RU2260672C1 - Casing-head stuffing box for sucker-rod pump - Google Patents

Abstract

FIELD: oil production industry, particularly for producing wells with high wellhead pressure.

SUBSTANCE: casing-head stiffening box comprises chamber with stuffing and lid for polished rod. Casing-head stiffening box also includes connection pipe with ball bearing located in tee socket. Freely suspended cylinder is attached to ball bearing from lower side thereof. Plugged plunger is arranged the cylinder so that plugged plunger may reciprocate inside the cylinder. Plunger is connected to knock-off block from lower side thereof and to polished rod from upper side thereof. Inner connection pipe cavity and cylinder zone above plunger are filled with grease and hydraulically communicated with hole annuity of wellhead fittings through check valve.

EFFECT: increased reliability, service life and maintenance convenience.

1 dwg

Description

The invention relates to the oil industry and may find application in production wells with high wellhead pressure.

A wellhead device for sealing a rod of a deep well pump is known, comprising a cylindrical detachable body with a cover mounted on a valve tee, pressure bushings, upper and lower glands and a centering unit for the wellhead located in the body. The housing and pressure bushings are made with tapered inner surfaces. In this case, the pressure bushings above and below the lower gland face the inner conical surfaces towards each other. The internal cavity of the housing between the seals is filled with lubricant [USSR Author's Certificate No. 1696672, cl. E 21 B 33/03, publ. 1991].

However, to ensure the tightness of this device at high wellhead pressure, an enhanced pull-up of the stuffing box seal is required, which leads to intensive wear and a quick failure of the stuffing box. There are inconveniences in service, the laboriousness of work on replacing the stuffing box packing and lubricant.

In addition, when replacing a polished rod, it is necessary to dismantle the wellhead reinforcement, which often requires killing the well.

Closest to the proposed invention is a wellhead seal containing a base with a cover, a self-aligning ball head, upper, middle and lower seals made in the form of a hollow truncated cone. The upper and middle seals are placed in a cage made in the form of a hollow cylinder, the inner surface of which has a tapered narrowing towards the center of the cylinder, and the cavity between these seals is filled with oil for lubricating the stuffing box [RF Patent No. 2093663, cl. E 21 B 33/03, publ. 1997.10.20 - prototype].

The use of this device in a donor well, which carries out the extraction of produced water by a rod pump and then injects it with high wellhead pressure through the pipeline into the injection well, leads to rapid wear of the stuffing box packing and depressurization of the wellhead. Moreover, the higher the pressure at the wellhead, the stronger it is necessary to tighten the stuffing box seal, which excessively increases the stress state of the seal, which causes intensive wear of the stuffing box packing. For this reason, constant monitoring of the seal tightness and frequent replacement, at least five to six times a month, of worn seals are necessary. Also, when replacing a polished rod, it is necessary to dismantle wellhead fittings.

The invention solves the problem of increasing reliability, durability and ensuring convenience in the work of the wellhead seal of the rod pump installation in the well with high wellhead pressure.

The problem is solved in that in the wellhead seal of the sucker rod pump installation, containing a chamber with stuffing box packing and a cover for sealing the wellhead polished rod connected with the suspension of the rod string, a nozzle with a ball bearing located in the valve tee socket, according to the invention, from the lower side to the ball bearing a freely suspended cylinder is connected to the nozzle, in which the muffled plunger is located with the possibility of reciprocating movement, while the plunger is connected to the column suspension from the bottom side rod, and from the top - with wellhead polished rod, and the inner cavity of the nozzle and the plunger zone of the cylinder are filled with grease and hydraulically connected with the annulus of the wellhead valves through the check valve.

The drawing shows a General view of the wellhead stuffing box sucker rod pump with the highest position of the polished rod.

