CN111980879A - High pressure pulse fluid output device and rock hydraulic fracturing method - Google Patents

Abstract

The invention discloses a high-pressure pulse fluid output device and a rock water fracturing method. The high-pressure pulse fluid output device comprises a double-acting hydraulic cylinder controlled by an electro-hydraulic servo valve, a first single-acting pulse boosting cylinder and a second The single-acting pulse booster cylinder, the second single-acting pulse booster cylinder is provided with a displacement sensor for indirectly measuring the moving speed of its internal booster piston, the first single-acting pulse booster cylinder and the second single-acting pulse booster cylinder are provided with a displacement sensor. The one-way liquid outlet is connected to the high-pressure output main pipe; the high-pressure output main pipe is provided with a pressure sensor and a flow sensor, and the pressure sensor, flow sensor, displacement sensor and electro-hydraulic servo valve are all electrically connected with the servo controller. The invention adopts the double-acting hydraulic cylinder controlled by the electro-hydraulic servo valve to be connected with the first single-acting pulse booster cylinder and the second pulse booster on both sides, which can realize precise hydraulic pulse pressure and pulse flow control, and has the advantages of simple structure and stable strong advantage.

Description

High pressure pulse fluid output device and rock hydraulic fracturing method

technical field

The invention belongs to the technical field of rock hydraulic fracturing, in particular to a high-pressure pulse fluid output device and a rock hydraulic fracturing method.

Background technique

In order to improve the permeability of rock or accelerate the wetting effect of rock, hydraulic fracturing technology has been widely used in oil and gas fields and downhole mining and other production fields. In the field of rock hydraulic fracturing technology, pulse hydraulic fracturing is an optimized fracturing technology for rock fracturing by converting continuous fluid into pulsed fluid through a pulse device. Compared with ordinary steady-flow static fracturing, pulse hydraulic fracturing has the dual-effect fracturing effect of water wedge action and fatigue action. In recent years, it has been applied in laboratory physical model tests and field mining.

However, the existing pulse hydraulic fracturing devices still have many performance defects. For example, the early pulse hydraulic fracturing device used the excitation cavity turbulence to form the pulse fluid, and its pulse effect and pulse frequency were difficult to control; the field-applied double-cylinder pulse pump directly output the pulse fluid, and its pulse frequency was controllable, but the frequency control The scope is small, the pulse waveform is single, and the flow output is unstable; later, in order to overcome the above problems, the patent CN108798673B discloses a water-driven high-pressure pulse fluid output device and operation method, using two sets of single-acting pulse booster cylinders to alternate high-pressure pulse fluids In the form of output, controllable pulse pressure output can be realized; however, the juxtaposition of two groups of single-acting pulse booster cylinders is more complex, and the control system is extremely demanding during the implementation process, and it is extremely difficult to control dual-cylinder anti-phase synergies. .

In conclusion, it is necessary to improve the existing technology.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a high-pressure pulse fluid output device and a rock hydraulic fracturing method, wherein a double-acting hydraulic cylinder controlled by an electro-hydraulic servo valve is connected to the first single-acting pulse booster cylinder and the second pulse booster on both sides , can realize accurate hydraulic pulse pressure and pulse flow control, and has the advantages of simple structure and strong stability.

To achieve the above object, the present invention adopts the following technical solutions:

The high-pressure pulse fluid output device includes a double-acting hydraulic cylinder controlled by an electro-hydraulic servo valve, and a first single-acting pulse boosting cylinder and a second single-acting pulse boosting cylinder with the same structure. Both ends are respectively butted with the boosting pistons of the first single-acting pulse boosting cylinder and the second single-acting pulse boosting cylinder on both sides;

The second single-acting pulse booster cylinder is provided with a displacement sensor for indirectly measuring the moving speed of its internal booster piston. The liquid outlet port is connected to the high pressure output main pipe;

The high pressure output manifold is provided with a pressure sensor and a flow sensor, and the pressure sensor, the flow sensor, the displacement sensor and the electro-hydraulic servo valve are all electrically connected with the servo controller.

Specifically, the servo controller is connected to an industrial computer.

Specifically, the displacement sensor adopts a magnetic displacement sensor, the boosting piston in the second single-acting pulse booster cylinder is provided with a measuring rod mounting hole, and the magnetic ring of the magnetic displacement sensor is fixedly mounted on the measuring rod In the mounting hole, the measuring rod of the magnetic displacement sensor is inserted into the measuring rod mounting hole through the magnetic ring coaxially, and the axis of the measuring rod mounting hole and the axis of the magnetic ring are the same as the increasing The movement direction of the pressure piston is parallel.

Specifically, the first single-acting pulse booster cylinder is provided with a first one-way liquid inlet hole, a first one-way liquid outlet hole and a liquid outlet hole, and the second single-acting pulse booster cylinder is provided with a first one-way liquid inlet hole, a first one-way liquid outlet hole and a liquid outlet hole. Two one-way liquid inlet holes and second one-way liquid outlet holes;

The first one-way liquid inlet hole is connected with a first normally open electromagnetic cut-off valve, the first one-way liquid outlet hole is connected with a second normally open electromagnetic cut-off valve, and the liquid outlet hole is connected with a second normally open electromagnetic cut-off valve. a first normally closed electromagnetic globe valve, a third normally open high-pressure globe valve is connected to the second one-way liquid inlet hole, and a two-position three-way high-pressure solenoid valve is connected to the second one-way liquid outlet port;

The first normally open electromagnetic globe valve, the first normally closed electromagnetic globe valve, the second normally open electromagnetic globe valve, the third normally open high pressure globe valve and the two-position three-way high pressure solenoid valve are all connected with the servo valve. Controller connection.

