RU2320843C1 - Method for well with remote bottom construction - Google Patents

Abstract

FIELD: well drilling, particularly to drill inclined, near-horizontal and horizontal wells having bottoms spaced tens of kilometers therefrom and located under water conservation zone, river or shelf water.

SUBSTANCE: method involves forming prospect-hole spaced admissible distance from shore line; installing curvilinear part of horizontal conductor in design azimuth in prospect-hole; drilling horizontal well bore from prospect-hole by trench or thenchless method so that the horizontal well bore is located near ground surface and/or water area bottom; pulling through or laying welded large-diameter pipe strings into horizontal well bore to provide horizontal conductor, wherein the pipe string terminates in end curved downwards through zenith angle and used as additional pipeline for produced liquid and/or gaseous hydrocarbon transportation. Well is drilled from under horizontal conductor bottom with the use of drilling string assembly. Drilling string is installed in horizontal conductor and includes initial drilling string section, central one and terminal one. Initial and central drilling string sections are rigidly connected with each other and include central pipe coaxial relatively inner pipe. Central section additionally has outer pipe. End section comprises inner pipe and mud pipe telescopically connected with outer pipe of central section. Hole annuity defined by mud pipe of end section and horizontal conductor, outer pipe of central section and horizontal conductor and central pipe of initial section and horizontal conductor, is filled with liquid having predetermined density. Hole annuity between central and outer pipes of central sections is filled with air or gas. Drilling string assembly is prepared at well head from drilling rig in the following order: rock-cutting tool, bottomhole drive, telemetering system, end, central and initial drilling string assembly sections.

EFFECT: possibility to create horizontal well bore of maximal possible length in rock having any strength, including unstable and liable to keyseating and caving one due to minimized load necessary to overcome drilling string movement resistance force.

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Description

The invention relates to the field of drilling directional, subhorizontal, horizontal wells, mainly with a bottom distance of tens of kilometers under the water protection zone on land, river and shelf, including in the Arctic shelf.

A known method of constructing wells with a horizontal direction by means of a drill pipe string consisting of separate drill pipes with drill joints at the ends interconnected (Handbook of a drilling engineer edited by V.I. Mishchevich, N. A. Sidorov. - M. 1973. Subsoil, Volume 1. S.518).

The disadvantage of this method is the large weight of the drill pipe string, including due to the presence of tool joints, and since its weight is directed to the bottom wall of the borehole or horizontal borehole, frictional forces arise that impede the movement of the drilling tool, which limits the length of the horizontal section of the well.

Of the known methods, the closest to the proposed one is a method of drilling a well to remote fields located under the water area, which consists in creating a mine direction in the immediate vicinity of the coastline and drilling a subhorizontal shaft by drilling from a horizontally installed drilling rig during horizontal assembly of a drill pipe string (see US patent No. 3840079, E21B 7/04, 1974).

The disadvantage of this method is that the construction of the entire length of the wellbore, including the subhorizontal section, is carried out by the traditional method of rock destruction, which leads to a significant investment of time and money, while increasing the likelihood of complications and accidents. In addition, the distance to the bottom with this method is limited by the capacity of the drilling rig and the strength of the drill pipe string.

The objective of the invention is to provide a method for constructing a well with a distant bottom hole, ensuring the formation of a horizontal wellbore of the maximum permissible length in rocks of any strength, including unstable, prone to trench and collapse formation, by minimizing the load on overcoming the resistance to movement of the drill pipe string.

