Pressure prediction model for deep profile control of expanded granular/viscoelastic movable gel formulation in low permeability reservoir

Abstract

The low permeability reservoir perfect an important role of energy replacement in petroleum industry. Aiming at the problem of low prediction accuracy of the deep profile control in low permeability reservoirs and the lack of theoretical basis for the tracking and adjustment of projects, the variation characteristics of relaxation time are determined based on the viscoelastic experiments of movable gels with different concentrations, shear rates and angular velocities. The viscoelastic mobile gel apparent viscosity model considering the relaxation time kinetics is established based on the Maxwell theory and the pressure prediction model for the expanded granular/mobile gel deep profile control in low permeability reservoirs is established. Finally, the real production data of profile control wells in Yushulin oilfield in China is taken as an example, the application effects of the new pressure prediction model considering the viscoelasticity, the pressure model without viscoelasticity and the numerical simulation model are compared and verified. The results show that the gel exhibits viscoelasticity at high shear rate, and when the gel concentration is increased from 500 mg/L to 1500 mg/L, the relaxation time decreases from 1.04 s to 0.08 s and from 6.3 s to 0.8 s before and after gelation, respectively. The application effects of the models show that the new model takes into account the viscoelasticity of the gel, which is 12.3 percentage points higher than that of the traditional pressure model based on the reservoir engineering method and 10.6 percentage points higher than that of the numerical simulation model.