CO2 pre-fracturing belongs to economically and environmentally valuable CCUS projects, but there is currently a lack of continuous and effective means to monitor the CO2 extraction rate post-fracturing. Current practices both domestically and internationally mainly rely on intermittent monitoring through handheld CO2 detectors or sampling bags for chemical analysis, which does not adequately meet actual operational needs. CO2 online monitoring technology monitors CO2 production to calculate CO2 storage rates.

• Does not require a three-phase separator;

• Capable of measuring the amount of CO2 dissolved in the liquid phase;

• Enables real-time online monitoring of CO2 content and remote data transmission.

1.Multiphase flow meter

2.Fixed online CO2 monitor

3.Portable CO2 monitor

XXX shale oil horizontal well injected a total of 3600 m³ of liquid carbon dioxide. After soaking, the tubing was connected to the CO2 online monitoring process. The well was opened for production until gas breakthrough, and real-time online monitoring began. Simultaneously, seven adjacent wells were monitored. After 32 days of production, the injection well showed minimal CO2 production, while only two neighboring wells detected ppm-level CO2 production (negligible). Approximately 1080 m³ of CO2 was extracted from the well group.

CO2 storage rate = (3600 - 1080) / 3600 * 100% = 70%.