Study on CO2 huff-n-puff of horizontal wells in continental tight oil reservoirs

- A poro-elasticity simulation model of tight oil reservoir was developed.
- Biot's coefficient has a significant influence on oil recovery factor.
- Sensitivity analysis of the injection parameters is conducted.

A poro-elasticity reservoir simulation model was developed to analyze the huff-n-puff operations in the Fuyu continental tight oil layer. The model was based on the “two-way” coupling of a geomechanical model and a compositional model. The pressures induced from the compositional model were set as input for the geomechanical model, and the effective stresses calculated from the geomechanical model were set as input for the compositional model. The results show that under specific assumptions, effective stress increases during the depletion and production period and decreases during the injection and soaking period, resulting in corresponding changes to the displacement and effective stress. Biot coefficient also has a significant and systematic influence on the resulting oil recovery factor of CO2 huff-n-puff. In addition, a sensitivity analysis of the injection parameters, including injection timing, production time, and soaking time, was performed in detail. This work provides a better understanding of the mechanisms of the CO2 huff-n-puff operations of horizontal wells in a continental tight oil sandstone formation.