Polymercationic Drilling Fluids for Well Construction in Challenging Mining and Geological Conditions

Background: Oil and gas well drilling involves the use water- and hydrocarbon-based drilling fluids for flushing. While hydrocarbon solutions offer several advantages—such as preventing rock softening on the wellbore walls, reducing the formation of caverns due to instability in clay rocks, and dissoving salts (like halite, sylvinite, and bischofite), and preserving the natural reservoir properties of productive formations—they also have significant drawbacks. These disadvantages are related to the properties of the dispersion medium, which limits their overall application. The dispersion medium in hydrocarbon solutions consist of compounds that are both environmentally and flammable, such as kerosene, diesel fuel, olefins, various oils, etc. Increasing concern from government and environmental organizations regarding the environmental impact of drilling fluids using hydrocarbon dispersion medium have promted the industry to focus on water-based solutions. Despite several significant disadvantages, water-based drilling fluids are still more in demand than hydrocarbon ones. Although there is a preference for hydrocarbon systems, approximately 85% of all drilling fluids used worldwide today are water-based. This study focuses on a new approach in the field of water-based drilling fluids: the development, creation and implementation of polymer cationic systems. The idea of developing new water systems involves creatng polymer cationic working fluids that combine the beneficial properties of hydrocarbon and aqueous solutions. Aim: To research and develop modern polymer cationic drilling fluids for well construction in the Republic of Kazakhstan. Materials and methods: Polymer cationic drilling fluids were selected as the objects of study. To address the research objectives, experiments were conducted under both laboratory and field conditions. Results: This article presents the findings of laboratory tests and field trials conducted in the fields of the Russian Federation and the Republic of Kazakhstan. Conclusion: For the first time in global practice, stable polymer cationic drilling fluids have been developed and successfully tested, combining the advantages of aqueous and hydrocarbon systems. Both theoretical and practical principles for managing the properties of polymer cationic solutions have been established. The application of modified polymer cationic drilling fluids in well construction at the at the Astrakhan field and the Uzen field has demonstrated their high performance. This innovation has enabled the prevention of production isuues, increased mechanical speed of drilling, improved wellbore condition, reduced cavern porosity, and successfully completed the construction of over 20 wells. Additionally, it facilitated implementation of high-density solutions for killing brine and other related tasks.