Nano-attapulgite for improved tribological properties of drilling fluids

Attapulgite (ATT) is purified, synthesized, characterized, functionalized, and tested in nano-form (10-25nm diameter) for its effectiveness to tailor the rheology of drilling fluids swiftly to reduce friction, discourage use of other expensive additives, and improve functionality. A schematic procedure for purification and synthesis of ATT to nano-level for uniform dispersion is established. X-ray diffraction and scanning electron microscopy (SEM) are utilized to analyze the nano-attapulgite (NATT) structure. The effects of NATT-modified drilling fluids on the tribological properties mainly the coefficient of friction (COF) between the drillstring and the wellbore are established. OFITE Lubricity Tester is used to measure the COF values of the test samples. To test for the performance of the NATT-modified drilling fluids, an in-house experimental setup that imitates the wellbore being drilled in the presence of surrounding drilling fluid was developed and utilized to investigate the effects of NATT size and composition on the axial force transfer of drillstring. Results show that the use of a NATT in drilling fluid significantly reduces the COF between the drillstring and the wellbore thus improves the axial force transfer considerably.