Considering the various tasks of the drilling fluids in oil and gas well drilling, the efficiency of the drilling mud is the result of the accurate and correct selection of the mud formulation. Both water-based and oil-based muds have advantages and drawbacks with specific applications that justify their usage in drilling operations according to them. In general, water-based muds are less toxic and less expensive to produce. Also, water-based muds are more compatible with the environment, specially about releasing drilling wastes into the sea. However, for many drilling operations with critical conditions, such as drilling deep formations with high temperature, drilling in the highly unstable shale layers, horizontal and directional drilling, drilling narrow wells that requires high torque, oil-based drilling muds are recommended to be used. On the other hand, the formulation of oil-based drilling mud is more complicated and their production cost is higher.

The advantages of oil-based drilling mud include high corrosion controlling, increasing therate of penetration (ROP), the possibility of reusing drilling mud in several wells, higher efficiency in high temperature-high pressure conditions and better lubricating the drill bit.

From technical point of view, in some cases, oil-based drilling muds are preferable to water-based drilling muds. For instance, when using water-based muds, more drilling waste is produced than oil-based muds. In addition, oil-based mud has higher resistance against different types of contaminations -such as cement, formation water, anhydrite particles, and etc.- compared to water-based muds.  On the other hand, due to the high cost of preparing oil-based muds compared to water-based muds with similar density, the economic justification of choosing an oil-based muds should be done according to its performance.

Drilling fluids used in Oil-based drilling mud

Calcium Chloride is used in drilling mud with powder or flakes appearance to to supply Calcium ions. Calcium Chloride is one of the drilling fluids weighting agents. It can adjust the activity of the water phase in invert-emulsion mud.

Advantages of Calcium Chloride usage in drilling mud over other weighting agents, is its low price in formulation of solid-free completion brines.

The maximum density obtainable is 11.6 Ibm/gal (SG 1.68) with the addition of Calcium Bromide. Calcium Chloride and other brine completion fluids, eliminate plugging of producing sands often encountered when perforations are made through drilling mud. These brine fluids, free of solids, eliminate the problem of cracking, solidification and settling of solid materials on packers.

Calcium Chloride is used to control the activity of oil-based mud and work over/completion fluids. It is also an effective means of providing high Chloride ion concentration levels in the aqueous phase of mud for balanced activity mud systems, for maximum shale stability.

CaCl2-containing drilling mud can be used in high pressure formations.

It is much easier to dilute this material in water and has the ability to absorb dust from drilling operations inside the well.

Introduction:The oil and gas industry is one of the largest and most important industries in the world, which is very important strategically and economically. With the development of environmental solutions in human societies, activities that endanger the environmental system will be seriously considered. For this reason, efforts have been made to reduce the environmental impact of drilling operations, especially in the use of drilling fluids. In this article, the management of green drilling fluid supply chain is investigated. First, the management of the green supply chain and related literature and the role of drilling fluids in the drilling process of oil and gas wells and the environmental effects of these materials if they are not controlled and monitored are stated. Then the management of green supply chain of drilling fluids is examined.

Green drilling fluid supply chain management