A "Dual Protection" Drilling Fluid System and Its Application

Excellent drilling fluid techniques are one of the significant guarantee measures to insure the safety, quality, efficiency, and speediness of drilling operations. However, these drilling fluids are generally discarded and become wastes, which have the largest number and the largest influence on the environment after the completion of drilling operations. These drilling materials and additives together with drilling cuttings, oil, and water entered formations constitute waste drilling fluids, which ultimately went into soil, surface water, groundwater, and air. Among all kinds of drilling fluid systems that have been developed and applied at present, acrylic acid and its derivatives drilling fluid system and polysulfonate drilling fluid system are widely used. Environment pollutions are serious in complex wells or high-temperature deep wells, and even in oil-based drilling fluid systems. This article is based on lots of laboratory experiments on the chemical toxicity, biological toxicity, and biodegradability of drilling fluid additives that are mostly used in domestic fields screened out fluid loss additives, inhibitors, anti-sloughing agents, lubricants and so on that fit a "dual protection" drilling fluid system. In addition, this article developed a dual protection drilling fluid system that met the requirements of safety, quality, efficiency, and speediness of drilling engineering; could reduced the pollution on environment in maximum; and could protect both hydrocarbon reservoir and environment.