H Reservoir Nitrogen Injection Flooding Enhanced Recovery Scheme Research

With medium porosity, low permeability, faults and side/bottom water, H reservoir had been through the steps of natural depletion, water injection, which had not achieve better results. Because of the limit of geological conditions, many enhanced oil recovery technologies can not be implemented in the reservoir. Oilfield development experience show that gas injection can be an effective method for low permeability reservoirCombined the development experience of similar reservoirs and the geological and development characteristics of H reservoir, this paper proposes the mean of nitrogen injection for EOR, summarizes the feasibility of nitrogen injection, performances the distribution of residua] oil and optimizes the gas injection parameters. The main understanding are listed as follows:?1? The ratio of side/bottom water volume to OOIP is 5. The oil recovery of the main area is 12.19% currently, the oil recovery of water flooding is 13.48% by prediction.?2? Through analyzing the reservoir geological conditions and fluid properties, as well as the literature research, combining with the screening criteria of oil recovery by nitrogen injection, it is concluded that nitrogen injection is an appropriate way to enhance oil recovery of H reservoir;?3? By the tubule experiment simulation and multi-contact simulation research to determine the minimum miscible pressure, the results show that the injected nitrogen could not be miscible in current conditions with the crude oil. Through the nitrogen flooding displacement test, the results show that the ultimate oil recovery is 61.5% when the injection of nitrogen at 0.9 HCPV.?4? On the basis of evaluation of reservoir development effect, this paper studies the remaining oil distribution by numerical simulation.As of May 2015, the remaining reserves of crude oil is 2024x 104t. The remaining oil saturation of S3X_?3?S3X_?2 is higher.?5? On the basis of reservoir numerical simulation, aiming at 5 well groups of the choosed precursor trial area, this paper optimizes the engineering parameters,parameters is as follows:the injection rate is 2-4×104m3/d,the injection volume is 0.17HCPV-0.25HCPV. After 15 years of simulation development, the oil recovery of nitrogen injection is 18.64%, which is 5.2% higher than water flooding. The oil recovery of WAG injection is 19.94% which is 6.5% higher than water flooding.The nitrogen injection parameters optimization and the prediction of optimization had important guiding meaning for the development of similar reservoir.