Optical Microscopy and pressure measurements of Enzymatically Induced Calcite Precipitation (EICP) in a microfluidic cell

Abstract

Content: This dataset includes raw as well as processed data from three experiments (Exp 1 - 3). Each dataset consists of the readouts from the pressure sensor(s), as logged with the use of QmixElements, raw images, and segmented images. Log files: Data in the log files are essentially the raw output of the software QMixElements which is used to operate the syringe pumps and log the pressure sensors. It consists of the columns time, inlet pressure, outlet pressure as well as the flow rates of the two syringes. We need to point out that each pressure sensor has an offset which needs to be accounted for in order to account for the actual pressure in the most accurate way. In order to derive the correct pressure drop (Δp) across the flow cell (outlet pressure - inlet pressure), a two minute period of no flow is applied. It is expected that in the absence of flow the pressure drop across the cell has to be zero and, therefore, the offset of the pressure drop can be determined. For each experiment there are separate log files for stage a) initial permeability measurement (Exp[Nr.]_PermInitial) stage b) continuous injection of reactive solution (Exp[Nr.]_ParallelInjection) stage c) final permeability measurement (Exp[Nr.]_PermFinal) In Experiment 2 the final permeability measurement was not conducted, since the cell was clogged, thus the corresponding log file is missing. Note: When estimating the permeability reduction over time during stage c), e.g K/K0 = Δp0/Δp(t) , the initial pressure drop (Δp0) is very crucial. Small variations and uncertainties effect the estimated permeability reduction tremendously. Due to the small flow rates in the experiments, the measured initial pressure drop is very small compared to the pressure range of the sensors and falls within the error limit of the sensor itself, casting the measurements quite uncertain. Therefore, it is recommended to back calculate the initial pressure drop based on the initial permeability measurement of stage a) and the flow rate of stage c). Raw images: Images taken by optical microscopy are given in the folder rawImages. These are synchronized with the pressure measurements found in the log files from QMixElements, which is realized by the following naming convention of each image: Exp[Nr.]_[timestamp in sec]. The timestamp in seconds corresponds to the time in the log file. While in Experiment 1 and 2 images were captured at 0.1 frames per second (fps), in Experiment 3 the frame rate was set to 1 fps. In Experiment 3 some images got dumped during the recording. The physical resolution of the images are: 3.34 μm/pixel (Experiment 1), 3.36 μm/pixel (Experiment 2) and 3.17 μm/pixel (Experiment 3). These were calculated based on the known length of the domain divided by the number of pixels. Segmented images: The segmented images are saved in the folder processedImages. Not all of the raw images were processed: The first processed image has the timestamp of 420 seconds and corresponds to the time when the continuous injection of the reactant solution started. One image every five minutes were processed. These images were also flipped vertically compared to the raw images.