The problem is achieved in that the method of constructing a well with a remote bottom hole, mainly when developing oil and gas fields located under the water protection zone and / or the water area of the Arctic shelf, consists in constructing a pit at an acceptable distance from the shoreline with installing a curved section of the beginning of the horizontal direction in design azimuth, followed by partially or completely trenching and / or trenchless methods in the immediate vicinity of the earth’s surface and / or the bottom of the water area of the horizontal section of the wellbore, with the dragging and / or laying of large diameter pipes pre-welded in a whip, forming a horizontal direction, ending with a bent downward to a predetermined zenith angle, performing the additional function of a pipeline for transporting produced liquid and / or gaseous hydrocarbons moreover, the process of drilling a well from under the shoe of the horizontal direction is carried out by means of the layout of the drill string, installed in horizontal direction, consisting of communicating with each other by means of an internal pipe with a flushing channel of the initial section of the drill string, the central section of the drill string, mounted with the possibility of buoyancy and regulation of its position in the horizontal direction and the end section of the drill string, based on the shoe horizontal direction, while the initial and the central section are rigidly interconnected and include a middle pipe coaxially mounted relative to the inner pipe between the annular flushing channels for backwashing, the central section additionally contains between the horizontal direction and the middle pipe an outer pipe with the formation between the latter of the annular space, the end section includes an inner pipe and an external slurry pipe telescopically connected to the outer pipe of the central section, and the annular space formed by a slurry pipe of the end section and a horizontal direction, an outer pipe of the central section and a horizontal the board and the middle pipe of the initial section and the horizontal direction, fill with fluid with a given density, and the annular space between the middle and outer pipes of the central section is filled with air or gas, while the assembly of the drill string is carried out at the mouth of the drilling rig in the following sequence: rock cutting tool, downhole motor, telemetry system, end L _KC , central L _CA and the initial section L _HCmin drill string layout, the lengths of which are determined based on the following expressions:

L _COP ≥L _SLE + L _IGN-2 ,

where: L _KC is the length of the end section of the drill string from the shoe of the horizontal direction to the end of the central section of the drill string, L _SLE is the maximum possible length of the wellbore from the shoe of the horizontal direction to the design bottom in the reservoir, L _IGN-2 is the length of the curved end of the horizontal direction ;

L _CA = L _K -L _IGN-1 -L _IGN-2 -2 · L _SLE ,

where: L _CS - the length of the Central section of the drill string, L _K - the length of the layout of the drill string from the mouth to the design bottom in the reservoir, L _IGN-1 - the length of the curved beginning of the horizontal direction;

L _HCmin ≥L _IGN-1 , and the maximum length: L _HCmax = L _IGN-1 + L _SLE .

The invention is illustrated by drawings. Figure 1 shows the layout of the drill string in the well with a horizontal direction; figure 2 shows a vertical section along aa of the initial section; figure 3 shows a vertical section along BB of the Central section; figure 4 shows a vertical section along BB of the final section; figure 5 shows a section of the Central section of the drill string and the diagram of the distribution of the forces acting on it.

In Figs. 1-5, the following designations are adopted: coastline - 1, pit - 2, curved section 3 of the beginning of the horizontal direction 4, the surface of the earth - 5, the water area - 6, the end 7 of the horizontal direction 4, the shoe of the horizontal direction - 8, the inner pipe - 9, direct flushing channel - 10, the initial section 11 of the drill string assembly, the central section 12 of the drill string assembly (Archimedean string), the end section of the drill string assembly - 13, the middle pipe - 14, the annular flushing channel for backwash - 15, the outer pipe - 16, annular space - 17 filled with gas, slurry pipe - 18, annular space - 19, filled with liquid, stuffing box packing - 20, drilling rig - 21, mouth - 22, rock cutting tool - 23, downhole motor - 24, telemetric system - 25, reservoir - 26.

The proposed method of constructing a well with a horizontal direction is as follows.

