RU2279522C2 - Multibranch well construction method - Google Patents

Abstract

FIELD: special methods or apparatus for drilling, particularly for deflecting the direction of boreholes.

SUBSTANCE: method involves cutting window in casing pipe of primary well bore, wherein the casing pipe is provided with splines and retrievable seating unit is installed on the splines, the retrievable seating unit includes inner splines arranged in upper seating unit part, outer splines located in lower seating unit part and seating casing pipe provided with clutch having auxiliary wedge member at upper clutch end; filling interval of retrievable seating unit installation with non-hardening viscous-plastic liquid having shearing strength determined from mathematical relation; drilling additional bore to design depth with the use of deflection wedge provided with splines in lower part thereof and with seating plate having angle of inclination equal to that of auxiliary wedge member; removing deflection wedge from well after additional bore drilling; delivering liner with casing pipes to head of newly-drilled additional bore; sealing additional bore head by lowering head packing unit in additional bore head, wherein head packing unit comprises shutoff packer provided with medium separation means and has wedge with channels for plugging composition and additional connection pipe with collars in upper part thereof; injecting plugging composition in liner and flushing the well; drilling upper part of additional connection pipe and removing seating unit after additional bore completion.

EFFECT: increased reliability of deflection wedge fastening for window cutting in casing pipe, prevention of mud accumulation in main well bore during additional bore drilling.

11 dwg, 1 tbl

Description

The invention relates to the mining industry and is intended for use in work on opening a window in a column and drilling to the design depth of a new trunk, uncoupling the mouth of additional new shafts during the construction of multilateral wells.

Known deflecting layouts for opening a window in the column and drilling multilateral wells, allowing to obtain predetermined radii of curvature depending on the geometric shape of the layout [1, 2]. The most widespread are deflecting wedges with fixing the hull in the column using dies or mounted on a cement face.

The variety of structures for securing wedge devices is associated with the lack of reliable securing of a deflecting tool for drilling additional shafts in cased wells. The most complex accidents are associated with turning a deflecting wedge around its axis. Such complex accidents usually cannot be eliminated.

In multilateral wells, composed of unstable rocks, additional new shafts are cased with shanks. In the process of drilling a new trunk, cementing and sealing the mouth of the liner, there are a number of technological and technical unsolved problems:

- sludge settling into the primary wellbore during the drilling of a new additional wellbore;

- involuntary cementing of the deflecting wedge during shank attachment;

- fixing of unstable rocks opened by a window in the column of the primary trunk in order to exclude collapse and talus of rocks during further operation of a multilateral well;

- loosening of the upper end of the liner during operation and repair of the well.

The proposed technical solution is aimed at: securely securing the deflecting wedge to open the window in the column and sealing the mouth of the liner during the construction of each new additional wellbore of a multilateral well, to prevent sludge (rocks and metal chips) from settling into the primary wellbore during drilling of a new additional wellbore using visco-plastic liquids.

The technical result is the ability to extract from the primary wellbore of individual wells of the device units and, if necessary, work in a specific additional wellbore, reuse the extracted nodes from the well, disconnect the mouth of the liner during the construction of each new additional wellbore.

The technical result is achieved by applying the method of constructing multilateral wells, including opening a window in the casing of the primary wellbore and drilling a new additional wellbore to the design depth using a whipstock, lowering the liner with casing at the mouth of the new additional wellbore and sealing the mouth of the new additional wellbore . According to the invention, the bottom of the casing of the primary wellbore is equipped with slots and the retrievable landing unit is planted on the slots of the casing of the primary wellbore, while the extracted landing unit, including the landing casing, is provided with internal slots above and below, as well as an auxiliary wedge, which is installed at the upper end of the sleeve of the casing pipe, after which the installation interval of the extracted casing assembly is filled with a non-hardening viscoplastic fluid Tew with a statistical shear stress satisfying the condition

where θ is the static shear stress of a viscoplastic fluid;

r is the radius of the sludge-rock, metal chips deposited in the process of drilling an additional new trunk;

ρ _n , ρ _W - respectively, the density of the rock, metal chips and non-hardening viscoplastic fluid;

