RU2444620C1 - Method for formation well bore zone treatment - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: method for treatment of formation well bore zone involves fluid pumping to borehole cavity, formation of depression pressure drop between formation well bore zone and borehole cavity by creating periodic pressure pulses in perforation zone in the form of a wave moving along borehole cavity. Wave is formed during periodic opening on mouth of borehole cavity which is under pressure and its closing using fluid drain and filling valves. Well pressure is increased by periodic opening. Valve opening is performed at the intervals providing its mass shaking. At that, pumping pressure and flow of pumped liquid is measured. Pumping is performed with gradual pressure increase during the time period which is enough for formation crack opening. Filling valve is closed and drain valve is opened after complete increase in pumping pressure and interruption of increase in fluid flow.

EFFECT: improving formation permeability.

Description

The invention relates to mining and can be used to develop and restore the production rate of production wells, decreased as a result of mudding of the bottomhole zone with asphalt-resin-paraffin formations and solids.

A known method of cleaning a well from deposits during its operation (Veliev F.G., Kurbanov R.A.-I., Aliev E.N. Patent No. 1700207, class ЕВВ 37/00), in which waves are periodically generated at the wellhead negative pressure, for which they block the valves on the flow line and maintain it in the closed state, then open.

However, the maximum change in pressure from water hammer when opening the flow line is 1.5 MPa for fractions of a second, which is not enough for the formation of a powerful wave, in addition, it is necessary to use a pump with its power supply.

There is a method of development and cleaning of the bottomhole zone of wells by pulse drainage (Nosov P.I., Senochkin P.D., Nurislamov N.B. et al. Patent No. 2159326, class Е21В 43/25), in which the formation of a pressure drop between the bottom-hole zone of the formation and the cavity of the well is made by pre-pumping fluid into the well, creating periodic pressure pulses in the bottom-hole zone of the formation in the form of a damped standing wave moving along the cavity of the well, and bleeding off the pressure when moving the fluid through the well from the bottom-hole ons of the formation to the day surface with a sharp opening of the well cavity.

However, the bottom-hole zone is poorly washed by well fluid since the water hammer has a short exposure time during which the formation cracks do not have time to fully open and close during the impact.

A known method of processing the borehole zone of the formation (Shipulin A.V. Patent No. 2266404, class ЕВВ 43/25), including the creation of periodic pressure pulses in the borehole zone of the formation in the form of a shock wave moving along the cavity of the well, which is formed when the well cavity is periodically opened at the wellhead using valves, one of which connects the well cavity with a drain tank, the second - with a source of liquid under pressure.

However, the bottom-hole zone is poorly washed by well fluid since the water hammer has a short exposure time during which the formation cracks do not have time to fully open and close during the impact.

A known method of processing the bottom-hole zone of the formation (Shipulin A.V. Patent No. 2383720, class ЕВВ 43/25), taken as a prototype, including the formation of a depression of the pressure difference between the bottom-hole zone and the cavity of the well by creating periodic pressure pulses in the bottom-hole zone in the form of a moving along the cavity of the borehole, waves of movement of the mass of fluid generated during the periodic opening of the borehole at the wellhead with a frequency that ensures the buildup of its mass in resonance mode, and the spout is carried out by abrupt Thiel fluid drain for generating a shock wave depression.

However, when implementing the method, the amount of injected fluid and its injection rate into the formation are not controlled, at which “collapse” of the formation cracks or forcing a large amount of contaminants into the collector depth is possible.

The objective of the invention is the periodic maximum and short-term opening of fractures in the reservoir for washing the borehole zone of the reservoir and the development of cracks in order to increase permeability.

