Completion method for natural-gas-hydrate large-borehole and multi-branch-radial-horizontal-borehole well

A technology for horizontal lateral wells and hydrates, which is applied in the directions of wellbore/well components, drilling compositions, drilling equipment and methods, etc. Poor diagenesis and other problems, to solve the difficulty of applying weight on bit, adjustable thickening time, and prevent water-gas channeling

Active Publication Date: 2016-02-03
CHINA UNIV OF PETROLEUM (EAST CHINA)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] Because the physical environment of hydrate reservoirs is deep water and shallow layers, it may have new characteristics such as poor formation diagenesis, formation strength, and poor permeability (due to hydrate solidification), so traditional hydraulic

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  • Completion method for natural-gas-hydrate large-borehole and multi-branch-radial-horizontal-borehole well
  • Completion method for natural-gas-hydrate large-borehole and multi-branch-radial-horizontal-borehole well
  • Completion method for natural-gas-hydrate large-borehole and multi-branch-radial-horizontal-borehole well

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Embodiment 1

[0034] Embodiment 1: in combination with Figure 1-7 , to further describe the present invention:

[0035] The present invention includes adopting a large-sized drill bit to drill to the target well depth at one time to form a large main borehole 5, and then using radial horizontal well technology to drill multiple horizontal branch boreholes 6 in the natural gas hydrate reservoir. The specific steps are as follows:

[0036] After the operation of a large main borehole 5 is completed, the downhole skewer 21 is lowered, and the whole set of devices is fixed on the casing 8 at the bottom of the well;

[0037] 2. Lower the build-up guide 9, insert it into the positioning hole 22 of the guide groove 23 of the first horizontal branch wellbore 6, and at the same time, run the high-pressure flexible nozzle into the guiding follow-up screen 10, guide the follow-up screen 10 The front end is equipped with a high-pressure jet drill bit 12, which can drill forward with the help of its o...

Embodiment 2

[0047] Example 2, the difference from Example 1 is that the window sealant used is composed of the following components by weight: 100 parts of G-grade oil well cement, 30 parts of reinforcing agent, 70 parts of hollow microspheres, and 3 parts of early strength agent , 1 part of dispersant, 3 parts of retarder, 1 part of defoamer, 4 parts of fluid loss reducer, 100 parts of water, density 1.2~1.7g / cm -3 ; Wherein the strengthening agent is fly ash and its physical properties are: fineness ≤ 20%, sulfur trioxide ≤ 3.0%; early strength agent is KAl(SO 4 ) 2 ; The dispersant is amino acid sulfonated formaldehyde-acetone condensation polymer, the relative molecular mass is 8000~60000; the retarder is citric acid; the defoamer is tributyl phosphate; the fluid loss reducer is carboxymethyl hydroxyethyl cellulose One of them, the viscosity of 2% aqueous solution at 25°C is 7000~12000mPa·s. The window sealant, that is, the cement slurry system is stable, which can not only meet the...

Embodiment 3

[0048] Example 3, the difference from Example 1 is that the window sealant used is composed of the following components by weight: 100 parts of G-grade oil well cement, 25 parts of reinforcing agent, 40 parts of hollow microspheres, and 3 parts of early strength agent , 1 part of dispersant, 2 parts of retarder, 1 part of defoamer, 3.7 parts of water loss reducer, 80 parts of water; wherein the strengthening agent is ultrafine slag, and the early strength agent is KAl(SO 4 ) 2 ; The dispersant is amino acid sulfonated formaldehyde-acetone condensation polymer; the retarder is citric acid; the defoamer is polyoxyethylene polyoxypropanolamine ether; The viscosity of the aqueous solution is 7000~12000mPa·s.

[0049] The window sealant, that is, the cement slurry system is stable, which can not only meet the special conditions of the natural gas hydrate formation, but also effectively prevent the hydrate layer from sealing shallow water-gas channeling, and has good construction p...

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Abstract

The invention relates to a completion method for a natural-gas-hydrate large-borehole and multi-branch-radial-horizontal-borehole well. According to the technical scheme, the completion method includes the steps that a large-size drill bit is adopted to drill by a target well depth at a time to form a large main borehole, a plurality of horizontal branch boreholes are drilled in a natural gas hydrate reservoir with a radial horizontal well technology, and the contact superficial area between the reservoir and the boreholes is increased to the maximum degree. The completion method has the advantages that underground complex conditions in the exploitation process are avoided or reduced, and the number of the branch boreholes can be greatly increased; the bare area and the depth of the natural gas hydrate reservoir are increased to the maximum degree through the multiple branch radial horizontal boreholes, the recovery ratio is greatly increased, the number of distributed wells is decreased, and development investment is reduced; adopted window sealants, namely cement paste systems are stable, strength development is rapid, thickening time is adjustable, hydrate-layer sealing shallow-layer water-gas channeling can be effectively prevented, and good construction performance is achieved.

Description

technical field [0001] The invention relates to the field of unconventional natural gas engineering, in particular to a completion method for multi-branch radial horizontal wells with large boreholes of natural gas hydrate. Background technique [0002] Natural gas hydrate is mainly distributed in deep-sea shallow sediments. It is an ice-like crystalline substance formed by natural gas and water under high-pressure and low-temperature conditions. Because it looks like ice and can burn when exposed to fire, it is also called " Combustible ice" or "solid gas" and "air ice". Its resources are equivalent to twice the sum of fossil fuel resources such as coal, oil and natural gas in the world. Natural gas hydrate is recognized as an important follow-up energy source with good prospects. It has the advantages of wide distribution, large amount of resources, high energy density and no pollution. Since the 1980s, many countries have paid great attention to the research of natural ...

Claims

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Application Information

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IPC IPC(8): E21B43/26E21B7/04E21B7/18
CPCE21B7/046E21B7/061E21B7/185E21B33/13E21B43/261E21B43/30C09K8/467E21B41/0099
Inventor 张怀文程远方韩修廷李梦来王伟韩忠英闫传梁袁华玉江龙
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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