Multi-physical field imaging method and system based on PET-CT and DAS

A multi-physical field imaging method based on positron emission tomography-computed tomography (PET-CT) and directed acoustic sensing (DAS), for studying a dynamic fluid-solid coupling effect in non-metallic material, to study hydraulic fracturing processes comprising:

• Step A:
• wrapping distributed acoustic sensors on a surface of a non-metallic sample to be tested, and then placing the non-metallic sample to be tested and the distributed acoustic sensors in a pressure device;
• wherein the distributed acoustic sensors are phase-sensitive optical frequency domain reflectometers, made of silicon dioxide, the phase-sensitive optical frequency domain reflectometers are configured to have a spatial resolution of 10 cm, a strain resolution of 1nε/√{square root over (Hz)}, and a vibration sampling frequency of 300 Hz, so as to obtain internal dynamic vibration signals generated from the fluid-solid coupling effect of the non-metallic samples to be tested;
• the pressure device is made of a composite material of polyether ether ketone filled with 40% by weight carbon fiber;
• Step B:
• utilizing electric metering pumps remotely controlled by a computer configured to load triaxial pressures on the non-metallic sample to be tested, performing different mechanical conditions to monitor interaction process between fluid and solid and the sample's physical response, setting pressures of the electric metering pumps remotely through the computer according to the requirement of the experiment, and recording pressure changes in real time;
• Step C:
• preparing a tracer fluid, and diluting the tracer fluid;
• Step D:
• pumping the diluted tracer fluid into the non-metallic sample to be tested through a metering pump remotely controlled by the computer;
• Step E:
• continuously and in-situ collecting PET images and CT images of internal structure of the non-metallic sample to be tested;
• meanwhile, monitoring internal acoustic emission events of the non-metallic sample to be tested by using distributed acoustic sensors in real time;
• Step F:
• combining the continuously-obtained PET images with the continuously-obtained CT images, to obtain PET/CT images;
• Step G:
• analyzing data from monitoring of the distributed acoustic sensors, locating the acoustic emission events, and obtaining occurrence time and spatial location of internal structural perturbation of the non-metallic sample to be tested;
• and
• Step H:
• combining continuous in-situ dynamic PET/CT images with locating results of the acoustic emission events, to analyze a mechanism of fluid-solid coupling effect in the non-metallic sample to be tested under loaded stress;
• projecting spatial location information of the acoustic emission events to three-dimensional PET/CT images, to analyze a fluid-solid coupling process in the non-metallic sample to be tested.