CO2 emulsion and method for reforming and exploiting natural gas hydrate reservoir by injecting CO2 emulsion

A hydrate and CO2 technology, applied in the fields of fluid production, earthwork drilling, wellbore/well components, etc., can solve the problems of poor diffusivity, inability to effectively cover natural gas hydrate reservoirs, wellbore blockage, etc.

Active Publication Date: 2020-06-12
CHINA UNIV OF PETROLEUM (BEIJING)
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, when injecting pure liquid carbon dioxide for reservoir transformation, there will be the following problems: 1. Due to its poor diffusivity, it cannot effectively cover the gas hydrate reservoir when injected into the sediment, which is not conducive to the formation of low-permeability caprock ; 2. Due to the extremely harsh reservoir conditions, carbon dioxide is very easy to block the wellbore due to the formation of hydrates during the injection process; 3. The hydrates generated based on liquid carbon dioxid

Method used

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  • CO2 emulsion and method for reforming and exploiting natural gas hydrate reservoir by injecting CO2 emulsion
  • CO2 emulsion and method for reforming and exploiting natural gas hydrate reservoir by injecting CO2 emulsion
  • CO2 emulsion and method for reforming and exploiting natural gas hydrate reservoir by injecting CO2 emulsion

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Embodiment 1

[0037] The volume fraction of distilled water in the emulsion is 50vol%, liquid CO 2 The volume fraction of is 50vol%, the mass fraction of surfactant AOT is 3wt%, the massfraction of Tween80 is 1wt%, the massfraction of tetrabutylammonium bromide (TBAB) is 0.1wt% (all based on water quantity calculation). The preparation temperature is 293.2K, the preparation pressure is 10MPa, and the stirring speed is 2000r / min. CO was generated under the condition of stirring for 3 hours 2 lotion. CO 2 When the emulsion is injected above the hydrate reservoir, the reservoir conditions are: temperature 278.2K, pressure 8MPa, methane hydrate saturation 29.29.

[0038] The emulsion construction method of this embodiment is to prepare CO2 under high temperature and high pressure conditions. 2 Emulsion, and inject the emulsion above the gas hydrate reservoir under the condition higher than the reservoir pressure to form CO 2 Hydrate cover. When CO 2 After the emulsion is converted into h...

Embodiment 2

[0040] In order to study the utilization of CO provided by the present invention 2 The effect of emulsion reformation on natural gas hydrate reservoirs and exploitation, the present invention uses a one-dimensional visualized hydrate simulation device to carry out corresponding simulation experiments. The reactor is composed of three sapphire tubes and four stainless steel tubes, with a height of 1m, an effective volume of 0.51L, and a uniform inner diameter of 2.54cm. The maximum operating pressure of the reactor is 32MPa, and four pressure sensors and temperature sensors are inserted in different positions in the reactor to measure the pressure and temperature changes in the reactor during the experiment. The specific steps are as follows: First, accurately weigh a certain amount of sand and 3.35% salt water and fully and uniformly mix the two. The sand-water mixture is then charged into the reactor. Accurately weigh a certain amount of seabed sediment, put it into the ket...

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Abstract

The invention discloses a CO2 emulsion and a method for reforming and exploiting a natural gas hydrate reservoir by injecting the CO2 emulsion. The CO2 emulsion comprises liquid CO2, at least two kinds of surface active agents, a hydrate generation accelerant and water. Di(2-ethylhexyl) sodium sulfosuccinate is at least included in the surface active agents. The mass percent concentration of the di(2-ethylhexyl) sodium sulfosuccinate ranges from 0.5% to 3%, and the mass percent concentration of the other components of the surface active agents ranges from 1% to 3%. The mass concentration of the hydrate accelerant ranges from 0.05% to 1%. The volume percentage of water in the emulsion ranges from 10% to 70%, and the volume of the liquid CO2 accounts for 30%-90% of the volume of the emulsion. By means of the exploiting method, the characteristics that the CO2 emulsion has good diffusibility in porous media and generated hydrates have ultralow permeability are utilized, the remarkable production increase function is achieved on exploitation of natural gas hydrates, meanwhile, the seabed CO2 sealing effect can be enhanced, and the exploitation safety coefficient of the natural gas hydrates can be improved.

Description

technical field [0001] The invention belongs to the field of natural gas hydrate exploitation; 2 Emulsion and injection thereof are used to modify and exploit natural gas hydrate reservoirs. Background technique [0002] Natural gas hydrate is a solid crystalline non-quantitative compound formed by water and natural gas under low temperature and high pressure conditions. Natural gas is mainly composed of methane, so it is also called methane hydrate. Under standard conditions, one cubic meter of methane hydrate decomposes to produce a maximum of 164 cubic meters of methane gas and 0.8 cubic meters of water. The energy density of methane hydrate is very high, which is 2-5 times that of conventional natural gas, and its combustion value is very high, and it hardly produces any residue after combustion. It is a rare clean energy. [0003] Although gas hydrate reserves are huge and have broad application prospects, due to the complexity of the environment in which it occurs a...

Claims

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Application Information

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IPC IPC(8): E21B43/22
CPCE21B43/16E21B43/164
Inventor 陈光进孙振峰孙长宇李楠刘蓓杨兰英
Owner CHINA UNIV OF PETROLEUM (BEIJING)
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