Experimental study of novel reservoir protection agents for low permeability reservoirs in water-based drilling fluids

The low permeability reservoirs in SL Oilfield are featured by large buried depth, poor physical properties, strong diagenesis and heterogeneity, and there exist serious water sensitivity damage and water lock during the drilling process, which significantly restricts the exploration efficiency and benefits of low permeability reservoirs. In order to solve the reservoir protection problems of low permeability reservoirs, novel polymer plugging agent and water lock prevention agent were optimized and characterized in detail, and the polymer plugging agent could work synergistically with water lock prevention agent to impart reservoir protection performance due to film-forming shielding effect and low surface tension. The low damage water-based drilling fluids were also established and evaluated, and the results indicated that low damage water-based drilling fluids exhibited excellent reservoir protection performance with permeability recovery of above 90%, and filtrate surface tension is 18.5mN/m. It could be concluded that the low damage water-based drilling fluids could be priority alternatives to low permeability reservoirs exploration in SL Oilfield.