Potential of Ethylhexyl Ester Oil to Enhance Drilling of HTHP Wellbores

Abstract

Ester-based drilling fluids have been accepted as an alternative to mineral oils in drilling applications and currently being utilized to drill oil or gas wells around the world. However, the ester-based fluids have deficiencies that limit its ability to carry and transfer drilled solids, stabilize the wellbore and drill the extended reach wells. Several approaches have been considered to overcome the ester limitations. Thus, the main aim of this study is to overcome these limitations by developing the high performance ester-based green drilling fluids for deep and ultra-deep wells. The low-pressure technology was applied in the synthesis of the ester to minimize ester hydrolysis and thermal instability issues during the drilling operation. The rapid ester synthesis involved the 2-ethylhexanol and vegetable oil-based methyl esters C12 in the presence of sodium methoxide as the catalyst. Performances of 2-EH ester-based drilling fluids behaviour was assessed under different hot rolling temperatures (121, 149, 177, and 200oC) for 16 hours. The rheological properties in terms of low shear rate of 6 and 3 rpm were superior which verified that these ester-based muds could be used in deep and ultra-deep wellbores without sagging, pipe sticking and unbalanced wellbore problems.