A multi-stage tandem plunger pump for a pumping unit

Abstract

The application discloses a kind of pumping unit multistage series plug pump stroke loss reduction technologies, the plug pump includes: plug pump containing component, including by several pump barrel segments and several tubing segments alternately connected to form containing pipe cylinder;Plug pump pumping component, including pumping rod and several plugs set on pumping rod, each plug is set in corresponding one pump barrel segment;Each plug is configured with corresponding pump cylinder, and the liquid displacement of the plug and pump cylinder above is greater than the liquid displacement of the plug and pump cylinder below.The application is configured with plug for the pump barrel of multiple segments, and the liquid displacement of the plug and pump cylinder above is greater than the plug below, when executing liquid pumping action each time, the space released by the plug above is greater than the liquid volume pushed up by the plug below, forms gap in pipe below each plug above, so that the liquid load of the plug above does not act on the plug below, thereby, stroke loss is reduced, and liquid pumping efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of oil and gas extraction, and in particular to a multi-stage tandem plunger pump for oil pumping units. Background Technology

[0002] The current principle of pumping unit plunger pump fluid discharge is as follows: the pumping unit is installed on the surface, and a plunger pump is connected to the tubing and installed downhole, at depths ranging from hundreds to thousands of meters. The pumping unit's pumping head is connected to the plunger of the downhole plunger pump via the sucker rod. The pumping head on the surface moves up and down repeatedly, which in turn drives the downhole plunger to move up and down repeatedly via the sucker rod, thereby drawing the downhole fluid to the surface.

[0003] like Figure 1 As shown, the system includes tubing and a pump barrel. When the pumping unit's head moves upward, it drives the plunger upward via the sucker rod. The fixed valve of the plunger pump opens, and the traveling valve on the plunger closes. The plunger pushes the liquid upward, and at this time, the sucker rod bears the weight of the liquid column above the plunger's cross-sectional area. When the pumping unit's head moves downward, the fixed valve of the plunger pump closes, and the traveling valve on the plunger opens. At this time, the sucker rod does not bear the weight of the liquid column.

[0004] Since the sucker rod is a non-rigid object, when the plunger moves upward with the piston head, the hydraulic load will cause the sucker rod to elastically elongate. Due to this elongation, the upward stroke of the downhole plunger will be less than the upward stroke of the piston head on the surface. This elongation is called stroke loss, and its value is proportional to the weight of the hydraulic column and the length of the sucker rod, i.e.: λ = E * W l *L; where:

[0005] λ—Stroke loss of the sucker rod caused by liquid load;

[0006] E—a constant related to the material and area of ​​the sucker rod;

[0007] W l —The liquid load acting on the plunger;

[0008] L—Length of sucker rod;

[0009] The longer the sucker rod or the heavier the fluid load, the greater the stroke loss caused by the fluid load. For deep well pumping, this value can reach 50% or even higher of the surface stroke of the plunger, meaning that the actual stroke of the downhole plunger may only be half or even less of the surface stroke.

[0010] Therefore, how to reduce the stroke loss caused by the liquid gravity on the sucker rod in the oil pumping unit and improve the pumping efficiency is a technical problem that urgently needs to be solved. Summary of the Invention

[0011] The main objective of this invention is to provide a multi-stage series plunger pump for oil pumping units, which aims to solve the technical problems of large stroke loss and low pumping efficiency caused by the weight of the liquid on the sucker rod when performing oil pumping tasks.

[0012] To achieve the above objectives, the present invention provides a multi-stage series plunger pump for oil pumping units, comprising:

[0013] A plunger pump housing assembly; wherein the plunger pump housing assembly includes a housing tube formed by alternating connections of several pump barrel sections and several oil pipe sections;

[0014] A plunger pump oil extraction assembly; wherein the plunger pump oil extraction assembly is disposed within the receiving tube, and the plunger pump oil extraction assembly includes a sucker rod and a plurality of plungers disposed on the sucker rod;

[0015] Each of the plungers is disposed within a corresponding pump barrel section;

[0016] Each plunger and its corresponding pump barrel are configured such that the pumping capacity of the upper plunger and pump barrel is greater than that of the lower plunger and pump barrel.

