酸气回注——以土库曼斯坦阿姆河右岸 封存场地适应性评价为例

酸气回注技术既是碳减排技术之一,又可在一定程度上缓解硫磺供需矛盾,降低酸雨发生频次,并有利于环境保护的绿色执行技术之一,因此,正日渐受到全球关注。土库曼斯坦阿姆河右岸区块是中国海外天然气的重要来源地之一,在中石油国际合作开发过程中,考虑到硫磺市场价格波动性及后续运输距离的不确定性等不利因素,与传统硫回收工艺相比,酸气回注技术值得研究与分析。限于中亚特殊地缘与环境特征,其酸气封存场地的选择尤为重要。本文参考二氧化碳封存选址原则,提出运用酸气回注的地质工程学方法,对阿姆河右岸酸气回注封存场地进行适应性评价。首先,选择适应酸气封存选址的指标,包括研究区地质构造稳定性、地震和断裂发育情况、地层压力、地温、储层孔隙度和渗透率、盖层封闭性等;然后根据区域实际地质情况,对每个指标进行权重赋值,运用层次分析法来进行盆地级评价;最后,参照利用沉积微相和更细的储层物性资料,进行了更细级别的封存场地优势带分析,为下一步工作指明方向。

Acid Gas Injection: A Suitability Evaluation for Sequestration Site in Amu Darya Basin, Turkmenistan

Acid gas injection (AGI) is not only one of carbon abatement technologies, but also one of the green technologies conducive to environmental protection because it can alleviate the sulfur supply and demand to some extent, and it can also reduce the potential frequency of acid rain. Therefore, AGI is increasingly affected by global concern. The Amu Darya right bank block in Turkmenistan is one of important sources of Chinese overseas natural gas exploitation. During the international development of this natural gas block, the adverse factors are taken into account according to uncertainty and volatility of the sulfur market and transportation, etc. It is found that acid gas injection is worthy of study and deep analysis with comparison to conventional sulfur recovery process technology. Limited to its special geopolitical and environmental characteristics, sequestration site selection of acid gas injection is particularly important in Central Asia. By reference to the selection principles of carbon dioxide sequestration site, a geoengineering method is proposed for acid gas injection, and the suitability evaluation of the Amu Darya right bank area is investigated for the potential sequestration of acid gases. Firstly, the suitability indicators are selected for sequestration site of acid gases, which include stability of geological structure of study area, earthquakes and faults, formation pressure, temperature, porosity and permeability of the reservoir, caprock, etc. Then, the indicators are assigned proper weighted coefficients according to the actual geological conditions of study area, and analytic hierarchy process (AHP) are used to conduct a basin level evaluation of sequestration suitability. Finally, according to micro facies of sedimentary environments and more detailed information of reservoir properties, a further analysis is carried out to seek a target zone of potential sequestration sites. It also points out the future work direction.