STUDY AND APPLICATION OF A WORKOVER FLUID——TB-O

During workover operation, non-solid and low solid workover fluid causes severe lost circulation and formation damage, and eventually leads to inefficient workover. To solve this problem, a type TB-O low damaging workover fluid system is developed, which possesses efficient temporary plugging property and sound plug releasing. YR-O1 oil soluble temporary plugging agent and HR water soluble non-ion surfactant is used as the dispersant for this system, and XT-20 hydroxyethyl cellulose is used as the viscosifier. Lab tests show the rapid forming of shielding band and drop of lost circulation, and the permeability return reach as high as 99.2% after plug releasing. Field using in ten wells further proves its advantages.