Impact of Environmental Regulations on Drilling-Fluid Technology

Abstract

Summary A multitude of new drilling-fluid products, systems, and treatment processes have been developed recently in response to increasingly stringent environmental regulations. Many fluid additives and systems that once played a major role in the drilling industry are in little use today or are no longer available. New water-based mud systems are approaching the performance levels typical of conventional oil-based muds, levels largely achieved by new synthetic-based fluids. However, these new drilling fluids do not have the adverse environmental impact associated with oil-based systems when waste fluids and cuttings are discarded. Introduction Drilling-fluid technology has undergone significant changes in the past 5 to 10 years. Much of the change has been in response to new demands placed by regulatory agencies on drilling-fluid disposal from offshore locations. The response has led to increased use of polymer drilling fluids, the application of glycol and glycerol additives, and the development of synthetic-based muds, water-based spotting fluids, and many other new additives. The tried-and-true drilling fluids of the 1970's and early 1980's now play a much smaller role in the industry. The successful response to changing environmental regulations resulted primarily from the efforts of service, oil, and chemical company laboratories working independently toward a common goal. The event that had the most profound effect on drilling-fluid technology in the U.S. occurred in 1986. On July 2, 1986, regulations took effect that placed a limit on the toxicity of water-based drilling fluids being discharged into the Gulf of Mexico. Until mid-1986, operators in the Gulf of Mexico were allowed to discharge water-based drilling fluids and cuttings that did not contain diesel oil or "free oil." The presence of free oil was defined as a visible sheen on the receiving waters. After the early 1980's and before the toxicity limitations, water-based muds could be discharged if they could be assigned to one of eight authorized (generic) mud systems and the composition held within prescribed limits. Oil-based drilling fluids and cuttings could not be discharged, particularly if the oil-based mud was formulated with diesel oil. Equally important to the changing environmental requirements are the performance demands dictated by the new types of wells being drilled- e. g., deepwater, extended-reach, horizontal, and slim-hole wells. Fluid requirements for such wells have also resulted in new systems and additives. Wells are being drilled at higher penetration rates over longer, higher-angle intervals without bit trips than in the past owing to improvements in rig, bit, drillstring, and directional technologies. These improvements must be met by enhanced drilling-fluid performance. Most of the changes in drilling-fluid technology have taken place at a time of low oil prices and reduced industry employment. In July 1986, oil prices dropped below $10/bbl from almost $28/bbl just 6 months earlier. This intensified the industry downsizing that had started in the early 1980's. While some research projects were terminated or delayed as resources were reduced, drilling-fluid technology continued to advance, and the performance of today's drilling fluids far exceeds those of just a few years ago.