RU2524238C2 - Borehole helical motor - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: invention relates to borehole helical motors. This motor consists of two, tope and bottom sections. Each of the latter comprises screw working members built around multistart gerotor mechanism with internal cycloidal engagement. Spindle with output shaft runs in axial and radial bearings. Hinge joint of rotor helical working members with output shaft and fluid passages. Helical working members stator of top section is fixed at drilling string. Bottom section output shaft is coupled with rock cutting tool. Top section output shaft is rigidly coupled with bottom section helical working member stator fitted in adapter bore coupling fixed bodies of spindles and concentrically spinning in adapter radial bearing.

EFFECT: enhanced power characteristics, particularly, higher output shaft rpm.

2 cl, 5 dwg

Description

The invention relates to the oil and gas industry, and in particular to equipment and technology for drilling oil and gas wells using hydraulic downhole motors.

Known downhole motors (VZD) for driving a rock cutting tool during drilling and workover [Baldenko DF, Baldenko FD, Gnoev AN Single-screw hydraulic machines, t.2. - M.: IRC Gazprom, 2007]. The working body of the VZD is a helical gear pair with internal cycloidal gearing, consisting of a metal rotor and a stator with an elastic lining, between which helical surfaces work chambers are formed.

During the operation of the VZD, the rotor, running around inside the lining of the fixed stator, performs a planetary motion (rotates relative to its own axis, which rotates around the stationary axis of the motor in a portable motion), and the output shaft connected to the rotor by means of a swivel joint performs concentric rotation in the radial bearings of the spindle section . The angular velocity of the rotor axis in portable motion is z ₂ times greater than the angular velocity of the rotor in absolute motion, which corresponds to the angular velocity of the output shaft and rock cutting tool, which, due to the action of inertial centrifugal forces, determines in many respects the permissible high-speed reverse-flow mode and limits the speed of multi-stroke high-torque engines (z ₂ > 5) at the level of 100-200 rpm.

At the same time, in modern drilling technologies in certain geological conditions, an increase in the efficiency of well construction can be achieved only through the use of moment-intensive PDC bits with polycrystalline or carbide inserts, for the rational development of which it is necessary to provide medium- and high-speed modes with a rotation speed of at least 300 rpm

When using the VZD of the standard design, the indicated high-speed mode can be achieved only by reducing the engine displacement by switching to screw pairs with a lower set-up. However, in this case, the required decrease in the working volume is accompanied by a decrease in the torque of the VZD, which does not correspond to the characteristics of PDC bits. In this regard, in order to create a VZD that simultaneously meets the requirements of a high speed and high torque, it is necessary to significantly increase the pressure drop in the working bodies, i.e. use elongated working bodies in order to ensure the necessary number of contact lines separating the inlet and outlet of the hydraulic machine, selected on the condition of the permissible inter-turn differential pressure between the chambers of the airway. The disadvantage of this technical solution is the increase in the axial dimension of the VZD and the complexity of the manufacturing technology of long working bodies, which negatively affects the technical and economic performance of the VZD.

Another possible technical solution in the development of a high-speed high-torque VZD is the transition to a non-standard kinematic scheme of its working bodies with additional mobility of one of the elements (rotor or stator), in which none of the elements of the screw pair remains stationary during the working process.

The closest technical solution adopted for the prototype is a VZD scheme with a nutting (performing a portable movement) rotor and a rotating stator, in which the bit is connected to an external element of the working bodies (stator) that performs concentric rotation, the teeth of which are rolled around an internal element (rotor), pivotally fixed at the end of the drill string [Tiraspolsky W. Hydraulic downhole drilling motors. Editions Technip, Paris, 1985].

The disadvantage of this scheme in relation to the technical problem under consideration is the relatively low speed of the output shaft (stator), which does not provide the necessary energy characteristics of the engine when drilling with PDC bits.

The objective of the proposed invention, which is a hydraulic downhole motor designed for high-speed well drilling technologies using PDC bits, is to expand the functionality of the PDM by implementing a kinematic scheme with additional mobility of the working bodies, which provides the possibility of increasing the rotational speed of the output shaft of the PDM while maintaining the required torque and permissible level of inertial loads.

The task is carried out due to the fact that the VZD is made according to the scheme of a two-section engine, each section (upper and lower) of which includes screw working bodies based on a multi-start gerotor mechanism with internal cycloidal engagement, a spindle with an output shaft mounted on axial and radial the bearings, the hinge connection of the rotor of the screw working bodies with the output shaft and channels for the passage of fluid, and the stator of the screw working bodies of the upper section is fixedly mounted on the column drill pipes, the output shaft of the lower section is connected to the rock cutting tool, and the output shaft of the upper section is connected via a rigid connection to the stator of the screw working bodies of the lower section, which is installed with a clearance in the bore of the sub connecting the stationary housings of the spindles of the sections and making concentric rotation in the radial bearings of the connecting sub, which allows for additional mobility of the rotor of the lower section, which is meshed with the stator of the lower section and makes the plan Container traffic, and thereby realize a high speed bit mining regime.

