RU2266392C2 - Method for well cleaning of asphalt-tar-paraffin and sulfide deposits - Google Patents

Abstract

FIELD: oil production industry, particularly to remove asphalt-tar-paraffin and sulfide deposits and composite precipitations from flow string of production well.

SUBSTANCE: method involves detecting area of asphalt-tar-paraffin and sulfide deposit forming on flow string surface; performing cyclic working agent injection in the well; controlling degree of flow string cleaning of deposits. At the beginning of asphalt-tar-paraffin and sulfide deposit formation universal coupling provided with flushing valve is installed on the flow string. The flushing valve is suction valve of sucker-rod pump. Working agent is preliminary heated and pumped over closed loop including well head-hole annuity-flushing valve-universal coupling-flow string-well head. Before working agent injection into hole annuity the working agent is additionally heated at well head. The working agent is heat carrier, namely oil or processing medium. Degree of flow string cleaning of asphalt-tar-paraffin and sulfide deposits and degree of removing thereof from the well is controlled by estimating current magnitude of pump motor or by lowering sample in the flow string.

EFFECT: increased efficiency of asphalt-tar-paraffin and sulfide deposits and increased time between well cleaning and repair operations.

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Description

The invention relates to the field of oil production, in particular, can be used to remove asphalt-resin-paraffin, sulfide-containing deposits and sludge of complex composition in the columns of tubing pipes of production wells.

A well-known valve device for flushing tubing (tubing) of asphalt-resin-paraffin deposits, installed in the tubing, containing a pipe with an equal passage channel for communication with the tubing, an eccentric valve body with upper and lower holes and a spring-loaded shutter (pat. RF) No. 2100572, E 21 B 37/00, 34/06, 1997).

The known valve has a complex structure and due to the complexity of the design does not always find application.

The closest in technical essence to the proposed solution is a method for removing salt-paraffin deposits, including the preparation of the wellhead for circulating the technological solution in a closed cycle, cyclic pumping of the technological solution into the well with a plunger pump, monitoring the degree of purification of tubing (Pat. RF No. 20033783, E 21 V 37 / 06, E 21 B 37/00, 1993).

The disadvantage of this method is the low efficiency of removing the paraffin from the surface of the downhole equipment and the short inter-treatment period of the well and the high cost of the method due to the need to use large volumes of hot oil, about 15-20 tons or process fluid for heating to 60 ° -70 ° C - temperature ASPO melting and cleaning the entire annulus and the entire tubing string with a pump. In addition, the application of the known method is difficult to achieve and not effective enough for wells equipped with UEDN, due to the small diameter of both the valve seat and the valve assembly itself.

The objective of the present invention is to increase the efficiency of dissolution and removal of paraffin deposits and sulfide-containing deposits from the surface of downhole equipment and to increase the inter-treatment and overhaul periods of the well by installing a universal coupling with a flushing valve on the tubing string and pumping the working agent — hot oil or process fluids.

This problem is solved by a known method for removing asphalt tar and sulfide-containing deposits from the well, including determining on the surface of the tubing string the formation zone of asphalt-tar and sulfide-containing deposits, cyclic injection of the working agent into the well and monitoring the degree of cleaning of the tubing, in which, according to the invention, on the tubing string at the beginning of the formation zone of asphalt-resin-paraffin and sulfide-containing deposits, a universal coupling with a flush valve is installed periodically pumped into the annulus of the well working fluid - the hot oil, or process solution, and the degree of purification column tubing from Fat determined to reduce the current load of the motor or pump tubing descent template.

Figure 1 shows a diagram of a method for removing asphalt-resin-paraffin and sulfide-containing deposits in a string of tubing of production wells. 1 - tubing string, 2 - UEDN, 3 - ASPO formation zone, 4 - universal coupling, 5 - flushing valve, 6 - wellhead, 7 - annulus of the well, 8 - casing; 9 - productive layer.

The method is as follows.

In the tubing string 1 equipped with UEDN 2, preliminary during the next underground repair, the zone of the greatest accumulation of asphalt-resin-paraffin, sulfide-containing deposits 3 and the qualitative characteristics of these compositions are determined. After that, at the beginning of the formation, accumulation of sedimentary paraffin deposits and sulfide-containing deposits, a universal coupling 4 with a flush valve 5 is installed on the tubing string. The approximate depth is 500-600 m. As a flush valve, a suction valve of the НВ-32 sucker rod pump, the passage section of which is larger diaphragm pump through passage 2.1 times.

Pre-heated to a temperature of 85 ° -90 ° C, the working agent - hot oil or technological solution is pumped through the wellhead 6 into the annular space of the well 7. It is pumped under pressure not exceeding the pressure of the casing string (OK) of the well 8, about 15 MPa. When hot coolant is pumped - oil or process solution into the annulus of the well, the flush valve of the universal flush clutch is opened, and the hot coolant or process solution enters the tubing into the zone of formation and greatest accumulation of paraffin deposits, sulfide-bearing deposits and complex sediments. In this case, dissolution and removal of sediments of a complex composition of paraffin deposits, washing and cleaning of tubing strings above the coupling installation interval occurs.

Thus, hot oil or technological solution is pumped in a closed cycle: wellhead - annulus - flushing valve - coupling - tubing string - wellhead. At the wellhead, the process solution or oil is additionally heated to 85 ° -90 ° C before being pumped into the annulus.

The degree of removal and cleaning of the tubing string from ASPO, sulfide-containing precipitates and precipitates of complex composition is controlled by reducing the current of the electric motor or by lowering a special template into the tubing string.

The frequency of repeated flushing of the tubing string with hot coolant or technological solution is determined by increasing the current load of the pump motor, reducing the flow rate of the well, changing the position of the dynamic level in the annulus of the well, or by lowering a template of a certain diameter into the tubing string.

High efficiency of well treatments equipped with universal couplings with flushing valves, both hot oil and process fluids, is ensured by reducing the treated surface, i.e., neither the annulus nor the tubing string with pump located below the universal clutch is processed. This eliminates the possibility of clogging of the pump valves with paraffin carried out during the processing of the well.

The use of a universal coupling also allows the circulation of the process fluid in the well through the annulus by the downhole pump with the wellhead bypass valve open during chemical treatments.

Thus, the use of a method for removing asphalt-resin-paraffin and sulfide-containing deposits using a universal coupling with a valve significantly increases the efficiency of pumping coolants and process fluids, contributes to an increase in the volume of produced products at lower costs, and an increase in the inter-treatment and overhaul periods of the well.

Claims (1)

A method for removing asphalt tar, salt deposits from a well, including determining on the surface of the tubing string (tubing) of the formation zone of asphalt tar, salt deposits, cyclic injection of the working agent into the well and controlling the degree of cleaning of the tubing string, characterized in that on the tubing string into at the beginning of the formation zone of asphalt-resin-paraffin and sulfide-containing deposits, a universal coupling with a flush valve is installed, which is used as a receiving valve the pan of the NV-32 sucker rod pump, the working agent is preheated and pumped in a closed cycle: wellhead - annulus - flushing valve - universal coupling - tubing string - wellhead, while the working agent is additionally heated at the wellhead before injection into the annulus , as a working agent, a coolant is used - oil or technological solution, and the degree of purification of the tubing string from asphalt-resin-paraffin and sulfide-containing deposits and their removal from the control well ruyut to reduce the magnitude of the pump motor current or descent in the tubing template.