RU2203412C2 - Method and facility for hydraulic fracturing of bed - Google Patents

Abstract

FIELD: oil production, intensified oil output. SUBSTANCE: method includes insulation of productive interval, filling of tubing string with fluid and formation of water hammer by means of fluid injection and pressure relief in tubing string. In accordance with invention fluid is pumped from well by hydraulic pump till tubing string is full. Interval of hydraulic fracturing is insulated by packer placed in well below dynamic level but above productive interval. Gate is shut off and excessive pressure is created in tubing string with the use of hydraulic pump, pressure is discharged into zone under packer when specified value is achieved with the aid of valve. After it well is opened periodically and output of well is measured. Hydraulic fracturing is stopped after stabilization of output. Facility for realization of method has tubing string, packer, pressure relief valve. Facility has gate to close space of tubing string, hydraulic pump to evacuate fluid from well, to fill tubing string and to form excessive pressure in tubing string. Pressure relief valve is tuned to opening pressure creating conditions for hydraulic fracturing and is mounted on tubing string between packer and hydraulic pump communicating space of tubing string with zone under packer. EFFECT: increased amplitude and frequency of water hammers, reduced expenses for hydraulic fracturing of bed. 2 cl, 2 dwg

Description

 The invention relates to the field of oil industry and can be used to intensify oil production.

 There is a method of intensifying the inflow from the well by creating pressure pulses using a pump plunger that pumps pressure into the tubing and releases it when the plunger leaves the piston in its highest position. Pressure pulses propagate in a well that is completely filled with fluid, and the underlying productive intervals are isolated by a cement bridge. A well is filled with a pumping unit on the surface, and leaks from the well are compensated from the reservoir connected to the well cavity [1].

 The specified method was adopted by us as a prototype.

The disadvantages of this method include
- the output of the plunger from the piston leads to shock loads on the rods and plunger, their oscillations, which can lead to distortions and jamming of the plunger, as well as the ingress of sand and other abrasive material into the plunger pair;
- high-pressure impulses, propagating throughout the wellbore, can violate the tightness of the casing, and a significant amount of annular space does not allow to obtain a significant amplitude and a steep front of pressure pulses;
- to fill the well, it is required to attract an additional pumping unit, which reduces the economic efficiency of the method.

 The objective of the proposed method is to increase the amplitude of water hammer with a steep pulse front while reducing the load on the device, as well as determining the necessary time for stimulation.

 To successfully solve this problem in a known method, including isolating the production interval, filling the tubing with liquid and creating water hammer by pumping and depressurizing the fluid in the tubing, it is new that the fluid is pumped out of the well with a hydraulic pump before the pump compressor pipes, then isolate the fracturing interval with a packer below the dynamic level in the well, but above the productive interval, close the well and pump the pump m in the tubing overpressure, dropping it into the under-packer zone when the specified value is reached by means of a valve, after which the well is periodically opened and the flow rate from the well is measured, and the creation of water hammer stops after flow rate stabilization.

 As a result of the application of the proposed method, in comparison with the known method, the amplitude and steepness of the front of the shock pulses increase, as well as the reliability of hydraulic fracturing, and the effectiveness of the technology is monitored during hydraulic fracturing.

 We are not aware of hydraulic fracturing methods using pressure pulses having a combination of the above characteristics, which means that the proposed method meets the requirements of the inventions.

 A device for hydraulic fracturing containing a burst valve installed in the tubing above the packer [2].

 The specified device is accepted by us as a prototype.

 The disadvantage of this device is the low efficiency due to a one-time action of the valve.

 The objective of the proposed device is to increase the frequency of water hammer, which reduces the cost of hydraulic fracturing, as well as determining the number of water hammer.

 To solve this problem in a known device for hydraulic fracturing, which includes a tubing string, a pressure relief valve and a packer, it is new that it contains a hydraulic pump, and a pressure relief valve is installed on the tubing between the packer and the hydraulic pump, connecting the cavity tubing with subpacker zone.

 These signs can eliminate the disadvantages inherent in the known devices for hydraulic fracturing, by creating a series of hydraulic shock with a high amplitude of pressure pulses.

 We are not aware of devices for hydraulic fracturing that have a combination of the above features, which means that the proposed device meets the requirements for inventions.

 In FIG. 1 shows a diagram of the device. Figure 2 shows a graph of changes in flow rate from the well at the wellhead in the process of operation of the device.

 The device consists of a rod hydraulic pump 1 installed in tubing 2 and driven by a rocking machine 3 by means of rods 4. Between the rod pump 1 and the packer 5, a pressure relief valve 6 is installed. The cavity of the tubing 2 is sealed with an oil seal 7 and can be closed using a valve 8.

 The work of the proposed device and the method of hydraulic fracturing with its help is as follows.

 After the descent of the tubing 2 along with the sucker rod pump 1 and the packer 4, the fluid is pumped out of the well using a rocking machine 3 and the rod string 4 with the valve open 8. After filling the tubing 2, the fracturing interval is isolated with a packer 4 below the dynamic the liquid level in the well and close the valve 8. In the closed cavity of the tubing 2, with each working stroke of the plunger, the sucker-rod pump 1 creates excessive pressure in them. When the excess pressure exceeds a predetermined value, to which the pressure relief valve 6 is configured, it opens and communicates the cavity of the tubing 2 with a sub-packer zone, the pressure in which increases sharply.

 Hydraulic fracturing in Western Siberia requires an excess of pressure over hydrostatic of the order of 16 MPa. A sucker-rod hydraulic pump can create an overpressure of up to 24 MPa, therefore, by adjusting the pressure on valve 6 to a value of 16 MPa, conditions are created for hydraulic fracturing.

 Impulses of pressure greater than the fracture pressure of the rock lead to the formation and propagation of cracks that are wedged by debris. There is an increase in the flow rate from the well (Fig. 2), which can be measured by periodically opening the valve 8. When the flow rate Q stops growing and the flow rate curve changes in time t (t. A), water hammer stops.

Sources of information
1. RF patent 2075596, publ. 03/20/97.

 2. USSR Author's Certificate 956766, publ. 09/07/82.

Claims (2)

 1. The method of hydraulic fracturing, including isolating the production interval, filling the tubing with liquid and creating water hammer by pumping and depressurizing the fluid in the tubing, characterized in that the fluid is pumped out of the well by a hydraulic pump before filling the tubing, then isolate the fracturing interval with a packer below the dynamic level in the well, but above the productive interval, close the valve and pump the hydraulic pump into the tubing x overpressure dropping it into packer area when reaching a predetermined value by a valve, after which periodically open borehole and measure the flow rate of the well, and the creation of fractures is stopped after the stabilization of flow rates.  2. A device for hydraulic fracturing, including a tubing string, a pressure relief valve and a packer, characterized in that it comprises a valve for closing the cavity of the tubing string, a hydraulic pump for pumping fluid from the well, filling the tubing string and creating excess pressure in them, and the pressure relief valve is set to the opening pressure, which creates the conditions for hydraulic fracturing, and is installed on tubing between the packer and the hydraulic pump to connect the cavity tubing with subpacker zone.

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