CN116816322B

CN116816322B - A method for synergistic fracturing of horizontal well oil reservoirs using liquid explosives and detonators

Info

Publication number: CN116816322B
Application number: CN202310964747.8A
Authority: CN
Inventors: 吴晋军; 刘敬; 段俊瑞
Original assignee: Xian Shiyou University
Current assignee: Xian Shiyou University
Priority date: 2023-08-02
Filing date: 2023-08-02
Publication date: 2025-11-04
Anticipated expiration: 2043-08-02
Also published as: CN116816322A

Abstract

The invention discloses a liquid powder-explosive collaborative fracturing method for an oil layer of a horizontal well, which comprises the following steps of firstly flushing the well, washing pollutants in the well bore, sequentially lowering a liquid powder-liquid explosive ignition and detonation device and a detonation device to a designated position through an oil pipe, secondly sequentially injecting prepared liquid powder, liquid explosive and various isolating liquids into a well bore destination stratum, thirdly injecting prepared isolating liquid into the well, injecting prepared liquid powder into the well, finally, injecting isolating liquid again above the liquid powder, arranging a wellhead detonation device, and injecting well killing liquid above the isolating liquid. The ignition operation is completed, and the liquid explosive is first produced into great amount of energy to fracture countless micro cracks in near well area to reach the aim of modifying stratum.

Description

Liquid gunpowder-explosive synergistic fracturing method for horizontal well oil layer

Technical Field

The invention belongs to the technical field of anhydrous fracturing, and particularly relates to a liquid gunpowder-explosive collaborative fracturing method for an oil layer of a horizontal well.

Background

Anhydrous fracturing has become an important research direction for oilfield formation fracturing. The reason for this is that water resources are scarce, and the pressure of geological environment pollution of the stratum is continuously expanding. In particular to the old oil field and the old oil layer which are in the middle and later stages, the hydraulic fracturing scale and the hydraulic fracturing quantity are continuously increased. The water demand for developing hydraulic fracturing by unconventional oil and gas resources such as shale gas, compact oil and the like is large. For the above reasons, anhydrous and low-water fracturing has become a new important research direction for fracturing hydrocarbon reservoirs.

The high-energy gas fracturing is based on the action principle of gunpowder and explosive, and specially develops a special oil-gas field yield increasing technology suitable for oil layer fracturing. High-energy gas fracturing has achieved important technical results in solid gunpowder fracturing, composite perforation fracturing and the like, and has achieved wide results in field application. In recent years, the development requirements of complex oil layers, especially ultra-low permeability compact oil layers, are difficult to meet due to the factors of limited total energy, protection of casing pipes and the like.

In recent years, the technical research of low-detonation-velocity explosive liquid explosive has made breakthroughs in the aspect of oil layer fracturing, and has better application safety in horizontal well oil layer field test.

The existing hydraulic fracturing is widely popularized and applied as a main technology for oil-gas field development, but the radial communication range is limited because the pressure of the hydraulic fracturing is slowly increased and only a single seam of opposite wings can be generated under the constraint of ground stress, the effective rate of the hydraulic fracturing is continuously reduced when the hydraulic fracturing faces to old oil layers of the old oil fields with increasing numbers, the effectiveness of the hydraulic fracturing is reduced when the hydraulic fracturing is rapidly developed by the number of horizontal wells, the fracturing cost is continuously increased, and in addition, the hydraulic fracturing is greatly polluted to the stratum and hurts the oil layers due to the fact that the hydraulic fracturing is greatly used for fracturing, so that the development of the anhydrous fracturing technology, namely the high-energy gas fracturing technology is promoted. High-energy gas fracturing has been facing complex oil reservoir fracturing for many years, especially ultra-low permeability compact oil reservoir, and it has been difficult to meet the development requirements of such complex oil reservoir due to the limited total energy, the need for casing protection, and other factors.

The liquid gunpowder technology facing the complex oil layer can generate longer cracks and a plurality of short cracks in the stratum, has almost no damage to the stratum, has low cost compared with hydraulic fracturing, and generates cracks without being constrained by ground stress, but is difficult to generate long cracks due to the limited total energy, especially facing the oil layer with extremely high ground stress. The medium-low speed liquid explosive explosion fracturing technology is based on the research of micro-crack networks generated in the deep part of the stratum, and is used in the horizontal well oil layer test at present, and because the explosion speed is much faster than that of gunpowder, countless micro-cracks are generated in the stratum instantly, and the large-range oil layer is difficult to communicate.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a liquid powder-explosive collaborative fracturing method for an oil layer of a horizontal well, which is characterized in that a large number of tiny cracks are generated by the explosion of liquid explosive to fracture the stratum, then the liquid powder burns to generate a large amount of high-temperature high-pressure gas to continuously supply energy for the tiny cracks, so that the tiny cracks are promoted to expand and extend to generate more cracks, and the aim of reservoir transformation is achieved.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

a liquid gunpowder-explosive synergistic fracturing method for an oil layer of a horizontal well comprises the following steps of;

