A Review on Impacts of Drilling Mud Disposal on Environment and Underground Water Resources in South of Iran

Abstract

In Drilling Oil Wells a system of complex fluids and chemical additives is used. Losses of these fluids in the well during drilling or disposal of them in well site could transfer pollutants to groundwater. In the present study a number of well sites, located in South of Iran, were studied to indicate types and magnitude of various pollutant materials that remain in the environment undestroyed and have considerable impacts on the underground water resources. Hydrocarbons used in Oil Base Muds (OBM) that can't be biodegrade readily in nature found to be the most severe pollutant material caused by disposal of Drilling Mud and Cuttings. Volume of drilling waste for these oil wells evaluated to be an average almost 0.5 m3 per one meter of drilled oil well. Available common treatment methods were compared to assess the most economically and environmentally attractive treatment scenarios. Thermal desorption and reserve pit without treatment are two most dominant methods could be conducted in Southern Oil Fields of Iran, each has its advantages and disadvantages. Due to geological structure and near surface aquifer in Khuzestan province thermal desorption should be conducted to disposal cuttings to reduce their hydrocarbon content to less than 5% according to European Standard. Major challenges of drilling waste management program in onshore oil fields of Iran were studied and clear principals for managing waste streams, which include: reduce, replace, reuse, recycle, recover, treat and final dispose, were listed along with material, equipment and strategies that should be considered in each step. Introduction Oil well drilling operations are responsible for the disposal of large quantities of drill cuttings and fluids. On a site of oil drilling, mud provide several important functions, lubrication of drilling bits, the maintenance of subsurface pressures, and transport of cuttings towards surface. It is a complex system of fluids based on water (WBM) or on oil (OBM), with several chemical and mineral additives. The formulation of these muds is adjusted with precision according to the physicochemical conditions of drilling, which change with the depth, and the nature of the crossed geological formations [3]. Other than the fluid (either water or oil or both) and the solid phases, different types of chemicals and polymers are used in designing a drilling mud to meet some functional requirements such as appropriate mud rheology, density, mud activity, fluid loss control property etc. Though the factors that guide the choice of a fluid base and the mud additives are complex, the selection of the additives must take account of both the technical and environmental factors to eliminate any environmental impact [4]. Due to potential detrimental effect of non-environment friendly drilling fluids, Environmental Protection Agency (EPA) and other regulatory bodies are imposing increasingly stringent regulations on the use and disposal of non-environment friendly drilling fluids, whether it is water-based or oil-based [4].

Deep Underground Injection of Waste from Drilling Activities—An Overview

“…The aforementioned microseismic events, caused by the injection process itself or naturally occurring events, can result in unwanted movement of disposed waste upwards towards the surface. Since the injected waste from drilling activities may contain certain amounts of oily cuttings, oil-based muds, lubricants, heavy metal ions, etc., its movement up towards the surface can have tremendous unwanted effects on underground sources of drinking water and the environment in general [87].…”

Hydrocarbon Exploration and Production- A Balance Between Benefits to the Society and Impact on the Environment

“…These compounds in drilling fluids affect man in different ways. Drilling fluids Lost in wells during drilling operations can filter into underground aquifer or their disposal at well sites can reach the aquifers or drain down to surface and sea waters [37]. Today, as part of the response of the oil industry to the need to preserve the environmental, cuttings and spent mud are now re-injected into underground rock formation or transported to the shores for proper treatment or recycling before dumping into the seas.…”