After the construction of a pit 2 at an acceptable distance from the water protection or shoreline 1, a curved section 3 of the beginning of the horizontal direction 4 is installed in it in the design azimuth, partially or completely, laid in a trench and / or trenchless manner in close proximity to the surface of the earth 5 and / or the bottom of the water area 6, with pulling and / or laying pre-welded pipes of large diameter horizontal direction 4 ending in a horizontal angle curved downward to a predetermined zenith angle α with the end 7 horizontal direction 4 and subsequently acting as a pipeline for transporting produced liquid and / or gaseous hydrocarbons. Moreover, the drilling process from under the shoe 8 of the horizontal direction 4 is carried out by means of a drill string arrangement installed in the horizontal direction 4, consisting of interconnected by means of the inner pipe 9 with the flushing channel 10 of the initial section 11 of the drill string, the central section (Archimedean string) 12 installed with the possibility of buoyancy and regulation of its position relative to the upper or lower walls of the horizontal direction 4, and the end section 13 of the drill string, support extending to the shoe 8 of horizontal direction 4. The initial section 11 is rigidly connected to the beginning of the central section (Archimedean column) 12, while both of these sections include a middle pipe 14 coaxially mounted relative to the inner pipe 9 with the formation of an annular washing channel 15 between them for backwashing and removal of sludge from the bottom of the well. The central section 12 further comprises an outer pipe 16 with the formation of an annular space 17 with the middle pipe 14. The end section 13 includes an inner pipe 9 and a slurry pipe 18 telescopically connected to the outer pipe 16. The slurry pipe 18 provides backwash and removal of slurry from the bottom while changing the length L _KS - end section 13. The annular space 19 formed by a slurry pipe 18 of the end section 13 and the horizontal direction 4, the outer pipe 16 of the Archimedean column 12 and the horizontal direction 4 and the middle her pipe 14 of the initial section 11 and the horizontal direction 4, is filled with liquid with a given density to ensure buoyancy of the Archimedean column 12. The annular space 17 between the middle 14 and the outer 16 pipes of the Archimedean column 12 is filled with air or gas. To ensure the tightness of the connection between the beginning of the slurry pipe 18 and the end of the outer pipe 16 of the Archimedean column 12, stuffing box seals 20 are installed.

In this case, the assembly of the drill string assembly is carried out from the drilling rig 21 at the wellhead 22 in the following sequence: rock cutting tool 23, downhole motor 24 (cannot be installed during rotary drilling), telemetry system 25, end section 13 of the drill string, the length of which is determined by the following expression:

L _COP ≥L _SLE + L _IGN-2 ,

where L _KS is the length of the end section 13 of the drill string from the shoe 8 of the horizontal direction 4 to the end of the Archimedean string 12, L _SCR is the maximum possible length of the wellbore from the shoe 8 of the horizontal direction 4 to the design bottom in the reservoir 26, L _IGN-2 is the length curved end 7 of the horizontal direction 4;

Archimedean column 12, the length of which is determined by the following expression:

L _CA = L _K -L _IGN-1 -L _IGN-2 -2 · L _SLE ,

where L _CS - the length of the Archimedean string 12, L _K - the length of the layout of the drill string from the mouth 22 to the design bottom in the reservoir 26, L _IGN-1 - the length of the curved beginning 3 of the horizontal direction 4;

the initial section of the drill string, through which build up the layout of the drill string from the mouth 22, the minimum length of which is: L _HCmin ≥L _IGN-1 , and the maximum length: L _HCmax = L _IGN-1 + L _SLE .

The following is a specific calculation example of the implementation of the proposed method.

Archimedean column 12 is the most rigid section of the drill string and to prevent the appearance of additional bending forces and, accordingly, resistance forces during its movement, the following restrictions are imposed during its assembly and operation: the Archimedean column should not be located in the curved beginning L of _IGN-1 and the curved end of L _{IGN-2 of} horizontal direction 4. For example, at L _K = 50,000 m, L _IGN-1 = 1000 m, L _IGN-2 = 500 m and L _SLE = 3000 m:

- the length of the Archimedean column is

L _CS = L _K -L _IGN-1 -L _IGN-2 -2 · L _SCR = 50000-1000-500-6000 = 42500 m;

- the length of the end section of the drill string is greater than or equal to

L _COP ≥L _CKB + L _IGN-2 ≥3000 + 500≥3500 m;

- the length of the initial section of the drill string before the deepening of the borehole below the horizontal shoe L _HCmin = L _IGN-1 = 1000 m, and after opening the reservoir and reaching the maximum well depth L _HCmax = L _IGN-1 + L _CKB = 1000 + 3000 = 4000 m.

When constructing a well with a horizontal direction of 4, more than 80-90% of the length of the drill string assembly is represented by an Archimedean string 12 with a direct flushing channel 10 filled with cleaned drilling fluid with a density of ρ _r , an annular flushing channel 15, through which a flushing fluid with a density of ρ _rSL with cuttings is discharged and annular space 17 filled with gas or air, ensuring buoyancy of the Archimedean column 12 in the horizontal direction 4, annular space 19 of which is densely filled with liquid Stu ρ _stretch.

