Device and method for solid-state fluidized mining of natural gas hydrates in shallow seabed

Patent metadata

Field	Value
Publication number	US-10822927-B2
Application number	US-201916601562-A
Country	US
Kind code	B2
Filing date	Oct 14, 2019
Priority date	Apr 24, 2018
Publication date	Nov 3, 2020
Grant date	Nov 3, 2020

Abstract

Disclosed is a device for solid-state fluidized mining of natural gas hydrates in a shallow seabed, including: a sea surface support system, a pipeline delivery system, and an undersea drilling system. The sea surface support system includes a hydrate drilling vessel floating on seawater. The pipeline delivery system includes a continuous double-layer oil pipe, a recyclable conduit installed in a sediment cover, an open-hole steering packer installed outside the recyclable conduit. The undersea drilling system includes a hydrate slurry separator, a single screw pump, a hydraulic motor, a jet head and a differential pressure sliding sleeve close to the hydrate drill bit. The present invention has the following beneficial effects. The device achieves a multi-directionally horizontal drilling and production in the hydrate reservoir with a single well head, improving the drilling efficiency and single well production.

First claim

What is claimed is:

1. A device for solid-state fluidized mining of natural gas hydrates in a shallow seabed, comprising:
a sea surface support system;
a pipeline delivery system; and
an undersea drilling system;
wherein the sea surface support system comprises a hydrate drilling vessel floating on seawater, a hydrate storage tank, a high-pressure pump set and a continuous double-layer oil pipe storage device arranged on the hydrate drilling vessel;
the pipeline delivery system comprises a continuous double-layer oil pipe, a recyclable conduit installed in a sediment cover, an open-hole steering packer installed outside the recyclable conduit; the continuous double-layer oil pipe penetrates the recyclable conduit; a head end of the continuous double-layer oil pipe is fixed on the continuous double-layer oil pipe storage device, wherein an inner channel of the continuous double-layer oil pipe is connected to the hydrate storage tank, and an outer channel of the continuous double-layer oil pipe is connected to an outlet port of the high-pressure pump set; and a tail end of the continuous double-layer oil pipe is connected to the undersea drilling system in a hydrate reservoir in the shallow seabed;
the undersea drilling system comprises a hydrate slurry separator, a first three-layer tube, an internal and external fluid exchange joint of double-layer tube and a second three-layer tube, connected successively; via the hydrate slurry separator, the outer channel of the continuous double-layer oil pipe communicates with a middle channel of the first three-layer tube, while the inner channel of the continuous double-layer oil pipe communicates with an inner channel of the first three-layer tube; a channel of the hydrate slurry separator is in communication with an outer channel of the first three-layer tube;
through the internal and external fluid exchange joint of double-layer tube, the middle channel of the first three-layer tube communicates with an inner channel of the second three-layer tube, while the inner channel of the first three-layer tube communicates with a middle channel of the second three-layer tube; the outer channel of the first three-layer tube communicates with an outer channel of the second three-layer tube;
a jet head is arranged in an end of the inner channel of the second three-layer tube; the jet head communicates with the second three-layer tube, and is equipped with a pressure differential sliding sleeve; a hydrate drill bit is fixed at an end of the jet head, and is provided with a seawater ejecting-drilling channel along an axial direction of the hydrate drill bit; and the seawater ejecting-drilling channel communicates with the jet head;
a single screw pump is fixed in the inner channel of the first three-layer tube, and a hydraulic motor is fixed in the inner channel of the second three-layer tube; via a coupling penetrating the internal and external fluid exchange joint of double-layer tube, one end of an output shaft of the hydraulic motor connects to an input shaft of the single screw pump, and the other end of the output shaft is fixedly connected to the jet head; a sediment backfilling casing is equipped outside the undersea drilling system, the sediment backfilling casing is defined as an outer portion of the first three-layer tube, the internal and external fluid exchange joint of double-layer tube and the second three-layer tube; one end of the sediment backfilling casing is connected to a sediment outlet of the channel of the hydrate slurry separator, and the other end of the sediment backfilling casing is arranged with a sediment backfilling channel; a plurality of jet holes communicating with the jet head are provided on a cylindrical surface of the sediment backfilling casing along a circumferential direction of the sediment backfilling casing, and a return port communicating with the outer channel of the second three-layer tube is further provided on the cylindrical surface of the sediment backfilling casing.