[0017] Optionally, the plunger pump assembly further includes a pumping head disposed at the end of the sucker rod near the ground pumping unit.

[0018] Optionally, when the pumping unit's donkey head performs each pumping action, it drives the sucker rod and several plungers mounted on the sucker rod to perform one upward movement and one downward movement.

[0019] Optionally, each time the sucker rod and the plurality of plungers disposed on the sucker rod perform an upward movement, an internal gap is formed in the upper pump barrel section of each group of adjacent pump barrel sections.

[0020] Optionally, in the plurality of alternately connected pump barrel sections and tubing sections of the plunger pump housing assembly, the first end of the housing barrel near the surface pumping unit is configured as the tubing section, the second end of the housing barrel near the liquid is configured as the pump barrel section, and the pump barrel sections and tubing sections are configured to be alternately connected between the first end and the second end of the housing barrel.

[0021] Optionally, a fixed valve is provided at the bottom of the pump section at the bottom end of the receiving tube.

[0022] Optionally, the fixed valve opens when the sucker rod and the plurality of plungers disposed on the sucker rod move upward; and closes when the sucker rod and the plurality of plungers disposed on the sucker rod move downward.

[0023] Optionally, each of the plungers is provided with a traveling valve.

[0024] Optionally, the traveling valve is closed when the sucker rod and the plurality of plungers disposed on the sucker rod move upward; the traveling valve is opened when the sucker rod and the plurality of plungers disposed on the sucker rod move downward.

[0025] Optionally, the plunger pump housing assembly includes a plurality of pump barrel sections and a plurality of oil pipe sections, wherein at least two of the pump barrel sections and the oil pipe sections are configured.

[0026] The beneficial effects of this invention are as follows: It proposes a multi-stage series plunger pump for an oil pumping unit, the plunger pump comprising: a plunger pump housing assembly; wherein the plunger pump housing assembly includes a housing tube formed by alternating connections of several pump barrel sections and several oil pipe sections; a plunger pumping assembly; wherein the plunger pumping assembly is disposed within the housing tube, the plunger pumping assembly includes a sucker rod and several plungers disposed on the sucker rod; wherein each plunger is disposed within a corresponding pump barrel section; wherein each plunger and its corresponding pump barrel are configured such that the pumping capacity of the upper plunger and pump barrel is greater than that of the lower plunger and pump barrel. This invention divides the receiving tube formed by the pump barrel and oil pipe into multiple sections, and equips each section with a plunger. The upper plunger and pump barrel have a greater pumping capacity than the lower plunger and pump barrel. Thus, when the sucker rod performs a pumping action, the upward movement of the upper plunger creates more space than the volume of liquid pushed up by the lower plunger. This creates an internal gap under each upper plunger, preventing the liquid load of the upper plunger from acting on the lower plunger. This reduces stroke loss and improves pumping efficiency. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a conventional pump in the upward direction in the prior art;

[0028] Figure 2 This is a schematic diagram of the multi-stage series plunger pump of the oil pumping unit of the present invention in the upward state;

[0029] Figure 3 This is a schematic diagram of the liquid load in a conventional pump in the prior art;

[0030] Figure 4 This is a schematic diagram of the liquid load of the multi-stage series plunger pump of the oil pumping unit of the present invention.

[0031] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1-oil pipe; 2-pump barrel; 3-donkey head; 4-sucking rod; 5-plunger pump; 6-liquid; 7-void. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0035] This invention provides a multi-stage series plunger pump for an oil pumping unit, as described in the following embodiment. Figure 2 , Figure 2 This is a schematic diagram of the structure of an embodiment of the multi-stage series plunger pump for oil pumping units of the present invention.