The problem is solved in that, using a method of processing the borehole zone of the formation, including pumping fluid into the cavity of the wellbore, forming a depressive differential pressure between the borehole zone of the formation and the cavity of the well by creating periodic pressure pulses in the perforation zone in the form of a wave generated along the cavity of the well, which is generated during periodic opening the well cavity under pressure at the mouth and closing it using valves, one of which is a fluid drain valve that connects the cavity b wells with a drainage tank and open the well cavity for leakage of the wellbore fluid and the formation of a shock wave of depression, the second - a fluid filling valve connects the wellbore to a source of fluid under pressure and periodically opens it increases the pressure in the well, the valves are opened with a frequency that ensures the buildup of its mass, the injection pressure and the flow rate of the injected liquid are measured, the injection is carried out with a gradual increase in pressure over a time sufficient for p hiding crack formation, refilling valve closing and opening the spout valve produced after full pressurization injection and cessation of increasing fluid flow.

This method allows you to gradually increase the injection of fluid into the well for the greatest opening of the cracks and determine the moment of their maximum opening for the timely implementation of the outflow operation with a depressive effect.

The method is implemented as follows. At the wellhead, valves are installed, the first of which connects the tubing cavity to the drainage tank, the second - the annulus with a source of fluid under pressure, for example, a fluid line designed to pump fluid into injection wells or CA-320 aggregate.

With the fluid drain valve closed, the topping valve is opened and the fluid injection pressure is gradually increased. The rate of increase in fluid injection pressure should be low enough to prevent “collapse” of the formation cracks due to the difference between the borehole and reservoir pressures and, at the same time, high enough to fill and expand. The rate of increase in injection pressure is selected empirically, based on geological and production well conditions.

With increasing pressure of the fluid injection, its flow rate increases and reaches a maximum at full pressure. After filling and expansion of the formation cracks in the near-wellbore zone, as well as due to the elastic properties of the reservoir rock, the increase in the flow rate of the injected fluid decreases. High reservoir clogging leads to a sharp decrease in the flow rate of injected fluid. With a decrease in flow rate, the injection is stopped and the valve for draining the liquid is suddenly opened. The moment of the beginning of the spout is chosen, on the one hand, to ensure maximum expansion of the cracks, on the other hand, the minimum volume of injected fluid and squeezers pressed in the depth of the collector, which accumulate in the bottomhole zone during its processing.

Downhole fluid begins to pour into the drain tank, the fluid pressure at the wellhead drops sharply to atmospheric pressure, a rarefaction wave forms, which moves from the wellhead to the bottom of the well and forms a depression impulse in the bottomhole zone.

The depression pulse contributes to the separation of adsorption deposits from the walls of the pore channels and cracks, as well as their removal into the cavity of the well for subsequent extraction to the day surface.

After the outflow of a portion of the borehole fluid, the operations of pumping the fluid to fill and expand the fractures of the formation and its repeated outflow are repeated.

Periodic reciprocating movement of the mass of fluid through the borehole zone of the formation contributes to its erosion, as well as the creation of new and development of existing fractures, which contributes to an increase in permeability.

Well fluid may contain chemicals for more productive processing. The processing method contributes to the saving of chemicals due to their controlled and limited injection into the reservoir. The method can be applied in conjunction with other types of bottom-hole treatment: acidic, thermal, vibrational, acoustic, etc.

Claims (1)

A method of processing a borehole zone of a formation, including pumping a liquid into a cavity of a well, forming a pressure drop between the borehole zone of a formation and a cavity of a well by creating periodic pressure pulses in the perforation zone in the form of a wave generated when the hole is located at the mouth of the well and is periodically open under pressure, and closing it using valves, one of which is a fluid drain valve that connects the well cavity to the drain tank and it covers the well cavity for leakage of the wellbore fluid and the formation of a shock wave of depression, the second - a fluid filling valve connects the well cavity to a source of fluid under pressure, and periodically opens it increases the pressure in the well, the valves are opened with a frequency that ensures the buildup of its mass, characterized in that the injection pressure and the flow rate of the injected liquid are measured, the injection is carried out with a gradual increase in pressure over a period of time sufficient to open the yn reservoir, refilling valve closing and opening the spout valve produced after full injection pressure increases and increasing fluid flow cease.