Effect of permeability and its horizontal anisotropy on enhanced coalbed methane recovery with CO2 storage: quantitative evaluation based on staged CH4 output inhibition
{"title":"Effect of permeability and its horizontal anisotropy on enhanced coalbed methane recovery with CO2 storage: quantitative evaluation based on staged CH4 output inhibition","authors":"Ziliang Wang, Shuxun Sang, Xiaozhi Zhou, Xudong Liu, Shouren Zhang","doi":"10.1007/s11707-022-1039-5","DOIUrl":null,"url":null,"abstract":"<p>The permeability and its horizontal anisotropy induce a critical influence on staged CH<sub>4</sub> output inhibition process. However, a quantitative evaluation of this influence has been rarely reported in the literature. In this work, the impact of horizontal anisotropic permeability on CO<sub>2</sub>-ECBM was numerically investigated. The variation in the staged CH<sub>4</sub> output inhibition was analyzed. The ideal displacement profile of the CO<sub>2</sub>-ECBM process was established for the first time. Moreover, the variation in CH<sub>4</sub> output of different wellbores was discussed. The results showed that 1) low-permeable or weak-anisotropic reservoirs were not conducive to enhanced CH<sub>4</sub> recovery owing to long inhibition time (> 1091 days) and high inhibition level (> 36.9%). As permeability and anisotropy increased, due to the accelerated seepage of free water, the hysteresis time and inhibition time could decrease to as short as 5 days and 87 days, respectively, and the inhibition level could weaken to as low as 5.00%. Additionally, the CH<sub>4</sub> output and CO<sub>2</sub> injection could increase significantly. 2) Nevertheless, high permeability and strong anisotropy easily induced CO<sub>2</sub> breakthrough, resulting in lower CH<sub>4</sub> production, CO<sub>2</sub> injection and CO<sub>2</sub> storage than expected. While maintaining high efficiency of CO<sub>2</sub> storage (> 99%), upregulating CO<sub>2</sub> breakthrough concentration from 10% to 20% might ease the unfavorable trend. 3) Along the direction of fluid flow, the ideal displacement profile consisted of CO<sub>2</sub> enriched bank, CO<sub>2</sub> and CH<sub>4</sub> mixed bank, CH<sub>4</sub> enriched bank, and water enriched bank, whereas a remarkable gap in the displacement profiles of the dominant and non-dominant seepage directions was observed. 4) The potential of CH<sub>4</sub> output might vary greatly among different wellbores. The producers along the dominant seepage direction held more potential for CH<sub>4</sub> recovery in the short-term, while those along the non-dominant seepage direction avoided becoming invalid only if a long-time injection measure was taken for the injectors. These findings pave the way to understand fluid seepage in real complex reservoirs during CO<sub>2</sub>-ECBM and conduct further field projects.</p>","PeriodicalId":48927,"journal":{"name":"Frontiers of Earth Science","volume":null,"pages":null},"PeriodicalIF":1.8000,"publicationDate":"2023-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Frontiers of Earth Science","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1007/s11707-022-1039-5","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The permeability and its horizontal anisotropy induce a critical influence on staged CH4 output inhibition process. However, a quantitative evaluation of this influence has been rarely reported in the literature. In this work, the impact of horizontal anisotropic permeability on CO2-ECBM was numerically investigated. The variation in the staged CH4 output inhibition was analyzed. The ideal displacement profile of the CO2-ECBM process was established for the first time. Moreover, the variation in CH4 output of different wellbores was discussed. The results showed that 1) low-permeable or weak-anisotropic reservoirs were not conducive to enhanced CH4 recovery owing to long inhibition time (> 1091 days) and high inhibition level (> 36.9%). As permeability and anisotropy increased, due to the accelerated seepage of free water, the hysteresis time and inhibition time could decrease to as short as 5 days and 87 days, respectively, and the inhibition level could weaken to as low as 5.00%. Additionally, the CH4 output and CO2 injection could increase significantly. 2) Nevertheless, high permeability and strong anisotropy easily induced CO2 breakthrough, resulting in lower CH4 production, CO2 injection and CO2 storage than expected. While maintaining high efficiency of CO2 storage (> 99%), upregulating CO2 breakthrough concentration from 10% to 20% might ease the unfavorable trend. 3) Along the direction of fluid flow, the ideal displacement profile consisted of CO2 enriched bank, CO2 and CH4 mixed bank, CH4 enriched bank, and water enriched bank, whereas a remarkable gap in the displacement profiles of the dominant and non-dominant seepage directions was observed. 4) The potential of CH4 output might vary greatly among different wellbores. The producers along the dominant seepage direction held more potential for CH4 recovery in the short-term, while those along the non-dominant seepage direction avoided becoming invalid only if a long-time injection measure was taken for the injectors. These findings pave the way to understand fluid seepage in real complex reservoirs during CO2-ECBM and conduct further field projects.
期刊介绍:
Frontiers of Earth Science publishes original, peer-reviewed, theoretical and experimental frontier research papers as well as significant review articles of more general interest to earth scientists. The journal features articles dealing with observations, patterns, processes, and modeling of both innerspheres (including deep crust, mantle, and core) and outerspheres (including atmosphere, hydrosphere, and biosphere) of the earth. Its aim is to promote communication and share knowledge among the international earth science communities