Optimum formulation design and properties of drilling fluids incorporated with green uncoated and polymer-coated magnetite nanoparticles

Study on the Behavior and State of Viscous Fractured Leakage Bridging and Plugging Slurry during the Pump-In and Pressurization Process

“…The viscosity of the plugging slurry in this well is around 30 mPa•s; therefore, in the simulation, the viscosity of the plugging slurry is set to five gradients of 10-50 mPa•s. According to previous research and on-site applications, the solids content in plugging slurry is usually 15%, and calcium carbonate particles, walnut shells, fiber materials, etc., are commonly used as plugging materials, with a density between 1.0-4.0 g•cm 3 . Therefore, the parameters shown in Figure 1 are selected for the simulation.…”

“…In traditional plugging mud, the solid particles employed are usually calcium carbonate particles. Initially, the density of the plugging slurry is 1.48 g/cm 3 , the particle density is 2.6 g/cm 3 , the particle concentration is 15% and the pumping speed of the plugging slurry is 0.7 m/s. The effects of solid particles before and after lifting and pressurization are explored when the viscosity of the plugging slurry is 10, 20, 30, 40 and 50 mPa•s.…”

“…Fracture-induced losses contribute to over 90% of the overall cost of controlling such losses [1]. As the main direction of oil and gas production gradually shifts towards unconventional reservoirs such as tight oil and shale gas with enormous resource potential, the development of fracture systems in these unconventional reservoirs has brought complex situations in controlling fluid-induced fracture losses [2,3]. The existing research on fracture loss mainly focuses on rock anisotropy, stratigraphy and fracture development, but the research on slurry plugging behavior during pumping is relatively limited, resulting in a lack of understanding of the change in slurry plugging in the lost layer [2,3].…”

“…As the main direction of oil and gas production gradually shifts towards unconventional reservoirs such as tight oil and shale gas with enormous resource potential, the development of fracture systems in these unconventional reservoirs has brought complex situations in controlling fluid-induced fracture losses [2,3]. The existing research on fracture loss mainly focuses on rock anisotropy, stratigraphy and fracture development, but the research on slurry plugging behavior during pumping is relatively limited, resulting in a lack of understanding of the change in slurry plugging in the lost layer [2,3]. The behavior of plugging slurry during static and pumping-squeezing states significantly affects the efficiency and accuracy of fracture sealing and bridging, while the settlement of weighting materials under the influence of gravity can lead to wellbore losses, stuck pipes, well control and cementing operation difficulties [4,5].…”

Preferred Ratio and Properties of Microfoam Drilling Fluid for Gas Extraction in Soft Coal Seams

“…Winding drill rods are utilized with mechanical debris removal in dry-coiled drilling. As the drilling depth increases, the drilling operation’s difficulty also escalates, resulting in lower drilling and debris removal speeds. , Additionally, without the presence of drilling fluid for lubrication and hole flushing, there is a higher risk of accidents such as overheating of the drill bit, aging of the drill bit, and rod jamming, making it challenging to achieve proper hole formation and affecting the drilling depth. − Air drilling involves using airflow as the drilling and flushing medium . During the drilling process, the low pressure exerted on the borehole walls creates a hostile pressure environment around the hole, increasing the likelihood of accidents such as borehole deformation and collapse in soft coal seams. , …”