Preparation of Lignin Graft Copolymer as a Fluid Loss Additive for Water-based Mud

During offshore oil and gas exploration, drilling at high temperature and pressure in a geological formation is usually the cause of damage to water-based mud. In this paper, a water-soluble lignin graft copolymer (LGC) was grafted via condensation polymerisation using soda lignin recovered from oil palm empty fruit bunch (OPEFB) fibre and itaconic acid. This LGC was applied in a water-based drilling mud formulation as a fluid loss control additive. Lignin graft copolymer was characterised using Fourier Transform Infrared (FTIR) spectroscopy and Differential Scanning Calorimetry (DSC) techniques. In tests of mud properties, the filtration performances of LGC and a commercial fluid loss additive (Ressinex II) were compared. Using an additive dosage determination test, we found the optimum dosage of LGC and Ressinex II to be 0.7%. The fluid loss properties measured after thermal aging showed that LGC can be used as a fluid loss additive for drilling operations at temperatures up to 190°C. The rheological performances of LGC and commercial fluid filtration additives were also compared. Compared to the commercial additives, LGC provides more tolerance to salt contamination at room temperature and at high temperatures.