Abstract
In order to improve the plugging and anti-collapse performance of water-based drilling fluid, a polymer film-forming plugging agent LWFD is synthesized by emulsion polymerization. The effect of the agent on rheology, API filtration loss, lubricity and film plugging of polymer drilling fluid and cationic drilling fluid is evaluated in laboratory. The experimental results show that the agent has little effect on the rheology and filtration loss of polymer drilling fluid and cationic drilling fluid, and can improve the lubricity of drilling fluid. The synthesized polymer film-forming plugging agent LWFD has good plugging properties for sand discs with different permeabilities, and the agent can effectively improve the film-forming plugging and temperature resistance of drilling fluid when combined with the inorganic nano-plugging agent NMFD. The high performance polymer drilling fluid formed by introducing polymer film-forming plugging agent LWFD and inorganic nano-plugging agent NMFD into polymer drilling fluid has comparable performance as Halliburton’s SHALEDRIL high performance drilling fluid, which can meet the requirements of on-site drilling and has application value.
Highlights
When conventional water-based drilling fluids drill hard and brittle shale, the filtrate will invade the cracks and pore of shale, causing the hydration expansion and spalling of shale, drilling sticking, wellbore instability and other complex downhole situations are induced
The high performance polymer drilling fluid formed by introducing polymer film-forming plugging agent LWFD and inorganic nano-plugging agent NMFD into polymer drilling fluid has comparable performance as Halliburton’s SHALEDRIL high performance drilling fluid, which can meet the requirements of on-site drilling and has application value
Infrared characterization results indicate that the styrene, butadiene, acrylic acid and unsaturated fatty acid monomers selected in the experiment are involved in the synthesis of the polymer film-forming plugging agent LWFD
Summary
When conventional water-based drilling fluids drill hard and brittle shale, the filtrate will invade the cracks and pore of shale, causing the hydration expansion and spalling of shale, drilling sticking, wellbore instability and other complex downhole situations are induced. Inorganic nano-plugging agent can effectively block the narrow pores and cracks in the formation by utilizing its particle size advantage. Polymer film-forming plugging agent has excellent deformation and adsorption capability, which can preferentially adsorb pores and cracks on the surface of wellbore to form a polymer film. The polymer film-forming plugging agent LWFD is a polymer emulsion polymer with multiple adsorption groups, which can effectively block the pores and cracks of the formation and form a weakly crosslinked network structure on the surface of the wellbore to reduce the filtration loss of the drilling fluid. The effect of polymer film-forming plugging agent LWFD combined with inorganic nano-plugging agent NMFD is studied to improve the film-forming plugging property of drilling fluid
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