Abstract:

Guided by the concept of 'reversible structure solution fracturing fluid',a new type of thickening agent as well as a new fracturing fluid system with the agent is developed.Tests show that the system is a typical viscoelastic structure solution with it's G′ constantly bigger than G″;with a viscosity of merely 30mPa·s(170s^-1),the system has a proppant-carrying capacity strong enough for operation;this viscosity can be easily achieved at the temperature of 150℃ by adding only 0.8wt% of the agent into the system and is not sensitive to the shearing time;the system has a "clean" viscosity break fluid,high proppant flow conductivity(more than 90%),and slight damage to core(lower than 10%).The application of the system in five wells,namely P65-9,Wen 99-20,Wei1 0-40,Weiche-214,and Wei 355-4,in Zhongyuan oil field,yields positive stimulation results and causes lesser damage to formations than that of conventional fracturing fluids.It is also user-friendly because of its simpler composition and preparation procedure,excellent proppant carrying capacity,small friction drag(22% of that of fresh water),and higher working temperature(up to 120℃).

Key words: reversible structure solution, fracturing fluid, clean fracturing fluid, thickening agent