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OS6C-3:HYDRATE FORMATION FLOWLOOP EXPERIMENTS
发布时间:2014-07-28
Giovanny A. GRASSO1, Zachary M. AMAN2, Patrick G. LAFOND1, Eric WEBB1, Luis E. ZERPA3, E. Dendy SLOAN1, Carolyn A. KOH1, Amadeu K. SUM1*
1. Center for Hydrate Research, Chemical and Biological Engineering Department, Colorado School of Mines, USA; 2. Centre for Energy, School of Mechanical and Chemical Engineering, The University of Western Australia, Crawley, Western Australia, Australia; 3. Petroleum Engineering Department, Colorado School of Mines, Golden, CO, USA
The oil and gas industry is moving towards more challenging production scenarios in deeper waters, where hydrate plugging risks are more severe and harder to avoid. In order to apply hydrate management strategies to reduce the risks of plugging pipelines, a better understanding of hydrate plugging mechanisms that differentiates between fluid systems is necessary. To address this challenge, we performed three series of experiments in the four-inch diameter flowloop at the ExxonMobil research facility at Friendswood, TX. For all three series of experiments, the variables studied included mixture velocity (0.75 to 3 m/s) and liquid loading (50 to 95%).
The first series of experiments were performed for 100% water cut (WC) and gas. These experiments corroborated the results gotten by Joshi et al. [1], where an irreversible onset of hydrate plugging was identified for a sharp increase in pressure drop. Joshi et al., found that this transition increases with increasing mixture velocity; the same was observed in this work. Moreover, it was found that this transition appears at a higher hydrate volume fraction for very high liquid loading (95% LL). The second series of experiments was for water in Conroe crude oil emulsions from 15 to 90% WC. From those experiments, higher pressure drops were observed for lower WC compared to those with a high WC; those results suggest that for the majority of those experiments bedding was the dominant phenomena instead of agglomeration. The last series of experiments were performed for King Ranch condensate for WC from 25 to 75%. From these experiments, it was evident that agglomeration played an important role on hydrate particles transportability.
We have identified several hydrate plugging mechanisms, which act in combination and jeopardize hydrate transportability in pipelines. Some of these mechanisms are: increase of slurry viscosity, distribution of particles dispersion, agglomeration of particles, and changes in the gas-liquid flow regime. For some cases, a hydrate plugging mechanism may be dominant, but in general, a combination of these phenomena need be considered for hydrates transportability.
[1] Joshi, S. V., Grasso, G. A., Lafond, P. G., Rao, I., Webb, E., Zerpa, L. E., Sloan, E. D., Koh, C. A., and Sum, A. K., 2013, "Experimental flowloop investigations of gas hydrate formation in high water cut systems," Chemical Engineering Science, 97(0), pp. 198-209.
1. Center for Hydrate Research, Chemical and Biological Engineering Department, Colorado School of Mines, USA; 2. Centre for Energy, School of Mechanical and Chemical Engineering, The University of Western Australia, Crawley, Western Australia, Australia; 3. Petroleum Engineering Department, Colorado School of Mines, Golden, CO, USA
The oil and gas industry is moving towards more challenging production scenarios in deeper waters, where hydrate plugging risks are more severe and harder to avoid. In order to apply hydrate management strategies to reduce the risks of plugging pipelines, a better understanding of hydrate plugging mechanisms that differentiates between fluid systems is necessary. To address this challenge, we performed three series of experiments in the four-inch diameter flowloop at the ExxonMobil research facility at Friendswood, TX. For all three series of experiments, the variables studied included mixture velocity (0.75 to 3 m/s) and liquid loading (50 to 95%).
The first series of experiments were performed for 100% water cut (WC) and gas. These experiments corroborated the results gotten by Joshi et al. [1], where an irreversible onset of hydrate plugging was identified for a sharp increase in pressure drop. Joshi et al., found that this transition increases with increasing mixture velocity; the same was observed in this work. Moreover, it was found that this transition appears at a higher hydrate volume fraction for very high liquid loading (95% LL). The second series of experiments was for water in Conroe crude oil emulsions from 15 to 90% WC. From those experiments, higher pressure drops were observed for lower WC compared to those with a high WC; those results suggest that for the majority of those experiments bedding was the dominant phenomena instead of agglomeration. The last series of experiments were performed for King Ranch condensate for WC from 25 to 75%. From these experiments, it was evident that agglomeration played an important role on hydrate particles transportability.
We have identified several hydrate plugging mechanisms, which act in combination and jeopardize hydrate transportability in pipelines. Some of these mechanisms are: increase of slurry viscosity, distribution of particles dispersion, agglomeration of particles, and changes in the gas-liquid flow regime. For some cases, a hydrate plugging mechanism may be dominant, but in general, a combination of these phenomena need be considered for hydrates transportability.
[1] Joshi, S. V., Grasso, G. A., Lafond, P. G., Rao, I., Webb, E., Zerpa, L. E., Sloan, E. D., Koh, C. A., and Sum, A. K., 2013, "Experimental flowloop investigations of gas hydrate formation in high water cut systems," Chemical Engineering Science, 97(0), pp. 198-209.
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