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ABSTRACT
Reservoir remediation fluids lower overall completion costs while optimizing production, they alter reservoir wettability of oil wet solids and reduce the interfacial tension between oil and water, and remove the near wellbore formation damage, owing to mud cake invasion during oil well construction. This study focuses on the extraction of biosurfactants (saponins) from roots of ginger, yellow yam and wild yam and the application of the extracted saponins in the formulation of biosurfactant solution, to function as a reservoir remediation fluid. Wild yam was harvested in a nearby bush at Isihor, near the University of Benin (Ugbowo) Campus. yellow yam and ginger were sourced from the Uselu market. The design of experiment was carried out using central composite design (Design Expert; version 11.0). The Saponins were extracted using suitable solvents (methanol, acetone and ethanol) adopting the solvent extraction method. The fit (quadratic) model provided an accurate description of the dependence of extraction yield on effects of process (independent) variables. The optimum process parameters were determined using response surface methodology (RSM). Using the numerical optimization, the optimal extraction conditions of mass (4.82g), temperature (52.85oC) and time (152.55mins) gave the yield of 63.22% for wild yam. Mass (2.895g), temperature (72.83oC) and time (224.46mins), gave extract yield of 62.29% for yellow yam. Ginger had optimum yield of 55.75% with mass (4.13g), time 297.03mins and temperature (54.30oC). The extracted saponins were characterized using the UV double beam spectrophotometer (UV-6300PC), FTIR (Agilent Cary 630), XRD (Empyrean X-ray Diffractometer), and XRF (Thermo Scientific) spectroscopy. The spectra suggested that steroidal saponins were extracted from the indigenous plants and were amorphous glycosides. The XRF gave the elemental composition of the crude saponin samples. The formulated biosurfactant solution was evaluated based on detergency, phase stability, filter cake removal ability and compatibility with reservoir fluids. Near wellbore formation damage due to the filter cake deposit from the non-aqueous drill-in fluid, within the vicinity of the wellbore and oil in the emulsion was solubilized leaving the solids and surfaces in a water wet state. The sized CaCO3 which served as bridging agent in the formation was removed by the acetic acid, while the remaining drill solids were completely dispersed and mobilized.
