THE ECONOMIC FEASIBILITY OF ENHANCED COALBED METHANE RECOVERY USING CO2 SEQUESTRATION IN THE SAN JUAN BASIN
二氧化碳排放及大气中二氧化碳水平升高被认为是导致全球变暖的的主要根源。煤层CO2封存是一种可以降低空气中CO2浓度的技术。此外，由于二氧化碳的化学和物理特性，二氧化碳封存也是大幅提高煤层气采收率（ECBM）的一种潜力技术。
圣胡安Fruitland煤矿拥有美国产量最高的煤层。对该盆地进行深入研究，调查了CO2封存和ECBM的潜力。根据储层性质，15号煤层的甲烷一次采收率在20-60%之间，而CO2封存可将煤层气采收率提高30%。
圣胡安盆地的渗透率分布范围为1 md至100 md。Fairway地区的渗透率范围更大，压力更低。在盆地的西部过渡带，其特征是渗透率范围较低，压力较高。由于过渡带的渗透率较低，因此不确定该区域是否适合CO2封存，以及是否能够提高煤层甲烷的采收率。
本研究的目的是确定封存CO2提高圣胡安盆地煤层过渡带煤层甲烷产量的经济可行性。研究具有双重目的：首先，确定是否有可能通过在圣胡安盆地过渡带注入二氧化碳来提高煤层气的采收率。第二是确定最佳设计策略，并利用敏感性分析确定CO2封存/ECBM在经济上是否可行。
研究得出4个160英亩面积布井最佳设计方案。通过10年的高速注入CO2，甲烷产量的采收率可提高30%，并封存10.5 BCF的CO2。该项目的经济价值为1756万美元，如果以每吨5美元的价格授予碳信用，则为1907万美元。如果不注入二氧化碳，经济价值只为1555万美元。
ABSTRACT
Carbon dioxide emissions are considered a major source of increased atmospheric CO2 levels leading towards global warming. CO2 sequestration in coal bed reservoirs is one technique that can reduce the concentration of CO2 in the air. In addition, due to the chemical and physical properties of carbon dioxide, CO2 sequestration is a potential option for substantially enhancing coal bed methane recovery (ECBM).
The San Juan Fruitland coal has the most prolific coal seams in the United States. This basin was studied to investigate the potential of CO2 sequestration and ECBM. Primary recovery of methane is controversial ranging between 20-60% based on reservoir properties in coal bed reservoirs15. Using CO2 sequestration as a secondary recovery technique can enhance coal bed methane recovery up to 30%.
Within the San Juan Basin, permeability ranges from 1 md to 100 md. The Fairway region is characterized with higher ranges of permeability and lower pressures. On the western outskirts of the basin, there is a transition zone characterized with lower ranges of permeability and higher pressures. Since the permeability is lower in the transition zone, it is uncertain whether this area is suitable for CO2 sequestration and if it can deliver enhanced coal bed methane recovery.
The purpose of this research is to determine the economic feasibility of sequestering CO2 to enhance coal bed methane production in the transition zone of the San Juan Basin Fruitland coal seams. The goal of this research is two-fold. First, to determine whether there is a potential to enhance coal bed methane recovery by using CO2 injection in the transition zone of the San Juan Basin. The second goal is to identify the optimal design strategy and utilize a sensitivity ana lysis to determine whether CO2 sequestration/ECBM is economically feasible.
Based on the results of my research, I found an optimal design strategy for four 160-acre spacing wells. With a high rate injection of CO2 for 10 years, the percentage of recovery can increase by 30% for methane production and it stores 10.5 BCF of CO2. The economic value of this project is $17.56 M and $19.07 M if carbon credits were granted at a price of $5.00/ton. If CO2 was not injected, the project would only give $15.55 M.
