A seabed shallow non-diagenetic natural gas hydrate pilot hole pull-back jet mining method and mining device

Abstract

The invention discloses a submarine shallow layer natural gas hydrate pilot hole pull-back jet break-up exploitation method and exploitation device, and belongs to the technical field of submarine hydrate exploitation. The exploitation method mainly comprises the following steps that a water insulation pipe is lowered to the position adjacent to a hydrate deposit, turn drilling is conducted in thehydrate deposit by means of mechanical or jet-flow drilling, and a pilot hole with a certain inclined angle is formed; after drilling reaches a preset position, a continuous pipe and an exploitationcrushing system are pulled back, meanwhile the surrounding hydrate ore body is crushed by means of a spray head jet flow, hydrate particles formed are collected into a closed pipeline with seawater, silt in the crushed particles is separated out by means of an in-pipe downhole separator, curing agent is added, then the particles are backfilled to a gob in situ, and the hydrate particles after separation are pumped to the sea surface for treatment together with the seawater. By means of the exploitation method and the exploitation device, efficient, safe and sustainable exploitation of the submarine shallow layer natural gas hydrate is achieved, the exploitation efficiency is ensured, and meanwhile a potential safety problem is effectively avoided.

Description

technical field [0001] The invention relates to the technical field of natural gas hydrate exploitation, in particular to a method and a mining device for a pilot hole pullback mining of non-diagenetic natural gas hydrate in the shallow layer of the seabed. Background technique [0002] Natural gas hydrate, also known as combustible ice, is a "cage compound" formed by methane-based hydrocarbon gas and water under certain temperature and pressure conditions, and has a white crystalline structure. Natural gas hydrate reserves are huge, with a carbon content more than twice that of the known carbon fossil fuels. They mainly exist in land permafrost and oceanic seabeds, and the reserves of oceanic seabed gas hydrates far exceed those in land permafrost areas. [0003] The main forms of hydrates are sandstone type, sandstone fissure type, fine-grained fissure type and dispersed type, among which the fine-grained fissure type and dispersed type hydrates account for the vast majori...

AI Technical Summary

Problems solved by technology

The surface solid fluidization mining method uses seabed mining institutions to excavate and break the hydrate ore bodies on the seabed surface during seabed movement; however, for shallow hydrate resources with tens of meters or even one to two hundred meters of cover The mud layer covering the upper part of the hydrate ore body can only be exploited before the hydrate ore body can be exploited, which will greatly increase the useless additional engineering workload, and it is difficult to ensure the economics of hydrate commercial mining

The shallow hydrate solid fluidization mining method partly draws on the traditional oil and gas horizontal drilling technology, and on this basis, the use of water jets or mechanical crushing to expand the wellbore has achieved the purpose of mining hydrate ore bodies; however, this method is currently stuck in the conceptual design , there is a lack of a set of specific and effective implementation process methods, and there are some technical problems that need to be overcome urgently, such as the cross conflict between the jet water and the return slurry flow path, and the mining surface caused by the untimely backfilling of the seabed underground goaf. and stratum collapse, excavation equipment is advancing forward, causing the pipeline to be in a suspended state, and backfilling mud and sand to bury the rear continuous pipe causes the pipeline to be withdrawn blocked

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