The principal kinematic feature of the proposed scheme is that the angle of rotation of the rotor in a portable motion does not significantly exceed the angle of rotation of the rotor in absolute motion, which provides an advantage with respect to the action of inertial forces and permissible speed.

To implement the mode of concentric rotation of the rotor of the lower section around its own axis, the working volumes of the screw working bodies of the upper and lower sections are assigned in accordance with the kinematic ratio of the working bodies of the lower section.

Figure 1 presents a General view of the inventive downhole motor, figure 2 shows the cross-section of the working bodies of the sections of the VZD in the case of their identical geometry, figure 3 - similar cross-sections in the case of different geometry of the working bodies of the upper and lower sections, in Fig .4 shows the change in the relative position of the profiles of the rotor and stator of the lower section for one working cycle of the gerotor mechanism with a kinematic ratio of 3: 4, and Fig. 5 shows the positions of the profiles of the rotor and stator for a special kinematic case when the moving position of the center of the rotor. For ease of perception of the kinematics of the profiles, the fixed points of the rotor are marked by large dots in FIGS. 4 and 5. The current position of the camera’s area, shading from zero to its maximum value and shrinking to zero again, is shaded in black.

The downhole screw motor with additional mobility is a two-section hydraulic motor, each section of which includes screw working bodies (2, 3 and 11, 12) based on a multi-start gerotor mechanism with internal cycloidal engagement (kinematic pair “metal rotor - stator with elastic lining »), A spindle with an output shaft (8 and 18) mounted on the axial (7 and 17) and radial (6 and 16) bearings, a hinge assembly (4 and 14) for connecting the rotor to the output shaft and channels for the passage of fluid (a, b), moreover, hnyaya section is arranged according to the scheme of the planetary train (fixed stator), while the lower section - of the differential mechanism scheme.

The stator 2 of the upper section is fixedly mounted on the drill pipe string 1, and the output shaft 18 of the lower section is connected to the rock cutting tool 19. The output shaft 8 of the upper section is connected by a rigid connection to the stator 11 of the lower section, which is placed with a gap in the bore of the sub 10 connecting the fixed housings 5 and 15 of the spindles of the sections, and is installed in the radial support 13 for the possibility of the rotational movement of the stator 11. To seal the output shaft 18 of the engine from pressure drop in The edges of the lower section in the bore of the connecting sub 10 can be installed end seal 9 or a sealing device of another type.

The device operates as follows (figure 1). When the drilling fluid is supplied through the hydraulic channel of the drill pipe 1 to the upper section of the working bodies, a working cycle is performed, in which the rotor 3 performs a planetary motion, rolling around the helical teeth of the fixed stator 2 with an eccentricity e _в equal to the center distance of the screw gerotor mechanism of the upper section. The rotation of the upper rotor 3 through the swivel joint 4 is transmitted to the output shaft 8 of the upper section installed in the radial 6 and axial 7 spindle bearings, which, in turn, drives the stator 11 of the lower section, which performs concentric rotation inside the sub 10 in the radial support 13, which provides additional mobility of the working bodies of the lower section, leading the rock cutting tool 19. When the stator 11 rotates, the rotor 12 of the lower section conjugated with it performs a planetary motion, in which the rotor rotates tsya around its own axis and revolves around the axis in the opposite direction of the movable stator shaft 11 with an eccentricity e _n screw gerotor mechanism for the lower section. The rotation of the lower rotor 12 through the swivel joint 14 is transmitted to the output shaft 18 of the lower section mounted in the radial 16 and axial 17 of the spindle bearings.

As a result, the output shaft of the lower section associated with the rock cutting tool, for example, with a PDC bit, rotates with a frequency depending on the ratio of the working volume of the screw pairs of the upper (V _in ) and lower (V _n ) sections (Fig. 2), as well as the flow rate Q drilling mud.

To carry out the rotation of the rotors of the upper and lower sections in one direction and thereby add the angular velocities on the output shaft of the VZD, the working bodies of the sections must have the same direction of screw cuts. The length of the working bodies must correspond to a given torque and is assigned depending on the permissible inter-turn differential pressure.