Specifically, the output device further includes a water tank, and the water tank is connected to the two-position three-way high-pressure solenoid valve, the first normally-open electromagnetic cut-off valve and the third normally-open high-pressure cut-off valve.

Specifically, an adjustable high-pressure overflow valve is arranged between the water tank and the high-pressure output main pipe.

Specifically, the second normally-open electromagnetic globe valve, the first normally-closed electromagnetic globe valve and the two-position three-way high-pressure solenoid valve are connected with the first high-pressure output pipe, the second high-pressure output pipe and the third high-pressure output pipe respectively The input end of the high-voltage output manifold is connected.

Specifically, a stainless steel accumulator is also arranged on the high-pressure output main pipe, a second normally closed electromagnetic shut-off valve is arranged between the high-pressure output main pipe and the stainless steel accumulator, and the second normally closed electromagnetic The shut-off valve is electrically connected with the servo controller.

Specifically, the output device further includes an oil tank, a hydraulic pump and a one-way valve for oil;

The oil tank is connected to the oil supply hole of the electro-hydraulic servo valve through an oil supply passage, the hydraulic pump and the oil check valve are arranged on the oil supply passage, and an overflow is also arranged on the oil supply passage Valves, gas-charged accumulators and pressure gauges;

The oil return port of the electro-hydraulic servo valve is connected to the oil tank through a high-pressure oil pipe, and the two output ports of the electro-hydraulic servo valve are respectively connected to the two oil inlet ports of the double-acting hydraulic cylinder.

Specifically, the oil supply passage is further provided with a first oil filter and a second oil filter.

The rock hydraulic fracturing method, using the above-mentioned high-pressure pulse fluid output device, includes the following steps:

Step 1. Pre-injection

Connect the high pressure output main pipe to the fracturing pipe in the rock fracturing hole, inject fracturing fluid into the water tank, take the movement speed of the booster piston monitored by the displacement sensor as the feedback signal, and input positive and negative symmetrical square waves to the servo controller The moving speed control signal, the electro-hydraulic servo valve controls the hydraulic piston of the double-acting hydraulic cylinder to reciprocate at a constant speed, and then push the booster pistons of the first single-acting pulse booster cylinder and the second single-acting pulse booster cylinder to reciprocate at a constant speed through the piston rod. Movement, the corresponding first single-phase liquid inlet hole and the second single-phase liquid inlet hole alternately absorb water from the water tank at a constant speed, and the corresponding first single-phase liquid outlet hole and the second single-phase liquid outlet hole alternately go to the high-pressure output main pipe at a constant speed without interruption When the detection value of the flow sensor and pressure sensor is stable, it indicates that the high-pressure output main pipe and fracturing pipe are basically filled with fracturing fluid;

Step 2. Preliminary pressure-controlled pulse injection

Control the boosting piston of the first single-acting pulse booster cylinder to retract to the limit position, that is, the first single-acting pulse booster cylinder is filled with water, control the first normally open electromagnetic cut-off valve and the second normally open electromagnetic cut-off The valve and the third normally open high pressure shut-off valve are closed; the action of the two-position three-way high-pressure solenoid valve is controlled, so that the second single-phase liquid outlet port is relieved of pressure through the two-position three-way high-pressure solenoid valve; the first normally closed electromagnetic cut-off valve is controlled Open, that is, the fluid in the corresponding liquid outlet is connected to the high-pressure output main pipe, at this time, only the first single-acting pulse booster cylinder is connected to the high-pressure output main pipe;

Using the liquid pressure monitored by the pressure sensor as the feedback signal, the pulse pressure control signal is input to the servo controller, and the pressure peak value is less than the theoretically calculated rock cracking pressure value. The electro-hydraulic servo valve controls the reciprocating motion of the hydraulic piston of the double-acting hydraulic cylinder. The booster piston of the first single-acting pulse booster cylinder is pushed by the piston rod to reciprocate. At this time, the fracturing fluid in the cylinder is alternately pushed out and inhaled from the liquid outlet, and the pressure rise and fall waveforms are generated in the high-pressure output manifold, and the servo control is adjusted. The input frequency, waveform and duration will generate the corresponding pulse pressure wave in the rock fracturing hole to achieve the fatigue pulse effect before fracturing;

Step 3. Medium-term continuous hydraulic injection fracturing

After the pressure-controlled pulse injection is completed, the moving speed monitored by the displacement sensor is used as the feedback signal, and a negative uniform moving speed control signal is input to the servo controller. The electro-hydraulic servo valve controls the hydraulic piston of the double-acting hydraulic cylinder to move to the first position. The single-acting pulse booster cylinder advances at a constant speed, and the booster piston of the first single-acting pulse booster cylinder is pushed forward at a constant speed through the piston rod, and the corresponding fracturing fluid in the cylinder is continuously pushed out from the liquid outlet, which promotes the high-pressure output manifold and The pressure in the fracturing tube continues to increase, and is monitored by the pressure sensor until it reaches the fracturing pressure of the fracturing hole; after hydraulic fractures are generated, the pressure-controlled liquid injection fails after the pressure drops sharply;

