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Collaborating Authors
Xiong, Xiaofei
Abstract Sustainable development of shale reservoirs and enhanced oil recovery have become a challenge for the oil industry in recent years. Shale reservoirs are typically characterized by nano Darcy-scale matrix, natural fractures, and artificially fractures with high permeability. Some of earlier studies have confirmed that gas huff-n-puff has been investigated and demonstrated as the most effective and promising solution for improving oil recovery in tight shale reservoirs with ultra-low permeability. Fractures provide an advantage in enhancing recovery from shale reservoirs but they also pose serious problems such as severe gas channeling, which led to rapid decline production from a single well. More studies are needed to optimize the process. This paper studies the method of foam-assisted N2 huff-n-puff to enhance oil recovery in fractured shale cores. The influence of foam on oil recovery was analyzed. The effect of matrix permeability, cycle number and production time on oil recovery are also considered. The shale core used in the experiment was from Sichuan Basin, China. For the purpose of comparation and validation, two groups of tests were conducted. One group of tests was N2 huff-n-puff, and the other was foam-N2 huff-n-puff. In the optimization experiment, matrix permeabilities were set as 0.01mD, 0.008mD and 0.001mD, cycle numbers ranged from one to five, the production time is designed to be 1 hour and 24 hours respectively. During the puff period of experiments, the history of oil recovery was closely monitored to reveal the mechanism. During a round of gas injection of fractured shale cores, foam-assisted N2 huff-n-puff oil recovery is 4.59%, which is significantly higher than that of N2 huff-n-puff is only 0.0126%, and the contrast becomes more obvious with the increase of matrix permeability. The results also showed that the cumulative oil recovery increased as the number of cycles was increased, with the same experimental conditions. There is an optimal production time to achieve maximum oil recovery. The cycle numbers, matrix permeability, and production time played important roles in foam-assisted N2 huff-n-puff injection process. Therefore, under certain conditions, foam-N2 huff-n-puff has a positive effect on oil development in fractured shale.
- Asia > China (0.87)
- North America > United States > Texas (0.68)
- North America > United States > North Dakota > Divide County (0.28)
- North America > United States > Texas > Permian Basin > Yeso Formation (0.99)
- North America > United States > Texas > Permian Basin > Yates Formation (0.99)
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
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Modeling Study of Wellbore Vortex Flow and Helical Angle Design of Downhole Vortex Tool
Zhou, Chao (SINOPEC Research Institute of Petroleum Engineering, China University of Petroleum-Beijing) | Zhang, Tongyi (SINOPEC Research Institute of Petroleum Engineering) | Wu, Xiaodong (China University of Petroleum-Beijing) | Zhao, Fei (Engineering Technology Research Institute of Huabei Oilfield Company) | Xiong, Xiaofei (China University of Petroleum-Beijing)
Abstract Vortex drainage gas recovery is a new drainage gas recovery technology. However, its operating mechanism has not been figured out. Theoretical analysis of force condition of the liquid film in the wellbore vortex flow field is still lacking, and dynamic analysis method of the liquid film is not established. The objective of the proposed paper is to establish the liquid film dynamic analysis model and calculate the optimal helical angle of the vortex tool. Dynamic analysis of the liquid film in the wellbore vortex flow field is carried out on the basis of the flow pattern and force condition of the liquid film. Expression of each acting force is determined and the force equilibrium equation is obtained. Referring to the annular flow theory, friction coefficient and average thickness of the liquid film are calculated. Through derivation of the vertical resultant force equation of the liquid film, the optimal helical angle of the vortex tool is obtained. Then, vortex tools were designed and deployed in the wellbore of a gas well in field. Field study shows that the relative difference of the optimal helical angle obtained by liquid film dynamic analysis relative to that obtained by numerical simulation is less than 4%. The optimal helical angle calculated by the liquid film dynamic analysis model is reliable and provides guidance for the structure optimization of vortex tools. Optimal helical angle would increase with well depth decreases because of enhancement of fluid-carrying capability of the gas. The liquid film dynamic analysis model can reasonably explain the motion and force condition of the liquid phase in the wellbore vortex flow. Compared with the conventional annular flow field, vortex flow filed includes additional centrifugal force on the liquid film, which may benefit the upward motion of the liquid film. The liquid film dynamic analysis model in the wellbore vortex flow field and the formula for calculating the optimal helical angle of the vortex tool are established for the first time, whose results fill the gap in existing studies and have a guiding significance for optimization design and field application of vortex tools.
- North America > United States > Texas (0.69)
- North America > United States > Gulf of Mexico > Central GOM (0.24)
- Asia > China > Hebei > Bohai Basin > Huabei Field (0.99)
- North America > United States > Louisiana > China Field (0.97)
- Europe > Russia > Northwestern Federal District > Komi Republic > Timan-Pechora Basin > Pechora-Kolva Basin > Usa Field (0.97)