Affiliation:
1. Oil and Gas Technology Research Institute, PetroChina Changqing Oilfield Company, Xi’an 710016, China
2. School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, China
Abstract
A novel micro-dispersed-gel (MDG)-strengthened-alkali-compound flooding system was proposed for enhanced oil recovery in high-water-cut mature oilfields. Micro-dispersed gel has different adaptability and application schemes with sodium carbonate and sodium hydroxide. The MDG-strengthened-alkali flooding system can reduce the interfacial tension to an ultra-low interfacial-tension level of 10−2 mN/m, which can reverse the wettability of rock surface. After 30 days aging, the MDG-strengthened-Na2CO3 flooding system has good viscosity retention of 74.5%, with an emulsion stability of 79.13%. The enhanced-oil-recovery ability of the MDG-strengthened-Na2CO3 (MDGSC) flooding system is 43.91%, which is slightly weaker than the 47.78% of the MDG-strengthened-NaOH (MDGSH) flooding system. The crude-oil-production mechanism of the two systems is different, but they all show excellent performance in enhanced oil recovery. The MDGSC flooding system mainly regulates and seals micro-fractures, forcing subsequent injected water to enter the low-permeability area, and it has the ability to wash the remaining oil in micro-fractures. The MDGSH flooding system mainly removes the remaining oil on the rock wall surface in the micro-fractures by efficient washing, and the MDG particles can also form weak plugging of the micro-fractures. The MDG-strengthened-alkali flooding system can be used as an alternative to enhance oil recovery in high-water-cut and highly heterogeneous mature oilfields.
Reference43 articles.
1. The optimization of the well pattern thinning at high water cut stages in CD Heterogeneity oilfield;Ming;Unconv. Resour.,2024
2. Experimental study on the effect of high water cut on the emulsifying properties of crude oil;He;Colloids Surf. A Physicochem. Eng. Asp.,2023
3. Remaining oil distribution characteristics in an oil reservoir with ultra-high water-cut;Yu;Energy Geosci.,2022
4. Quantitative investigation of core heterogeneity’s impact on water flooding using nuclear magnetic resonance imaging;Guo;Chem. Eng. Sci.,2023
5. Influence of micro-heterogeneity of fractured-porous reservoirs on the water flooding mobilization law;Zhao;Sustain. Energy Technol. Assess.,2022