2. The device of claim 1 , wherein a derrick is further provided on the hydrate drilling vessel.

3. The device of claim 2 , wherein a jet head of continuous double-layer oil pipe is provided on the derrick.

4. A mining method using the device for solid-state fluidized mining of natural gas hydrates in the shallow seabed of claim 1 , comprising:
1) drilling
1a) driving the hydrate drilling vessel to a hydrate collection site and anchoring the hydrate drilling vessel;
1b) lowering the continuous double-layer oil pipe and the recyclable conduit down to a seabed;
1c) opening the high-pressure pump set and pumping the seawater into the outer channel of the continuous double-layer oil pipe; ejecting the pressurized seawater from the drilling channel of the hydrate drill bit to the sediment cover by successively passing through the hydrate slurry separator, the middle channel of the first three-layer tube, the internal and external fluid exchange joint of double-layer tube, the inner channel of the second three-layer tube, the hydraulic motor and an inner cavity of the jet head; at the same time, when the high-pressure seawater is injected into the hydraulic motor, driving the output shaft of the hydraulic motor to rotate to drive the input shaft of the single screw pump through the coupling to rotate, while driving the jet head to rotate to drive the hydrate drill bit to rotate, so that the hydrate drill bit drills into the hydrate reservoir, drilling into the sediment cover by injecting the high-pressure seawater and rotating the hydrate drill bit;
1d) fixing the open-hole steering packer in a well drilled in step 1c, and installing the recyclable conduit in the open-hole steering packer;
1e) releasing the continuous double-layer oil pipe to disengage from the recyclable conduit, wherein the continuous double-layer oil pipe continues to drill;
1f) adjustment of a drilling angle: during the drilling of the continuous double-layer oil pipe in the hydrate reservoir, adjusting the drilling angle of the continuous double-layer oil pipe via a deflecting technique, wherein the recyclable conduit rotates around the open-hole steering packer to assist a deflection of the drilling of the continuous double-layer oil pipe according to a drilling direction in the hydrate reservoir, that is, to increase a deflecting angle of the continuous double-layer oil pipe to ensure an effective drilling length of the continuous double-layer oil pipe in a horizontal direction in the hydrate reservoir which is shallow;
1g) resetting of the pressure differential sliding sleeve: reducing the pressure of the high-pressure pump set for pumping the seawater to allow a pressure of the pumped seawater to be lower than a pressure of the seawater from the drilling channel, so that the pressure differential sliding sleeve is in an inner end of the jet head to close the jet holes;
1h) driving the hydrate drill bit to continue to drill in a horizontal direction until a pilot hole is completed;
2) mining the natural gas hydrates
2a) opening the pressure differential sliding sleeve:
increasing the pressure of high-pressure pump set for pumping the seawater to allow the pressure of the pumped seawater in the jet head to be higher than the pressure of the seawater from the drilling channel, so that the pressure differential sliding sleeve is forced to move forward to block the drilling channel and to open the jet holes;
2b) circumferential breaking: ejecting the high-pressure seawater from the jet holes; breaking the hydrate reservoir in a circumferential direction of the pilot hole to expand the pilot hole in a circumferential direction, thus obtaining a hydrate sediment mixing slurry;
2c) pulling back the continuous double-layer oil pipe to break the hydrate reservoir along an axial direction of the pilot hole, and gradually expan

Assignees

• Univ Southwest Petroleum

Inventors

• Tang Yang
• Wang Guorong
• Zhou Shouwei
• Liu Qingyou
• Zhong Lin
• Li Wang
• Li Qingping
• Fu Qiang
• He Yufa
• Wang Chuan
• Wang Leizhen

Classifications

• E21B7/043 Primary

  for underwater installations · CPC title

• E21B41/0099

  specially adapted for drilling for or production of natural hydrate or clathrate gas reservoirs; Drilling through or monitoring of formations containing gas hydrates or clathrates · CPC title

• E21B43/01 Primary

  specially adapted for obtaining from underwater installations · CPC title

• E21B43/29

  Obtaining a slurry of minerals, e.g. by using nozzles · CPC title

• E21B17/18

  Pipes provided with plural fluid passages {(E21B17/203 takes precedence)} · CPC title