Step 4. Post-flow-controlled pulse injection

Control the first normally closed electromagnetic globe valve to close, that is, the liquid outlet is disconnected from the outside world; then, control the first normally open electromagnetic globe valve, the second normally open electromagnetic globe valve and the third normally open high pressure globe valve Open, control the reset of the two-position three-way high-pressure solenoid valve, so that the second one-way liquid outlet is connected to the high-pressure output main pipe through the two-position three-way high-pressure solenoid valve;

The movement speed monitored by the displacement sensor is used as the feedback signal, and the movement speed control signal is input to the servo control. The electro-hydraulic servo valve controls the reciprocating non-uniform movement of the hydraulic piston of the double-acting hydraulic cylinder, and then pushes the first single-acting pulse pressurization through the piston rod. The booster pistons of the cylinder and the second single-acting pulse booster cylinder reciprocate at a non-uniform speed, and the corresponding first one-way liquid inlet hole and the second one-way liquid inlet hole alternately absorb water from the water tank at a non-uniform speed, and the corresponding first one-way liquid outlet The liquid hole and the second one-way liquid outlet alternately pump water to the high-pressure output main pipe at a non-uniform speed to form a pulse flow output. The flow sensor monitors the pulse flow output state. At this time, the fracturing fluid in the fracturing pipe continues in the form of flow pulses. input, and produce further pulse effect on the formed hydraulic fracture, which continues to act on the later expansion process of the hydraulic fracture.

Compared with the prior art, the present invention has the following beneficial effects:

1. Precise and controllable pulse flow: a double-acting hydraulic pulse booster mechanism is adopted, and the reciprocating displacement stroke and speed of the booster piston are controlled through the cooperation of the displacement sensor and the electro-hydraulic servo valve, and then converted into a pair of first single-acting pulses. Precise control of real-time flow pulses in the booster cylinder and the second single-acting pulse booster cylinder.

2. The pulse pressure is precise and controllable: a double-acting hydraulic pulse booster mechanism is adopted, and the first single-acting pulse booster cylinder is provided with a liquid outlet hole. When the pulse pressure waveform is output, the liquid outlet hole is directly connected to the high-pressure output main pipe. On, in the state of locking other liquid inlet and outlet, the closed-loop control of the pressure waveform is carried out, and the high-precision control of the whole pulse pressure waveform is realized.

3. Simplified structure and high stability: when the double-acting hydraulic pulse booster mechanism is used to implement the hydraulic output coupled with pressure pulse and flow pulse, only one set of double-acting hydraulic cylinder, one set of electro-hydraulic servo valve and one set of servo controller are required , all functions can be realized by cooperating with the relevant solenoid valve. Compared with the existing device, its structure is simple, no coordinated control is required, the stability of the device is improved, and the cost is reduced.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

1 is a schematic structural diagram of a high-voltage pulsed fluid output device provided by an embodiment of the present invention;

2 is an axonometric view of a double-acting hydraulic pulse booster mechanism provided by an embodiment of the present invention;

3 is a main cross-sectional view of a double-acting hydraulic pulse booster mechanism provided by an embodiment of the present invention;

Among them: 1- hydraulic oil source and control mechanism; 2- double-acting hydraulic pulse booster mechanism; 3- high-pressure fluid output mechanism; 4- hydraulic oil source device; 5- fluid control device; 6- high-pressure oil pipe; 7- fuel tank; 8-First oil filter; 9-Hydraulic pump; 10-Oil check valve; 11-Second oil filter; 12-Relief valve; 13-Pneumatic accumulator; 14-Pressure gauge; 15-Three Position four-way electro-hydraulic servo valve; 16-servo controller; 17-industrial computer; 18-oil supply hole; 19-oil return port; 20-output port; 21-double-acting hydraulic cylinder; 22-first single-acting pulse increase Pressure cylinder; 23-The second single-acting pulse booster cylinder; 24-Stainless steel booster cylinder; 25-Booster piston; 26-Cylinder head; 27-The first one-way liquid inlet hole; 28-The first one-way liquid outlet hole; 29- liquid outlet hole; 30- liquid inlet check valve; 31- first normally open electromagnetic globe valve; 32- liquid outlet one-way valve; 33- second normally open electromagnetic globe valve; 34- first Normally closed electromagnetic globe valve; 35- the second one-way liquid inlet; 36- the second one-way liquid outlet; 37- the third normally open high-pressure globe valve; 38- two-position three-way high-pressure solenoid valve; 39- Displacement sensor connecting hole; 40-step round hole; 41-magnetic displacement sensor; 42-magnetic ring; 43-measuring rod; 44-electronic processing unit body; 45-high pressure sealing ring; 46-hydraulic piston; 47-piston rod ; 48- the first high-pressure output pipe; 49- the second high-pressure output pipe; 50- the third high-pressure output pipe; 51- high-pressure output manifold; 52- water tank; 53- the first output port; Sensor; 56-Stainless Steel Accumulator; 57-Second Normally Closed Electromagnetic Globe Valve; 58-High-Pressure Relief Valve; 59-Second Output Port; 60-High-Pressure Pipeline.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Referring to FIG. 1, a high-pressure pulse fluid output device includes a hydraulic oil source and a control mechanism 1, a double-acting hydraulic pulse booster mechanism 2 and a high-pressure fluid output mechanism 3, and the hydraulic oil source and the control mechanism 1 match the double-acting hydraulic pulse booster The mechanism 2 is used to provide hydraulic drive oil source and servo control commands; the double-acting hydraulic pulse booster mechanism 2 is connected to the high-pressure fluid output mechanism 3 to output controllable high-pressure pressure pulsation and flow pulsation.

