5th Thermal and Fluids Engineering Conference (TFEC) April 5–8, 2020 New Orleans, LA, USA TFEC-2020-32112 *Corresponding Author: anoop.baby@qatar.tamu.edu INFLUENCE OF CNT-NANOPARTICLES IN THE FILTRATE CHARACTERISTICS AND FILTER CAKE FORMATION OF A WATER-BASED DRILLING FLUID Anoop Kanjirakat *1 , Arnel Carvero 2 , Reza Sadr 3 , Mahmood Amani 3 1 Mechanical Engineering Program, Texas A&M University at Qatar, Doha, Qatar 2 Petroleum Engineering Program, Texas A&M University at Qatar, Doha, Qatar 3 J. Mike Walker ’66 Department of Mechanical Engineering, Texas A&M University, College Station, USA ABSTRACT In a reservoir drilling application, the drilling mud should minimize the amount of the filtrate fluid entering into the reservoir formation. To ease the drilling process, the filter cake formed should also be thin, stable, and of uniform distribution. The addition of nanoparticles into the drilling mud is expected to improve these functionalities. In the present work, the effect of addition of carbon nanotubes (CNT) into a water-based drilling mud sample in improving its filtrate characteristics is studied. The filtrate volume, dry and wet weights, and thickness of the filter cakes are measured to evaluate the filtrate characteristics. Ceramic disks of two pore-throat sizes are used in the experimentation. The addition of CNT particles is observed to beneficial in reducing the filtrate amount or fluid loss. An increase in nanoparticle loading is observed to have increased the filtrate cake thickness. The porosity of the filter cake formed is observed to be lower than that of the ceramic disk used. KEYWORDS: drilling mud, nanoparticles, filter cake, fluid loss, carbon nanotubes. 1. INTRODUCTION The selection of drilling fluids and the proper control of its solid contents play a significant role in the overall economics of the oil and gas industry. In a drilling process, the drilling fluid assists in drilling boreholes into the earth’s surface. It is pumped to the bottom of the borehole to cool and lubricate the drill bit. This fluid also aids removing the rock debris from drilling area and convey it to the surface. Proper selection of the drilling fluid is vital to reduce cost, have a low impact on the environment, and to enhance the production efficiency for a specific well. The viscosity, gel strength, and filtration (or fluid loss control) are among the significant properties that determine the behavior of drilling mud at high-pressure high- temperature (HPHT) drilling applications. Drilling fluid, along with being a cooling agent, should also limit the fluid loss into the formation by forming a layer of solid mud on the walls of the borehole. There are various types of drilling fluids, namely; pneumatic, water-based mud, oil-based mud, and synthetic-based that are being used in various reservoir fields. Water-Based mud is widely (approximately 80 % of all wells) used drilling fluid in the oil and gas industry, owing to its environmentally friendly nature [1]. Water-Based mud is mostly composed of water and barite and some ingredients to control pH and viscosity. Barite is added to increase and adjust the drilling fluid density. In most drilling conditions (also termed as an over-balanced drilling condition), the drilling mud is kept at a pressure higher than that excreted by the pore fluid in the formation. Under such circumstances, the drilling fluid would invade into the rock formations with a minimal amount of the filtrate entering into the reservoir formation. To achieve this functionality, clay-forming materials (such as bentonite) are added to the drilling fluid. During the drilling process, the solid particles from the drilling mud are deposited on the walls to form a layer of mud cake (also known as filter cake). An ideal filter cake forms a thin, low permeable layer, which minimizes the further intrusion of fluid into the formation, reducing the fluid loss from the drilling mud. The fluid movement into the formation is then controlled by the permeability of the filter cake. However, an uncontrolled buildup of the filter cake could contribute to a surge in pressure creating irreversible damage to the borehole. Hence, the 247