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Silty mudstone natural gas hydrate storage compound type drilling fluid

A drilling fluid and natural gas technology, applied in the field of natural gas hydrate exploitation, can solve the problems of temperature and pressure condition damage, easy collapse and fracturing of wellbore, increase of drilling fluid viscosity, etc., to reduce and prevent repeated breakage and avoid serious enlargement of pore diameter , the effect of good low temperature stability

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

[0004] (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
[0005] (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, which further reduces the stability of the well wall, 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
[0007] (4) For natural gas hydrate storage in silty mudstone, due to the high clay content in silty mudstone, a large amount of clay enters the drilling fluid during drilling, which increases the viscosity of the drilling fluid and makes it easier to form natural gas in the drilling fluid Hydrates, clogging ducts and blowout preventers, causing serious safety incidents
However, the drilling fluid does not consider the low temperature of gas hydrate storage and the problem of hydrate inhibition.

Method used

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  • Silty mudstone natural gas hydrate storage compound type drilling fluid
  • Silty mudstone natural gas hydrate storage compound type drilling fluid
  • Silty mudstone natural gas hydrate storage compound type drilling fluid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] Embodiment 1, the content of each component in the drilling fluid is: the mass ratio of polyethylene glycol is 2.8%, the mass ratio of sodium chloride is 8%, the mass ratio of ethylene glycol is 14%, the mass ratio of potassium chloride is 4.5%, The mass ratio of potassium humate is 1.8%, the mass ratio of potassium polyacrylate is 1.8%, the mass ratio of xanthan gum is 0.4%, the mass ratio of polyvinyl caprolactam is 0.8%, the mass ratio of polyvinyl methyl ether is 0.8%, The mass ratio of tetra-n-hexyltrimethylammonium bromide is 0.8%, and the remaining components are preparation water.

Embodiment 2

[0038] Embodiment 2, the content of each component in the drilling fluid is: the mass ratio of polyethylene glycol is 3%, the mass ratio of sodium chloride is 10%, the mass ratio of ethylene glycol is 15%, the mass ratio of potassium chloride is 5%, The mass ratio of potassium humate is 2%, the mass ratio of potassium polyacrylate is 2%, the mass ratio of xanthan gum is 0.5%, the mass ratio of polyvinyl caprolactam is 1%, the mass ratio of polyvinyl methyl ether is 1%, The mass ratio of tetra-n-hexyltrimethylammonium bromide is 1%, and the remaining components are preparation water.

Embodiment 3

[0039] Embodiment three, the content of each component in the drilling fluid is: the mass ratio of polyethylene glycol is 3.2%, the mass ratio of sodium chloride is 12%, the mass ratio of ethylene glycol is 16%, the mass ratio of potassium chloride is 5.5%, The mass ratio of potassium humate is 2.2%, the mass ratio of potassium polyacrylate is 2.2%, the mass ratio of xanthan gum is 0.6%, the mass ratio of polyvinyl caprolactam is 1.2%, the mass ratio of polyvinyl methyl ether is 1.2%, The mass ratio of tetra-n-hexyltrimethylammonium bromide is 1.2%, and the remaining components are preparation water.

[0040] 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:

[0041] 1 Evaluation of drilling fluid shale hydration inhibition

[0042] Inhibition evaluation experiment is an important part of the indoor evaluation of drilling fluid rel...

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Abstract

The invention discloses silty mudstone natural gas hydrate storage compound type drilling fluid, and relates to the field of natural gas hydrate exploitation. The drilling fluid is prepared from the following components: polyethylene glycol, sodium chloride, ethylene glycol, potassium chloride, potassium humate, potassium polyacrylate, xanthan gum, polyvinyl caprolactam, polyvinyl methyl ether, tetrahexyltrimethyl ammonium bromide and prepared water. The silty mudstone natural gas hydrate storage compound type drilling fluid can be used for silty mudstone natural gas hydrate storing and drilling, has the effects of resisting a low temperature, inhibiting and reducing the solid phase; a kinetic inhibitor and a synergist are added into the drilling fluid for compounding, so that relatively strong hydrate generation inhibition effect is achieved; and moreover, the drilling fluid is small in environmental harm by components, and has the advantages of being efficient, environmentally friendly, adopting cheap and easily available raw materials, and the like.

Description

technical field [0001] The invention relates to a compound drilling fluid for silty mudstone 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. The proportion of sand and mud in natural gas hydrate storage has a great influence on the properties of the formation itself and the saturation of hydrate in it. The storage is divided into silty mudstone, argillaceous siltstone, siltstone, sandstone and glutenite. Its hydrate content can reach up to 95%; the silty mudstone is mainly composed of clay minerals, containing a small amount of silty; the silt content is 25%-50%, and the clay content is 75%-50%; the silty mudstone reserves With unique structural features, it is mainly divided into massive structure,...

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 李海洋黄岩付强刘继颖宋鑫袁鹏飞张晓丽
Owner DALIAN DONGYOU RUIJIA PETROLEUM TECH CO LTD
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