Study On Drilling Fluid System Using Enzyme To Remove Reservoir Blockage

As one perspective applied technique,enzyme based system for removal of formation damage induced by drilling fluids has advantages of no pollution, no corruption, no wasting in using process and so on, this technique has been focused on more and more attention at home and abroad recently.Two kinds of right degrading enzymes including XV1 and DF2 were selected for drilling fluids by measuring viscosity reduction. Further the dynamic studies of these two kinds of enzymes were carried out to determine and optimize service conditions. The optimum working temperatures of enzymes were enhanced by substrate protection and enzyme immobilization.The temporary plugging technique and the new enzyme based system for removal of formation damage were applied. The optimum drilling fluid treating chemicals and blocking agents were determined by wellbore filter-cake removal methods and permeability recovery tests. Three formulations of drilling fluid system using enzyme to remove reservoir blockage were developed by candidate selection process. Laboratory evaluation including wellbore filter-cake removal methods, core flow experiments and high temperature aging tests show that the enzyme system can provide remarkable wellbore filter-cake removal, core permeability recovery and high temperature resistance. It shows that the protecting reservoir effect of drilling fluid system which use enzyme to remove reservoir blockage is preferable. And the foundation of developing the applied technique of enzyme based system for removal of formation damage induced by drilling fluids as soon as possible has been built.