高含水油藏不稳定注水提高采收率技术及其影响因素OA

In order to solve the problems of aggravated ineffective water cycling and decreased displacement efficien-cy encountered in continuous water injection during high water-cut development stage of oilfields,based on the pressure diffusion equation model,multiphase elastic energy storage model and multi-field coupling mathematical model,a numerical simulation software integrating multi-field coupling effects is developed to study unsteady water flooding for enhanced oil recovery(EOR).The results show that,unsteady water flooding is proposed herein to break oil-water balance through dynamic pressure gradients generated by pressure fluctuations,while elastic force provides additional driving force via an energy storage-release cycle.Static factors influencing the recovery of unsta-ble water flooding are reservoir heterogeneity and natural water body energy,while dynamic factors include pres-sure fluctuation amplitude,injection-production half-cycle duration,and injection-production alternation mode.For high water-cut complex fluvial heavy oil reservoir in Q Oilfield,the optimized scheme involves a pressure fluctu-ation amplitude of 10%of the original pressure,an injection-production half-cycle of 90 days,and an asynchronous injection-production pattern between oil and water wells,with daily oil production increased by 11.5-14.6 m3 per well pattern.The research provides reliable theory and technology for EOR in high water-cut mature oilfields.