Referring to Figure 1, the hydraulic oil source and control mechanism 1 is mainly composed of a hydraulic oil source device 4 and a fluid control device 5; the hydraulic oil source device 4 includes an oil tank 7, a hydraulic pump 9 and an oil check valve 10, an oil tank 7, a hydraulic pump 9 and the oil check valve 10 are connected in sequence through the high-pressure oil pipe 6 to form an oil supply passage. The oil supply passage is also provided with a relief valve 12 that controls the pressure of the oil supply passage, and a gas-filled accumulator that maintains a stable pressure in the oil supply passage. 13 and a pressure gauge 14 showing the oil pressure in the oil supply passage; the fluid control device 5 is mainly composed of a three-position four-way electro-hydraulic servo valve 15, a servo controller 16 and an industrial computer 17; the oil supply hole 18 of the electro-hydraulic servo valve 15 is connected to the The oil passage is connected, the oil return port 19 of the electro-hydraulic servo valve 15 is connected to the oil tank 7 through the high-pressure oil pipe 6, and the two output ports 20 of the electro-hydraulic servo valve 15 are connected to the double-acting hydraulic pulse boosting mechanism 2 through the high-pressure oil pipe 6; The servo valve 15 is also electrically connected to the servo controller 16 and the industrial computer 17 in sequence.

In addition, in practical applications, the first oil filter 8 and the second oil filter 11 can also be arranged on the oil supply passage, and the relief valve 12, the gas-filled accumulator 13 and the pressure gauge 14 are arranged on the oil check valve. 10 and the oil supply passage between the second oil filter 11.

1-3, the double-acting hydraulic pulse boosting mechanism 2 includes a double-acting hydraulic cylinder 21 controlled by the electro-hydraulic servo valve 15, a first single-acting pulse boosting cylinder 22 connected to one end of the double-acting hydraulic cylinder 21, and a The second single-acting pulse booster cylinder 23 at the other end of the double-acting hydraulic cylinder 21 has the same structure as the first single-acting pulse booster cylinder 22 and the second single-acting pulse booster cylinder 23, both of which are plunger-type booster structures. All include stainless steel booster cylinder 24, booster piston 25 and cylinder head 26;

In practical application, a first one-way liquid inlet hole 27 , a first one-way liquid outlet hole 28 and a liquid outlet are provided in the stainless steel pressurizing cylinder 24 at the front end of the pressurizing piston 25 of the first single-acting pulse pressurizing cylinder 22 Hole 29; the first one-way liquid inlet hole 27 is connected to the outer side of the stainless steel booster cylinder 24 with a first normally open electromagnetic stop valve 31; the first one-way liquid outlet hole 28 is connected to the outside of the stainless steel booster cylinder 24 with a second constant The open electromagnetic cut-off valve 33; the liquid outlet hole 29 is connected with a first normally closed electromagnetic cut-off valve 34 to the outside of the stainless steel booster cylinder 24; the stainless steel booster cylinder at the front end of the booster piston 25 of the second single-acting pulse booster cylinder 23 24 is provided with a second one-way liquid inlet hole 35 and a second one-way liquid outlet hole 36; the second one-way liquid inlet hole 35 is connected to the outside of the stainless steel booster cylinder 24 with a third normally open high-pressure cut-off valve 37; The two one-way liquid outlet holes 36 are connected with a two-position three-way high-pressure solenoid valve 38 to the outside of the stainless steel booster cylinder 24; A liquid inlet one-way valve 30 is provided on the top, and the first one-way liquid outlet hole 28 and the second one-way liquid outlet hole 36 refer to a liquid outlet one-way valve 32 provided on the liquid outlet hole.

A displacement sensor connecting hole 39 is also opened in the center of the stainless steel booster cylinder 24 at the front end of the booster piston 25 of the second single-acting pulse booster cylinder 23 . There is also a stepped circular hole 40 in the booster piston 25; the front side of the stainless steel booster cylinder 24 of the second single-acting pulse booster cylinder 23 is provided with a magnetic displacement sensor (magnetostrictive) for indirectly measuring the moving speed of the booster piston. Displacement sensor) 41, the magnetic ring 42 of the magnetic displacement sensor 41 is coaxially assembled at the front end of the stepped circular hole 40, the measuring rod 43 of the magnetic displacement sensor 41 is inserted into the cylinder through the displacement sensor connecting hole 39, and is further passed through the magnetic ring 42. The center is coaxially inserted into the stepped circular hole (measuring rod mounting hole) 40; the rear end of the measuring rod 43 is connected to the electronic processing unit 44 of the magnetic displacement sensor 41 outside the stainless steel booster cylinder 24, and the electronic processing unit 44 is bolt-fastened On the outside of the sensor connection hole 39, a high-pressure sealing ring 45 is arranged at the connection; the hole depth of the stepped circular hole 40 is twice the length of the measuring rod 43, the hole diameter is larger than the rod diameter of the measuring rod 43, and the center of the double-acting hydraulic cylinder 21 is set The hydraulic piston 46 is connected with the booster pistons 25 on both sides through the piston rod 47 , and the area of the hydraulic piston 46 is three to six times that of the booster piston 25 . Of course, other types of displacement sensors can also be used, but the magnetic displacement sensor 41 is used. Since the movable magnetic ring 42 for determining the position and the measuring rod (sensitive element) 43 are not in direct contact, the sensor can be used in extremely harsh industrial environments. It is not easily affected by oil stains, solutions, dust or other contamination.

