A marine natural gas hydrate mortar replacement mining method and mining device

A mining method and hydrate technology, applied in the direction of mining fluid, earthwork drilling, wellbore/well components, etc., can solve problems such as unfavorable formation stability, decreased seepage capacity of formation near wellbore, and formation deficit, so as to prevent large-area formation Deficit, the effect of maintaining formation stability

CN107676058BActive Publication Date: 2019-04-16QINGDAO INST OF MARINE GEOLOGY
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2019-04-16

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Abstract

The invention discloses a marine natural gas hydrate mortar replacement mining method and a mining device. The mining method properly relaxes the sand-retaining precision of the mechanical screen so that the formation muddy and sandy fine particles flow into the wellbore production string under controllable conditions and At the same time, the coarse-grained mortar is continuously injected into the hydrate reservoir, and the replacement of the coarse-grained mortar with the formation fine particles and the hydrate space is realized through the cooperation of the hydrate reservoir sand production management technology and the mortar injection technology; The production equipment includes production casing, production tubing, wellbore water injection pipe and mortar reinjection pipe. The lower end of the production casing is connected with a mechanical screen, and the upper and lower ends of the mechanical screen are respectively installed with an upper mechanical packer and a lower mechanical seal. Spacer; the gas separation device is installed at the inlet end of the production tubing, the wellbore water injection pipe is connected with the production tubing above the upper mechanical packer, and the mortar reinjection pipe extends through the upper mechanical packer and the lower mechanical packer to the hydration zone. The bottom boundary of the production layer of the material reservoir is connected with the gravel packing tool, and the purpose of continuous and efficient production is achieved through the above method and device.
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Description

technical field

[0001] The invention belongs to the field of high-efficiency exploitation of marine natural gas hydrates, and in particular relates to a mortar replacement mining method and a mining device for natural gas hydrates in sea areas, which are suitable for mining by the depressurization method or formation fluid extraction method. Background technique

[0002] Gas hydrate is a kind of energy that has existed stably for millions of years and has huge reserves. More than 90% of the gas hydrate resources are stored in deep-sea shallow sediments. Strong research interests. If the natural gas hydrates in the surrounding seas of my country can be exploited safely and effectively, it will greatly promote the improvement of my country's energy structure. In 2017, my country's first sea area natural gas hydrate trial production project hosted by the China Geological Survey achieved a historic breakthrough of continuous drainage for 60 days and an average daily gas product...

Examples

Embodiment 1

[0037] Embodiment 1. This embodiment discloses a mortar replacement mining method for marine natural gas hydrate, which includes the following steps: (1) Open the overlying strata of the hydrate reservoir, use the production casing to lower the strata above the hydrate reservoir and perform solidification. Well operation; (2) Open the hydrate reservoir and open hole gravel packing, install and lower the wellbore string combination; (3) Use the depressurization method or formation fluid extraction method to start hydrate production, and at the same time inject liquid into the wellbore, Sand-carrying production; while step (3) is being carried out, large-size mortar is filled into the formation to continue production, and during the implementation of step (3), real-time adjustment of liquid injection parameters and mortar injection parameters to maintain production.

[0038] According to conventional procedures, a hydrate production well is opened with a large borehole drill bit,...

Embodiment 2

[0050] Example 2. Based on the mining method proposed in Example 1, this example proposes a marine natural gas hydrate mortar displacement mining device, which is designed according to the principle of "1+3", that is, one large-diameter casing + three small Diameter casing (or tubing), ref. figure 2 , including production casing 1, production tubing 2 arranged in production casing 1 and parallel to the axis of production casing, wellbore water injection pipe 3 and mortar reinjection pipe 4; production tubing 2, wellbore water injection pipe 3 and mortar reinjection pipe The annular space formed between the outer wall of the production casing 1 and the inner wall of the production casing 1 is the gas circulation channel 12 .

[0051] Specifically, such as figure 1 As shown in the schematic diagram of the principle structure, the lower end of the production casing 1 is connected with a matching mechanical screen 9, and the production casing 1 is located above the production la...