• It can increase the viscosity and gel strength of the drilling fluid, which can improve the hole cleaning, cuttings transport, and solids suspension capabilities of the drilling fluid.
• It can reduce the fluid loss and filtrate invasion of the drilling fluid, which can prevent formation damage, wellbore instability, and differential sticking problems.
• It can enhance the shale inhibition and wellbore strengthening properties of the drilling fluid, which can prevent shale hydration, dispersion, swelling, and collapse.
• It can improve the lubricity and rheology of the drilling fluid, which can reduce torque and drag, friction, and wear of the drill string and bit.
• It can modify the wettability and emulsification of the drilling fluid, which can improve the oil recovery, water control, and corrosion inhibition of the drilling fluid.

Adhensive for drilling fluid can be classified into different types according to its chemical composition, such as:

• Natural polymers: These are derived from natural sources, such as starch, cellulose, guar gum, xanthan gum, etc. They are biodegradable, environmentally friendly, and cost-effective. However, they may have limited thermal stability, compatibility, and performance in harsh conditions.
• Synthetic polymers: These are synthesized from chemical reactions, such as polyacrylamide (PAM), polyacrylate (PA), polyvinyl alcohol (PVA), etc. They have high thermal stability, compatibility, and performance in harsh conditions. However, they may be expensive, toxic, and non-biodegradable.
• Inorganic compounds: These are composed of metal ions or salts, such as bentonite clay, attapulgite clay, sodium silicate, potassium silicate, etc. They have high viscosity and gel strength in low concentrations. However, they may be affected by salinity, hardness, pH, and temperature of the drilling fluid.

Adhensive for drilling fluid works by following different mechanisms depending on its type and function, such as:

• Hydrogen bonding: This is a type of intermolecular force that occurs between molecules that have hydrogen atoms bonded to electronegative atoms (such as oxygen or nitrogen). Hydrogen bonding can increase the viscosity and gel strength of the drilling fluid by forming cross-links between polymer chains or between polymer chains and water molecules.
• Electrostatic attraction: This is a type of intermolecular force that occurs between molecules that have opposite charges (such as cations and anions). Electrostatic attraction can increase the viscosity and gel strength of the drilling fluid by forming ionic bonds between polymer chains or between polymer chains and metal ions.
• Van der Waals forces: This is a type of intermolecular force that occurs between molecules that have temporary or permanent dipoles (such as polar or non-polar molecules). Van der Waals forces can increase the viscosity and gel strength of the drilling fluid by forming weak attractions between polymer chains or between polymer chains and solid particles.
• Physical entanglement: This is a type of physical interaction that occurs between long-chain molecules that have high molecular weight (such as polymers). Physical entanglement can increase the viscosity and gel strength of the drilling fluid by forming knots or loops between polymer chains or between polymer chains and solid particles.

Adhensive for drilling fluid is an important component of drilling fluid that can improve the performance and efficiency of drilling operations by enhancing the adhesion and cohesion of the drilling fluid. Adhensive for drilling fluid can be classified into different types according to its chemical composition, such as natural polymers, synthetic polym.