RU2109987C1 - Oil-well sucker-rod pump - Google Patents

Abstract

FIELD: oil industry; pumping out of oil from deep wells. SUBSTANCE: inner and outer threaded surfaces are made on pump members interconnected by threaded conjugations. Threaded surfaces are provided with conical hole and spherical projection with side recess. Value of radius of spherical projection is specified by relationship given in description of invention. EFFECT: enlarged operating capabilities. 3 dwg

Description

 The invention relates to oilfield equipment, in particular to the design of well sucker rod pumps for pumping oil from deep wells.

 A well-known sucker rod pump containing structural parts interconnected using threaded mates, and comprising a cylinder with a suction valve, a plunger with a heating valve, a rod and a lock securing the pump to the column of sucker rods [1].

 A well-known sucker-rod pump containing structural elements interconnected by means of threaded couplings, and comprising a cylinder with a suction valve, a plunger with a discharge valve, a rod with a rod adapter connecting the plunger to the column of pump rods, and the lock of the pump to the column [2].

 A disadvantage of the design of the well-known borehole sucker-rod pump is its low resource of operation, due to the impossibility of achieving, during the manufacture and assembly of exact mating of the pump structural elements by means of threaded joints used in this case. The threaded connections used in oil pumps, along with the fastening function, the main and traditional function for fastening threads, must also fulfill the function of accurately relocating a number of structural elements mating in series with each other. In this case, the exact relative position of the threaded parts connected in series with each other should be achieved due to the highly accurate manufacturing of threads, which are difficult to achieve by technological means, on which the base parts of the pump are based on the threads.

 Well sucker-rod pumps have overall restrictions on the diametric dimensions and do not have significant restrictions on the length of the product. A large number of pump parts mating on threaded surfaces form a lengthy product. With such a combination of pump parts, an accidental algebraic summation of base errors and relative positions of parts becomes inevitable. This ultimately leads to misalignment of the assembled parts, a violation of the most important structural radial clearances between the parts from the point of view of pump operability, an increase in their wear rate, a decrease in the pump's operating life, and a decrease in its efficiency.

 The invention solves the problem of increasing the service life of the pump by increasing the accuracy of mutual coupling (positioning) of structural elements.

 This is achieved by the fact that on the structural elements of the pump connected to the threaded surfaces, additional spherical conical joints are made, which increase the accuracy of the mutual basing of pump parts.

 The essence of the invention lies in the fact that in a known borehole sucker rod pump containing structural elements interconnected by means of threaded joints with internal and external threaded surfaces and including a cylinder with a suction valve, a plunger with a discharge valve, a rod with a rod adapter connecting the plunger to the column sucker rods, and a lock for attaching the pump to the column on a structural member having an external threaded surface, an additional spherical protrusion with a side undercut, and a structural member having a threaded inner surface that is conical hole, wherein the radius of the spherical protrusion is determined by calculation dependent parameter takes into account the particular pump mating parts.

 Figure 1 shows a General view of a downhole sucker rod pump (left - lower part of the pump, right - upper); figure 2 - the relative position of the mating structural elements of the pump; figure 3 - scheme for determining the structural parameters of the mating surfaces.

 The downhole sucker rod pump contains structural elements interconnected by means of threaded joints. The downhole sucker rod pump consists of a solid cylinder 1 with a suction valve 2, from a plunger 3 with a discharge valve 4, and from a rod 5 with a rod adapter 6 connecting the plunger 3 of the pump with a string of pump rods (not shown). In the column, the pump is mounted using a lock 7, one of the structural varieties of which are shown in figure 1.

 The structural elements of the pump are interconnected by means of threaded mates. The mating surfaces of the pump parts have internal 8 and external 9 threaded surfaces, a conical hole 10 with an annular end 11 and a spherical protrusion 12 with a side undercut 13 and an annular end 14.

где
γ - угол образующей конуса конического отверстия, град;
α - угол поворота осей сопрягаемых элементов конструкции, град.Based on the conditions of increasing the accuracy of mutual basing of pump structural elements and improving the accuracy of their positioning according to the alignment of parts in the assembly unit, the radius of the outer spherical surface according to the construction (Fig. 3) is determined by the ratio
R = (D _av l + B • m - D _n • n) / 2, mm
Where
D _cf - the average diameter of the conical hole, mm;
B is the width of the spherical surface in the axial direction, mm;
D _n - the outer diameter of the mating element, mm;
l, n, m - substitution coefficients:

Where
γ is the angle of the generatrix of the cone of the conical hole, deg;
α is the angle of rotation of the axes of the mating structural elements, degrees.

