Drill-power-based directional hydraulic fracturing system for downhole quick slotting and method thereof

Patent metadata

Field	Value
Publication number	US-10774591-B2
Application number	US-201816616790-A
Country	US
Kind code	B2
Filing date	Dec 25, 2018
Priority date	Apr 12, 2018
Publication date	Sep 15, 2020
Grant date	Sep 15, 2020

Abstract

Provided are a drill-power-based directional hydraulic fracturing system for downhole quick slotting and a method thereof. The directional hydraulic fracturing system includes a water injection pump, a high pressure rubber pipe arranged on the water injection pump is in communication with a drill, a dedicated sealing drill rod for hydraulic fracturing is arranged on the drill, a front segment of the drill rod may be connected with a directional borehole sealer through threads and a sealing ring is provided at the threaded connection. The main steps include drilling, slotting, borehole sealing and fracturing. Firstly, a drill-cut integrated tool is installed at a front end of the drill rod. After drilling is completed, hydraulic slotting, permeability improvement and pressure relief are performed without changing a drill bit. After slotting is completed, the drill bit is retreated, and the directional borehole sealer is installed and pushed to a predetermined position for efficiency sealing. After sealing is completed, high pressure water injection fracturing is performed to increase fissure density and scope with “high pressure penetration” as main. Thus, water injection for the coal seam with high ground pressure and low porosity is realized. In this way, coal bumps are effectively prevented, the powder dust concentration is reduced and the disasters such as gas and fire are prevented.

First claim

The invention claimed is:

1. A drill-power-based directional hydraulic fracturing method for downhole quick slotting, comprising a drill-power-based directional hydraulic fracturing system for downhole quick slotting, comprising a drill, wherein a water injection pump and a drill are connected with a high pressure rubber pipe and a dedicated sealing drill rod is arranged on the drill; a drill-cut integrated tool is arranged at a front end of the drill rod; three gas-water outlets with hole diameters of 6 mm-8 mm are designed on a three-wing drill bit and a reaming drill bit of the drill-cut integrated tool; after drilling is completed, hydraulic slotting is performed directly without retreating the drill bit; a plurality of directional borehole sealers are arranged on the drill rod, the directional borehole sealer comprises an outer shell which is internally provided with a communicating pipe, a lower straight-through opening of the communicating pipe is in communication with a transition pipe, an upper straight-through opening of the communicating pipe is in communication with a water inlet pipe, the communicating pipe between the upper straight-through opening and the lower straight-through opening is provided with a side-through water inlet respectively, and the side-through water inlet is provided with a side through opening; a borehole sealing capsule is provided on the outer shell, a sealing ring is provided on both sides of the borehole sealing capsule respectively, and a plurality of through holes are arranged uniformly on the outer shell in the borehole sealing capsule, and transition pipes between two adjacent directional borehole sealers are connected with a water pipe connector; the directional borehole sealer and the drill rod are arranged in the borehole; the drill rod is a dedicated sealing drill rod for hydraulic fracturing and is provided with a sealing ring so that high pressure water enters the directional borehole sealer through the drill rod,
wherein the method is performed according to the steps of drilling—slotting—borehole sealing—fracturing as follows:
A. a drill-cut integrated tool is installed at a front segment of the drill rod to perform drilling by starting the drill; during the drilling, the gas-water outlets on the three-wing drill bit and the reaming drill bit act to discharge slags; after the hydraulic cut drilling reaches a predetermined position, the water injection pump is started and switched to high pressure water; the drill remains in a rotation state, and a coal mass is cut with the hydraulic power in the borehole to form a hydraulic slot; after slotting requirements are satisfied, rotation and high pressure water are both stopped and the drill rod is pulled out slowly;
B. the drill-cut integrated tool is disassembled and the directional borehole sealer is assembled; the threaded connection of the drill rod and the directional borehole sealer is well sealed; the drill is started to push the directional borehole sealer to a predetermined position; the water injection pressure is set to less than 5 MPa; the pressurized water supplied by the water injection pump is transported to the drill through a high pressure rubber pipe so that the pressurized water enters the drill rod and further enters the directional borehole sealer; low pressure water enters the interior of the borehole sealing capsule through the water inlet pipe of the directional borehole sealer; the lower straight-through opening serves as a water inlet and the upper straight-through opening serves as a water outlet; water is injected into the borehole sealing capsule through the side-through opening; the outer shell has a through hole connected with the borehole sealing capsule; both ends of an outer wall of the outer shell are provided with a sealing ring for fixing the borehole sealing capsule respectively; when the borehole sealing capsule is filled up with water, the borehole sealing capsule has a diameter of greater than 94 mm and thus effectively seals the borehole; when the water injection pressure exceeds 5 MPa, a pressure control valve on the directional borehole sealer will open to allow high pressure water to enter the borehole;
C. after the borehole sealing is completed, hydraulic fracturing is performed; the water injection pressure is slowly increased to 30 MPa while change of a pressure gauge is observed; the high pressure water injection is performed for 10 minutes; the first stage of fracturing work is completed; after the water injection pump is shut down and the pressure is released, the directional borehole sealer restores to a normal size;
D. the drill is adjusted to pump the directional borehole sealer to the second stage of fracturing work; the second stage of the fracturing work is performed by repeating steps B and C and so on until the fracturing work is completed.

2. The drill-power-based directional hydraulic fracturing method for downhole quick slotting according to claim 1 , wherein the above drill-cut integrated tool comprises a reaming drill bit, a three-wing drill bit is provided at a front end of the reaming drill bit, and gas-water outlets are provided on the three-wing drill bit and the reaming drill bit behind the three-wing drill bit.

Assignees

• Univ Shandong Science & Tech

Inventors

• Wang Gang
• Cheng Weimin
• Zhou Xiaohua
• Sun Lulu
• Jiang Chenghao
• Liu Zhen

Classifications

• E21B10/32

  with expansible cutting tools · CPC title

• E21B43/26

  by forming crevices or fractures · CPC title

• E21B43/114

  Perforators using direct fluid action {on the wall to be perforated}, e.g. abrasive jets · CPC title

• E21C37/12

  by injecting into the borehole a liquid, either initially at high pressure or subsequently subjected to high pressure, e.g. by pulses, by explosive cartridges acting on the liquid (slitting by jets of water E21C25/60; blasting by explosives F42D) · CPC title

• E21B7/18 Primary

  Drilling by liquid or gas jets, with or without entrained pellets (E21B7/14 takes precedence) · CPC title