Drilling Fluids

 Drilling Fluids Mechanism

Drilling technologies have been improving with every passing day with more and more challenging job requirements on the offing. And, an integral part of this ever improving drilling process is the drilling fluids or mud, the usage of which has generated remarkable improvements in the drilling process. Basically, the drilling of longer, deeper and tougher wells have only been possible only because of the usage of highly advanced and sophisticated drilling fluids. Drilling fluids are introduced into the wellbore in order to facilitate the process of mechanical drilling by controlling pressure, suspending cuts, stabilizing the exposed rock masses, ensuring optimum lubrication and cooling as also by providing the desired amount of buoyancy.

The earliest forms of drilling fluids used were pure water which is used to permeate the soil when drilling was carried out for hydrocarbons. The term “mud” became synonymous to drilling fluids when drillers in the U.S. ran a cattle herd cross a watered field and the resultant muddy sludge was used for facilitating drilling purposes. Although the allied chemistry and technology governing the functioning of drilling fluids these days have become complex, the core concept of functioning has remained intact. These drilling fluids are indeed essential for the drilling success for minimizing the time and effort and also for maximizing recovery.

The Functions and Purposes of Drilling Fluids

During the process of drilling, the creation of cuttings is common. However, cuttings do not always cause problems till drilling ceases due to mechanical damages to the drill-bit and other associated problems. When such stoppages occur, drilling fluids aren’t needed and the cuttings fill up the hole again. However, drilling fluids act as a suspension tool that could prevent such stoppages from happening altogether. When movement decreases, the drilling fluid becomes more and more viscous. This allows the fluid to retain a liquid form when drilling is in progress and transform into a near solid state once the drilling ceases. Cuttings can then be suspended into the well, till the drill is inserted again to resume drilling. The gel like compound returns to liquid form again as drilling resumes.

The drilling fluids also aid in controlling pressure within a well by neutralizing the pressure exerted by the rock formations and the hydrocarbons. Weighting agents which are added to these fluids increases its density and the associated pressure exerted on the walls of the borehole as well. Drilling fluids also help in rock stabilization. Here again, additive compounds have a huge role to play. They ensure that the drilling fluid does not get absorbed by the rock formations within the well and that the pores on the surface of the rock formations do not get clogged.

The longer the well you wish to dig up, the more pipes you would need for drilling successfully. As the drill pipe gets heavier, the fluid adds to the buoyancy factor, reducing mechanical stress. Additionally, fluids also help in reducing the frictions with the rocks, thus reducing heat. The lubricating effect of the fluids along with the cooling it generates helps to keep the drill-bit in working condition for longer.

Along with the properties and the chemical composition of the well, a fluid engineer must also take into account the associated environmental hazards when prescribing a specific drilling fluid for a drilling job. For instance, oil based non aqueous fluids would be best choices when there are saltier rocks. Drilling fluids with an aqueous based are considered better choices for the environment for offshore drilling. Disposing drilling fluids once they have been used could also pose challenges. Recycling drilling fluids could also be an option.