In the embodiment of the present application, a double-acting hydraulic pulse boosting mechanism is adopted, and the reciprocating displacement stroke and speed of the boosting piston are controlled by the cooperation of the displacement sensor and the electro-hydraulic servo valve, and then converted into a single-acting pulse boosting mechanism for the first single-acting pulse booster. Precise control of real-time flow pulses for pressure cylinders and second single-acting pulse booster cylinders.

1-3, the high-pressure fluid output mechanism 3 is composed of a first high-pressure output pipe 48, a second high-pressure output pipe 49, a third high-pressure output pipe 50, a high-pressure output manifold 51 and a water tank 52; The second high-pressure output pipe 49 , the third high-pressure output pipe 50 and the high-pressure output main pipe 51 are all high-pressure hard pipes; The high-pressure fluid from the liquid outlet is connected to the high-pressure output main pipe 51; the second high-pressure output pipe 49 is connected to the first normally-closed electromagnetic shut-off valve 34, and the high-pressure fluid in the liquid outlet hole 29 is connected to the high-pressure output main pipe 51 when the valve is opened, and the third high-pressure output The pipe 50 is connected to the first output port 53 of the two-position three-way high-pressure solenoid valve 38, and communicates the high-pressure fluid in the second one-way liquid outlet hole 36 to the high-pressure output manifold 51 when the valve is opened. The high-pressure output manifold 51 is provided with a pressure sensor 54. The flow sensor 55 and the stainless steel accumulator 56, a second normally closed electromagnetic shut-off valve 57 is also arranged between the high pressure output main pipe 51 and the stainless steel accumulator 56, and an adjustable high pressure is arranged between the water tank 52 and the high pressure output main pipe 51 The overflow valve 58 and the water tank 52 are also connected to the second output port 59 of the two-position three-way high-pressure solenoid valve 38 , the first normally-open electromagnetic cut-off valve 31 and the third normally-open high-pressure cut-off valve 37 via the high pressure pipeline 60 .

Referring to FIG. 1 , the servo controller 16 is also connected with the first normally open electromagnetic stop valve 31, the second normally open electromagnetic stop valve 33, the third normally open high pressure stop valve 37, the first normally closed electromagnetic stop valve 34, The second normally closed electromagnetic globe valve 57 , the two-position three-way high-pressure electromagnetic valve 38 , the magnetic displacement sensor 41 , the pressure sensor 54 and the flow sensor 55 are electrically connected in parallel.

In the embodiment of the present application, a double-acting hydraulic pulse booster mechanism is adopted, and the first single-acting pulse booster cylinder is provided with a liquid outlet hole. When the pulse pressure waveform is output, the liquid outlet hole is directly connected to the high-pressure output manifold. When the other inlet and outlet ports are locked, the closed-loop control of the pressure waveform is carried out, and the high-precision control of the whole pulse pressure waveform is realized.

In addition, the embodiment of the present application only needs a set of double-acting hydraulic cylinders, a set of electro-hydraulic servo valves, and a set of servo controllers, and all functions can be realized in cooperation with relevant solenoid valves. Compared with the existing device, the structure is simple and does not require Coordinated control improves device stability and reduces costs.

Referring to Fig. 1-Fig. 3, the specific process of hydraulic fracturing rock by using the high-pressure pulse fluid output device of the above-mentioned embodiment is as follows:

Step 1. Pre-injection

First, use the high pressure pipeline 60 to connect the high pressure output main pipe 51 to the fracturing pipe in the rock fracturing hole, inject the fracturing fluid into the water tank 52, and adjust the adjustable high pressure relief valve 58 to a very low level of leakage. Then, start the high-pressure pulse fluid output device, and control the second normally closed electromagnetic cut-off valve 57 to open, to communicate with the stainless steel accumulator 56, and use the moving speed monitored by the magnetic displacement sensor as a feedback signal to the servo controller. 16 Input positive and negative symmetrical square wave moving speed control signal;

Immediately, the electro-hydraulic servo valve 15 controls the hydraulic piston 46 of the double-acting hydraulic cylinder 21 to reciprocate at a constant speed, and then pushes the first single-acting pulse boosting cylinder 22 and the second single-acting pulse boosting cylinder 23 via the piston rod 47. The piston 25 reciprocates at a constant speed, the corresponding first one-way liquid inlet hole 27 and the second one-way liquid inlet hole 35 alternately absorb water from the water tank 52 at a constant speed, and the corresponding first one-way liquid outlet hole 28 and the second one-way liquid outlet hole. 36 Alternately draw water to the first high-pressure output pipe 48 and the third high-pressure output pipe 50 at a constant speed, and collect into the high-pressure output main pipe 51 without interruption to form a continuous flow, and is controlled by the stainless steel accumulator 56 to further maintain a stable flow rate. The flow sensor 55 The steady flow output is monitored; after that, when the adjustable high pressure relief valve 58 reaches the set pressure value, the flow is opened and the pressure signal of the pressure sensor 54 remains stable, indicating that the high pressure pipeline 60 and the fracturing pipe are basically filled with fracturing fluid.

