1
|
Jiang W, Lv W, Jia N, Cheng K, Wan Y, Wang K. Molecular Insights into Soaking in Hybrid N 2-CO 2 Huff-n-Puff: A Case Study of a Single Quartz Nanopore-Hydrocarbon System. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024. [PMID: 38990799 DOI: 10.1021/acs.langmuir.4c00989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/13/2024]
Abstract
Hybrid N2-CO2 huff-n-puff (HnP) has been experimentally demonstrated to be a promising approach for improving oil recovery from tight/ultratight shale oil reservoirs. Despite this, the detailed soaking process and interaction mechanisms remain unclear. Adopting molecular dynamic simulations, the soaking behavior of hybrid N2-CO2 HnP was investigated at the molecular and atomic levels. Initially, the soaking process of fluid pressure equilibrium after injection pressure decays in a single matrix nanopore connected to a shale oil reservoir is studied. The study revealed that counter-current and cocurrent displacement processes exist during the CO2 and hybrid N2-CO2 soaking, but cocurrent displacement occurs much later than counter-current displacement. Although the total displacement efficiency of the hybrid N2-CO2 soaking system is lower than that of the CO2 soaking system, the cocurrent displacement initiates earlier in the hybrid N2-CO2 soaking system than in the CO2 soaking system. Moreover, the N2 soaking process is characterized by only counter-current displacement. Next, the soaking process of fluid pressure nonequilibrium before the injection pressure decays is investigated. It was discovered that counter-current and cocurrent displacement processes initiate simultaneously during the CO2, N2, and hybrid N2-CO2 soaking process, but cocurrent displacement exerts a dominant influence. During the CO2 soaking process, many hydrocarbon molecules in the nanopore are dissolved in CO2 while simultaneously exhibiting a substantial retention effect in the nanopore. After pure N2 injection, there is a tendency to form a favorable path of N2 through the oil phase. The injection of hybrid CO2-N2 facilitates the most significant cocurrent displacement effect and the reduction in residual oil retained in the nanopore during the soaking process, thus resulting in the best oil recovery. However, the increase rate in total displacement efficiencies of the different soaking systems over time (especially the hybrid N2-CO2 soaking system) was significantly larger before than after injection pressure decays. Additionally, the displacement effect induced by oil volume swelling is significantly restricted before the injection pressure decays compared to the soaking process after the injection pressure decays. This study explains the role of CO2-induced oil swelling and N2-induced elastic energy played by hybrid N2 and CO2 at different stages of the hybrid N2-CO2 soaking process before and after pressure decays and provides theoretical insights for hybrid gas HnP-enhanced recovery. These pore-scale results highlight the importance of injection pressure and medium composition during the soaking process in unconventional oil reservoirs.
Collapse
Affiliation(s)
- Wen Jiang
- College of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
- Institute of Porous Flow and Fluid Mechanics, University of Chinese Academy of Sciences, Langfang 065007, China
- Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, P. R. China
| | - Weifeng Lv
- Institute of Porous Flow and Fluid Mechanics, University of Chinese Academy of Sciences, Langfang 065007, China
- State Key Laboratory of Enhanced Oil and Gas Recovery, Beijing 100083, China
- Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, P. R. China
| | - Ninghong Jia
- State Key Laboratory of Enhanced Oil and Gas Recovery, Beijing 100083, China
- Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, P. R. China
| | - Kai Cheng
- Beijing Key Laboratory for Greenhouse Gas Storage and CO2-EOR Unconventional Petroleum Research Institute, China University of Petroleum (Beijing), Beijing 102249, P. R. China
| | - Yidi Wan
- Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, P. R. China
- School of Earth and Space Sciences, Peking University, Beijing 100871, P. R. China
| | - Kai Wang
- College of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
- Institute of Porous Flow and Fluid Mechanics, University of Chinese Academy of Sciences, Langfang 065007, China
- Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, P. R. China
| |
Collapse
|
2
|
Jiang W, Lv W, Jia N, Lu X, Wang L, Wang K, Mei Y. Study on the Effects of Wettability and Pressure in Shale Matrix Nanopore Imbibition during Shut-in Process by Molecular Dynamics Simulations. Molecules 2024; 29:1112. [PMID: 38474624 DOI: 10.3390/molecules29051112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 02/18/2024] [Accepted: 02/27/2024] [Indexed: 03/14/2024] Open
Abstract
