OS HEC - Hydroxyethyl Cellulose
Brines are a water based solution of inorganic salts that are used as a well control fluid during the workover and completion phase of the well. These fluids are clear and solids free so as to minimise formation damage and maximise well productivity. OS HEC is used to viscosify these fluids as unlike other available water soluble polymers it is acid soluble as well as being recognised as having the least damaging effect on formations.
OS HEC is a hydroxyethyl cellulose viscosifier for use in workover and completion fluids. OS HEC is the primary viscosifier used in non damaging drilling fluids.
Typical Physical Properties
Appearance - White free flowing powder
DS - 1.8 – 2.0
pH - 6.0 – 8.0
Transparent - 80 % min
Moisture - 7% max
Ash - 10% max
Particle size - min. 95% pass through 40 mesh
Water Insoluble Residue - 0.5%
Viscosity - 4,500 – 6,500 cps
(1% aqueous solution, 25oC, Brookfield LVF spindle 4# @ 30rpm)
OS HEC is water soluble and works well in all brines as a viscosifier. Using any viscosifier it is inevitable that some will remain in the pores thus impairing permeability. Unlike other water soluble polymers, OS HEC is Acid soluble and can thus be broken down and removed using HCL.
OS HEC is a hydroxyethyl cellulose viscosifier mainly applicable in workover and completion brines of mono and divalent cations and in preparation non-damaging fluids for drilling oil reservoir zone in vertical, deviated and horizontal wells.
OS HEC viscosifier maintains high apparent viscosity and yield point but low gel strength. OS HEC controls the fluid loss and maintains very thin filter cake which forbids drilling problems and damages to the reservoir as far as it is completely soluble in hydrochloric acid.
OS HEC is the main viscosifier in preparation lost circulation viscous pills with different grades of CaCO3 to stop losses in pay zone. OS HEC is an efficient viscosifier in all brines.
OS HEC should be mixed through the hopper at a rate of 20 min/sack.
The recommended concentration in workover / completion brines and non-damaging drilling fluids from 1-2 ppb, while in LCM viscous pills 3-4 ppb.
OS HEC is packaged in 25 kg sacks.