Post-fracturing Evaluation Method of the Deep Coal Bed Methane Reservoir Stimulated with CO2/Foam Fracturing Technology
In order to evaluate the applicability of CO2 foam fracturing to deep coal bed methane and analyze the fracturing geological characteristics of deep coal,this paper takes the CO2 foam fracturing operation of Well X1 in the deep coal bed methane horizontal well in the Ordos Basin as an example,and evaluates the influence of the fracturing geological characteristics,fracture propagation characteristics and fracturing fluid type on the post-frac-turing effect of Well X1 by using pressure diagnosis methods such as pump-stopping pressure drop rate analysis,G-function pressure drop curve analysis and friction analysis of the pipeline along the fracturing injection.The re-sults show that:the deep coal bed methane reservoir in the Ordos Basin has good permeability.The CO2 foam fracturing process can meet the fracturing needs of deep coal bed methane horizontal wells in in the Ordos Basin,and the advantages of energy enhancement and drainage are prominent,and the effect of post-fracturing stimula-tion is obvious.Compared with guar gum fracturing fluid,the pump-stopping pressure drop rate is faster and per-meability better after the application of CO2 foam fracturing fluid.The permeability of the formation can be im-proved by increasing the single-cluster injection intensity and increasing the pressure in the fracture.In addition,compared with the operation in sandstone reservoir,the CO2 flow rate and concentration of CO2 are lower after CO2 foam fracturing in deep coal bed methane,which confirms the expectation that CO2 is adsorbed in formation.This study can provide experience and suggestions for the optimization of fracturing process and fracturing param-eters in deep coal and rock gas.
deep coal bed methaneCO2 foam fracturingpressure diagnosispost-fracturing evaluation
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