Step 2. Preliminary pressure-controlled pulse injection

First, control the boosting piston 25 of the first single-acting pulse boosting cylinder 22 to retract to the limit position, that is, the first single-acting pulse boosting cylinder 22 is filled with water; then, control the second normally closed electromagnetic cut-off valve 57 Close to disconnect the stainless steel accumulator 56 from the high pressure output main pipe 51, and adjust the adjustable high pressure relief valve 58 to the maximum pressure relief pressure; then, control the first normally open electromagnetic cut-off valve 31, the second normally open The electromagnetic shut-off valve 33 and the third normally open high-pressure shut-off valve 37 are closed, that is, the corresponding first one-way liquid inlet hole 27, first one-way liquid outlet hole 28 and second one-way liquid inlet hole 35 are closed; control two The three-position three-way high-pressure solenoid valve 38 is actuated, so that the second one-way liquid outlet 36 is connected to the water tank 52 through the second output port 59 of the two-position three-way high-pressure solenoid valve 38 to relieve pressure; the first normally closed electromagnetic stop valve 34 is controlled. Open, that is, the fluid in the corresponding liquid outlet hole 29 is connected to the high pressure output main pipe 51 through the second high pressure output pipe 49. At this time, only the first single-acting pulse booster cylinder 22 is connected to the high pressure output main pipe 51;

Then, take the liquid pressure monitored by the pressure sensor 54 as the feedback signal, input the pulse pressure control signal of sine wave, square wave, triangle wave or arbitrary waveform to the servo controller 16, and the pressure peak value is less than the theoretically calculated rock fracture initiation pressure value; , the electro-hydraulic servo valve 15 controls the reciprocating motion of the hydraulic piston 46 of the double-acting hydraulic cylinder 21, and pushes the first single-acting pulse booster cylinder 22 booster piston 25 to reciprocate through the piston rod 47. At this time, the fracturing fluid in the cylinder flows from The liquid outlet hole 29 is pushed out and sucked alternately, and the pressure rise and fall waveform is generated in the high pressure output main pipe 51. By adjusting the frequency, waveform and duration of the servo control input, a corresponding pulse pressure wave is generated in the rock fracturing hole, and the fracturing is achieved. Pre-fatigue pulse effect.

Step 3. Medium-term continuous hydraulic injection fracturing

After the pressure-controlled pulse injection is completed, the moving speed monitored by the magnetic displacement sensor is used as the feedback signal, and a negative uniform moving speed control signal is input to the servo controller 16; further, the electro-hydraulic servo valve 15 controls the double-acting hydraulic cylinder 21. The hydraulic piston 46 of the first single-acting pulse booster cylinder 22 advances at a constant speed in the direction of the first single-acting pulse booster cylinder 22, and the booster piston 25 of the first single-acting pulse booster cylinder 22 is pushed forward at a constant speed through the piston rod 47, and the corresponding fracturing fluid in the cylinder moves from The liquid outlet hole 29 is continuously pushed out, which makes the pressure in the high pressure output main pipe 51 and the fracturing pipe continue to increase. It is monitored by the pressure sensor 54 until it reaches the fracturing pressure of the fracturing hole. Injection failed.

Step 4. Post-flow-controlled pulse injection

Control the first normally closed electromagnetic stop valve 34 to close, that is, the liquid outlet 29 is disconnected from the outside world; then, control the first normally open electromagnetic stop valve 31, the second normally open electromagnetic stop valve 33 and the third normally open valve The first one-way liquid inlet hole 27, the first one-way liquid outlet hole 28 and the second one-way liquid inlet hole 35 are opened; the two-position three-way high-pressure solenoid valve 38 is controlled to reset, so that the The second one-way liquid outlet hole 36 is connected to the third high-pressure output pipe 50 through the first output port 53 of the two-position three-way high-pressure solenoid valve 38; at this time, the double-acting hydraulic pulse booster mechanism 2 returns to the state of the first step;

Next, keep the stainless steel accumulator 56 disconnected from the high-voltage output manifold 51, take the movement speed monitored by the magnetic displacement sensor as the feedback signal, and input positive and negative symmetrical sine waves or occupied square waves or triangle waves or arbitrary waveforms to the servo control. The electro-hydraulic servo valve 15 controls the reciprocating non-uniform motion of the hydraulic piston 46 of the double-acting hydraulic cylinder 21, and then pushes the first single-acting pulse booster cylinder 22 and the second single-acting pulse booster through the piston rod 47 The booster piston 25 of the cylinder 23 reciprocates at a non-uniform speed, the corresponding first one-way liquid inlet hole 27 and the second one-way liquid inlet hole 35 alternately absorb water from the water tank 52 at a non-uniform speed, and the corresponding first one-way liquid outlet hole 28 and The second one-way liquid outlet hole 36 alternately draws water to the first high pressure output pipe 48 and the first high pressure output pipe 48 at a non-uniform speed, and is collected into the high pressure output main pipe 51 for intermittent connection to form a pulse flow output. The flow sensor 55 monitors the pulse flow output. At this time, the fracturing fluid is continuously input in the form of flow pulses in the fracturing tube, and further pulses are generated on the formed hydraulic fractures, which continue to act on the later expansion process of the hydraulic fractures.

