Experimental Study on the Sweep Law of CO 2 Miscible Flooding in Heterogeneous Reservoir in Jilin

Wen Li (), Hongwei Yu, Zhengming Yang, Jinlong Li, Xinliang Chen and Longfei Ma
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Wen Li: College of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
Hongwei Yu: State Key Laboratory of Enhanced Oil Recovery, PetroChina Research Institute of Petroleum Exploration and Development, Beijing 100083, China
Zhengming Yang: Institute of Porous Flow and Fluid Mechanics, Chinese Academy of Sciences, Langfang 065007, China
Jinlong Li: PetroChina Jilin Oilfield Company, Songyuan 138099, China
Xinliang Chen: College of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
Longfei Ma: College of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China

Energies, 2022, vol. 15, issue 15, 1-14

Abstract: It is very important to effectively describe the sweep characteristics of CO 2 miscible flooding based on physical models for actual reservoir development. In this study, based on the geological characteristics of the Jilin ultra-low permeability reservoir, which has significant vertical heterogeneity, a two-dimensional double-layer heterogeneous visualization model with a permeability contrast of 10 and thickness contrast of 2 was designed to perform experimental research on the sweep law of CO 2 miscible flooding with an injection-production mode of “united injection and single production”. With the goal of determining the obvious differences in the gas absorption capacity and displacement power of the two layers, the CO 2 dynamic miscible flooding characteristics were comprehensively analyzed, and the sweep law of CO 2 miscible flooding, including the oil and gas flow trend, migration direction of the oil–gas interface, and distribution characteristics of the miscible zone, was further studied in combination with the oil displacement effect. In this experiment, the gas absorption capacity was the key factor affecting the sweep efficiency of the CO 2 miscible flooding. Under the combined influence of the internal and external control factors of the reservoir thickness, permeability, and injection-production mode, the gas absorption capacity of the high-permeability layer was much greater than that of the low-permeability layer, resulting in the retention of a large amount of remaining oil in the low-permeability layer, which effectively displaced and swept the oil in the high-permeability layer. The gas absorption capacity of the reservoir, gravitational differentiation, and miscible mass transfer were key factors affecting the migration of the oil–gas interface and distribution of the miscible zone. The entire displacement process could be divided into three stages: ① The gas-free rapid oil production stage, which was dominated by the displacement; ② the low gas–oil ratio stable oil production stage, which was jointly affected by the displacement and miscible mass transfer; and ③ the high gas–oil ratio slow oil production stage, which was dominated by the effect of CO 2 carrying.

Keywords: CO 2 miscible flooding; vertical heterogeneity; sweep law; 2D visual model; gas absorption capacity (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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