Technology Focus: Drilling and Completion Fluids (November 2018)
Authors: Jacobs Trent 
Published: October 2018

Technology Focus
It is no secret that drilling fluid is crucial in drilling operations. The main function of drilling fluids is to transport drill cuttings from the bottom of the hole up to the surface. Drill cuttings then will be separated on the surface before the fluid is recycled for further drilling. This is to ensure a smooth drilling operation. A drilling-fluids rheological study is a must when drilling a well. Mud engineers and drilling engineers work hand-in-hand to ensure the desired drilling fluid with the right rheological properties is achieved on the basis of reservoir requirements and conditions such as reservoir pore pressure and temperature. Numerous additives are included in drilling fluids to fine-tune the drilling-fluid properties. Such additives include barites for weighting, lime, caustic soda, soda ash, and bicarbonate of soda, as well as other common acids and bases for pH control, amine- or phosphate-based products, and other specially formulated chemicals for corrosion control.
In addition, nanofluid also has been introduced to drilling fluid to improve drilling-fluid rheological properties further. Some researchers have worked on nanofluids-enhanced water-based mud prepared using the nanofluids of copper oxide and zinc oxide (sizes of less than 50 nm) in a xanthan-gum aqueous solution as a base fluid. The formulated drilling fluid showed improved thermal and electrical properties by approximately 35% compared with conventional water-based mud.
Furthermore, numerous researchers also have studied the application of graphene in drilling fluids. The addition of graphene in drilling fluids improves drilling-fluid properties, specifically with regard to fluid filtration. Graphene-based drilling fluid seems to produce thin, firm, and impermeable mudcake. This, in turn, minimizes the invasion of fluid from wellbore to reservoir rock and minimizes formation damage. Graphene, however, is an expensive additive; 50 g of graphene is approximately $250. Thus, the real challenge is to source graphene from “unwanted” graphite-related waste.
In this column, I have highlighted three papers with different novel ideas. One paper discusses the use of a novel polymer over conventional clay as a viscosifier and filtration-control agent. Another paper presents the lesson learned from high-temperature water-based mud offshore Sarawak. The last paper discusses a novel modified rectorite that provides reliable rheology and suspendabilty for biodiesel-based drilling fluids.
I hope you enjoy and benefit from the selected and highlighted papers. Other interesting papers are on the recommended additional reading list and in the OnePetro online library.
Recommended additional reading at OnePetro: www.onepetro.org.
SPE/IADC 189344 Drilling Fluids Automix by Vidar Hestad, Cameron, et al.
SPE 186233 Design and Application of Aerated and Foam Drilling Fluid, Case Study in Drilling Operations in Indonesia by WA Nugroho, Pertamina, et al.
SPE 187135 Dry Liquids on Silica as Secondary Emulsifiers for Drilling-Mud Applications by V. Lifton, Evonik, et al.