Study of CO2 properties and transportation for injection well into reservoir

Abstract

One of the possible solutions to reduce CO2 emission in atmosphere is to inject for storage in reservoir. This action is known as the residual gas geological storage project. One of the important aspects in this project is the transportation of CO2. CO2 needs to be transported from the place where it is captured or extracted into reservoir. In this work,our concern is transportation from wellhead to reservoir. When planning the CO2 injection in an injection well, TOTAL MGR-team found that there is error about 15% in pressure profile calculated using oil and gas commercial software. This work is inspired by TOTAL experts in this area. The work done here is to expand understanding on CO2 behavior when injected. We start our work from finding CO2 properties as the function of pressure and temperature from some correlations and methods. The accuracy of the results of each correlation/method is analyzed by comparing them and also with some other known software such us ALLPROPS and PVTSIM. The relative error from the comparison is then used as the indicator of selecting the “right” correlation/method to be used in pressure and temperature profile calculation. This is followed by calculation of pressure and temperature profile along tubing for injection process. The work here is only limited to Adiabatic injection process (i.e. no heat in/out to/from the injection fluid) and one diameter straight vertical tubing. The flow condition studied are Steady State and Unsteady State/Transient flow. Hypothetical injection parameters are made as the base case for the analysis. For Steady State flow, several scenarios such as: Static pressure, Isenthalpy process, Unisenthalpy-friction approach, and Unisenthalpy-constant internal energy are proposed and analyzed to get depth understanding of the injection process and its relation to the fluid properties and injection parameters. A cross check is also done with some commercial software (IPM-PROSPER and UNISIM). To observe the effect of injection parameters to the behavior of pressure and temperature profiles along tubing, sensitivity analyses are investigated and the results are discussed and analyzed. For unsteady state/transient period, we proposed some scenarios for special injection cases such as: Isothermal filling and Linearity approach. Those approaches are aim to give rough approximation of transient pressure and temperature along the pipe. However, it seems interesting to continue this work that explores different approaches. All the calculations above are done with the help of programs made in MATLAB. Some examples of program code are given in appendix.