 When connecting the structural elements of the pump, a threaded protrusion 9 of one of the mating elements is introduced into the threaded hole 8 of the other element. As a result of screwing the threaded protrusion into the hole, the outer spherical surface 12 comes into contact with the inner conical surface 10. Due to the fact that the contact of the mating surfaces 10 and 12 of the pump structural elements has taken place, further screwing of the elements is accompanied by elastic deformations of these surfaces. The presence of such contact with continued screwing and further elastic deformation of the surfaces of the mating elements of the pump leads to a new primary contact of other surfaces: an arbitrary portion of the surface of the annular end 14 with the mating portion of the surface of the annular end 11. A complete fit of the ends 11 and 14 at this stage of mating of the pump elements cannot yet due to the skew α of the axes of the elements, due to the inevitable technological error of their manufacture. However, with their subsequent screwing, the possibility of angular self-installation of the elements is ensured due to their conjugation along the inner conical surface 10 and the outer spherical surface 12. In this case, the inevitable distortions and misalignment of the axes of the pump structural elements are corrected until the ring ends 11 and 14 are fully contacted. The creation of elastic deformations on the surfaces of the mating elements of the pump makes it possible to use it as a prestressed structure.

,
где
d - внутренний диаметр резьбы резьбового выступа, мм;
L - длина резьбового выступа, мм;
D_н - наружный диаметр сопрягаемого элемента, мм;
Y - максимальное перемещение конца резьбового выступа, мм;
[σ_р] - предел прочности на растяжение материала сопрягаемого элемента конструкции насоса, МПа;
E - модуль продольной упругости материала сопрягаемого элемента, МПа.The threaded protrusion 9 of the pump structural member has the necessary ability to elastically deform during assembly with the reciprocal structural member. This is achieved by increasing the length of the console of the threaded protrusion 9 due to the execution on it of a side recess 13, which increases its compliance. The length of the threaded protrusion is related to its diameter by the ratio

,
Where
d is the inner diameter of the thread of the threaded protrusion, mm;
L is the length of the threaded protrusion, mm;
D _n - the outer diameter of the mating element, mm;
Y is the maximum movement of the end of the threaded protrusion, mm;
[σ _p ] is the tensile strength of the material of the mating element of the pump design, MPa;
E is the modulus of longitudinal elasticity of the material of the mating element, MPa.

 All structural elements of the pump can be interfaced in the same way.

 The downhole sucker rod pump is driven by a rocking machine. When the plunger 3 moves upward, a vacuum is created under it, the suction valve 2 opens under pressure of the liquid column in the annulus and the formation fluid enters the cavity of the pump cylinder 1. At this time, the discharge valve 4 on the plunger 3 is closed by the pressure of the liquid column located above it.

 When the plunger 3 moves down, the suction valve 2 closes, and the pressure in the cylinder cavity increases. In this case, the discharge valve 4 on the plunger 3 is opened, and the fluid located in the cavity of the cylinder 1 flows from the subplunger zone of the cylinder into the supraplunger. With the continuous operation of the plunger 3 in the cylinder 1, the processes of suction and discharge occur simultaneously and the pumped liquid flows through the tubing string to the surface.

 Using the design of the described sucker rod pump allows to eliminate the disadvantages caused by the inaccuracy of mutual basing and mating of parts due to the introduction of new additional surfaces - spherical conical mates to the design of mating parts, which increase the accuracy of mutual basing of pump parts. At the same time, the use of spherical conical joints allows sealing the joints of pump parts without the use of additional sealing means.

Claims (1)

A downhole sucker rod pump containing structural members interconnected by threaded couplings with internal and external threaded surfaces, including a cylinder with a suction valve, a plunger with a discharge valve, a rod with a stem adapter connecting the plunger to the column of sucker rods, and a pump mounting lock to a column, characterized in that on the structural member having an external threaded surface, a spherical protrusion with a side recess is additionally made, and on the structural member having Cored oil threaded surface, - a conical hole, wherein the radius of the spherical protrusion is determined by the relation
R = (D _{with p} • l + B • m - D _n • n) / 2,
where D _{with p} is the average diameter of the conical hole, mm;
B is the width of the spherical surface in the axial direction, mm;
D _n - the outer diameter of the mating element, mm;
wildcard coefficients:
l = (1-tgαtgγ) / cosα ;,
m = (1-tgαtg ² γ) / cosα ;,
n = (tgαtgγ) / cosα ;,
where γ is the angle of the generatrix of the cone of the conical hole, deg .;
α is the angle of rotation of the axes of the mating structural elements, degrees.

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