The Study Of Fuzzy Ball Composite Plugging Drilling Fluid System

For the leakage formation, we often use the foam drilling fluid. But foam drilling fluid has many limitions: it is very easy to be limited by water pumped and the foam drilling fluid can not self circulation,it must uses special degassing device in the well bore after returning. The cost will higher than before.In addition, if handled the foam drilling fluid improperly after it used,it may pollute the environment.For these problems, a kind of plugging drilling-Fuzzy Ball Composite Plugging Drilling Fluid System was prepared. Select two kinds of surface active agents(sodium dodecyl benzene sulfonate SDBSand dodecyl dimethyl betaine BS-12), mixed to them as a kind of Air bag agent according to the mass ratio of 6:4; two kinds of polymer assistants(poly acryla mide PAM and high viscosity carboxy methyl cellulose HV-CMS) were mixed as the fabric layer by 1:1 proportion. They can make a special "velvet bag structure of high strength micro bubble system in the drilling fluid, then add the water swellable particles in it, forming new fuzzy ball composite plugging drilling fluid system. By a lot of experiments,the formula of composite plugging drilling fluid system will be determined: 4% bentonite run +0.4%DSJ+0.4%SPNH+0.3%KPAM+0.24% sodium carbonate+0.2% air bag agent+0.35%velvet layer agentt +3% absorbent bulk.The experiment results of the composite plugging drilling fluid performance that under different conditions showed that at high temperature,the stability and anti-salt, calcium and other pollution ability of the compiosite plugging drilling fluid system is so strong. Core plugging experiments show that the plugging rate of large pores, leakage loss formation and small pores lost layer of fuzzy ball composite plugging drilling fluid system reached 92%, the plugging effect is much higher than the general drilling fluid.