Preparation and performance evaluation of nano-composite fracturing fluid with good oil displacement ability in tight reservoir

Using slickwater fracturing fluid is an efficient stimulation method in low-permeability reservoirs. The drag reducing ability of drag reducing agents is very important for fracturing fluids. In this paper, we developed a new nanomaterial and added it to the slickwater fracturing fluid to enhance the performance of the NCS (nanomaterial composite slickwater) fracturing fluid and make it has a certain oil displacement ability. The nanomaterials was synthesized by a two-step synthesis method. The experimental results show that the novel nanomaterial has better performance than the commercial nanomaterials. The composite fracturing fluid shows a good stability at 90 °C, and the particle size of the nanomaterials in the fracturing fluid does not significantly change. The experimental results demonstrate that the drag reduction ability of the composite fracturing fluid can be maintained at more than 70%. In addition, the core displacement experiments show that the composite fracturing fluid has a very low-permeability reduction of 1.03%. In the imbibition experiment, the oil recovery rate of the composite fracturing fluid reaches 36%, the oil recovery rate of the pure water is less than 30%. In the end, the mechanism of enhanced oil recovery by nanomaterials and the mechanism of synergistic drag reduction between nanomaterials and polymers, are studied. The proposed NCS fracturing fluids, with both fracturing and oil displacement capabilities, and is expected to become a potential method for tight oil reservoir development.