Method and device for restoring horizontal well productivity and stimulating a formation

Abstract

The group of inventions relates to the oil and gas production industry, and more particularly to cleaning the near-wellbore region of a horizontal well and also existing filters, as well as to stimulating oil production. The present method includes lowering a complex device consisting of an electrohydraulic emitter with a plasma discharger, a geophysical unit, and an acoustic emitter into a horizontal wellbore as far as the end of the horizontal section, using the geophysical unit to calibrate the instruments and measure the parameters of the wellbore prior to treatment, carrying out acoustic cleaning of the pores of the formation and the filters in the horizontal wellbore region, carrying out plasma treatment of the cleaned region to activate stagnant zones of the formation, measuring the current parameters using the geophysical unit, and repeating these processes throughout the entire horizontal section of the wellbore. The present device comprises a surface-based multifunctional monitoring and control panel, and the following downhole elements connected by a cable: a radial-type acoustic emitter, a geophysical instrument unit, and an electrohydraulic emitter with a plasma discharger, which are connected to one another by geophysical subs. The invention makes it possible to improve cleaning of the near-wellbore region of a formation and also to restore well production.

1 . A method for restoring productivity of a horizontal well and stimulating a reservoir, comprising:
 lowering a complex device, comprising an electrohydraulic transducer with a plasma discharger, a geophysical unit and an acoustic transducer, into the horizontal well bore up to the end of a horizontal section of the horizontal well, wherein the complex device is bound by means of the geophysical unit and the well bore parameters are measured before the next step;   acoustically cleaning pores of the reservoir and filters of the horizontal section of the well;   treating the cleaned area with a plasma to draw stagnant zones of the reservoir into operation with a source;   measuring current parameters of the well by the geophysical unit;   repeating the abovementioned processes throughout the entire horizontal section of the well.   
     
     
         2 . The method according to  claim 1 , characterized in that the acoustic cleaning of pores of the reservoir and filters of the horizontal well is carried out by periodic exposure to an elastic oscillation field of an ultrasonic frequency range in a continuous mode and by means of a pulse low-frequency acoustic effect, wherein in the continuous mode, the exposure is carried out by a high-frequency oscillation of the ultrasonic range of 2000 Hz, and in the pulse mode, the exposure is carried out with a frequency of 100 Hz. 
     
     
         3 . The method according to  claim 1 , characterized in that the plasma treatment is produced by a high-pressure shock wave with an energy of up to 3 kJ. 
     
     
         4 . The method according to  claim 1 , characterized in that it can be used in horizontal wells for shale oil extraction. 
     
     
         5 . The method according to  claim 1 , characterized in that it can be used in sidetrack wells. 
     
     
         6 . A complex device for restoring productivity of a horizontal well and stimulation of a reservoir, comprising: a ground-based multifunctional control board, a downhole acoustic transducer of a radial type, a geophysical unit, an electrohydraulic transducer with a plasma discharger connected via coil-tubing and connected to each other by means of geophysical adapters. 
     
     
         7 . The device according to  claim 6 , characterized in that the ground-based multifunctional control board consists of the following units: a power and control unit for the acoustic transducer, a log recorder, a power supply unit and control unit for the electrohydraulic transducer. 
     
     
         8 . The device according to  claim 6 , characterized in that the acoustic transducer comprises:
 an electronics unit, an upper head providing connection with a contact device for a cable lug, a lower head, a conduit for electric wires and metal airproof housings interconnected into one structure, in which piezoelectric transducers are mounted, and the outer and inner surface of each housing have trough-like deepenings,   wherein in the housings there are bushings with screw-nuts placed on them and made to provide a possibility of connection and fixation of two adjacent housings one to another by means of metal wires attached simultaneously to two screw-nuts of the adjacent housings, in addition, the housings are also connected to each other with the help of parts formed by pouring a rubber-plastic composition in the butting positions with the gap of the two adjacent housings.   
     
     
         9 . The device according to  claim 6 , characterized in that it comprises an electrohydraulic plasma transducer of a modular design, which allows to regulate the energy emission from 0.5 to 3 kJ using capacitors which make it possible to reduce the size of the transducer, and a mechanical metal wire feeding unit involving easy replacement in field conditions. 
     
     
         10 . The device according to  claim 6 , characterized in that the geophysical unit comprises a gamma-ray logging and a magnetic coupler locator, temperature and pressure sensors, a moisture meter and a flow meter. 
     
     
         11 . The device according to  claim 6 , characterized in that the downhole electrohydraulic device is made of a modular design and comprises a stabilization unit, a capacitor unit and a plasma discharger,
 wherein the stabilization unit comprises a step-up and decoupling transformer, which also supplies a plasma ignition unit in the discharge interval.   
     
     
         12 . The device according to  claim 11 , characterized in that the capacitors in the capacitor unit are connected in parallel. 
     
     
         13 . The device according to  claim 11 , characterized in that the power of the downhole electrohydraulic device is regulated in the range from 0.5 to 3 kJ by means of additional capacitor units. 
     
     
         14 . The device according to  claim 11 , characterized in that the plasma discharger comprises a housing with an internal cavity, wherein the upper part is connected to a coupling bushing, and the lower part is connected to a bearing sleeve, the housing cavity contains a cylinder mounted on the middle part of the bearing sleeve, and the cylinder has a piston with a rod and a spring, a wire feeding machine is made in the form of a lever with a support platform and a wing with a spring is mounted on the upper part of the piston, on the support platform and on the wing on the side facing the wire there are directional notches, four rods are attached to the cylinder, that are the basis for a coil mount fitting, in the bearing sleeve there are holes for fixing positive and negative electrodes, and the electrodes are insulated with open areas providing a plasma discharge, in the negative electrode there is an axial hole for the wire, at the bottom of the bearing sleeve there is a guide cone mounted by means of racks.