| Oil-based mud systems have been the standard mud systems for the southern zone of Texas specially for Webb and Zapata counties. Recent environmental regulations imposed by Environmental Protection Agency require disposal of oil-based mud cuttings in approved disposal sites, away from the oil fields. To avoid the environmental problems associated with oil-based mud disposal, a group of South Texas operators including Conoco and Integrity Industries, Inc. have started experimenting with water-based mud system to replace the oil-based mud. Conoco has experimented several new water-based systems and more recently they formulated a water-based mud containing Limonene as an additive.;This formulation with a terpene (Limonene) is environmentally safe and also makes the rate of penetration (ROP) faster than oil-based mud based on actual field data gathered by Conoco.;In our laboratory study we have observed that the Limonene as an additive in the drilling fluids decreases the surface tension, increases the plastic viscosity, and has detergency characteristics that eventually lead to an increase in the rate of penetration (ROP). It is also believed that terpenes penetrate the formation and improve the hydrocarbon recovery from the reservoir. |
