摘要：Wellbore instability is an important problem in drilling operation, especially in high temperature and pressure shale formations. This problem has been addressed using zeolite or other particles as drilling fluid additives. In the present study, the effect of cli- noptilolite-rich zeolite (CZ) as an additive (in the range of 1 to 7 % w/v) on the rheological and filtration properties of the water based Na-bentonite drilling fluid was investigated. The chemical composition, crystallinity and the morphological properties of the plain drilling fluid and the CZ added drilling fluid were analyzed using X-ray powder diffraction (XRD), Fourier transform in^ared (FTIR) and scanning electron microscope (SEM). The rheological properties such as apparent viscosity (AV), plastic viscosity (PV), yield point (YP) and gel strength of the CZ added drilling fluid were determined with a FANN 35 viscometer. The filtration properties were also examined using an API Filter Press. All physical measurements were carried out according to the American Petroleum Institute (API) standards. The results showed that the CZ was a good candidate as a drilling fluid additive due to the reduction in the loss of filtrate (30 %) and the increasing PV (33 %), AV (45 %), YP (62.5 %) and gel strengths (10-second 127 % and 10-minute 48.5 %).
关键词：Clinoptilolite-rich zeolite;Water based drilling fluid;Rheological property;Filtration property