In the general case, excluding volumetric losses, the rotational speed of the output shaft of the VZD or the absolute rotational frequency of the rotor of the lower section

$$\text{n}={\text{n}}_{\text{at}}+{\text{n}}_{\text{rel}\text{.н}},\text{(one)}$$

where n _in - the frequency of rotation of the output shaft of the upper section, n _in = Q / V _in ;

n _rel. n is the relative rotational speed of the rotor of the lower section, n _rel. n = Q / V _n .

Thus, the rotational speed of the output shaft of the VZD can be represented as a function of the rotational speed of the rotor of the upper section and the ratio of the working volumes of the screw pairs of the sections:

$$n=\left(\mathrm{one}+\frac{V_{\mathrm{at}}}{V_n}\right)n_{\mathrm{at}}.\text{(2)}$$

The kinematic indicator characterizing the workflow of the IDR with additional mobility is a multiplier equal to the ratio of the frequencies of rotation of the output shaft and the rotor of the upper section:

$$k=\frac{n}{n_{\mathrm{at}}}.\text{(3)}$$

Taking into account expression (2), the multiplication coefficient and the ratio of the working volumes of screw pairs are related by the following dependence:

$$k=\mathrm{one}+\frac{V_{\mathrm{at}}}{V_n}.\text{(four)}$$

In the particular case, when the working bodies of the upper and lower sections have the same working volumes (V _n = V _in ), which can be achieved by using identical screw pairs (Fig. 3) with the same kinematic ratio, eccentricity and pitch of the screw surfaces, the output shaft speed SZD

$$n=2n_{\text{at}};\text{k}=\text{2}\text{. (5)}$$

Thus, when using the same screw pairs in the considered circuit, the frequency of rotation of the output shaft doubles.

For any kinematic VZD scheme with additional mobility (stator or rotor), the cycle of the working process, during which the fluid volume equal to the volume of the working chambers passes through the working bodies with the number of stator and rotor strokes z ₁ and z ₂ , respectively, is performed when the rotor rotates in absolute corner movement

$$\Delta \varphi =\frac{2\mathrm{<figure-callout\; id="2"\; label="\pi \; z"\; filenames="00000017.png,00000018.png"\; state="\{\{state\}\}">\pi \; </figure-callout>}}{z_{}}+{\varphi }_{d\mathrm{about}P}=\frac{k}{k-\mathrm{one}}\cdot \frac{2\mathrm{<figure-callout\; id="2"\; label="\pi \; z"\; filenames="00000017.png,00000018.png"\; state="\{\{state\}\}">\pi \; </figure-callout>}}{z_{}},\text{(6)}$$

where φ _add - rotation angle due to additional rotation, φ _add = 2πn _in t (t is the time corresponding to a relative rotation angle of 2π / z ₂ ).

Those. the multiplicity of the action of the VZD with additional mobility, corresponding to the number of duty cycles per revolution of the output shaft

$$j=\frac{2\pi }{\Delta \varphi }=\frac{k-\mathrm{one}}{k}\cdot {\mathrm{<figure-callout\; id="2"\; label="z"\; filenames="00000017.png,00000018.png"\; state="\{\{state\}\}">z</figure-callout>}}_2.\text{(7)}$$

The characteristics and operability of the structural elements of the VZD with additional mobility largely depend on the ratio of the angular velocities of the absolute and figurative motion of the rotor.

In the General case, the angle of rotation of the center of the element (rotor or stator), making planetary motion in the VZD with additional mobility (respectively, the stator or rotor) is determined as follows

$${\varphi }_{PeR}=\pm z_{Pl\mathrm{but}n}{\varphi }_{\mathrm{about}tn}+{\varphi }_{d\mathrm{about}P},\text{(8)}$$

where z _plan is the number of visits of the planetary moving element of the working bodies (internal z ₂ or external z ₁ ); φ _Rel - the angle of rotation of the center in relative motion with respect to the concentric rotating element, rotated by an angle φ _add .

The plus sign refers to the case of a planetary moving stator, the minus sign refers to the case of a planetary moving rotor as in the present invention. Here, the rotation angle φ _add corresponds to the rotation angle of the output shaft of the upper section: φ _add = φ _in .

Insofar as

$${\varphi }_{\text{îòí}}=\varphi \text{-}{\varphi }_{d\mathrm{about}P}\text{, (9)}$$

then the ratio of the angular displacements of the portable and absolute motion takes the form

$$\frac{{\varphi }_{PeR}}{\varphi }=\frac{\pm z_{Pl\mathrm{but}n}+\frac{{\varphi }_{d\mathrm{about}P}}{{\varphi }_{\mathrm{about}tn}}}{\mathrm{one}+\frac{{\varphi }_{d\mathrm{about}P}}{{\varphi }_{\mathrm{about}tn}}}.\text{(10)}$$

