The Performance of Iraqi Palygorskite in Salt Drilling Fluid

Abstract

In drilling fluid program, selecting the drilling fluid that will reduce the lost time is the first objective, and will be economical regardless of its cost. The amount and type of solids in drilling fluid is the primary control of the rheological and filtration properties. Palygorskite clay (attapulgite) is an active solid that has ability to reactive with its environment and form a gel structure within a fluid and due to its stability in the presence of brines and electrolytes this type of clay is preferred for use. The aim of this study is to calculate the yield of clay for both types of local PAL in both fresh and salt water based mud. Determine the effect of aging time. Besides that, the effect of chloride sodium (NaCl) on rheological properties of drilling fluid by preparing salt water based drilling fluid with Bahr Al-Najaf PAL in three different procedures. The palygorskite claystone of Late Cretaceous age is present in the Western Desert within the Digma Formation. In this study, from two areas in Western Desert palygorskite were obtained, Bahr Al-Najaf and Trefawi. The results showed that, the clay yield of Bahr Al-Najaf PAL (49.54 bbl/ton), Trefawi PAL (57 bbl/ton), and commercial PAL (166.8 bbl/ton) in fresh water environment was higher than in salt water environment. As observed in this study, the clay yield of Bahr Al-Najaf PAL, Trefawi PAL, and commercial PAL in salt water environment were 37.9, 50.7, and 135.6 bbl/ ton respectively.  Poor yield of clay was obtained with Trefawi PAL (Grinding) so it was not used to prepare samples in this study. This experimental investigation, 16 hours aging time after preparation drilling fluids was applied.