RU2014440C1 - Method and device for running a high-viscosity oil well - Google Patents

Abstract

FIELD: oil and gas industry. SUBSTANCE: lift 1 and washover 2 strings are lowered into well. Hollow circulating valve 3 and a sub 4 with support seat 5 for subsurface pump are installed between said strings. Shoe of washover string 2 is positioned level with oil stratum 13. Pump with extension is lowered into lift string 1 on sucker rods so that extension comes short of washover valve 3. Hole is washed by reverse circulation of hot agent to remove resin and paraffin plugs. Then pump is run in onto support seat 5 and circulating valve 3 is opened by extension. Oil is pumped out of annular space 15 through circulating openings 8 in body 7 of valve 3. EFFECT: higher efficiency of downhole pumping equipment in deep high-viscosity oil wells. 2 cl, 2 dwg

Description

 The invention relates to the oil and gas industry, and in particular to methods and devices for operating wells with high viscosity oil.

In the development of high-viscosity oil deposits, particularly those containing a high percentage of asphalt-resinous substances (over 15%) there are difficulties (for bedding at great depths: 2000 m and more, when the bottom hole temperature exceeds ^about 50 C).

 In the process of well downtime (turning off electric energy, etc.), the oil filling the wellbore assumes the temperature of the surrounding rock mass. Therefore, in the middle part along the depth of the well and especially in the upper part, the temperature may be lower than the crystallization temperature of paraffin, resins, asphaltenes, etc. Resins deposited in the sediment settle down and clog the lower part of the wellbore. When trying to start a well in operation, as a rule, this fails. The submersible pump pumps out all the oil located in the annulus above the intake of the pump and chokes. Since the liquid does not flow from below, the pump stops supplying oil from the well.

 There is a method of operating a well with highly viscous oil, which consists in lowering the lifting column, lowering the deep insert pump into it, flushing the well with a hot agent and pumping the oil with a pump (1).

 Since with this method the lower part of the wellbore is not tested, the plugs made of resins, paraffin and asphaltenes remaining below the pump intake do not allow the well flow rate to be restored. To flush the well, you can allow the lifting column to the bottom and flush the well to the full depth, but such an additional operation requires considerable time. In this case, tarry, etc. also occur. And it is not possible to restore the previous flow rate.

 The aim of the present invention is to increase the efficiency of downhole pumping equipment in wells with high resin content.

 This goal is achieved by the fact that in the known method of operating a well with highly viscous oil, including lowering the lifting string, lowering the deep insertion pump into it, flushing the well with hot oil and pumping the oil out, the washing string is suspended from the lifting string with its shoe set at the level of the oil reservoir washing is done to the entire depth of the well, and before starting the pump, circulation windows are opened in the upper part of the washing column.

 A device for implementing the known method, comprising a lifting column and a deep-well plug-in pump with a shank (2).

 This device does not allow you to flush the well to its entire depth. As a result, plugs from the tarry part of the oil remain below the pump intake, the well is not cleaned properly, and the downhole pumping equipment is inefficient.

 The aim of the present invention is to increase the efficiency of downhole pumping equipment in wells with high viscosity oil.

 This goal is achieved by the fact that in the known device for implementing the method of operating a well with highly viscous oil, it further comprises a flushing column suspended from the lifting column, a hollow circulation valve is installed between the lifting and washing columns with the possibility of opening it when the plug-in deep pump is planted in the support seat .

 Figure 1 shows a device for implementing the proposed method at the time of flushing the well before starting the downhole pump; figure 2 is the same at the time of operation of the deep insertion pump.

 The device comprises a lifting column 1 and a washing column 2, between which a hollow circulation valve 3 and a sub 4 with a supporting seat 5 for a pump 6 are installed.

 The circulation valve 3 has a housing 7 with circulation windows 8, closed by a sleeve 10 spring-loaded by means of a spring 9, which interacts with the shank 11 of the plug-in deep pump 6.

 The lower end of the spring 9 rests on the shoulder 12, available in the lower part of the housing 7 of the valve 3, and its upper end - in the lower end of the sleeve 10.

 The lower end of the flushing column 2 is installed at the level of the oil reservoir 13. The upper part of the lifting column 1 is connected to the production string 14. An outlet line 16 is connected to the annular space 15 of the well.