[0036] In this embodiment, a multi-stage series plunger pump for an oil pumping unit includes: a plunger pump housing assembly; wherein the plunger pump housing assembly includes a housing tube formed by alternating connections of a plurality of pump barrel sections 2 and a plurality of oil pipe sections 1; and a plunger pumping assembly; wherein the plunger pumping assembly is disposed within the housing tube, and the plunger pumping assembly includes a sucker rod 4 and a plurality of plungers disposed on the sucker rod 4; wherein each plunger is disposed within a corresponding pump barrel section 2; wherein each plunger and its corresponding pump barrel section 2 are configured such that the pumping capacity of the upper plunger and pump barrel section 2 is greater than that of the lower plunger and pump barrel section 2.

[0037] In a preferred embodiment, the plunger pump assembly further includes a pumping head 3 disposed at the end of the sucker rod 4 near the surface pumping unit. During each pumping action, the pumping head 3 drives the sucker rod 4 and several plungers disposed on the sucker rod 4 to perform one upward movement and one downward movement. Each time the sucker rod 4 and the several plungers disposed on the sucker rod 4 perform an upward movement, an internal gap 7 is formed in the upper pump section 2 of each group of adjacent pump sections 2.

[0038] In a preferred embodiment, among the several alternately connected pump barrel sections 2 and oil pipe sections 1 of the plunger pump housing assembly, the first end of the housing barrel near the surface pumping unit is configured as oil pipe section 1, the second end of the housing barrel near the liquid 6 is configured as pump barrel section 2, and the pump barrel sections 2 and oil pipe sections 1 are configured to be alternately connected between the first end and the second end of the housing barrel.

[0039] In a preferred embodiment, a fixed valve is provided at the bottom of the pump section 2 at the bottom end of the receiving tube. When the sucker rod 4 and the plurality of plungers disposed on the sucker rod 4 perform upward movement, the fixed valve opens; when the sucker rod 4 and the plurality of plungers disposed on the sucker rod 4 perform downward movement, the fixed valve closes.

[0040] In a preferred embodiment, each plunger is provided with a traveling valve. When the sucker rod 4 and the plurality of plungers disposed on the sucker rod 4 perform upward movement, the traveling valve is closed; when the sucker rod 4 and the plurality of plungers disposed on the sucker rod 4 perform downward movement, the traveling valve is opened.

[0041] In practical applications, the plunger pump housing assembly includes several pump barrel sections 2 and several oil pipe sections 1, wherein at least two pump barrel sections 2 and oil pipe sections 1 are configured.

[0042] In this embodiment, a multi-stage series plunger pump for an oil pumping unit is provided. By dividing the receiving tube formed by the pump barrel section 2 and the oil pipe 1 into multiple sections, and configuring a plunger for each section, the pumping capacity of the upper plunger and the pump barrel section 2 is configured to be greater than that of the lower plunger and the pump barrel section 2. Thus, when the sucker rod 4 performs a pumping action, the space cleared by the upward movement of the upper plunger is greater than the volume of liquid pushed up by the lower plunger. This creates an internal gap 7 under each upper plunger, preventing the liquid load of the upper plunger from acting on the lower plunger. This reduces stroke loss, improves pumping efficiency, and expands the application range of the plunger pump 5.

[0043] Specifically, one or more pump barrel sections 2 and plungers are connected in series between the ground and the plunger pump 5, such that the displacement of each series pump barrel section 2 and plunger is greater than the displacement of the next stage pump barrel section 2 and plunger. When the ground donkey head 3 moves upward, each stage of plunger moves upward, and the valves on each plunger close. Since the displacement of each stage plunger is set to be greater than that of the next stage plunger, the space cleared by the upward movement of the upper stage plunger is greater than the volume of liquid pushed up by the lower stage plunger. Therefore, a gap 7 is formed under each upper stage plunger. The existence of this gap 7 prevents the liquid column load of the upper stage plunger from being transmitted to the lower stage plunger. Thus, the liquid load borne by each stage plunger is only the sum of the liquid load on the plunger itself and the liquid load of each stage plunger below it; the liquid load of the upper stage plunger no longer acts on that stage plunger. Obviously, the elastic elongation of the sucker rod 4 between the upper and lower stage pumps will decrease during the upward movement. The decrease is equal to the elastic elongation of the sucker rod 4 caused by the liquid load above the upper stage plunger. Therefore, the stroke loss of the sucker rod 4 caused by the gravity of the liquid 6 will be greatly reduced.

