Laboratory Evaluation Experiment for Adaptability Analysis of Nitrogen Injection in Yanchang Oil Field

Abstract

Yanchang Oilfield conducts systematic research on nitrogen injection to enhance oil recovery. Through the research of this project, the energy supplement method of horizontal wells suitable for the study area is determined, and its injection system and process parameters are optimized and determined. The optimal energy replenishment method selected by the mine field test achieves the following economic and technical indicators: Provide a nitrogen suitability evaluation plan; Complete the nitrogen flooding matching process design of the target well; Complete the design of the injection-production plan for the target well; Compare with other energy supplement methods. Through the analysis of two supplementary energy methods of water injection and gas injection in indoor and similar reservoirs, the following understandings have been obtained: (1) Nitrogen is insoluble in water, slightly soluble in oil, good swelling, large elastic energy, is an inert gas, exists widely in the atmosphere, inexhaustible, inexhaustible, has a wide range of sources. (2) the recovery rate of nitrogen flooding is significantly higher than that of water flooding. (3) The field test results of water injection and nitrogen test in similar reservoirs show that the supplementary formation energy of nitrogen injection is suitable for the later development of Chang 64 and Chang 71 in the Haobasi oil field. (4) Compared with deep ultra-low permeability reservoirs, it is more economical to use nitrogen to supplement formation energy and change oil. The rate is higher. From the above analysis, it can be seen that the supplementary energy of Chang 64 and Chang 71 reservoirs in the Haobasi oil area should be nitrogen injection as the main supplement, and water injection as a supplement. Gas/water alternate injection is used to adjust the gas injection profile to slow down the escape of injected nitrogen. . Although water injection supplements the formation energy with greater uncertainty, it can be used as a technical means of fluidity control in the gas injection process and is relatively economical.