β = 18-50 - flow coefficient,

 the diverter wedge is equipped with slots in the lower part and the landing pad, the inclination angle of which is equal to the angle of inclination of the auxiliary wedge, and after drilling a new additional wellbore to the design depth, the deflector wedge is removed from the well; including a packer-cutter with a medium separator, containing a wedge having openings for the passage of the grouting mixture, and an auxiliary pipe with cuffs in the upper part, forcing grouting the mixture into the liner and flushing the well, after which the auxiliary nozzle with cuffs in the upper part is drilled with a chisel and after the completion of the development of a new additional barrel, the landing unit is removed.

The flow coefficient, which depends on the shape and size, is considered in the work of Mirzadzhanzade A.Kh. “Issues of hydrodynamics of visco-plastic and viscous liquids in oil production”, Baku, 1959, p. 58.

Rock particles torn from the well wall from a known formation, under the influence of gravity in a non-hardening viscoplastic solution meets resistance, the value of which is expressed by the formula:

where r is the radius of the rock torn from the wall of the well;

β is the flow coefficient depending on the shape and size;

η is the dynamic coefficient of viscosity, kgf · sec / cm ² (Poise);

υ is the particle velocity;

θ is the static shear stress of a viscoplastic fluid.

In liquids, the falling rock is under the action of two opposing forces. From top to bottom, the force of gravity of the rock f ₁ acts, which is equal to the product of its volume and its density - ρ _n :

where ρ _n is the density of the rock.

From bottom to top, a buoyancy force acts on the rock, which, according to the Archimedes law, is equal to the mass of the displaced fluid in the rock volume, with a density

where ρ _W is the density of a visco-plastic fluid;

then

To ensure the equilibrium condition F ₁ = F _{2 the} static shear stress should be

An increase in the density of a viscoplastic fluid leads to a decrease in the rate of deposition of solid particles collapsed from the walls of the well bore, however, the rate of deposition of the rock ceases only with increasing static shear stress of the viscoplastic fluid, i.e. when υ = 0.

Then the criterion for the magnitude of the static shear stress is the formula

The density of the rocks of an opening well is always greater than the density of a viscoplastic fluid. The cessation of the movement of solid particles in a liquid only by increasing the density of a viscoplastic fluid is practically impractical. Using formula 6, it is possible to determine the static shear stress of a non-hardening viscoplastic cement slurry in relation to specific well conditions, so that the deposition rate of the falling rocks is zero.

The values of static shear stress at which the deposition of solids (rocks) in non-hardening viscoplastic fluids ceases.

No. p / p Density, g / cm ³ Diameter of solid particles, mm The value of the static shear stress of a viscoplastic fluid, at which the deposition of solid particles (rocks), mg / cm ² Particulate matter Viscoplastic fluid Laboratory data The calculated data according to the formula 6 one 2,4 1,2 3.0 thirty 26.66 2. 7.8 1.4 3.0 135 141.7 3 2,4 1,2 7.5 60 66.6 four 7.8 1.42 7.5 320 354 5 2,4 1,2 twenty 200 177 6 7.8 1.4 twenty 640 945 7 2,4 1,2 35 340 311 8 7.8 1.4 35 1200 1654 9 2,4 1,2 fifty 450 444 10 7.8 1.4 fifty 2500 2362

The implementation of temporary well attachment allows to solve the problem of reservoir separation in various mining and geological conditions during well attachment, to extract a casing string after completion of well research and operation.

The choice of the formulation of non-hardening mixtures for temporary plugging of wells is described in detail in the work of Z. M. Shakhmaev and V. R. Rakhmatullin “Technology of well completion” - Ufa, 1996, p. 140.

Non-hardening grouting mixtures prepared on the basis of the following minerals were investigated:

- bentonite and calcium clays;

- Devonian oil;

- diesel fuel;

- surface-active substances (NPS, SAB-1, etc.);

- various mineral salts.

