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Drilling mud is one of the important components in deep drilling of oil wells. Drilling mud consists of two phases: liquid phase (i.e. sweet water, salt water, seawater) and solid phase (such as clay
minerals). Rheological characteristics of ordinary mud change in deep wells under high pressure and temperature, therefore, the mud is unable to perform its duties specially transportation of the cuttings. Different methods are used for
modification of these properties. One of these methods incorporates use of polymers in drilling mud. The present study investigates the properties of polymeric muds under conditions present
in drilling operation in Iran with the aim of eliminating the problems and poor efficiency oftraditional muds.
In this study the effects of two kinds of polymers (PHP A and XC) on the physical and rheological behavior of liquid base mud is investigated together with the effects of two kinds of pollutants (CaSO4 and MgSO4) on the behavior and properties of polymeric mud. The results demonstrate that polymer based mud can improve
rheological and thixotropic properties of the mud, decreasing of water loss, and has no effect on PH balance. Also, the above
mentioned polymers become viscose when exposed to saturated salt water and are resistant to other ionic pollutants. They keep the initial specifications and viscosity
in high shear rates. Increasing of temperature results in increasing of shear stress for bentonite and decreasing of shear stress for XC and PHP A polymers. Also increasing the temperature (of bentonite based mud) results in increasing of yield point, viscosity and thixotropic properties, but has a reverse effect on mud containing XC and PHPA polymers.