New Engineering Approach for Environmental Impact Mitigation in Drilling Operations

Abstract

Drilling waste generated during the drilling of wells using oil-based muds (OBMs) can often contain a high level of oily waste liquid as a result of surface mud losses, fluid displacements, rig wash down activities, and rig tank cleaning. This type of waste commonly known as "drilling slops" represents a significant volume of the overall waste generated while drilling a well and contributes to the overall environmental impact, cost of waste haul, and final disposal. In addition, the use of emulsifiers and other chemicals in OBMs leads to these liquids becoming difficult and expensive to treat efficiently with conventional separation and treatment systems. This paper sets out a new method for treatment and recycling of this type of waste for land drilling operations that achieved a 73% reduction in waste volumes generated compared to other wells drilled in the same area. The results in the paper will also demonstrate that the oil and water recovered by this system was within the recommended quality parameters for recycling in the drilling operation. This system significantly reduces the need to transport wastes for offsite treatment and disposal while reducing the overall environmental impact of the drilling operation. After analyzing the source of wastes generated during drilling at a land location in Algeria, a methodology was devised to segregate drilling wastes and avoid the co-mingling of different waste types before sending the drilling slops to the system for treatment. Lab tests were carried out to determine the optimum flocculants and dosing rates required to separate and recover the oil and water from the solids. This new method for treating and recycling these waste is an integrated chemical flocculation and dewatering system using a container fabricated from a specially engineered textile that provides confinement and drying of drill solids inside the container while allowing the liquids to permeate through the engineered textile for recycling and reuse on the rig. This system reduces the amount of liquid wastes hauled off site for treatment leaving dried solids that are easily handled and disposed of with conventional treatment methods. The use of this technology can have an important and cost effective contribution to reducing the environmental impact of land drilling operations using OBMs in Algeria and beyond.