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Compound drilling fluid applied to deposit of natural gas hydrates in seafloor

A drilling fluid and hydrate technology, applied in the direction of drilling composition, chemical instruments and methods, etc., can solve the problems of fracture pressure reduction, temperature and pressure condition damage, easy wall collapse and fracturing, etc., to achieve hydrate formation Inhibition effect enhances, reduces and prevents repeated crushing, and avoids the effect of severely expanding the pore size

Inactive Publication Date: 2018-08-03
DALIAN DONGYOU RUIJIA PETROLEUM TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] (1) When drilling in natural gas hydrate formations, due to the release of formation stress near the well wall and bottom of the reservoir, the formation pressure will decrease; and the drill bit will cut rock, and the friction between the bottom drilling tool and the well wall and core will generate a large amount of Thermal energy destroys the temperature and pressure conditions for the stable existence of hydrates; thus triggering the decomposition of hydrates, resulting in instability of the well wall and adverse effects on drilling operations
[0004] (2) The invasion of drilling fluid and the decomposition of hydrates will lead to the increase of formation pore pressure in different degrees, and the increase of pore pressure will increase the density of drilling fluid required to maintain the stability of the wellbore wall, which not only seriously affects the penetration rate, but also increases the pressure of the wellbore wall. Seepage increases the pore pressure around the well, thereby further reducing the stability of the well wall and forming a vicious circle
Moreover, the decomposition of hydrates will also increase the permeability of the formation, and the drilling fluid will seep into the well wall to generate osmotic pressure, which will increase the collapse pressure of the formation and reduce the fracture pressure, making the well wall more likely to collapse and fracture, reducing the stability of the well wall
[0006] (4) For subsea natural gas hydrate storage, during the drilling process of natural gas hydrate storage, the decomposition of gas hydrate will rapidly increase the ultra-static pore pressure in the storage soil, which may cause submarine landslides or instability of the subsea foundation, which may lead to Cause damage to drilling holes, drilling platforms, submarine pipelines and other facilities
The above drilling fluids all have certain effects on the drilling of natural gas hydrate reservoirs, but none of them consider the use of compound hydrate inhibitors

Method used

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  • Compound drilling fluid applied to deposit of natural gas hydrates in seafloor
  • Compound drilling fluid applied to deposit of natural gas hydrates in seafloor
  • Compound drilling fluid applied to deposit of natural gas hydrates in seafloor

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Embodiment 1, the content of each component in the drilling fluid is: the mass ratio of polyethylene glycol is 5%, the mass ratio of sodium chloride is 9%, the mass ratio of methanol is 4.5%, the mass ratio of ethylene glycol is 14%, the mass ratio of humic The mass ratio of potassium acid potassium is 1.8%, the mass ratio of xanthan gum is 0.4%, the mass ratio of polyvinylpyrrolidone K90 is 0.8%, the mass ratio of propylene glycol phenyl ether is 0.8%, and the mass ratio of polyvinyl methyl ether is 0.8%. Divided into prepared water.

Embodiment 2

[0035] Embodiment 2, the content of each component in the drilling fluid is: the mass ratio of polyethylene glycol is 6%, the mass ratio of sodium chloride is 10%, the mass ratio of methanol is 5%, the mass ratio of ethylene glycol is 15%, the mass ratio of humic The mass ratio of potassium acid potassium is 2%, the mass ratio of xanthan gum is 0.5%, the mass ratio of polyvinylpyrrolidone K90 is 1%, the mass ratio of propylene glycol phenyl ether is 1%, and the mass ratio of polyvinyl methyl ether is 1%. Divided into prepared water.

Embodiment 3

[0036] Embodiment three, the content of each component in the drilling fluid is: the mass ratio of polyethylene glycol is 7%, the mass ratio of sodium chloride is 11%, the mass ratio of methanol is 5.5%, the mass ratio of ethylene glycol is 16%, the mass ratio of humic The mass ratio of potassium acid potassium is 2.2%, the mass ratio of xanthan gum is 0.6%, the mass ratio of polyvinylpyrrolidone K90 is 1.2%, the mass ratio of propylene glycol phenyl ether is 1.2%, and the mass ratio of polyvinyl methyl ether is 1.2%. Divided into prepared water.

[0037] The drilling fluid configuration methods of the above-mentioned examples 1, 2, and 3 are conventional drilling fluid configuration methods, and are evaluated by the following experimental methods:

[0038] 1 Evaluation of drilling fluid shale hydration inhibition

[0039] Inhibition evaluation experiment is an important part of the indoor evaluation of drilling fluid related performance. The present invention adopts mud shal...

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Abstract

The invention provides compound drilling fluid applied to deposit of natural gas hydrates in the seafloor and relates to the field of exploitation of natural gas hydrates. The drilling fluid comprisesthe following components: polyethylene glycol, sodium chloride, methyl alcohol, ethylene glycol, potassium humate, xanthate gum, polyvinylpyrrolidone K90, propylene glycol phenyl ether, polyvinyl methyl ether and prepared water. The drilling fluid is capable of being applied to drilling with deposit of the natural gas hydrates in the seafloor, is free of solid phase and has resistance to low temperature; a kinetic inhibitor is added into the drilling fluid and is compounded with a synergist; the drilling fluid has an excellent effect of inhibiting generation of hydrates; meanwhile, the components of the drilling fluid are low in harm to the environment; and the drilling fluid has the advantages of high efficiency, environment friendliness and cheap and easily available raw materials.

Description

technical field [0001] The invention relates to a compound drilling fluid for seabed natural gas hydrate storage, in particular to the field of natural gas hydrate exploitation. Background technique [0002] Natural gas hydrates are mainly distributed in the deep-water areas of the continental margins and the permafrost areas on land, and the former accounts for the vast majority of the discovered quantities. Natural gas hydrate is one of the potential alternative energy sources, and the research on natural gas hydrate is a hot spot in contemporary earth science and energy industry development research. There are a large amount of natural gas hydrates in seabed sediments. Drilling is an essential means to explore and develop natural gas hydrates at a certain depth underground. The phase equilibrium property of gas hydrate determines that drilling in this type of formation is very different from drilling in general oil and gas formations, and it also leads to more complex in...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09K8/12
CPCC09K8/12C09K2208/12C09K2208/22
Inventor 龚鑫晶李海洋宋鑫袁鹏飞张晓丽李新
Owner DALIAN DONGYOU RUIJIA PETROLEUM TECH CO LTD
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