Estudo do efeito da sedimenta??o pr?via na filtra??o de fluidos n?o-Newtonianos

• Autor(a) principal: Silva, Beatriz Penido da
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFRRJ
• Texto Completo: https://tede.ufrrj.br/jspui/handle/jspui/5495
• topic: Fluido confinado; Sedimenta??o; Filtra??o e permea??o; Fratura; Sedimentation; Filtration and permeation; Fracture; Confined fluid; Qu?mica; Engenharia Qu?mica

During the drilling of an oil well, part of the drilling fluid is confined to the annular regions in order to aid in the stabilization of the well. From the confinement of the fluid to the beginning of production it takes a few months, even years, for the well to be concluded. During this time, the well reaches thermal equilibrium with the environment, remaining at low temperatures characteristic of the deep waters. There is also sedimentation of the weighting material found in the drilling fluid, forming a particle bed on the bottom of the annular region. With the start of the production, the oil is extracted from the reservoir at high temperatures, resulting in a transfer of heat from the hot oil to the cold well. The increase in temperature causes the volumetric expansion of the confined drilling fluid, which causes an increase in pressure in the annular region. This phenomenon is known as Annular Pressure Build-up (APB). Increased pressure can cause irreparable damage to the structure of the well, and may even lead to abandonment. To relieve the pressure, mitigation methods, such as the open shoe, which allows direct contact of the confined fluid with the rock formation, are used. Increased pressure causes desired fractures in this region, allowing the drainage of the fluid to the rock formation and decreasing the pressure in the annulus. The highest pressure is observed at the bottom of the annular region, due to the higher hydrostatic and higher temperature. Thus, the open shoe is purposely located in this region, because it is where the fractures are more likely to occur. The doubt about this process is in relation to the bed of particles formed during the sedimentation, also on the bottom of the annular region. The sediment formed can clog the shoe and may make it difficult to relieve pressure. The drainage of the fluid through the particle bed is characterized as a filtration process. Therefore, this work had as its objective to understand the effect of the previous sedimentation in the filtration of non-Newtonian fluids. The drilling fluid studied consists of water, xanthan gum (0.5 lb/bbl), barite (15% w/w), and glutaraldehyde (0.5 lb/bbl). The rheological analysis of the fluid was done in a rheometer and the viscoelastic and shear thinning behavior was verified. Sedimentation was observed in an online microscope, where corridors of reduced viscosity and particle chaining were verified. Filtration experiments with and without previous sedimentation were conducted using HTHP filtration cells. Sedimentation occurred within the filtration cell itself and was monitored during the interval of one to seven days. It was possible to conclude from the experiments that the volume of filtrate increases as the sedimentation time goes by, favoring the relief of the pressure in the annular region.