Ignition Features of a High-Voltage Electric Discharge in Water Under Conditions of Deep Oil Wells

Approaches to improving the electrode system of submersible electrohydropulse devices used for treating the bottom-hole zone of deep oil wells are analyzed with the purpose of increasing the oil flow rate at a hydrostatic pressure of up to 50 MPa and electric field strengths within the range of (0.5–1.5)∙10⁷ V/m. The feasibility of increasing the voltage at the dielectric–liquid–metal interface up to E_ign = 3∙10⁷ V/m to ignite a discharge under high pressure conditions is demonstrated. The hysteresis of breakdown voltage in various liquids, such as an invert water-in-oil emulsion, formation water, and process water, is described and analyzed. Experiments are carried out at different values of hydrostatic pressure in the well. A possible mechanism for the appearance of hysteresis during repeated breakdowns of liquids during a decay and rise in operating voltage is explained. The necessity of taking the hysteresis effect into account when calculating the discharge ignition intensity in deep wells is shown. The efficiency of the impact of breakdown and corona discharges in water on the bottom-hole zone is compared. Options for using electrode systems with an increased electric field strength in the area of the pulse shaper in electrohydropulse devices for treating wells are shown. These include a dielectric patch with a small hole on the flat part of the working electrode. Types of plastic materials that could increase the level of electric field strength and carry out the required number of stable breakdown discharges for one hoisting operation, at least 4.0∙10 ⁴ pulses, are described.