The above-mentioned embodiments are only examples to clearly illustrate the present invention, and are not intended to limit the embodiments. For those of ordinary skill in the art, changes or modifications in other different forms can also be made on the basis of the above description. Neither need nor can all embodiments be exhaustive here. And the obvious changes or changes derived from this are still within the protection scope of the present invention.

Claims (10)

1. High-pressure pulse fluid output device, its characterized in that: the hydraulic system comprises a double-acting hydraulic cylinder controlled by an electro-hydraulic servo valve, and a first single-acting pulse pressurizing cylinder and a second single-acting pulse pressurizing cylinder which are same in structure, wherein two ends of a piston rod of the double-acting hydraulic cylinder are respectively butted with pressurizing pistons of the first single-acting pulse pressurizing cylinder and the second single-acting pulse pressurizing cylinder on two sides;

a displacement sensor for indirectly measuring the moving speed of a pressurizing piston in the second single-action pulse pressurizing cylinder is arranged on the second single-action pulse pressurizing cylinder, and one-way liquid outlet holes of the first single-action pulse pressurizing cylinder and the second single-action pulse pressurizing cylinder are connected to a high-pressure output main pipe;

and the high-pressure output main pipe is provided with a pressure sensor and a flow sensor, and the pressure sensor, the flow sensor, the displacement sensor and the electro-hydraulic servo valve are all electrically connected with the servo controller.

2. The high-pressure pulsed fluid output device according to claim 1, characterized in that: the displacement sensor is a magnetic displacement sensor, a pressurizing piston in the second single-action pulse pressurizing cylinder is provided with a measuring rod mounting hole, a magnetic ring of the magnetic displacement sensor is fixedly mounted in the measuring rod mounting hole, a measuring rod of the magnetic displacement sensor coaxially penetrates through the magnetic ring and is inserted into the measuring rod mounting hole, and the axis of the measuring rod mounting hole and the axis of the magnetic ring are parallel to the moving direction of the pressurizing piston.

3. The high-pressure pulsed fluid output device according to claim 2, characterized in that: the first single-action pulse pressurizing cylinder is provided with a first one-way liquid inlet hole, a first one-way liquid outlet hole and a liquid outlet hole, and the second single-action pulse pressurizing cylinder is provided with a second one-way liquid inlet hole and a second one-way liquid outlet hole;

the first one-way liquid inlet hole is connected with a first normally-open electromagnetic stop valve, the first one-way liquid outlet hole is connected with a second normally-open electromagnetic stop valve, the liquid outlet hole is connected with a first normally-closed electromagnetic stop valve, the second one-way liquid inlet hole is connected with a third normally-open high-pressure stop valve, and the second one-way liquid outlet hole is connected with a two-position three-way high-pressure electromagnetic valve;

the first normally-open type electromagnetic stop valve, the first normally-closed type electromagnetic stop valve, the second normally-open type electromagnetic stop valve, the third normally-open type high-pressure stop valve and the two-position three-way high-pressure electromagnetic valve are all connected with the servo controller.

4. The high-pressure pulsed fluid output device according to claim 3, characterized in that: the output device further comprises a water tank, and the water tank is connected with the two-position three-way high-pressure electromagnetic valve, the first normally-open type electromagnetic stop valve and the third normally-open type high-pressure stop valve.

5. The high-pressure pulsed fluid output device according to claim 4, characterized in that: an adjustable high-pressure overflow valve is arranged between the water tank and the high-pressure output main pipe.

6. The high-pressure pulsed fluid output device according to claim 4, characterized in that: the second normally open type electromagnetic stop valve, the first normally closed type electromagnetic stop valve and the two-position three-way high-pressure electromagnetic valve are respectively connected with the input end of the high-pressure output main pipe through a first high-pressure output pipe, a second high-pressure output pipe and a third high-pressure output pipe.

7. The high-pressure pulsed fluid output device according to claim 4, characterized in that: still be equipped with the stainless steel energy storage ware on the high pressure output house steward, the high pressure output house steward with be provided with the normal close formula electromagnetism stop valve of second between the stainless steel energy storage ware, the normal close formula electromagnetism stop valve of second with servo controller electric connection.

8. The high-pressure pulsed fluid output device according to any one of claims 4 to 7, characterized in that: the output device also comprises an oil tank, a hydraulic pump and an oil check valve;

the oil tank is connected with an oil supply hole of the electro-hydraulic servo valve through an oil supply passage, the hydraulic pump and the oil check valve are arranged on the oil supply passage, and an overflow valve, an inflatable accumulator and a pressure gauge are further arranged on the oil supply passage;

an oil return port of the electro-hydraulic servo valve is connected with the oil tank through a high-pressure oil pipe, and two output ports of the electro-hydraulic servo valve are respectively connected with two oil inlets of the double-acting hydraulic cylinder.