Firstly, flushing a well, washing out pollutants in the well, and sequentially lowering a liquid gunpowder-liquid explosive ignition explosion device and a detonation device to a designated position through an oil pipe;

secondly, respectively and sequentially injecting the prepared liquid gunpowder, liquid explosive and various isolating liquids into a shaft destination stratum;

thirdly, injecting the prepared isolating liquid into the well, and injecting the prepared liquid gunpowder into the well;

and finally, injecting the isolating liquid again above the liquid gunpowder, arranging a wellhead initiator, and injecting the well killing liquid above the isolating liquid.

Further, the liquid explosive is placed on the explosion device, the liquid gunpowder is placed on the detonation device, an isolating liquid is arranged between the liquid explosive and the liquid gunpowder, an isolating liquid is arranged between the liquid gunpowder and the well killing liquid, and the well killing liquid is covered on a wellhead.

Further, the shaft comprises a vertical direction and a horizontal direction, the tail end of the underground vertical direction is communicated with the horizontal direction, the detonating device and the explosion device are positioned in the horizontal direction, the detonating device is positioned in the vertical direction, and the isolation liquid between the well control liquid and the liquid gunpowder is positioned at the joint of the horizontal direction and the vertical direction.

Further, after the injection process is finished, the wellhead sealing is finished, an impact rod ignition mode or a pressure detonation mode is selected, the ignition operation is finished, the explosion device is firstly exploded through liquid explosive, and a large amount of energy is generated by the liquid explosive to fracture countless micro cracks in a near-wellbore zone;

And then the liquid gunpowder is ignited by the liquid gunpowder ignition device, a large amount of high-temperature high-pressure gas is generated by burning the liquid gunpowder, and energy is continuously supplied along the tiny cracks generated by explosion of the liquid explosive, so that the tiny cracks further extend to generate a plurality of long cracks, extend short cracks, increase the communication probability of the fracturing cracks and the natural cracks, form a complex fracture network structure, and enlarge the oil extraction communication range so as to achieve the aim of stratum transformation.

The invention has the beneficial effects that:

the invention adopts a technical method of the combined fracturing synergistic effect of liquid explosive and explosive in an oil layer of a horizontal well, and the principle is the combined effect of the liquid explosive and the explosive. The liquid gunpowder and liquid explosive fracturing technology is simultaneously used for oil layer fracturing, the synergistic effect is exerted, innumerable tiny cracks are generated by the liquid explosive in the oil layer by explosion fracturing, the stratum fracturing pressure is effectively reduced, a plurality of long cracks are immediately fractured by the liquid gunpowder, short and small cracks are extended, the penetration range is effectively enlarged, and the comprehensive effect is improved. The method has the technical function of large-scale transformation of the oil field stratum, can perform single-well fracturing and block fracturing, and plays a role in integral fracturing. Provides a new technical approach for developing and reforming the stratum of the complex oil layer.

The invention is mainly characterized in that the liquid explosive firstly generates numerous short cracks, reduces the formation fracture pressure, assists the liquid explosive to fracture to generate longer long cracks, drives the short cracks to expand and extend, enlarges the effective range of communicating the formation, increases the communication probability of the fracturing cracks and the natural cracks, forms a complex fracture network structure, improves the comprehensive fracturing effect, and is beneficial to protecting the formation environment.

Drawings

Fig. 1 is a schematic diagram of the structure of the present invention.

Detailed Description

The invention is described in further detail below with reference to the drawings and examples.

As shown in figure 1, the method for fracturing the liquid powder-explosive synergistic effect of the oil layer of the horizontal well comprises the following steps of;

The construction steps of the invention include:

first) a preparation section:

1. preparing liquid distribution equipment of tank trucks, square tanks, pump trucks and boiler trucks on site, and configuring liquid gunpowder, liquid explosive and isolating liquid on site to respectively reach the design dosage;

2. The initiating tube column comprises an initiator, a liquid explosive ignition device, a liquid explosive explosion device, a delay control ignition system and the like.

