Application of Low Damage Drilling Fluid in Yibei Area

A low damage drilling fluid has been developed to protect the low permeability reservoir in the Block 43,Yibei,Shengli oilfield.The development of the new drilling fluid is based on a "synergistic effect" of a drilling fluid for use in drilling low permeability reservoirs.AMP-2,a reservoir protection agent for the new drilling fluid,has strong plugging capacity and good stability;no settling has ever been found after standing for 30 days.FCS,a water blocking agent,does not settle at low temperature to -20℃.Invasion depth of the new drilling fluid on FA sand bed is only 4.0 cm,and on HTHP sand bed this invasion depth is 5.2 cm.The low surface tension of the mud filtrates is 22.1 mN/m,which is efficient in minimizing the damage caused by water block.Recovery of permeability is greater than 90%,an indication of good reservoir protection.Application of this drilling fluid technology on 4 wells reveals that the drilling fluid has stable performance,its properties easy to maintain,and average drilling time reduced by 11.73 days.Wells drilled with this drilling fluid do not necessitate acidization and fracturing,and flow at first production.The average flowing production rate has been 7.88 t/d.This drilling fluid has been successfully used in the Block 43,and the practices are of importance for the development of old oilfields in Shengli area.