New Drilling Fluid Formulation Using 750 Molecular Weight Polyethylene Glycol Base Surfactant Derived From Natural Oil

This research is carried out to formulate a new drilling fluid that suitable to drill an injection well for surfactant flooding field. Shortages of conventional drilling fluid caused it to be unsuitable to drill in this area. According to Chinenye C. Ogugbue (2010), surfactant based fluid typically have little residue or formation damage compared to biopolymer systems, thereby gaining acceptance as reservoir drilling fluids. Low interfacial tension existing between surfactant based fluid and the produced or injected fluid is one of major criteria for this reduction in formation damage. In addition, a controlled flocculated mud system incorporating non-ionic surfactant plus water soluble electrolytes proved thermally stable which would give good hole condition and logging characteristics as reported by Burdyn (1956).

In this study, a new method is discussed to improve the stability of rheology modifiers and fluid loss polymers of drilling fluid utilizing a non-ionic surfactant used in surfactant flooding. The one that used in surfactant flooding has been utilized in drilling fluid which is Polyethylene Glycol (PEG) 750 molecular weight base surfactant. This method exploits the interactions of polysaccharides (Xanthan gum) and cellulosics (PAC) with polyglycols surfactant. The non-ionic PEG 750 surfactant was added gradually and the best concentration of the surfactant was determined. The rheological and fluid loss properties below and above the CPT which are 50°C and 100°C respectively were evaluated and compared with PETRONAS drilling fluid bench mark. The CPT for PEG 750 is 65°C.

Polymer and polyglycols were found to associate by intermolecular hydrogen bonding and hydrophobic interactions with the best concentration of 2% v/v of PEG surfactant. This association was found to benefit fluid loss polymers with reduction of 38%, a reduction from 5.4ml to 3.6ml fluid loss compare to the base fluid at temperature below the CPT at 50°C. Besides, the improvement on the rheology properties was observed due to stabilization of the suspending polymers by the polyglycol system.