Conditions location Archimedean column 12 in the horizontal direction 4 - equality reduced weight of the three pipes 9, 14 and 16 force displacement Archimedean column 12 immersed in liquid density ρ _drawing.

The force of displacement in this case will be equal to:

Where

D _ЦСнар - outer diameter of the outer pipe 16, m;

_stretching ρ - density of the fluid in the annulus 19, kg / m ^3;

L _ЦС - length of the central section 12, m.

The weight of the design of the Central section in working condition is equal to:

where F _i - the specific gravity of the medium (filling fluid, column material), N / m

We substitute (3) and (5) in the condition of buoyancy of the column:

F = F _{stretch cord} then

The buoyancy of the Archimedean column is governed by the density of the liquid ρ _outward . To calculate this we express the density ρ of the _drawing (3):

Thus, the buoyancy of the columns in the liquid depends on the material and the geometric dimensions of the columns and the liquids with which the columns are in contact. By changing these parameters, you can adjust the position of the Archimedean column 12 within the horizontal direction 4.

During the descent of the string into the well with a horizontal direction 4 several tens of kilometers long, it is necessary to evaluate the load of overcoming the resistance forces to the movement of the drill string assembly.

For the central section

Provided that the column is in a floating state (in the absence of contact of the column with the walls of the horizontal direction), it is only necessary to evaluate the friction force of the surfaces that make up the annular space with the liquid, and to evaluate the pressure required to move the liquid in the annular space, i.e.

where Q is the flow rate of the fluid displaced from the well, m ³ / s;

L is the length of the well along the bore (the length of the column), m;

ρ _rShL - fluid density in the annular space, kg / m ³ ;

η is the viscosity of the liquid, Pa · s;

τ ₀ - ultimate shear stress, dPa;

D _inner - outer diameter of the inner column, m;

D _cf - diameter of the middle column, m

When lowering the column with the shoe closed, the flow rate of the fluid displaced from the well is calculated by the formula:

перепишем (6):At

we rewrite (6):

where U _sp - the descent speed of the column, m / s.

Substituting (7) into (5), we obtain a certain value of ΔР, overcoming of which in the region of the shoe of the descent column is necessary for the movement of the column at a speed of U _c .

Knowing the geometry of the column, we express the pressure acting from the side of the shoe along the line of movement of the column during its descent:

Thus, the axial load required for the movement of the central section is expressed as

.where ΔP = f (Q, L, ρ _drawing, η, τ _0, D _NAR, D _{for example)} with

.

Let us estimate the force required for lifting a pipe string 42500 m long in a tangential section with α = 80 ° and a friction coefficient μ = 0.4 (metal by rock).

The normal component of the weight of the column will be equal to:

The normal component of the friction force

Axial force projected on normal

We calculate the density of the liquid in which the buoyancy of concentrically arranged steel _{pipes is ensured} (ρ _METvnut = ρ _METav = ρ _nar = 7850 kg / m ³ ) of pipes with D _inner = 127 mm = 0.127 m with a wall thickness Δ = 7 mm = 0.007 m, D _cf = 194 mm = 0.194 m with Δ = 9 mm = 0.009 m and D _nar = 504 mm = 0.504 m with Δ = 10 mm = 0.01 m. The inner column is filled with cleaned drilling fluid (ρ _p = 1100 kg / m ³ ) , and the inner annular space of the drilling _fluid with sludge (ρ _rShL = 1120 kg / m ³ ). It is permissible to neglect the weight of air in the outer annular space:

Conclusion: With the given parameters, the Archimedean column retains its buoyancy in weakly mineralized water.

We calculate the flow rate of the liquid emanating during the descent of the column. In this case, we assume that the column with a diameter of D _drug = 504 mm = 0.504 m moves uniformly with a speed of U _sp = 0.2 m / s, then

We calculate ΔP = f (Q, L, ρ _MY, η, τ _0, D _NAR, D _{for example)} with the following initial data: Q = 598 l / sec; L _CA = 42500 m; _stretching ρ = 1041 kg / m ^3; η = 0.023 Pa · s; τ ₀ = 10 dPa; D _nar = 504 mm; D _e.g. = 1000 mm.

