Effect of temperature on the rheological properties of neat aqueous Wyoming sodium bentonite dispersions

Abstract

Temperature affects significantly the rheological behavior of neat water Wyoming Na-bentonite dispersions. The results of a very systematic study are presented regarding rheological measurements of 7% mass concentration at different temperatures, ranging between 25 and 80°C at atmospheric pressure. Higher temperature increased the shear stresses at low shear rates while the effect was much smaller at higher shear rates. The Herschel-Bulkley rheological model fitted extremely well all data. The yield stress increased linearly with temperature by almost threefold , the flow consistency index decreased exponentially with temperature by almost five-fold and the flow behavior index increased by about 20%, tending towards the Newtonian value. At low shear rates (b 100 rpm corresponding to b170 1/s Newtonian shear rates), which represent very well the shear rates experienced by drilling fluids in the critical annulus region, all rheograms appeared fairly linear and the Bingham plastic model fitted well all data. The Bingham yield stress, from the low shear rate data, increased linearly with temperature, while the plastic viscosity decreased with temperature, in a manner very similar to the decrease of water viscosity with temperature. The plastic viscosity and Bingham yield stress data, from the low shear rate range, can be fitted well by an Arrhenius-type equation, with the activation energy for the plastic viscosity very similar to the activation energy for water viscosity, while for the Bingham yield stress, the activation energy is equal but opposite in sign to that of the plastic viscosity. A hypothesis is stated for the the observed linear increase of the yield stress with temperature, in the temperature range studied. One should be concerned when non-standard preparation and measurement procedures are followed which makes extremely difficult to understand any differences observed when reporting rheological data of water bentonite dispersions. A standard methodology is proposed, complementary to API, which can give very consistent results.

Nano-Based Drilling Fluids: A Review

“…Apparent viscosity, at all shear rates, also increased at higher temperatures. Addition of CM Fe3O4 NP at 0.5 wt % showed optimal filtration characteristics with a reduction of 40% of fluid Vryzas et al [20,21] that were used as base fluid in this study was reported in other studies [9,22]. They found that the yield stress and apparent viscosity, at all shear rates, became increasingly sensitive to temperature.…”

“…Addition of Vryzas et al [20,21] investigated novel custom-made (CM) magnetite (Fe3O4) NP ( Figure 8a) as drilling fluid additives, with diameters of approximately 8 nm, to improve the rheological and filtration properties of Na-bentonite based fluids. Full characterization of Na-bentonite suspensions that were used as base fluid in this study was reported in other studies [9,22]. They found that the yield stress and apparent viscosity, at all shear rates, became increasingly sensitive to temperature.…”

“…Factors such as the pre-shearing time, the hydration of additives, the raw materials, the mixing time and the order of adding the different additives are crucial that can significantly affect the reported results. Caution should thus be taken when comparing results of drilling fluid samples among different, but also even within same, laboratories, because preparation and measurement procedures are vital for producing consistent results and this is another challenge facing researchers and oil companies in order to take full advantage of such superior drilling fluids [22].…”

“…The American Petroleum Institute (API) procedures and specifications [79][80][81] were developed in order to establish common procedures but sometimes these specifications do not deal with newer additives or newer requirements that are used or needed in different mud formulations that perform difficult tasks under varying conditions [82]. So, it is very difficult to compare results from different researchers and laboratories because mixing and preparation protocols are almost never the same [22]. Factors such as the pre-shearing time, the hydration of additives, the raw materials, the mixing time and the order of adding the different additives are crucial that can significantly affect the reported results.…”

Sensitivity of Clay Suspension Rheological Properties to pH, Temperature, Salinity, and Smectite‐Quartz Ratio

“…In our experiment, there was no apparent change in the rheological parameters within the temperature range of 2–30°C, which is consistent with the results of Coussot and Piau (). At higher temperatures, of up to 80°C, Vryzas et al () reported a gradual strengthening in the yield stress and reduced viscosity of sodium montmorillonite dispersions. The authors argued that thermally activated Brownian motion may cause flexures and strong associations between the smectite platelets, which may in turn cause a higher yield stress at higher temperatures.…”