Abstract
This article examines the mechanisms of reducing drilling fluid losses through the use of polymer reagents. Particular attention is paid to the physicochemical effects of polymers on the formation, the processes of colmatation, and the formation of a filter cake. Loss of drilling fluid leads to circulation failure, reduced wellbore stability, and increased drilling costs. Traditional methods for combating fluid losses (use of lightweight drilling fluids and lost circulation materials) are not always effective, especially under conditions of microfractured reservoirs.The conducted laboratory bench tests demonstrate that the modified drilling fluid based on polyacrylonitrile and fatty acid distillation tars contributes to an overall reduction in fluid loss and decreases the average filtration rate to an optimal level. An experimental setup representing a homogeneous linear formation model is proposed. The setup consists of a steel pipe filled with rock material and equipped with flanges at both ends. Using this installation, experimental dependences of drilling fluid loss on the concentration of the MPAN reagent were obtained. The results show that the developed MPAN-based reagent is characterized by a relatively low production cost, as it is synthesized from polyacrylonitrile and vacuum distillation tars of fatty acids. The reagent can be recommended as a modifying additive to drilling fluids for drilling oil and gas wells under complex geological conditions.