According to the method described in (Leonov E.G. Improving the technology of drilling on the area; textbook, GANG named after IM Gubkin. M .; 1993),

? P = f (Q, L, ρ _drawing, η, τ _0, D _NAR, D _voltage) = 4.16 MPa.

We calculate the axial load necessary for the movement of the specified pipe string with a speed U _c = 3 m / s:

For a numerical evaluation of the effectiveness of the proposed method of well construction in comparison with the prototype, we calculate the force required to lift the pipe string SBT 140 × 9 with a length of 42500 m in a tangential section with α = 80 ° and μ = 0.4 (metal by rock):

F _axes ^" = (0.4 · 0.98 + 0.17) · m · g = 4.55 · 10 ⁶ N = 4550 kN.

Conclusion: The axial load on the hook when lifting the pipe string SBT 140 × 9 with a length of 42500 m in the open trunk in a tangential section with α = 80 ° and μ = 0.4 is more than 5 times higher than the load when lifting the Archimedean column 12.

The proposed method of constructing a well in comparison with traditional drilling many times reduces the amount of work associated with the formation of a wellbore in unstable and solid rocks, significantly reducing the load on overcoming the resistance forces to the movement of the drill pipe string, which can significantly reduce the load capacity of the drilling rig to provide an opening productive layer, remote tens of kilometers from the mouth.

Claims (1)

A method of constructing a well with a remote bottom hole, mainly during the development of oil and gas fields located under the water protection zone and / or the water area of the Arctic shelf, which consists in constructing a pit at an acceptable distance from the shoreline with the installation of a curved section in it that begins the horizontal direction in the design azimuth, followed by wiring partially or completely with a trench and / or trenchless method in the immediate vicinity of the earth’s surface and / or the bottom of the horizontal water area the wellbore tissue, with the pulling and / or laying in it of large diameter pre-welded pipes in a whip, forming a horizontal direction, ending with a bent downward to a predetermined zenith angle, performing an additional function of the pipeline for transporting produced liquid and / or gaseous hydrocarbons, the drilling process wells from under the shoe of the horizontal direction are carried out by means of the layout of the drill string installed in the horizontal direction, consisting from the interconnected by means of an inner pipe with a flushing channel of the initial section of the drill string, the Central section of the drill string, installed with the possibility of buoyancy and regulation of its position in the horizontal direction, and the end section of the drill string, based on the shoe horizontal direction, while the initial and central sections are rigidly interconnected and include a middle pipe coaxially mounted relative to the inner pipe with the formation of an annular flushing between them channel for backwashing, the Central section additionally contains between the horizontal direction and the middle pipe an outer pipe with the formation between the last annular space, the end section includes an inner pipe and an external sludge pipe telescopically connected to the outer pipe of the Central section, and the annular space formed by a slurry pipe the end section and the horizontal direction, the outer tube of the central section and the horizontal direction and the middle pipe of the initial sections and horizontal direction, filled with fluid with a given density, and the annular space between the middle and outer pipes of the Central section is filled with air or gas, while the assembly of the drill string is carried out at the mouth of the rig in the following sequence: rock cutting tool, downhole motor, telemetry system , end L _КС , central L _ЦС and initial section L _{HCmin of the} drill string assembly, the lengths of which are determined based on the following expressions: L _ks ≥L _SLE + L _ign-2 , where L _KS - the length of the end section of the drill string from the shoe horizontal direction to the end of the Central section of the drill string; L _SLE - the maximum possible length of the wellbore from the shoe of the horizontal direction to the design bottom in the reservoir; L _IGN-2 - the length of the curved end of the horizontal direction; L _CA = L _K -L _IGN-1 -L _IGN-2 -2 · L _SLE , where L _cs - the length of the Central section of the drill string; L _K - the length of the layout of the drill string from the mouth to the design bottom in the reservoir; L _IGN-1 - the length of the curved beginning of the horizontal direction; L _{HCmin ≥L} Ign _-1 , and the maximum length: L _HCmax = L _IGN-1 + L _SLE .

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