A modified Ester-branched thickener for rheology and wettability during CO fracturing for improved fracturing property.

The thickening performance of CO fracturing fluid was poor because of the low apparent viscosity. In this paper, the thickening performance of a modified silicone on liquid CO is measured, and a rheology was investigated according to the consistency coefficient K and rheological index n. Meanwhile, a reservoir model was established to evaluate the fracturing property. Results showed that the modified silicone contributes to improve the apparent viscosity of liquid CO and decrease the rheology of liquid CO. With the thickener content or pressure increase, the apparent viscosity of liquid CO increases, and the rheological index n decreased obviously. A reduced apparent viscosity is shown as the flow rate or temperature rises, but the rheology increased gradually. The fracturing simulation herein shows that thickened CO fracturing fluid could improve obviously the fracture property. This modified thickener possesses the potential as a thickener and could be a reliable alternative to the thickener in CO fracturing technology, and the large contact angle improved the backflow property of this CO thickener from rock surfaces. The development of CO fracturing technology provides basic data for the improvement of greenhouse effect and clean mining of energy.