The wellhead gland of the sucker rod pump installation consists of a nozzle 1 with a ball bearing 2, mounted with a ball cap 3 in the socket of the tee 4, which is connected by a faceplate 5 to the wellhead fittings 6. A cylinder 7 with a grooved plunger 8 is connected and freely suspended (hereinafter, the plunger) from the deep sucker rod pump, which is located in the valve 6 and the upper part of the first pipe of the tubing string 9. The plunger 8, located in the cylinder 7 with the possibility of reciprocating movement, plugs Yen and on the lower side is connected to the string of pump rods 10, and on the upper side - with a polished wellhead rod 11 of the suspension of the rocking machine (not shown). A sealing chamber 12 with a stuffing box 13 and a cover 14 is screwed onto the upper part of the pipe 1. The internal cavity of the pipe 1 is hydraulically connected to the annular space 15 of the wellhead 6 through valves 16, 17 and the check valve 18. In this case, the internal cavity of the pipe 1 and the plunger zone of the cylinder 7 are filled with lubricant 19 for lubricating the plunger pair and stuffing box 13.

Wellhead seal works as follows.

Before mounting the assembled wellhead seal without check valve 18 to the faceplate 5 of the wellhead 6, the lower end of the plunger 8 is connected to the last rod 10 of the suspension column. The adjustment of the position of the plunger 8 in the cylinder 7 is carried out in such a way that at the upper extreme position of the rocker head of the rocking machine, the plunger 8 is located in the upper part of the cylinder 7. After installing the cable suspension (not shown) of the polished rod 11 and aligning it in the sealing chamber 12 using ball bearings 2 of the pipe 1, then the internal cavity of the pipe 1 and the supra-plunger zone of the cylinder 7 are filled with grease 19. For this, a lubricated container is connected to the valve 16, and when the plunger 8 moves slowly down and expense to create a vacuum above it is filled above-plunger cylinder lubrication zone 7 19. Excess grease is extruded from the nozzle 1 by the reverse movement of the plunger 8 up. The check valve 18 is turned to the valve 16 and the valve 17 is opened. At the same time, the check valve 18 closes, because the pressure in the annulus of the valve 6 is greater than in the plunger zone of the cylinder 7. But during the operation of the sucker rod pump installation, even a slight gas leak in the plunger pair during the upward stroke of the plunger 8 may increase the pressure of the closed volume of the plunger zone of the cylinder 7. In this case, when the pressure in the pipe 1 exceeds the annular pressure of the valve 6, the check valve 18 opens, and the gas or fluid in a volume equal to the leakage per cycle of the rocking machine is discharged into the annular space 15 of the valve 6. Thus, the sealing chamber 12 with the stuffing box 13 experiences the maximum pressure available in the annular space of the well, and only with the upward stroke of the plunger 8 Since in the donor well the pressure in the annulus is an order of magnitude lower than the buffer pressure (injection pressure), the sealing gland, ensuring the tightness of the wellhead, will not be stressed by high pressure occurrence of injection.

As a lubricant, you can use a thick lubricant, for example solid oil, which, being in the gap between the grooved plunger 8 and the cylinder 7, significantly increases the tightness in the plunger pair.

If it is necessary to replace the polished rod 11, the pump installation is stopped and the residual pressure in the tee 4 is discharged through the wellhead into the annulus 15 of the well. The valve 16 is closed and the sealing chamber 12 is turned off. Next, the polished rod 11 with the sealing chamber 12 and the rod string suspension are lifted. until the first chute of the plunger 8 is above the end of the pipe 1. A special clip is installed in this chute that holds the suspension of the rod string; stock 11 and replace it with a new one.

The proposed device is unified, does not require changes in standard wellhead fittings, significantly reduces the stress state of the packing, increases its reliability and durability, ensures trouble-free operation of the well, environmental protection at high buffer pressures in the well. Allows to replace the polished rod of the rocking machine without mounting the wellhead valves and easily fill the wellhead seal with lubricant.

The application of the proposed device will improve reliability, durability and provide convenience in the work of the wellhead seal of the sucker rod pump unit in the well with high wellhead pressure.

Claims (1)

The wellhead gland of the sucker-rod pump installation, comprising a chamber with a stuffing box packing and a cover for sealing the wellhead polished rod connected with the suspension of the rod string, a nozzle with a ball bearing located in the valve tee socket, characterized in that a freely suspended suspension is connected to the ball bearing of the nozzle a cylinder in which a muffled plunger is located with the possibility of reciprocating motion, while the plunger is connected to the suspension of the rod string from the lower side and to the mouth from the upper side th polished rod, wherein the inner tube and the above-plunger cavity of the cylinder area are filled with grease and fluidically communicated with the annulus of wellhead through a check valve.