Primary Study on Isoelectric Drilling Method and Zero Potential Drilling Fluid

Abstract:

The concepts of isoelectric drilling method and zero potential drilling fluid are presented. By the concept of isoelectric drilling method, zeat potential on rock surface is zero, that is, in IEP state, both penetration rate and bit service life can be improved with consequent higher drilling efficiency. As for zero potential drilling fluid, that is changing currently used Na-bentonite with zeta(-40～-35 mv)potential into bentonite with zero potential(-5～ 5 mv); changing “anion suspension system(ζ potential＞-45 mv)” of the drilling fluid into “cationsuspension system(zeta potential close to zero potential)” and changing anionic treating agents, such as filtrate reducer and viscosifier, into cationic or nonionic ones to form the drilling fluid with the corresponding performance. Drilling experiment shows that drilling efficiency can be effectively improved by isoelectric drilling method and zero potential drilling fluid. Some understandings of the relevant research are put forward.