ABSTRACT
Collection of data during an experiment is sometimes tedious and can even be close to impossible. When performing a displacement study, several variables are often monitored with time. Some of these monitored variables might include injection pressure, core pressure or temperature, or water-oil ratio. These data points may need to be collected at specific times, at high rates, or at odd intervals. To simplify the data collection process, an economical data acquisition system was designed. The proposed system monitors any or all of the above variables as per the experimenter's specifications of time and frequency.
The data acquisition system described in this paper was designed to operate on any IBM-PC* or close compatible computer environment. The programs comprising the data collection part of the system are general enough such that only the transducer type and constants need to be known. Therefore, any pressure transducer or any thermistor can be used. This approach allows the system to be used for more than just displacement studies. Once an experiment is started, the experimenter has access to all data collected as either graphs or lists. This availability facilitates the detection of trends and/or problems.
The proposed data acquisition system has been tested and used successfully in various experimental environments. Discussion and data are provided for three specific experiments to highlight the unique aspects of the system designed. First, the effect of steep temperature gradients on two-phase relative permeability characteristics was investigated using this system. Both pressure and temperature variations along the core were measured and recorded as functions of time.
Next, the system was used to measure the rate of propa-gation of a pressure pulse through a slim tube. This pressure pulse rate was then used to calculate the permeability in a tight sand column. Finally, the rate of mud filtrate invasion has also been monitored with this same system. All of these examples demonstrate the capabilities and versatility of the proposed data acquisition system.
