Thickening agent for liquid carbon dioxide fracturing and preparation method thereof

Abstract

The invention discloses a thickening agent for liquid carbon dioxide fracturing and a preparation method thereof, relates to a thickening agent formula for the liquid carbon dioxide fracturing, and belongs to the technical field of oilfield chemistry. The thickening agent for the liquid carbon dioxide fracturing and the preparation method thereof are provided for solving the deficiency that existing liquid carbon dioxide fracturing viscosity is low. The thickening agent for the liquid carbon dioxide fracturing consists of constituents of, by weight percentage, 20-30% of long-chain alkyl trimethyl quaternary ammonium salt, 10-20% of long-chain alkyl dihydroxy ethyl methyl quaternary ammonium salt, 5-15% of organic acid, 10-20% of small molecular alcohol and the balance clear water. The thickening agent for the liquid carbon dioxide fracturing is made of raw material which is low in cost and easy to obtain, can substantially improve liquid carbon dioxide fracturing viscosity, reduces filtration loss of liquid carbon dioxide in the fracturing, and improves sand carrying capacity of the liquid carbon dioxide.

Description

technical field [0001] The present invention relates to a liquid CO 2 The invention relates to a thickener formula for fracturing, which belongs to the technical field of oil field chemistry. Background technique [0002] Liquid CO 2 Fracturing is a process that takes the form of pure liquid CO 2 It is also called dry fracturing as a technology for fracturing with sand-carrying fluid. Its many advantages are mainly reflected in: 1. No water phase, completely eliminate water sensitivity and water lock damage; fracturing fluid has extremely low interfacial tension, and can completely and quickly return from the reservoir after being heated and gasified; The residue has a good cleaning effect on the supporting fracture diversion bed, and maintains a high fracture conductivity and a long effective fracture length. [0003] Liquid CO 2 CO during fracturing 2 Maintain liquid state (or supercritical state), CO after construction 2 It becomes a gaseous state and is quickly di...

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Problems solved by technology

However, domestic and foreign practical experience shows that liquid CO 2 The biggest problem in fracturing is its low viscosity (about 0.1mPa.s) and poor sand-carrying capacity, which leads to the need for large pump injection displacement, resulting in high wellbore friction, high construction pressure, and increased construction difficulty and cost. And since liquid CO 2 The temperature during fracturing construction is extremely low, and the low temperature causes the substances in the existing fracturing fluid system to increase the viscosity of the fracturing fluid to be applied to liquid CO 2 There is basically no viscosity-increasing effect during fracturing, and no liquid CO has been retrieved so far. 2 Patents related to special viscosifiers for fracturing

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