For example, the temporary fastening of a well, in the context of which there are terrigenous deposits, corresponds to the parameters of a non-hardening viscoplastic cement slurry composition (in grams):

clay powder 350 oil 150 Surfactant 200 SAB-1 150 water 431 Solution density 1.28 g / cm ³

Wells, in the context of which there are deposits with temperatures up to -9 ° C (permafrost), correspond to the parameters of non-hardening viscoplastic cement slurries of the composition (in grams):

clay powder 500 oil 250 Surfactant one hundred NaCl - Sodium Chloride 150 water 356 Solution density 1.36 g / cm ³

The figures show a sequence diagram of the installation of the extracted landing node:

figure 1 - the position of the slots in the primary trunk of a multilateral well;

figure 2 - the position of the extracted landing site after landing on the slots in the primary wellbore;

figure 3 - the final position of the equipment of the top of the landing unit after landing a wedge for drilling a window in the column of the primary trunk of a multilateral well.

1. Casing.

2. Shoe.

3. Separation plug.

4. Cement.

5. Internal splines in the primary trunk.

6. Landing casing.

7. The outer slots of the landing pipe.

8. The inner slots of the landing pipe.

9. The centralizer.

10. Auxiliary wedge.

11. Wedge deflector for opening the window in the column of the primary trunk.

12. Slots from the whipstock to open the window in the column of the primary trunk.

13. Filling the extractable landing site viscoplastic fluid.

Figure 4-6 is a diagram of the installation of the sealing unit of the shank mouth.

14. Packer cutter with a medium separator.

15. Wedge for fixing unstable rocks, opened by a window in the casing of the primary trunk.

16. Auxiliary branch pipe with cuffs in the upper part.

Figure 7 shows the layout of the bottom of the casing of the primary well of a multilateral well equipped with splines.

The slots in the casing 1 are installed above the nozzle of the installation site of the "stop ring" 17.

On Fig shows the layout of the extracted landing site.

The extracted landing unit consists of a casing 6, external 7 and internal 8 slots, centralizers 9, an auxiliary wedge 10, screwed on the upper end of the casing sleeve 6. The length of the removed landing node is determined from the installation of the slot of the bottom of the primary casing string to the window opening in the column. It descends on drill pipes ending in left-hand thread. Using a magnetic sub mounted in the drill pipe string, the bevel plane of the auxiliary wedge is turned in the direction of opening the window in the string of the primary wellbore.

After the retrievable landing site is planted on the slots of the casing of the primary wellbore, the installation interval of the retrieved landing site is filled with a viscoplastic fluid. The drill pipe string is then rotated clockwise to disconnect from the retrievable landing assembly. To prevent sticking of the recoverable planting unit due to settling of cuttings and metal chips during the drilling of additional new shafts, the installation interval of the reclosable planting unit is filled with a viscoplastic fluid with a static shear stress satisfying the following condition

where θ is the static shear stress of a viscoplastic fluid;

r is the radius of the sludge of the rock, metal chips deposited in the process of drilling an additional new trunk;

ρ _n , ρ _W - respectively, the density of the rock, metal chips and non-hardening viscoplastic fluid;

β is the flow coefficient depending on the shape and size, according to the experimental data of R.I. Shishchenko β = 18-50.

The extracted landing unit is fixed using splines in the primary wellbore and is left in the string at the design depth to open the window in the string and drill a new well to the design depth.

Figure 9 shows the wedge-deflector for opening the window in the column.

The deflecting wedge for opening the window in the column consists of a deflecting wedge 11 with an oblique direction, the cross-section is semicircular, the outer slot is on the lower part, and its landing angle is equal to the angle of the auxiliary wedge 10. The deflecting wedge is removed from the well after opening the window in the column and the achievement of drilling design depth of a new additional trunk in the desired direction. The deflector wedge is lifted from the well using a fishing tool (tap).

Figure 10-11 shows a node for sealing the mouth of the shank.

The node for sealing the mouth of the liner consists of a barrel (casing) with holes 18, an adapter cylinder 19, calibrated safety screws 20, a piston 21. A piston with a wedge 22 is held in the cavity of the adapter using calibrated safety screws 20. The wedge 22 interacts with the inner surface of the rubber conical cuffs 14, a wedge 15 is screwed onto the half-couplings 23 to separate the unstable rocks exposed by the window into the casing of the primary wellbore and an auxiliary pipe 16 with cuffs in the upper parts.