Two) pigging and flushing:

1. verifying wellhead pressure, discharging liquid and releasing pressure when the pressure is greater than 0MPa, and pulling the pressure to a designated place by using a tank truck;

2. When the pressure is reduced to 0MPa, the wellhead is disassembled, the original well string is lifted, and a 350-type christmas tree is installed;

3. Placing a replacement washing pipe column, and performing replacement washing on the multi-point position of the oil layer well section by using clear water in a large discharge amount until the density difference of water at an inlet and an outlet is less than 0.01g/cm ³, wherein the replacement washing is stopped if the density difference is qualified;

4. And closing the well for 24 hours, filling clear water from the oil pipe until the water outlet of the sleeve stops, and calculating the fluid loss of the stratum.

Third), pumping in and detonating the liquid gunpowder and liquid explosive:

1. The method comprises the steps of firstly, pumping a liquid replacing pipe column to a liquid replacing design position, pumping liquid explosive into the pipe column according to a liquid explosive pumping design program and the use amount, and pumping the liquid explosive into the pipe column in sequence, wherein the basic pumping sequence comprises the steps of pumping the liquid replacing liquid according to the design use amount, namely, isolating liquid A, liquid explosive, isolating liquid B, liquid explosive, isolating liquid C and replacing liquid, so that the liquid explosive liquid is pumped into the design position of a horizontal well section, staying for 1-2 hours, and lifting out and pumping the liquid replacing pipe column.

2. The lower detonating tube column is sequentially connected with the detonating tube column, the detonating device, the liquid explosive ignition device, the delay control ignition system and the like, and when passing through a tail tube hanger seat, a deflecting section and a horizontal well section, the lower detonating tube column controls the lowering speed of an oil tube (less than 20 pieces per hour) and slowly passes through the lower detonating tube column until the lower detonating device is positioned at a designed position and the well head device is arranged on a mounting seat;

3. the well head device is well seated to close the sleeve gate, the high-pressure taking device is arranged on the sleeve valve at one side, the valve is rapidly closed after the rod is thrown and detonated, and the orientation and the form of the microseism crack are prepared for monitoring before the rod throwing and detonating, so that the on-site detection is carried out.

4, Adopting a throwing rod to detonate or pressure detonate, closing the well for 5 hours after the detonation is successful, observing the pressure change condition of the sleeve, if the pressure of the well head is more than 10MPa, closing the well to reduce the pressure, and connecting a blowout pipeline from an oil pipe to a pulling oil tank truck to slightly open a production valve, performing blowout production, and taking out a detonation string when the pressure of the well head is reduced to 0MPa, so as to carry out bailing production;

5. And detecting and collecting production data by the oil extraction team, and comprehensively evaluating the fracturing effect.

Claims

1. A method for synergistic fracturing of horizontal well oil reservoirs using liquid explosives and detonators, characterized by comprising the following steps;

First, the well is cleaned and flushed to remove contaminants from the wellbore. Then, the explosive device, detonator, and initiator are sequentially lowered to the designated location via the tubing.

Secondly, liquid explosives, isolation fluid, liquid gunpowder, and isolation fluid are pumped in sequence.

Finally, inject kill fluid over the isolation fluid;

The liquid explosive is placed on the detonation device, the liquid gunpowder is placed on the detonation device, the liquid explosive and the liquid gunpowder are separated by an isolation fluid, the liquid gunpowder and the well kill fluid are separated by an isolation fluid, and the well kill fluid covers the wellhead;

The wellbore includes a vertical direction and a horizontal direction, with the vertical end connected to the horizontal direction underground. The detonating device and the explosive device are located in the horizontal direction, the detonator is located in the vertical direction, and the isolation fluid between the kill fluid and the liquid explosive is located at the connection between the horizontal and vertical directions.

2. The method for synergistic fracturing of liquid gunpowder and explosive in horizontal well oil reservoirs according to claim 1, characterized in that, after the injection process is completed, the wellhead is sealed, and the ignition operation is completed by selecting the impact rod ignition method or the pressure detonation method. The liquid explosive is first detonated by the explosive device, and the liquid explosive generates a large amount of energy to fracture countless tiny cracks in the near-wellbore area.

The liquid gunpowder is then ignited using a liquid gunpowder detonation device. The combustion of the liquid gunpowder produces a large amount of high-temperature and high-pressure gas, which continuously provides energy along the tiny cracks created by the liquid explosive explosion. This causes the tiny cracks to extend further, producing multiple long cracks and extending short cracks. This increases the probability of communication between the fracturing cracks and natural cracks, forming a complex fracture network structure. This expands the oil production communication range, thereby achieving the purpose of formation modification.