Abstract: The reasonable water injection rate is an important factor in waterflooding reservoir. The determination method of a reasonable injection rate using the capillary pressure curve wasn’t reported before. Based on hydrodynamics theory and the simplified porous medium model (pore doublet model) ,and according to poiseuille equation and capillary pressure curve , we obtained
equations of reasonable rate proportion and oil rate calculation between the two parallel connection capillaries , and we also established a method of determination the reasonable water injection rate in waterflooding reservoir. The field case studies showed that the calculated results went well with the real injection rate , which means the determination method of reasonable
water injection rate using the capillary pressure curve presented in this paper is reliable and practical.

Key words: capillary pressure curve, flowing pore volume