[0044] On the other hand, using a multi-stage plunger pump 5 can also reduce leakage between the plunger and the pump. This leakage is proportional to the gap between the plunger and the pump and the pressure difference between the upper and lower parts of the plunger. In a single-stage plunger pump 5, the pressure above the plunger is the pressure of the liquid column extending one string depth above the plunger. However, with a multi-stage plunger pump 5, the liquid column is divided into multiple segments, and the pressure on the plunger is only the pressure of a small segment of the liquid column. The pressure difference between the upper and lower parts of the plunger is reduced, and the leakage naturally decreases.

[0045] To explain this application more clearly, a specific example of a multi-stage tandem plunger pump for an oil pumping unit is provided below.

[0046] like Figure 3 and Figure 4 As shown, the following explanation uses a comparison between installing one plunger pump 5 and installing three plunger pumps 5 as examples. To simplify the discussion, the following assumptions are made: When there is only one plunger pump 5, 1. The liquid load is W. l The plunger pump 5 (length of sucker rod 4) is lowered to a depth of L; when lowering the three-stage plunger, 2. the three-stage plungers have the same area as the plunger of a single plunger pump 5; 3. the depth of the lowest stage pump is the same as the depth of a single pump; 4. the sucker rod 4 has the same diameter and material; 5. the three sections of sucker rod 4 between the three-stage plungers have the same length; 6. the effect of submersion on the liquid load of the lowest stage plunger is not considered.

[0047] When there is only one plunger pump 5, the stroke loss caused by the liquid load is: λ=E*W l *L; When the three-stage plunger pump 5 is lowered, since the plungers have the same area and the distance between the plungers is the same, the liquid load on each stage plunger is: W l / 3. The three sections of sucker rod 4 between the three plungers are of the same length, so the length of sucker rod 4 between each plunger is: L / 3.

[0048] The length of sucker rod 4 above the top-level (first-stage) plunger is L / 3, and the fluid load is the fluid load W on this stage plunger. l / 3 and the liquid load 2*W on its lower secondary plunger l / 3.

[0049] The stroke loss of the first-stage sucker rod is: λ1 = E * (W) l / 3+2*W l / 3)*L / 3=E*W l *L / 3.

[0050] The stroke loss of the second-stage sucker rod is: the fluid load is the fluid load W on the plunger of this stage. l / 3 and the fluid load W on its next stage plunger l / 3. λ2=E*(W l / 3+W l / 3)*L / 3=2*E*W l*L / 9.

[0051] The stroke loss of the third-stage sucker rod is: the fluid load is the fluid load W on the plunger of this stage. l / 3. λ3=E*W l / 3*L / 3=E*W l *L / 9. The total stroke loss of sucker rod 4 is: λ'=λ1+λ2+λ3=2 / 3*E*W l *L=2 / 3*λ.

[0052] In this example, compared to installing only one plunger pump 5, installing three plunger pumps 5 reduces the stroke loss of the sucker rod 4 caused by fluid load by one-third. It can be concluded that installing more stages of plunger pumps 5 will further reduce the stroke loss of the sucker rod 4.

[0053] During the on-site installation of the tandem plunger pump 5, each pump stage is connected to its corresponding position on the tubing 1 according to the design depth and lowered into the well along with the tubing 1. After the tubing 1 is lowered, liquid 6 is poured into the tubing 1 until the liquid level in the tubing 1 submerges the position of the uppermost pump. The plungers and sucker rods 4 are then lowered, and the positions of each plunger connected to the sucker rod 4 should correspond to the positions of each pump stage to ensure that each plunger moves within its corresponding pump barrel section 2 during pumping unit operation. Pouring liquid 6 into the tubing 1 before lowering the plungers and sucker rods 4 prevents the upper pump stages from being unsubmerged during the initial operation of the pumping unit, thus avoiding dry friction damage to the plungers and pumps.

