Synthesis, Characterization, and Performance Evaluation of Starch-Based Degradable Temporary Plugging Agent for Environmentally Friendly Drilling Fluid

Reservoir protection in well drilling and well completion is one of the most significant challenges that have been connected with the quality of the temporary plugging zone and the recovery value of the reservoir permeability when the foreign water invaded into the reservoir copied with the temporary plugging agents. The regular temporary plugging agents are linked with high demand for the matching rate about the pore throat of formation, effect of a single, and poor environmental performance, etc. which markedly impact the operational efficiency. This work reports the synthesis and characteristic of starch-based degradable water-absorbent resin to protect the layer during drilling. Both degradable and excellent SDTA through introducing the nanometre calcium carbonate composites which used as the rigid core were synthesized, characterized, and revalued with standard methods. After purification, there were some groups including the carboxylic acid group, amide group, methyl group, and S=O which reflected the successful synthesis of the monomers. The composites displayed remarkable salt resistance and calcium resistance with 5% and 0.5% as well as thermal stability of 130 degrees C and degradation rate of 50%, respectively. Results also demonstrated that SDTA composites could make the mud cake structure more compact and exhibit self-adaptive to the formation. The SEM images of mud cake treated SDTA revealed that the mechanism could be base on the collaborative action of the structure compact and holes plugging to form an impressive filter cake which could effectively avert the water molecules invasion into the reservoir. Hence, SDTA composites could be a suitable material as a degradable temporary plugging agent for well drilling and completion.

Automated summary

This study reports the synthesis of a starch-based degradable water-absorbent resin for reservoir protection during drilling, which displays good salt resistance, calcium resistance, and thermal stability while exhibiting adaptability to the formation. The SEM images reveal that the resin can effectively prevent water molecule invasion into the reservoir by forming a compact filter cake.