Experimental investigation of the application of Eucalyptus bark to prevent lost circulation in pay zones with acid dissolution capability

Loss of drilling fluid is a common problem during the drilling of wells and it restricts the appropriate functionality of muds. Drilling fluid loss significantly increases drilling costs and non-productive time as well as the drilling operation risks. Various investigations have been carried out in order to find appropriate mud additives that either block fractures and pores or reduce fluid loss by improving the fluid rheology. Cheap, environmentally friendly and effective additives are still required by the drilling industry. Hence, the application of available materials in each region, to produce appropriate additives, is a challenge for the oil industry. In this study, Eucalyptus Camaldulensis (EUC) bark powder has been chosen as a new, fibrous, cheap, environmentally friendly and available material to control fluid loss, particularly in southern Iran. Different characterization tests, such as acid dissolution and fluid loss control, were carried out to study the performance of the new proposed additive. Removal by hydrochloric acid and sulfuric acid were studied at various acid concentrations and temperatures. Dynamic fluid loss was also measured at different EUC concentrations. Our study showed that EUC powder can reduce the final fluid loss by 88–97%, the initial fluid loss by 45–66%, and the total loss by 87–94%, which is a satisfactory level.