[0054] Therefore, when multiple plungers of equal area form a series pump and move upwards, the displacement of the upper stage plunger pump 5 is greater than that of the lower stage pump, thus creating a gap 7 under the plunger of the upper stage pump. This gap 7 prevents the liquid column load on the upper stage plunger from being transferred to the lower stage plunger. The reason is as follows:

[0055] Let's take the example of three plungers of equal area connected in series as an illustration.

[0056] Let the plunger diameter be D, the stroke be S, and the stroke losses of the sucker rod between the three plungers be λ1, λ2, and λ3, respectively. Then the displacement of each series plunger in each stroke is as follows:

[0057] The displacement of the first stage (topmost stage) is Q1 = (S - λ1) * π * D 2 / 4;

[0058] Second-stage (intermediate stage) displacement Q2 = (S - (λ1 + λ2)) * π * D 2 / 4;

[0059] The displacement of the third stage (lowest stage) is Q3 = (S - (λ1 + λ2 + λ3)) * π * D 2 / 4;

[0060] Clearly, as the plunger moves upward, the space cleared by the first-stage plunger is greater than the volume of liquid pushed up by the second-stage plunger, creating a void 7 below the first-stage plunger. Similarly, a void 7 also forms below the second-stage plunger. The existence of these voids 7 prevents the transfer of the liquid column load from the upper plunger to the lower-stage plunger, and the elongation of the sucker rod 4 will decrease due to the reduced load.

[0061] It is understood that in the description of this specification, references to terms such as "one embodiment," "another embodiment," "other embodiments," or "first embodiment to Nth embodiment," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0062] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0063] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0064] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A multi-stage tandem plunger pump for a pumping unit, characterized by, The application relates to a plunger pump containing assembly, comprising: a plunger pump containing assembly; wherein the plunger pump containing assembly comprises a containing cylinder formed by alternately connecting a plurality of pump cylinder segments and a plurality of oil pipe segments; a plunger pump oil pumping assembly; wherein the plunger pump oil pumping assembly is arranged in the containing cylinder, and the plunger pump oil pumping assembly comprises an oil pumping rod and a plurality of plungers arranged on the oil pumping rod; wherein each of the plungers is arranged in a corresponding one of the pump cylinder segments; wherein each of the plungers and the corresponding pump cylinder are configured such that the pumping displacement of the plunger and pump cylinder located above is greater than the pumping displacement of the plunger and pump cylinder located below; a pumping machine horse head arranged at one end of the oil pumping rod close to a ground pumping machine; the pumping machine horse head drives the oil pumping rod and the plurality of plungers arranged on the oil pumping rod to perform one upward movement and one downward movement during each pumping operation; wherein each time the oil pumping rod and the plurality of plungers arranged on the oil pumping rod perform one upward movement, a pipe internal gap is formed in the pump cylinder segment located above in each group of adjacent pump cylinder segments; the bottom of the pump cylinder segment at the bottom end of the containing cylinder is provided with a fixed valve; wherein the fixed valve is opened when the oil pumping rod and the plurality of plungers arranged on the oil pumping rod perform upward movement, and the fixed valve is closed when the oil pumping rod and the plurality of plungers arranged on the oil pumping rod perform downward movement; each of the plungers is provided with a traveling valve; wherein the traveling valve is closed when the oil pumping rod and the plurality of plungers arranged on the oil pumping rod perform upward movement, and the traveling valve is opened when the oil pumping rod and the plurality of plungers arranged on the oil pumping rod perform downward movement. The plurality of alternately connected pump cylinder segments and oil pipe segments of the plunger pump containing assembly are configured as oil pipe segments at the first end of the containing cylinder close to the ground pumping machine, as pump cylinder segments at the second end of the containing cylinder close to the liquid, and as alternately connected pump cylinder segments and oil pipe segments between the first end and the second end of the containing cylinder. The plunger pump containing assembly comprises a plurality of pump cylinder segments and a plurality of oil pipe segments, and the pump cylinder segments and the oil pipe segments are configured as at least two. ​ ​ ​ ​ ​ ​ ​ ​ 2. The pumping unit multi-stage tandem plunger pump of claim 1, wherein, ​ 3. The pumping unit multi-stage tandem plunger pump of claim 1, wherein, ​

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