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A water unlocking agent for low water cut oil wells

A water-blocking agent and low water content technology, applied in wellbore/well components, drilling compositions, production fluids, etc., can solve the problem of high cost, injection of surfactants to reduce two-phase flow resistance, and failure to fundamentally eliminate Water lock effect and other problems can be solved to reduce the start-up pressure, eliminate the two-phase seepage resistance, and increase the relative permeability of the oil phase.

Inactive Publication Date: 2018-08-31
CHINA UNIV OF PETROLEUM (EAST CHINA)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the cost of fracturing reconstruction is too high, and the injection of surfactant can only reduce the seepage resistance of two-phase flow, but does not fundamentally eliminate the water locking effect

Method used

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  • A water unlocking agent for low water cut oil wells
  • A water unlocking agent for low water cut oil wells

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0013] Take 10g of nano-silica with an original particle size of 15-30nm and 990g of ethylene glycol monobutyl ether and mix evenly to obtain a water-dissolving and locking agent with a mass fraction of nano-silica of 1%.

Embodiment 2

[0015] Take 30g of nano-silica with an original particle size of 15-30nm and 970g of ethylene glycol monobutyl ether and mix them evenly to obtain a water-splitting and locking agent with a mass fraction of nano-silica of 3%.

Embodiment 3

[0017] Take 50g of nano-silica with an original particle size of 15-30nm and 950g of ethylene glycol monobutyl ether and mix them evenly to obtain a water-splitting and locking agent with a mass fraction of nano-silica of 5%.

[0018] Add 1.5mL of water and 1.5mL of crude oil to each of the three graduated cylinders, then add 1.5mL of the hydrolysis-locking agents prepared in the above three examples to each of the three graduated cylinders, and put the graduated cylinders into a 70°C water bath , stand still and observe the dissolution status. Experiments show that without external stirring at 70°C, the interface between oil and water disappears obviously after 6-6.5 hours, and the whole system becomes a uniform and stable single-phase system, which shows that the oil-water interface can be eliminated by solubilizing oil and water with the water-dissolving and locking agent .

[0019] Table 1 Miscibility time of the system

[0020] Nano silica mass fraction, %

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Abstract

The invention provides a water-blocking agent for releasing water-locking damage in low-water oil wells, which is composed of nano-silica with an original particle size of 15-30nm and ethylene glycol monobutyl ether, wherein nano-silica accounts for 1% of the total weight %-5%. When the volume ratio of the water-blocking agent to water is greater than 1:1, the water-blocking agent can solubilize the water phase and the oil phase within 6 hours, and the two phases of oil and water can be changed into one phase, thereby eliminating the two-phase seepage resistance, and the nanometer two Silica can enhance the hydrophilicity of the rock surface, allowing free water to adsorb to the rock surface to form a water film, thereby increasing the relative permeability of the oil phase and reducing the start-up pressure of oil phase seepage. For oil wells with water-locking damage, according to the leakage of well-washing fluid recorded during the well-washing operation, inject a water-blocking agent of the same volume as the water loss into the formation through the casing annulus, shut down the well for more than 6 hours and then open the well for production. Effectively remove the water lock damage of low water cut oil wells.

Description

Technical field: [0001] The invention relates to a water-blocking agent for releasing water-blocking damage of oil wells, which is used for reservoir protection of oil wells with low water content. Background technique: [0002] During the development of oilfields, due to operations such as pump replacement and pump inspection, it is necessary to use well-entry fluid to circulate and clean the casing annulus and tubing. At present, the water phase with surfactants is mainly used as the well-flushing fluid, but for the water content In lower oil wells, after the water phase in the well fluid invades the oil layer, a high water saturation zone will be formed around the wellbore, which changes the flow form of crude oil in the oil layer from single-phase flow to two-phase flow, greatly reducing the oil phase flow. The relative permeability increases the resistance of crude oil flow, thereby affecting the oil production of the oil well. The phenomenon that the water phase invade...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C09K8/58C09K8/584E21B43/22
CPCC09K8/58C09K8/584C09K2208/10C09K2208/22E21B43/16
Inventor 蒋平吴昊葛际江张贵才裴海华孙铭勤
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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