Performance, Economy and Waste Management of an Emulsion Glycol Mud Formulation to Replace OBMs While Drilling Asmari Formation in Maroun Oilfield

Oil-based invert systems are the most reliable drilling fluids while drilling troublesome shales. However, due to environmental problems and economics, efforts have been made to replace invert systems with less-toxic, and most cost effective water-based fluids. Glycol muds are one alternative. Low toxicity to the environment, high degree of inhibition, lubricity, anti-bit balling properties and polymer stability are the main advantages offered by glycol muds. Also compared to OBMs, typical glycol muds are cheaper to prepare which would become of economic significance in areas with high rates of mud loss to the formation.Oil-based drilling fluids are quite popular in Iranian drilling industry. Considering environmental acceptability, domestic availability, economics and performance criteria, glycol muds have the highest prospect to replace oil-based muds in the Iranian oilfields. The possibility of the replacement was considered in a laboratory research, conducted at Pars Drilling Fluid Co. (PDF) in 2006. Present study further considers this possibility, focusing on weight optimization and contamination effects. The main objective of the present work was to design a low-density glycol mud to replace the OBMs currently used to drill the Asmari formation in Maroon oilfield. An emulsion glycol mud with a density of 60 PCF was designed and compared with the oil-based formulation of similar density. Overall, the results were convincing. The performance of the system was acceptable. Its diesel content was recoverable to meet disposal requirements. Savings up to 40% in initial fluid cost are also expected with this replacement. Considering high rates of loss to the Asmari formation in this field, reduced initial costs from this replacement is an important economic achievments. The emulsion glycol system was proposed to NISOC to meet their economic and environmental requirements while selecting the proper mud to drill subnormally-pressured Asmari formation in Maroon oilfield.

Keywords:

OBMs , WBMs , Shale Inhibition , Glycol Mud , Cloud Point Engineering , Emulsion uds , WeightOptimization , DrillingMudEmulsifiers , Contamination , emulsification Waste Management , Economy