 In the shank 11 of the pump 6 there are side windows 17 through which fluid flows from the well to the intake of the pump 6.

 Possible and other mounting options for the plug-in pump 6, for example using a collet gripper or a hydraulically locked chamber, etc. But there is one requirement in this case - when the pump 6 is planted in its attachment point, the shank 11 must open the circulation windows 8 of the valve 3.

 The proposed method using the above device is as follows.

 The method was tested on a well with a depth of 4200 Monastyrishchenskoye oil fields. Casing ⌀ 146 mm. The oil horizon in the range of 4107-4130 m. In oil tar up to 20%.

 A flushing column 2 of tubing ⌀ 60.3 mm, 2164 m long, and a lifting column 1 of 1946 m length from tubing ⌀ 73 mm was lowered into the well. A circulation valve 3 and a sub 4 were installed between them. Inside the tubing ⌀ 73 mm, a deep-well push-in pump was lowered on the sucker rods 6. The pump was started 6. After oil was pumped out in the volume of the annulus 15 from the wellhead to pump 6, the flow of fluid from the well was stopped. This indicated that pump 6 pumped out all the fluid from the annulus 15 before pump 6 was received, and oil did not flow from reservoir 13, which indicated that the bottom of the wellbore was plugged with a resin and paraffin plug.

 To clean the well of tar and paraffin sediment, the pump 6 was raised so that the liner 11 exited the circulation valve 3 and the sleeve 10 rose up and closed the windows 8. After that, the unit was connected to flow line 16 and hot oil was pumped through the annular space in the amount of one cycle (see figure 1). Hot oil dissolved the resins deposited in the annulus and carried them to the surface. At the end of the oil pumping process, pump 6 was again lowered down to fit into the support seat 5. At the same time, the shank 11 of pump 6 moved the sleeve 10 down and opened the circulation windows 8 of valve 3. Pump 6 was put into operation. Since the cavity of the sleeve 10 is almost completely blocked by the shank 11, the oil (liquid) from the annulus 15 to the pump 6 entered through the circulation windows 8 and the side windows 17 in the shank 11. Since the cross section of the annular space 15 is lower than the pump 6 when using the proposed device a lot less than when operating by known methods (the known ones do not have a wash string 2 and the well operates the entire cross section of the production string 14), then the oil from the formation 13 arrives faster and does not have time to cool so that a wasp can be given resin and a waxy substance. Therefore, the operation of the well and the work of the downhole pumping equipment takes place in the best conditions.

 If it is necessary to conduct a new washing of the well, the pump 6 is stopped and lifted so that the liner 11 leaves the sleeve 10 and is flushed as described above.

 When the well was operated by the proposed method, cases of non-start-up of the downhole pumping equipment (pump 6) were stopped and due to this, an increase in well production by 18% was achieved.

Technical appraisal and economic advantages of the proposed method and device:
1. The overhaul period of the well increases, since there is no need to repair it to start the deep pumps 6.

 2. The flow rate of wells increases due to improved conditions for lifting oil to the pump 6.

 3. The implementation of the proposal simplifies the work of the field staff as there is no need to organize repair work on the wells.

 The method adopted for testing it in fields having high-viscosity oil production, NGDU po Ukrnafta.

Claims (2)

 1. A method of operating a well with highly viscous oil, including the descent of a lifting string into the well, installation of an insertion deep pump in it on the support seat, subsequent flushing of the well with a hot agent and pumping of oil by a pump, characterized in that, in order to increase the efficiency of the method when using it in deep wells, the lifting column is equipped with a washing column, the shoe of which is placed at the level of the oil reservoir, and before the insertion pump is put into the support saddle, the well is flushed with a hot agent at depths promyvochkoy lowered and lifting columns, after which the pump is lowered into the support saddle and launch it into operation.  2. A device for operating a well with high viscosity oil, comprising a lifting column with a supporting saddle for placement of an inserted deep-well pump with a liner, characterized in that, in order to increase efficiency when used in deep wells, it is equipped with a flushing column installed in the lower parts of the lifting column, and a hollow circulation valve located between them, located with the possibility of opening it when the plug-in deep pump fits into the support saddle.

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