Oil utilization degree at various pore sizes via different displacement methods

Abstract A reasonable displacement method is essential to improve the oil efficiency of tight reservoirs. In this study, three different methods were utilized on core samples obtained from Yanchang Formation Chang 8 and 9 reservoirs: spontaneous imbibition displacement, various water flooding rate after imbibitions; furthermore, utilization degree residual in pores was discussed. The imbibitions approximately 26.91% 29.56% for samples, respectively. With an increasing rate, features inverse “V”-like tendency, a 0.06 mL/min optimal value as; achieved 63.56% 60.27% 9, When compared with imbibitions, at imbibition, could be further increased 50.02% 30.35%, differences using are primarily related pores. progressively refined pore classification used study pores, reservoir can divided into four types: P1, P2, P3 P4. Regarding dominantly determined by present P2 pores; as massively accumulates discharging part finally determines when rates changed. At enhanced, particularly P3, P4 structure contributes increase efficiency. Using method, complexity distribution reservoirs studied quantitatively elaborately, results efficiently guide development