom with a bit 1.5-3% less internally clutchless diameter of the column-flying detachment.

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