Shut-in after fracturing is generally adopted for wells in shale oil reservoirs, and imbibition occurring in matrix nanopores has been proven as an effective way to improve recovery. In this research, a molecular dynamics (MD) simulation was used to investigate the effects of wettability and pressure on nanopore imbibition during shut-in for a typical shale reservoir, Jimsar. The results indicate that the microscopic advancement mechanism of the imbibition front is the competitive adsorption between "interfacial water molecules" at the imbibition front and "adsorbed oil molecules" on the pore wall. The essence of spontaneous imbibition involves the adsorption and aggregation of water molecules onto the hydroxyl groups on the pore wall. The flow characteristics of shale oil suggest that the overall push of the injected water to the oil phase is the main reason for the displacement of adsorbed oil molecules. Thus, shale oil, especially the heavy hydrocarbon component in the adsorbed layer, tends to slip on the walls. However, the weak slip ability of heavy components on the wall surface is an important reason that restricts the displacement efficiency of shale oil during spontaneous imbibition. The effectiveness of spontaneous imbibition is strongly dependent on the hydrophilicity of the matrix pore's wall. The better hydrophilicity of the matrix pore wall facilitates higher levels of adsorption and accumulation of water molecules on the pore wall and requires less time for "interfacial water molecules" to compete with adsorbed oil molecules. During the forced imbibition process, the pressure difference acts on both the bulk oil and the boundary adsorption oil, but mainly on the bulk oil, which leads to the occurrence of wetting hysteresis. Meanwhile, shale oil still existing in the pore always maintains a good, stratified adsorption structure. Because of the wetting hysteresis phenomenon, as the pressure difference increases, the imbibition effect gradually increases, but the actual capillary pressure gradually decreases and there is a loss in the imbibition velocity relative to the theoretical value. Simultaneously, the decline in hydrophilicity further weakens the synergistic effect on the imbibition of the pressure difference because of the more pronounced wetting hysteresis. Thus, selecting an appropriate well pressure enables cost savings and maximizes the utilization of the formation's natural power for enhanced oil recovery (EOR).
Collapse
Affiliation(s)
- Wen Jiang
- College of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
- Institute of Porous Flow and Fluid Mechanics, University of Chinese Academy of Sciences, Langfang 065007, China
- Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, China
| | - Weifeng Lv
- Institute of Porous Flow and Fluid Mechanics, University of Chinese Academy of Sciences, Langfang 065007, China
- Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, China
- State Key Laboratory of Enhanced Oil and Gas Recovery, Beijing 100083, China
| | - Ninghong Jia
- Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, China
- State Key Laboratory of Enhanced Oil and Gas Recovery, Beijing 100083, China
| | - Xiaoqing Lu
- School of Materials Science and Engineering, China University of Petroleum, Qingdao 266580, China
| | - Lu Wang
- School of Materials Science and Engineering, China University of Petroleum, Qingdao 266580, China
| | - Kai Wang
- College of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
- Institute of Porous Flow and Fluid Mechanics, University of Chinese Academy of Sciences, Langfang 065007, China
- Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, China
| | - Yuhao Mei
- College of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
- Institute of Porous Flow and Fluid Mechanics, University of Chinese Academy of Sciences, Langfang 065007, China
- Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, China
| |
Collapse
|
3
|
Wu H, Li Z, Wang Y, Zhu W. Surface Decoration of Cetyltrimethyl Ammonium Bromide on SiC Particles and Its Effects on the Co-Deposition Process. J Phys Chem B 2021; 125:4874-4882. [PMID: 33929854 DOI: 10.1021/acs.jpcb.0c09901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cetyltrimethyl ammonium bromide (CTAB) is used to decorate the SiC particle surface. The mechanism of the decoration process has been studied by simulation and experimental approaches. Molecular dynamics (MD) simulation finds a bilayer adsorbed structure of CTAB on the SiC particles, which is then verified by Fourier-transform infrared and thermal gravimetric analysis measurements. The MD simulation also finds that the decorative effects of CTAB on the SiC particle surface are related to the surface charge condition of the SiC particles and the concentration of CTAB. The measured zeta potential of the SiC particles shows dependence on the pH condition and the concentration of CTAB. The decorated SiC particles are used to produce composition by the co-deposition technology. With the help of CTAB, SiC particles are successfully incorporated in the deposited layer, where the content of SiC particles is dependent on the concentration of CTAB and the pH of the bath.
Collapse
Affiliation(s)
- Houya Wu
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.,State Key Laboratory of High Performance Complex Manufacturing, School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China
| | - Zhiyi Li
- State Key Laboratory of High Performance Complex Manufacturing, School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China
| | - Yan Wang
- State Key Laboratory of High Performance Complex Manufacturing, School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China
| | - Wenhui Zhu
- State Key Laboratory of High Performance Complex Manufacturing, School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China
| |
Collapse
|