Study on the Rheological Properties of Ultra-High Temperature CGA Drilling Fluids

Colloidal gas aphron (CGA) drilling fluids are a kind of environmentally-friendly underbalanced drilling technique, which has attracted more attention in depleted reservoirs and other low-pressure areas. With the shortage of global oil/gas resources, drilling has gradually shifted to high-temperature and deep wells. Hence, a study on the ultra-high temperature rheology properties of CGA fluids is lacking and urgently needed. In this study, a novel CGA drilling fluid system was prepared by modified starch and amino acid surfactant, and rheological properties after 120-300°C aged was investigate. Results show that: (1) Herschel-Bulkley model is the preferred model to predict CGA drilling fluid at ultra-high temperatures; (2) It was proved that CGA drilling fluid is a high-quality drilling fluid with extremely high value of LSRV and shear thinning property within 280°C. Compared to the traditional XG-based CGA drilling fluid, the improvement of LSRV at ultra-high temperatures is a significant advantage of EST-based CGA drilling fluid which is conducive to carrying cuttings and sealing formation pores.

Effectiveness of Colloidal Gas Aphron Fluids Formulated with a Biosurfactant Enhanced by Silica Nanoparticles

<p>At-balance drilling technology applications demand the use of special drilling fluids, For example, colloidal-gas-aphron fluids (CGA) are being deployed to good effect in drilling applications. GCA-based drilling fluids have physico-chemical attributes that enable them to usefully influence and control downhole conditions. Furthermore, the involvement of nanoparticles and surfactants in their formulations enhances the performance and stability of CGA suspensions. This study describes the stability analysis, rheological characterization and filtration properties of CGA suspensions for the novel eco-friendly biosurfactant, <i>Olea europaea </i>(common olive), in presence of nanoparticles. Filtration and stability analysis was performed using API filtration tests and the static drain-rate technique, respectively. Several rheological models are developed to quantify the shear-flow characteristics of Olea-nano-based CGA suspensions. The Herschel-Bulkley and the Mizhari-Berk models provided the best shear-flow prediction accuracy with very small error values in terms of root mean squared error. Results reveal that the introduction of the biosurfactant improves the CGA-based fluid properties. Moreover, the observed improvements are further enhanced by including silica and fumed silica nanoparticles in the formulations. The Olea-nano-CGA-based fluids exhibit non-Newtonian behavior. The rheology of CGA-based fluids depends upon base-fluid viscosity, as it does in aqueous polymeric foams. The optimum concentrations of nanoparticles in Olea-nano-based CGA fluids is identified to provide them with fluid-flow indices ranging between 0.15 and 0.30. </p>

Effectiveness of Colloidal Gas Aphron Fluids Formulated with a Biosurfactant Enhanced by Silica Nanoparticles

<p>At-balance drilling technology applications demand the use of special drilling fluids, For example, colloidal-gas-aphron fluids (CGA) are being deployed to good effect in drilling applications. GCA-based drilling fluids have physico-chemical attributes that enable them to usefully influence and control downhole conditions. Furthermore, the involvement of nanoparticles and surfactants in their formulations enhances the performance and stability of CGA suspensions. This study describes the stability analysis, rheological characterization and filtration properties of CGA suspensions for the novel eco-friendly biosurfactant, <i>Olea europaea </i>(common olive), in presence of nanoparticles. Filtration and stability analysis was performed using API filtration tests and the static drain-rate technique, respectively. Several rheological models are developed to quantify the shear-flow characteristics of Olea-nano-based CGA suspensions. The Herschel-Bulkley and the Mizhari-Berk models provided the best shear-flow prediction accuracy with very small error values in terms of root mean squared error. Results reveal that the introduction of the biosurfactant improves the CGA-based fluid properties. Moreover, the observed improvements are further enhanced by including silica and fumed silica nanoparticles in the formulations. The Olea-nano-CGA-based fluids exhibit non-Newtonian behavior. The rheology of CGA-based fluids depends upon base-fluid viscosity, as it does in aqueous polymeric foams. The optimum concentrations of nanoparticles in Olea-nano-based CGA fluids is identified to provide them with fluid-flow indices ranging between 0.15 and 0.30. </p>