Preparation and Self-Growth Characteristics of In Situ Self-Growing Dispersed Gel System for Offshore Large-Well-Distance Reservoirs

The loose sandstone oil reservoirs in the sea mostly adopt gravel packing completion, which leads to a decrease in permeability in the near-well area. Conventional blocking agents were difficult to simultaneously meet the requirements of water cut reduction and oil production increase. Therefore, this paper constructs a temperature-resistant in situ self-growing dispersed gel system and evaluates its displacement performance. The research results show that the formulation of the dispersed gel system is optimized through thermogravimetric analysis, with the monomer concentration determined to be 12 wt % and the cross-linking agent concentration determined to be 0.7 wt %. To improve injectability, the initial water content of the preinjected emulsion is selected as 40%, and its solubilization ability is determined to be 498.8%. During the solubilization process (from 40% to 80% water content), the viscosity increases from 67.89 to 3836 mPa·s. The influence of the change in emulsion water content during the solubilization process on the particle size of the dispersed gel particles is clarified; that is, the particle size first increases and then decreases, reaching the maximum at 70%, and the particle size distribution range becomes wider. In addition, this dispersed gel system shows good strength and long-term stability under different salinities. This study provides a new idea for controlling water and increasing oil production in large well-spacing, loose sandstone oil reservoirs in the sea.