| الملخص | Samples of calcium bentonite clay (calcium montmorillonite claystone) from Wadi Bashiera deposit in the Western Desert were activated with sodium carbonate and evaluated for oil well drilling application. The chemical analysis of these raw bentonite samples (4 samples) shows no significant differences in their chemical composition, but does shows differences in XRD- pattern particularly at 2Ø 5.36º (main montmorillonite peak). The conversion of these raw samples to sodium type was firstly via dry method ,and the rheological properties of the activated samples were tested according to API specification .In conjunction with sodium carbonate ,three materials additives ( EDTA, sodium citrate and Na-CMC ) were used to control the rheological properties .Rheological data obtained, indicated that, sodium citrate and Na-CMC are more efficient than EDTA .The rheological properties resulted from this study shows that; a- the raw bentonite can be converted to sodium type by the dry process ,b- the rheological properties were significantly improves with the addition of sodium citrate and Na-CMC (individually or together ) with sodium carbonate and become consistent or closely conform the API specification and ,c- among the activated bentonite samples, only one presented abnormal rheological behavior with very high viscosities (out of specification). Semi dry method (using extruder) was also used as a means for activation. The rheological properties of the activated sample obtained were significantly improved with addition of tetra sodium pyrophosphate and Na–CMC. The results were satisfactory and conform very closely to API specification. The amount of sodium carbonate used to affect activation was (2.5 wt%) which is much lower than that used (6 wt%)in the dry activation | |
