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Enhanced rheology modification for completion fluids using slurried hydroxyethyl cellulose

By: Description: 6 pOnline resources: Summary: Completion fluids are widely used at the final moments of a well production. These fluids must be clean, free of solids and should be used to control the wells during the completion process. The fluid is prepared in a way to avoid damage to the formation’s permeability and to promote the density capable of providing higher hydrostatic pressure in the well column. Typically brines of 8.4 and 19.2 lb/gal are utilized as completion fluids that contain salts like KCl, NaCl, CaCl2 among others. Sometimes, to enhance the capability to remove residual cuttings from drilling muds and cements, rheology modifiers are added to the system allowing the viscosity to increase and therefore helping the sweeping and suspension characteristics of the fluid. The rheology modifiers used for this application are usually water soluble polymers based on Hydroxyethyl Cellulose (HEC), Carboxymethyl Cellulose (CMC) among others, but mainly due to its resistance for degradation under high conditions of temperature and pressure, HECs are the most common products used. These polymers need to be well hydrated in order to give the desired effect of viscosity increase. To fully hydrate, the polymer should be "uncoiled" to expose its active functional groups along the polymer chain to the substrate, in this case the completion brine. During the blending/addition step, when agitation and dispersion commences, a film of concentrated polymer solution builds up around the polymer particles. This makes them "gluey" and subject to sticking to each other to form aggregates or agglomerations. These agglomerations are commonly called "fisheyes" and reduce the effectiveness of hydration and thus rheology modification. Slurried versions of HEC in polar solvents have been developed in order to facilitate polymer dispersion and faster uncoiling into brines. As a result of the pre-dispersed slurry, less fisheyes are formed and more polymer is incorporated to the solution. In this study, a HEC slurry generated under the same conditions of agitation, yield higher levels of viscosity when compared to the powder HEC. These differences in performance were based on the measurements from a FANN 35A rheometer and the visual validation of lower amounts of "fisheyes" as demonstrated in the pictures. For NaCl brine HEC slurry generated almost 20 fold increase of viscosity for rotational speeds of 200, 300 and 600 RPM.
Item type: Congresos (trabajos presentados)
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Colección Digital IAPG Not for loan 200062723

Completion fluids are widely used at the final moments of a well production. These fluids must be clean, free of solids and should be used to control the wells during the completion process. The fluid is prepared in a way to avoid damage to the formation’s permeability and to promote the density capable of providing higher hydrostatic pressure in the well column. Typically brines of 8.4 and 19.2 lb/gal are utilized as completion fluids that contain salts like KCl, NaCl, CaCl2 among others. Sometimes, to enhance the capability to remove residual cuttings from drilling muds and cements, rheology modifiers are added to the system allowing the viscosity to increase and therefore helping the sweeping and suspension characteristics of the fluid. The rheology modifiers used for this application are usually water soluble polymers based on Hydroxyethyl Cellulose (HEC), Carboxymethyl Cellulose (CMC) among others, but mainly due to its resistance for degradation under high conditions of temperature and pressure, HECs are the most common products used. These polymers need to be well hydrated in order to give the desired effect of viscosity increase. To fully hydrate, the polymer should be "uncoiled" to expose its active functional groups along the polymer chain to the substrate, in this case the completion brine. During the blending/addition step, when agitation and dispersion commences, a film of concentrated polymer solution builds up around the polymer particles. This makes them "gluey" and subject to sticking to each other to form aggregates or agglomerations. These agglomerations are commonly called "fisheyes" and reduce the effectiveness of hydration and thus rheology modification. Slurried versions of HEC in polar solvents have been developed in order to facilitate polymer dispersion and faster uncoiling into brines. As a result of the pre-dispersed slurry, less fisheyes are formed and more polymer is incorporated to the solution. In this study, a HEC slurry generated under the same conditions of agitation, yield higher levels of viscosity when compared to the powder HEC. These differences in performance were based on the measurements from a FANN 35A rheometer and the visual validation of lower amounts of "fisheyes" as demonstrated in the pictures. For NaCl brine HEC slurry generated almost 20 fold increase of viscosity for rotational speeds of 200, 300 and 600 RPM.



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