Looking for breakthrough ideas for innovation challenges? Try Patsnap Eureka!

Compound drilling fluid for natural gas hydrate (NGH) reservoir in siltstone

A drilling fluid and natural gas technology, which is applied in the field of natural gas hydrate exploitation, can solve the problems of easy collapse and fracturing of the wellbore, increase the formation collapse pressure, and increase the permeability of the wellbore, so as to avoid the serious enlargement of the pore diameter and the strong shale inhibition ability. , inhibiting and reducing the effect of the solid phase

Inactive Publication Date: 2018-10-02
DALIAN DONGYOU RUIJIA PETROLEUM TECH CO LTD
View PDF3 Cites 1 Cited by
  • 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 siltstone gas hydrate storage, due to the depositional environment, rhythmic bedding, and high clay content of siltstone, a large amount of clay enters the drilling fluid during drilling, which increases the viscosity of the drilling fluid and makes it easier to deposit in the drilling fluid. Natural gas hydrates are formed in the gas, blocking the pipes and blowout preventers, causing serious safety accidents
However, none of the above drilling fluids addresses the problem of excessive clay content during drilling in siltstone reservoirs.

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Compound drilling fluid for natural gas hydrate (NGH) reservoir in siltstone

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] Embodiment 1, the content of each component in the drilling fluid is: the mass ratio of sodium formate is 2.8%, the mass ratio of sodium chloride is 9%, the mass ratio of ethylene glycol is 9%, the mass ratio of potassium chloride is 4.5%, humic acid The mass ratio of potassium 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 ethylene glycol butyl ether is 0.8%, tetra-n-butyl The mass ratio of ammonium phosphate is 0.8%, and the remaining components are prepared water.

Embodiment 2

[0037] Embodiment 2, the contents of each component in the drilling fluid are: the mass ratio of sodium formate is 3%, the mass ratio of sodium chloride is 10%, the mass ratio of ethylene glycol is 10%, the mass ratio of potassium chloride is 5%, humic acid The mass ratio of potassium 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 ethylene glycol butyl ether is 1%, tetra-n-butyl The mass ratio of ammonium phosphate is 1%, and the remaining components are prepared water.

Embodiment 3

[0038] Embodiment three, the contents of each component in the drilling fluid are: the mass ratio of sodium formate is 3.2%, the mass ratio of sodium chloride is 11%, the mass ratio of ethylene glycol is 11%, the mass ratio of potassium chloride is 5.5%, humic acid The mass ratio of potassium 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 polyvinylcaprolactam is 1.2%, the mass ratio of ethylene glycol butyl ether is 1.2%, tetra-n-butyl The mass ratio of ammonium phosphate is 1.2%, and the remaining components are prepared water.

[0039] 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:

[0040] 1 Evaluation of drilling fluid shale hydration inhibition

[0041] Inhibition evaluation experiment is an important part of the indoor evaluation of drilling fluid related...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

The invention discloses a compound drilling fluid for natural gas hydrate (NGH) reservoir in siltstone, and relates to the field of NGH exploitation. The drilling fluid comprises following components:sodium formate, sodium chloride, glycol, potassium chloride, potassium humate, potassium polyacrylate, xanthan gum, polyvinyl caprolactam, ethylene glycol butyl ether, tetra-n-butyl ammonium phosphate, and make-up water. The drilling fluid is suitable for NGH drill wells in siltstone reservoir, is resistant to low temperature, and can inhibit and reduce the solid phase. The drilling fluid is compounded with a kinetic inhibitor and a synergist to inhibit the generation of hydrates. Moreover, the components of the drilling fluid are basically harmless to the environment, and the drilling fluidhas the advantages that the efficiency is high, the environment is protected, and the raw materials are cheap and easily available.

Description

technical field [0001] The invention relates to a compound drilling fluid for siltstone 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%; siltstone is produced in an environment that has undergone long-distance transport, relatively quiet hydrodynamic conditions, and slow deposition; it can gradually become sandstone or claystone in the horizontal and vertical directions, and form Rhythmic bedding; ...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Applications(China)
IPC IPC(8): C09K8/12
CPCC09K8/12C09K2208/12C09K2208/22
Inventor 袁鹏飞张晓丽李新宋鑫王磊李海洋龚鑫晶黄岩
Owner DALIAN DONGYOU RUIJIA PETROLEUM TECH CO LTD
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Patsnap Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Patsnap Eureka Blog
Learn More
PatSnap group products