The unit for sealing the mouth is connected in the lower part by means of a nipple with a shank. The shank is equipped with a shoe, a non-return valve and, optionally, a seat 24 and a ball 25, designed for a certain holding pressure of the latter. The upper part of the node is connected by a device for cementing the liner with the preliminary disconnection of the drill string. The assembly thus mounted for sealing the liner mouth together with the casing pipes is lowered into the well and installed with precise georeferencing on the mouth of an additional new shaft, and the wedge 15 for fixing unstable rocks opened by the window in the primary shaft casing is set to the calculated place using magnetic sub installed in the drill string.

Further, the circulation of the drilling fluid is restored. When the ball 25 is seated on the saddle 24, an increase in pressure in the column is recorded, and the packer element is activated at a pressure of 45-50 kgf / cm ² . When the pressure in the column reaches 75-95 kgf / cm ² , guaranteeing a cut of the screws of the wedge 22, as a result, the wedge 22 moves and circulation is restored through the packer-cutter with a medium separator. A ball 25 with a saddle 24 falls on the catcher 26. Next, the cement mixture is pumped and other work is carried out according to the approved technology of the consumer enterprise.

When the calculated volume of the grouting mixture is injected into the liner, the grouting mixture passes through the liner shoe, the holes in the wedge 22 of the packing element (inlet), the medium separator of the packing element and enters the space between the walls of the auxiliary pipe 16 with cuffs in the upper part and the drill string, then into the casing the primary trunk of a multilateral well. Then, the excess cement mixture using direct or reverse washing is completely washed out of the casing of the primary well of a multilateral well.

After the hardening of the grouting mixture is completed, the auxiliary branch pipe with cuffs is drilled in the upper part with a chisel.

Then, after the completion of the development of an additional new multilateral wellbore, the extracted landing unit is removed from the well and transferred to the enterprise operating the multilateral well. Then there is a repetition of work on preparing for drilling a new additional barrel, using similar nodes and technology.

A device for the construction of multilateral wells, consisting of separate nodes provides:

- reliability of fixing the deflecting wedge for opening the window in the column and sealing the mouth of the liner during the construction of each new additional multilateral wellbore, convenience in the primary and secondary use of individual nodes when opening the window in the column and repair work and increasing the technological capabilities of the device;

- minimum metal consumption of the device, the scarcity of the materials used;

- ease of manufacture and ease of use.

Claims (1)

A method of constructing multilateral wells, including opening a window in the casing of the primary wellbore and drilling a new additional wellbore to the design depth using a whipstock, lowering the liner with casing at the mouth of a new additional wellbore and sealing the mouth of the new additional wellbore, characterized in that the bottom of the casing of the primary wellbore is equipped with slots and the retrievable landing unit is planted on the slots of the primary casing of the wellbore, wherein the retrievable landing assembly, including the landing casing, is provided with internal slots at the top and the outer bottom, as well as an auxiliary wedge, which is installed on the upper end of the coupling of the landing casing, after which the installation interval is filled with a non-hardening viscous-plastic fluid with static shear stress satisfying the condition

, Where

- static shear stress of a viscoplastic fluid,  r is the radius of the sludge - rocks, metal chips deposited in the process of drilling an additional new trunk,

,

- respectively, the density of the sludge and viscous plastic fluid,

= 18 ÷ 50 - flow coefficient, the diverter wedge is equipped with slots in the lower part and the landing pad, the inclination angle of which is equal to the angle of inclination of the auxiliary wedge, and after drilling a new additional wellbore to the design depth, the deflector wedge is removed from the well; including a packer-cutter with a medium separator, containing a wedge having openings for the passage of the grouting mixture, and an auxiliary pipe with cuffs in the upper part, forcing grouting the mixture into the liner and flushing the well, after which the auxiliary pipe with cuffs in the upper part is drilled with a chisel and after the completion of the development of a new additional barrel, the landing unit is removed.

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