Study of Temperature Effects on Economic Performance of CO2 Enhanced Shale Gas Recovery

Abstract CO2 displacement has been proposed to enhance shale gas recovery and unlock a big potential market for CO2 beneficial utilization. Theoretically, gas adsorption is inversely related to the temperature, so gas can be desorbed by elevating the temperature. This paper investigates the economic performance of enhancing shale gas recovery by injecting CO2 at high temperatures through displacement as well as desorption by rising temperatures. Influences of operation temperature and injection pressure were studied for three potential shale plays in China. Study results show that both factors exerted obvious impacts, and CO2 procurement was the largest cost component. It is found that the net revenue was not always proportional to the operation temperature, but more controlled by the injection–production ratio. This is because of the different temperature impacts to the various patterns of adsorbed CH4 and CO2 contents. Consequently, in some cases, more CO2 is needed to displace CH4 when operation temperature is raised, resulting a higher cost. The modeling results demonstrate that based on the adsorption characters of reservoirs, the productivity and profitability of CO2 enhanced gas recovery can be further improved by choosing appropriate operation temperatures.

Download Full-text

Molecular Investigation on the Displacement Characteristics of CH4 by CO2, N2 and Their Mixture in a Composite Shale Model

Energies ◽

10.3390/en14010002 ◽

2020 ◽

Vol 14 (1) ◽

pp. 2

Author(s):

Liang Gong ◽

Yuan Zhang ◽

Na Li ◽

Ze-Kai Gu ◽

Bin Ding ◽

...

Keyword(s):

Energy Consumption ◽

Shale Gas ◽

Injection Pressure ◽

Gas Production ◽

Formation Temperature ◽

Displacement Efficiency ◽

Gas Recovery ◽

Displacement Capacity ◽

Molecular Investigation ◽

Shale Reservoirs

The rapid growth in energy consumption and environmental pollution have greatly stimulated the exploration and utilization of shale gas. The injection of gases such as CO2, N2, and their mixture is currently regarded as one of the most effective ways to enhance gas recovery from shale reservoirs. In this study, molecular simulations were conducted on a kaolinite–kerogen IID composite shale matrix to explore the displacement characteristics of CH4 using different injection gases, including CO2, N2, and their mixture. The results show that when the injection pressure was lower than 10 MPa, increasing the injection pressure improved the displacement capacity of CH4 by CO2. Correspondingly, an increase of formation temperature also increased the displacement efficiency of CH4, but an increase of pore size slightly increased this displacement efficiency. Moreover, it was found that when the proportion of CO2 and N2 was 1:1, the displacement efficiency of CH4 was the highest, which proved that the simultaneous injection of CO2 and N2 had a synergistic effect on shale gas production. The results of this paper will provide guidance and reference for the displacement exploitation of shale gas by injection gases.

Download Full-text

Impact of gas adsorption on apparent permeability of shale fracture and shale gas recovery rate

Scientia Sinica Technologica ◽

10.1360/n092017-00196 ◽

2018 ◽

Vol 48 (8) ◽

pp. 891-900

Author(s):

HongYan QU ◽

Yan PENG ◽

JiShan LIU ◽

ZhangXing CHEN ◽

KeLiu WU ◽

...

Keyword(s):

Shale Gas ◽

Recovery Rate ◽

Gas Adsorption ◽

Apparent Permeability ◽

Gas Recovery ◽

Shale Fracture

Download Full-text

Study on Competitive Adsorption and Displacing Properties of CO2 Enhanced Shale Gas Recovery: Advances and Challenges

Geofluids ◽

10.1155/2020/6657995 ◽

2020 ◽

Vol 2020 ◽

pp. 1-15

Author(s):

Shuyang Liu ◽

Baojiang Sun ◽

Jianchun Xu ◽

Hangyu Li ◽

Xiaopu Wang

Keyword(s):

Shale Gas ◽

Adsorption Mechanism ◽

Competitive Adsorption ◽

Gas Adsorption ◽

Organic Matter Content ◽

Gas Production ◽

Gas Recovery ◽

Model Studies ◽

Displacement Experiments ◽

Adsorption Of Co2

CO2 enhanced shale gas recovery (CO2-ESGR) draws worldwide attentions in recent years with having significant environmental benefit of CO2 geological storage and economic benefit of shale gas production. This paper is aimed at reviewing the state of experiment and model studies on gas adsorption, competitive adsorption of CO2/CH4, and displacement of CO2-CH4 in shale in the process of CO2-ESGR and pointing out the related challenges and opportunities. Gas adsorption mechanism in shale, influencing factors (organic matter content, kerogen type, thermal maturity, inorganic compositions, moisture, and micro/nano-scale pore), and adsorption models are described in this work. The competitive adsorption mechanisms are qualitatively ascertained by analysis of unique molecular and supercritical properties of CO2 and the interaction of CO2 with shale matrix. Shale matrix shows a stronger affinity with CO2, and thus, adsorption capacity of CO2 is larger than that of CH4 even with the coexistence of CO2-CH4 mixture. Displacement experiments of CO2-CH4 in shale proved that shale gas recovery is enhanced by the competitive adsorption of CO2 to CH4. Although the competitive adsorption mechanism is preliminary revealed, some challenges still exist. Competitive adsorption behavior is not fully understood in the coexistence of CO2 and CH4 components, and more experiment and model studies on adsorption of CO2-CH4 mixtures need to be conducted under field conditions. Coupling of competitive adsorption with displacing flow is key factor for CO2-ESGR but not comprehensively studied. More displacement experiments of CO2-CH4 in shale are required for revealing the mechanism of flow and transport of gas in CO2-ESGR.

Download Full-text

Performance Evaluation of CO2 Huff-n-Puff Gas Injection in Shale Gas Condensate Reservoirs

Energies ◽

10.3390/en12010042 ◽

2018 ◽

Vol 12 (1) ◽

pp. 42 ◽

Cited By ~ 8

Author(s):

Xingbang Meng ◽

Zhan Meng ◽

Jixiang Ma ◽

Tengfei Wang

Keyword(s):

Oil Recovery ◽

Shale Gas ◽

Injection Pressure ◽

Gas Condensate ◽

Dew Point ◽

Gas Condensate Reservoirs ◽

Gas Recovery ◽

Point Pressure ◽

Shale Reservoirs ◽

Dew Point Pressure

When the reservoir pressure is decreased lower than the dew point pressure in shale gas condensate reservoirs, condensate would be formed in the formation. Condensate accumulation severely reduces the commercial production of shale gas condensate reservoirs. Seeking ways to mitigate condensate in the formation and enhance both condensate and gas recovery in shale reservoirs has important significance. Very few related studies have been done. In this paper, both experimental and numerical studies were conducted to evaluate the performance of CO2 huff-n-puff to enhance the condensate recovery in shale reservoirs. Experimentally, CO2 huff-n-puff tests on shale core were conducted. A theoretical field scale simulation model was constructed. The effects of injection pressure, injection time, and soaking time on the efficiency of CO2 huff-n-puff were examined. Experimental results indicate that condensate recovery was enhanced to 30.36% after 5 cycles of CO2 huff-n-puff. In addition, simulation results indicate that the injection period and injection pressure should be optimized to ensure that the pressure of the main condensate region remains higher than the dew point pressure. The soaking process should be determined based on the injection pressure. This work may shed light on a better understanding of the CO2 huff-n-puff- enhanced oil recovery (EOR) strategy in shale gas condensate reservoirs.

Download Full-text