RU2082879C1 - Method of treatment of bottom-hole formation zone - Google Patents

Abstract

FIELD: operation of oil wells equipped with electric centrifugal pumps; may be used in well completion, or intensification of formation fluid inflow in course of well operation. SUBSTANCE: electric centrifugal pump is connected to industrial mains via thyristor converter. Current frequency is increased up to the value to ensure stable maximum well fluid production rate. Then, after and interval, current frequency is reduced, and pump is changed-over for supply from industrial mains. Duration of depression effect on formation is limited by the moment of stall of delivery of electric centrifugal pump. EFFECT: higher efficiency.

Description

 The invention relates to methods for operating oil wells equipped with submersible electric centrifugal pumps (ESP), and can be used to develop or intensify the flow of formation fluid into the wells.

 There is a method of developing and operating wells with submerged ESPs with a frequency-controlled drive [1] For the operation of wells, a pump is selected from the conditions for ensuring operation parameters after well completion, and development of the well is carried out at an increased current frequency (revolutions of the ESP shaft) and a corresponding increase in pump parameters.

 The method does not provide the ability to create deep depressions on the reservoir.

A known method of influencing the bottom-hole zone of wells equipped with ESPs, including the creation of depressions by displacing the liquid level with gas and subsequent discharge of the well into the flow line [2]
The disadvantage of this method is that for its implementation requires special equipment, it is time consuming and time consuming. May damage the power cable.

A known method of influencing the bottom-hole zone of a well during its operation, including connecting a borehole electric centrifugal pump to an industrial power grid through a thyristor current frequency converter and creating depression by increasing the productivity of a borehole electric centrifugal pump by increasing the current frequency [3]
The known method is intended for pumping a heavy killing fluid, and after the pumping is completed, the electric centrifugal pump is put into operation, which indicates a low efficiency of well operation, since it does not increase its oil flow rate.

 The objective of the invention is to obtain a technical result, expressed in an increase in the flow of fluid from the formation into the well and the possibility of switching to an operating mode with a higher oil rate.

 This is achieved by the fact that during the operation of the well, including immediately after its development, the pump is transferred to work with an increased frequency, ensuring the maximum stable flow rate of the well in liquid.

 The method is implemented as follows.

 In the process of exposure to the bottomhole zone of a well equipped with an ESP, including the creation of deep depressions on the formation, the ESP is connected to the power supply through a current frequency converter to a value that ensures maximum well production by liquid, and after the well is excited, the ESP is switched to power from an industrial frequency current.

 The method is easily implemented using thyristor current frequency converters (TFC).

The well is equipped with an ESP with a separator, which ensures the operation of the pump on gas-liquid mixtures with a high content of free gas at the pump intake. The power to the pump motor is supplied through a TFC, the current frequency is adjusted to the maximum permissible 70 80 Hz. The performance of the pump increases by 1.6 times. High rates of fluid withdrawal lead to the creation of a deep depression on the formation, ensuring its cleaning and inclusion of low-permeability layers in the work, while the content of free gas at the pump intake rises to 30 60
After the liquid with a high content of free gas arrives at the pump’s intake, the flow rate of the well begins to drop until the ESP supply is cut off, which serves as a signal to the end of the reservoir stimulation process. The frequency of the current supplying the ESP is reduced to industrial value and the pump is switched to power from the industrial mains.

 After repair at many wells, the flow rate at the Pravdinskoye field is not restored. In one of the wells equipped with an ESP, the frequency of the current supplying the pump electric motor was brought to 80 Hz for 15 min using a TFC. Pumping out the killing fluid from the well was 1.3 times faster than usual. After 3.5 hours, a pressure of 2.7 MPa was established at the pump inlet, while before the repair, the well worked with a pressure at the pump intake of 5.7 MPa. In this mode, the well worked for 9 hours, after which there was a disruption in supply and the pump was turned off. After 3 hours of waiting for the accumulation of fluid, the pump was put into operation from the industrial mains and the well entered the mode. Well production increased by 12% compared to production before repair. The bottom hole formation was drained.

 The application of the method will effectively affect the bottomhole formation zone.

Claims (1)

 A method of influencing the bottom-hole zone of a well during its operation, including connecting a borehole electric centrifugal pump to an industrial power grid through a thyristor current frequency converter and creating depression by increasing the productivity of a borehole electric centrifugal pump by increasing the current frequency, characterized in that the current frequency is increased to providing a stable maximum flow rate of the well in the liquid, after which they pause, and then the frequency of the supply о the electric centrifugal pump reduces the current to industrial value and switches the electric centrifugal pump to power from the industrial mains, while the duration of the depressive effect on the formation is limited by the moment the electric centrifugal pump is cut off.