Abstract
Interaction of polymer-containing injected fluids with shale is a widely studied phenomenon, but much is still unknown about the interaction of charged polyacrylamides such as anionic and cationic polyacrylamides with shale. The nature of interaction of charged polyacrylamides with shale is not well understood, especially from the perspective of assessing the potential for polyacrylamides to cause formation damage. Zeta potential and rheological measurements were made for Chattanooga and Pride Mountain shales suspended in polyacrylamide solutions with and without inorganic salts and tetramethyl ammonium chloride (TMAC). The change in zeta potential and viscosity with time was recorded. The magnitude of decrease in the absolute value of zeta potential with time is indicative of adsorption of polymer on the surface of shale and serves as a measure of the extent of polymer interaction with shale. The salts that were used in this study are potassium chloride (KCl), sodium chloride (NaCl). This study quantified the interaction of anionic and cationic polyacrylamide with different North American shales. From the experimental results, it was determined that the polyacrylamides can interact strongly with shale, particularly the cationic polyacrylamide. The objective of this study was to determine the extent of interaction of anionic and cationic polyacrylamide with each shale sample in the presence of additives such as salts.
Highlights
Interaction of injected fluids such as drilling, fracturing and completion fluids with shale has been a problem for many decades in the oil field, and shale constitutes 75% of all the formations drilled by the oil and gas industry (Khodja et al 2010)
Zeta potential and rheological measurements were made for Chattanooga and Pride Mountain shales suspended in polyacrylamide solutions with and without inorganic salts and tetramethyl ammonium chloride (TMAC)
Zeta potential measurements were made for Pride Mountain and Chattanooga shale samples in different suspending media to quantify the polyacrylamide–shale interaction
Summary
Interaction of injected fluids such as drilling, fracturing and completion fluids with shale has been a problem for many decades in the oil field, and shale constitutes 75% of all the formations drilled by the oil and gas industry (Khodja et al 2010). Interactions between shale and injected fluids are of concern for a variety of reasons. The interaction of injected fluids with shale leads to wellbore instability (Tan et al 1996; Yu et al 2003; Muniz et al 2005), and the productivity of the wells decreases due to this instability, which increases the drilling cost (Lal 1990; Mahto and Sharma 2004). Water-based mud (WBM) is the most commonly used type of drilling fluid, and shale is highly sensitive to the additives and the clays present in the WBM (Gomez and He 2012; He et al 2014). It is important to use all the necessary additives in injected fluids, but it is important to use additives that do not potentially weaken the shale
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