Affecting analysis of the rheological characteristic and reservoir damage of CO2 fracturing fluid in low permeability shale reservoir

The fracturing property of liquid CO 2 fracturing fluid varies greatly due to the rheology of fracturing fluid during fracturing process. The main objective of this investigation is to study the rheology property of thickened liquid CO 2 by measuring the viscosity of thickened liquid CO 2 in different physical parameters of this prepared thickener and explain the causes of rheological changes. The results show that thickener content, branching content, and molecular weight of a thickener for all could significantly improve the rheology of liquid CO 2 ; the consistency coefficient K increased as they rose, but the rheological index n presented a decreased trend. Meanwhile, the mesh structure is proposed as a model to explain the rheological changes, and the large wetting angle means an excellent backflow, low reservoir damage, and low adsorption property. These results herein provide a basic reference to improve the CO 2 fracturing technology and molecular design of CO 2 thickener.