Study On High Temperature And High Density Biodiesel-based Drilling Fluid System

Traditional oil-based drilling fluids has many problems,such as high production costs,environmental pollution,severely limit the use of oil-based drilling fluids.Meanwhile,for the more and more deep ultra-deep drilling requirements,this paper chose environmentally friendly and renewable biodiesel as the drilling fluid base oil,then selected emulsification agents,wetting agents,organic soil,heat stabilizers,and fluid loss control agents,that suitable for the high temperature and high density drilling fluid system successfully developed a biodiesel drilling fluid system which can resistance high temperature near 200? and high density 2.4g/cm~3.The experiments used oil-water drilling fluid system which oil ratio is 9:1,and kept the balance between drilling fluid system and formation water by using saturated brine.The paper selected the SP-85 and OP-10 as primary emulsifier,DTAB as supplemented emulsifiers,oil-soluble resin as high temperature stabilizer,barite as weighting agent.Prepared organic soil for high-density system,selected SZ02-WET which is environmentally friendly as wetting agent.The experiments determined formula of the high temperature and high density drilling fluid systems based biodiesel is: Biodiesel + saturated brine + 1%SP-85 + 1%OP-10 + 0.5%DTAB + 2%organic soil + 0.8%SZ02-WET + 2%ZBM-1 + 2%oil-soluble resins,oil-water ratio is 9:1,barite as weighting agent so the highest density can be 2.4g/cm~3.The paper evaluated the ability about contamination resistance of drilling fluid based biodiesel,the experiment proved that the system has good resistance to high temperature performance,and has a certain ability to resist water intrusion,inferior soil invasion and calcium invasion.