Because

$$\frac{{\varphi }_{d\mathrm{about}P}}{{\varphi }_{\mathrm{about}tn}}=\frac{\mathrm{one}}{k-\mathrm{one}},\text{(eleven)}$$

then expression (10) finally takes the following form

$$\frac{{\varphi }_{PeR}}{\varphi }=\frac{\pm z_{Pl\mathrm{but}n}(k-\mathrm{one})+\mathrm{one}}{k}.\text{(12)}$$

For the invention under consideration with a planetary moving rotor (an internal element of the working bodies), the rotation angles of the rotor in a portable and absolute motion are related as

$$\frac{{\varphi }_{PeR}}{\varphi }=\frac{-z_2(k-\mathrm{one})+\mathrm{one}}{k}=-\left(z_2-\frac{z_{\mathrm{one}}}{k}\right).\text{(12a)}$$

Note that in this case, the rotor and the center of the rotor, as well as in the typical scheme of the VZD with a fixed stator, rotate in opposite directions. The principal kinematic feature of the proposed scheme is that the angle of rotation of the rotor in portable motion is always less than z ₂ times the angle of rotation of the rotor in absolute motion, which distinguishes the scheme with respect to the action of inertial forces and permissible speed compared to another possible scheme with planetary moving stator, as well as a variant of a typical VZD.

As an example, consider the kinetics of the VZD with additional mobility due to the rotation of the stator, taking the kinematic ratio of 3: 4 (z ₂ = 3; z ₁ = A) and the multiplier k = 2 (figure 4).

The multiplicity of the action of the screw mechanism j = 3/2, the cycle of the working process of this kinematic scheme is carried out when the rotor is rotated through an angle φ = Δφ = 2π / j = 240 °, while the stator rotates through an angle of 120 °, and the rotor axis is rotated through an angle φ _per = - (3-2) ∙ × 240 = -240 °.

When the condition is met

переносная скорость ротора становится равной нулю (φ_пер=0), т.е. в этом особом случае ротор совершает концентричное вращение вокруг собственной неподвижной оси (малая точка на фиг.5), что превращает рабочие органы нижней секции в бироторный механизм. Для соблюдения условия (13) необходимо, чтобы рабочие объемы винтовых пар верхней и нижней секций назначались в соответствии с кинематическим отношением рабочих органов нижней секции согласно зависимости $$k=z_{\mathrm{one}}/z_2\text{(13)}$$

portable rotor speed becomes equal to zero (φ _per = 0), i.e. in this special case, the rotor performs a concentric rotation around its own fixed axis (small point in Fig. 5), which turns the working bodies of the lower section into a birotor mechanism. To comply with condition (13), it is necessary that the working volumes of screw pairs of the upper and lower sections are assigned in accordance with the kinematic ratio of the working bodies of the lower section according to the dependence

$$\frac{V_{\mathrm{at}}}{V_n}=\frac{z_{\mathrm{one}}}{z_2}-\mathrm{one.}\text{(fourteen)}$$

According to the accepted classification, the proposed VZD arrangement relates to a variant of the kinematic scheme of a screw gerotor mechanism of type B-I, in which additional mobility is due to the rotation of the stator, and the output shaft associated with the rotor and the stator rotate at different angular velocities [Baldenko D.F. ., Baldenko F.D., Gnoev A.N. Single-screw hydraulic machines, t.1.- M .: IRC "Gazprom", 2005, p. 28].

The technical result and the economic effect of using the proposed device is achieved by increasing the efficiency of drilling with PDC bits due to the possibility of implementing optimal high-speed modes of their development.

Claims (2)

1. A downhole screw motor, consisting of two sections - upper and lower, each of which includes screw working bodies made on the basis of a multi-start gerotor mechanism with internal cycloidal engagement, a spindle with an output shaft mounted on axial and radial bearings, articulated the connection node of the rotor of the screw working bodies with the output shaft and channels for the passage of fluid, and the stator of the screw working bodies of the upper section is fixedly mounted on the drill pipe string, and the output shaft of the lower projections associated with the rock cutting tool, characterized in that the output shaft of the upper section is connected through a rigid connection to the stator screw bottom section working bodies mounted with clearance in the bore of the sub, which connects the fixed spindle housing sections, and committing concentric rotation in the radial bearing of the connecting sub. 2. The downhole screw motor according to claim 1, characterized in that the working volumes of the screw working bodies of the upper and lower sections are assigned in accordance with the kinematic ratio of the working bodies of the lower section according to the dependence
$$\frac{V_{\mathrm{at}}}{V_n}=\frac{z_{\mathrm{one}}}{z_2}-\mathrm{one,}$$

where V _in , V _n - the working volume of the upper and lower sections, respectively;
z ₁ , z ₂ - the number of visits, respectively, of the stator and rotor of the lower section.

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