9. The high-pressure pulsed fluid output device of claim 8, wherein: the oil supply passage is also provided with a first oil filter and a second oil filter.

10. Rock hydraulic fracturing method using a high pressure pulsed fluid output device according to any of claims 4 to 9, characterized in that it comprises:

step one, pre-injecting liquid

Connecting a high-pressure output main pipe with a fracturing pipe in a rock fracturing hole, injecting fracturing fluid into a water tank, taking the moving speed of a pressurizing piston monitored by displacement sensing as a feedback signal, inputting a square wave moving speed control signal with positive and negative symmetry to a servo controller, controlling the reciprocating uniform motion of a hydraulic piston of a double-acting hydraulic cylinder by an electro-hydraulic servo valve, further pushing the pressurizing pistons of a first single-acting pulse pressurizing cylinder and a second single-acting pulse pressurizing cylinder to reciprocate at a uniform speed through a piston rod, alternately sucking water from the water tank at a uniform speed through a corresponding first single-phase liquid inlet hole and a corresponding second single-phase liquid inlet hole, alternately pumping water to the high-pressure output main pipe at a uniform speed, and indicating that the high-pressure output main pipe and the fracturing pipe are basically filled with the fracturing fluid after detection values of a flow sensor and a pressure sensor are stable;

step two, pressure control type pulse liquid injection in early stage

Controlling a pressurizing piston of the first single-action pulse pressurizing cylinder to retract to a limit position, namely controlling the first normally-open electromagnetic stop valve, the second normally-open electromagnetic stop valve and the third normally-open high-pressure stop valve to be closed, wherein the first single-action pulse pressurizing cylinder is filled with water; controlling the two-position three-way high-pressure electromagnetic valve to act, so that the second single-phase liquid outlet hole is decompressed through the two-position three-way high-pressure electromagnetic valve; controlling the first normally closed type electromagnetic stop valve to be opened, namely, the fluid in the corresponding liquid outlet hole is communicated to the high-pressure output main pipe, and at the moment, only the first single-action pulse pressure cylinder is connected with the high-pressure output main pipe;

the method comprises the steps that liquid pressure monitored by a pressure sensor is used as a feedback signal, a pulse pressure control signal is input to a servo controller, the pressure peak value is smaller than a rock cracking pressure value calculated theoretically, an electro-hydraulic servo valve controls a hydraulic piston of a double-acting hydraulic cylinder to reciprocate, a pressurizing piston of a first single-acting pulse pressurizing cylinder is pushed by a piston rod to reciprocate, at the moment, cracking liquid in the cylinder is alternately pushed out and sucked from a liquid outlet hole, the frequency, waveform and duration time of servo control input are adjusted, and a corresponding pulse pressure wave effect is generated in a rock cracking hole, so that a fatigue pulse effect before cracking is achieved;

step three, middle-period continuous liquid injection fracturing

After pressure control type pulse injection is finished, a moving speed monitored by a displacement sensor is used as a feedback signal, a negative constant-speed moving speed control signal is input into a servo controller, an electro-hydraulic servo valve controls a hydraulic piston of a double-acting hydraulic cylinder to advance towards a first single-acting pulse pressurizing cylinder at a constant speed, the pressurizing piston of the first single-acting pulse pressurizing cylinder is pushed to advance at a constant speed through a piston rod, corresponding in-cylinder fracturing fluid is continuously pushed out from a liquid outlet, the pressure in a high-pressure output header pipe and a fracturing pipe is continuously increased, the pressure is monitored by a pressure sensor until the fracturing pressure of a fracturing hole is reached, and after a hydraulic crack is generated, the pressure control type injection fails after the pressure is suddenly reduced;

step four, later-period flow control type pulse liquid injection

Controlling the first normally closed electromagnetic stop valve to be closed, namely disconnecting the liquid outlet hole from the outside; then, the first normally-open type electromagnetic stop valve, the second normally-open type electromagnetic stop valve and the third normally-open type high-pressure stop valve are controlled to be opened, and the two-position three-way high-pressure electromagnetic valve is controlled to be reset, so that the second one-way liquid outlet hole is connected with the high-pressure output main pipe through the two-position three-way high-pressure electromagnetic valve;

the method comprises the steps that a moving speed monitored by a displacement sensor is used as a feedback signal, a moving speed control signal is input to a servo controller, an electro-hydraulic servo valve controls a hydraulic piston of a double-acting hydraulic cylinder to do reciprocating non-uniform motion, the piston rod pushes pressurizing pistons of a first single-acting pulse pressurizing cylinder and a second single-acting pulse pressurizing cylinder to do non-uniform reciprocating motion, a corresponding first one-way liquid inlet hole and a corresponding second one-way liquid inlet hole alternately suck water from a water tank at a non-uniform speed, a corresponding first one-way liquid outlet hole and a corresponding second one-way liquid outlet hole alternately pump water to a high-pressure output main pipe at a non-uniform speed to form pulse flow output, a flow sensor monitors a pulse flow output state, at the moment, fracturing liquid is continuously input in a fracturing pipe in a flow pulse mode, further pulse action is generated on a formed hydraulic crack, and the fracturing.

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