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Study on filtration patterns of supercritical CO 2 fracturing in unconventional natural gas reservoirs
Author(s) -
Wang Jintang,
Sun Baojiang,
Wang Zhiyuan,
Zhang Jianbo
Publication year - 2017
Publication title -
greenhouse gases: science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.45
H-Index - 32
ISSN - 2152-3878
DOI - 10.1002/ghg.1721
Subject(s) - supercritical fluid , filtration (mathematics) , pressure drop , permeability (electromagnetism) , oil shale , natural gas , chemistry , mechanics , petroleum engineering , mineralogy , materials science , geology , mathematics , paleontology , biochemistry , statistics , physics , organic chemistry , membrane
Taking the supercritical CO 2 (SC‐CO 2 ) Joule–Thomson coefficient and the effects of adsorption between CO 2 ‐shale‐CH 4 into consideration, a two‐phase filtration rate calculation model of SC‐CO 2 fracturing in unconventional natural gas reservoirs is proposed. With the help of an experimental apparatus of fluid filtration in shales, it has been found that the theoretical calculation and experimental measurement have an absolute error of 3.31% of the steady filtration rate under specific conditions. Under different pressure differentials between the reservoir and the fracture, the absolute average error of the calculated filtration rate is 2.53%, compared with the experimental data. The filtration of the SC‐CO 2 fracturing in an unconventional natural gas reservoir is characterized by the filtration rate, which gradually decreases with time, and the rate of its decrease tends to reach equilibrium in the late stage. The funnel‐like pressure distribution occurs near the fracture during the transmission of the filtration pressure. A non‐linear relationship exists between the filtration rate and the permeability, which indicates that higher permeability enlarges the effective range of the fracturing fluid pressure as well as the invasion region. Moreover, the steady filtration rate and the pressure drop magnitude present a nearly linear increase with the increasing filtration pressure differential. In the site operation of the SC‐CO 2 fracturing, the injection temperature, pressure, and pump rate can be optimized using the proposed chart. Thickening of the SC‐CO 2 fracturing fluid can effectively decrease the filtration rate, and thus development of thickened SC‐CO 2 fracturing fluid systems that prevent formation damage is needed. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.