Publication: Development of guar gum-based polymer for water shutoff treatment
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Date
2021-11-01
Authors
Kamarulizam, Siti Nuraffini
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Abstract
This research was conducted to introduce a new polymeric water shutoff agent (PWSA) developed from the combination of Guar Gum (GG), Acrylonitrile (AN), Acrylic Acid (AA), and Chitosan (CHI) to stop water entrance experienced in the mature oil well. This graft copolymerisation of vinyl monomers (AN and AA) into natural polymers (GG and CHI). The efficiency of the synthesised polymer as a polymeric water shutoff agent (PWSA) was studied at targeted gelation time (GT), rigid gel time (RGT), and temperature. For this study, the GT was targeted in 120 minutes and RGT of 720 minutes at 60°C. Safer approaches in making PWSA using Ce4+ instead of Cr3+ and natural polymer to replace synthetic was the essence for synthesising this polymer. This polymer was attained to stop water entrance through porous features to prevent excessive water-borne problems with water-like initial viscosity. The synthesised polymer was validated as PWSA by the polymer characteristic. The relationship among materials was expressed in the stable empirical model by the statistical analysis approach. Synthesised PWSA was evaluated in typical and extreme wellbore conditions and mimicking wellbore conditions for polymer effectiveness. Polymer synthesis was started with the selection of backbone polymer, polymer strengthener, and time delay agent. Selected (GG, AA, CHI) materials were polymerised in a single batch at a given temperature to obtain the optimised composition. The optimised composition PWSA were 0.1%v/v GG, 4%v/v AN, 0.03%v/v CAN, 4%v/v AA, and 20%v/v CHI. This formulation was agreed with targeted GT, RGT, with accepted polymer strength at 0.68 bar. This polymer showed a swelling water capacity of 557% with an initial viscosity of 0.0009 Pa.s. The elastic properties were a good PWSA indication. The thermal profile of the polymer also showed that weight loss ranging from 50% to 90% was detected at temperature 80°C to 110°C. For the heat flow curves, the polymer showed the reaction was started at 78°C, and the final degradation was at 120°C to 130°C. Approached with the statistical method, the mathematical model showed the summarised estimation of the gelation process, and the expression was fit to resemble the whole experiment. The polymer also reacted to elevated temperature, added salts, and pH variation during polymerisation and reacted polymer. The elevated temperature at 110°C showed the most influence on PWSA behaviour. This PWSA had successfully reduced water permeability throughout the Berea sandstone core from 186 mD to 0 mD. This polymer was succeeded in blocking 100% water entrance.