Investigation of Back Pressure Effects on Transient Gas Flow Through Porous Media via Laboratory Experiments and Numerical Simulation

Liu, X. , Limpasurat, A., Falcone, G. and Teodoriu, C. (2014) Investigation of Back Pressure Effects on Transient Gas Flow Through Porous Media via Laboratory Experiments and Numerical Simulation. In: ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering, San Francisco, CA., 8-13 June 2014, V005T11A030. ISBN 9780791845455 (doi: 10.1115/OMAE2014-24648)

Abstract

When developing a transient numerical reservoir simulator, it is important to consider the back pressure effects that waves propagating from one end of the porous medium will have on the temporal distribution of pore fluid pressure within the medium itself. Such waves can be triggered by changing boundary conditions at the interface between reservoir and wellbore. An example is given by the transient reservoir response following pressure fluctuations at the wellbore boundary for gas wells suffering from liquid loading. Laboratory experiments were performed using a modified Hassler cell to mimic the effect of varying downhole pressure on gas flow in the near-wellbore region of a reservoir. Gauges were attached along a sandstone core to monitor the pressure profile. The results of the experiments are shown in this paper. A numerical code for modelling transient flow in the near-wellbore region was run to mimic the experiments. The comparisons of simulations and laboratory test results are presented here, for the initial and final steady-state flowing conditions, and where the inlet pressure was maintained constant while initiating a transient pressure build up at the core outlet. The concept of the U-shaped pressure profile along the near-wellbore region of a reservoir under transient flow conditions, originally proposed by Zhang et al. [1], was experimentally and numerically reproduced for single-phase gas flow. This is due to a combination of inertia and compressibility effects, leading to the reservoir response not being instantaneous. The results suggest that, in two phase gas-liquid conditions, liquid re-injection could occur during liquid loading in gas wells. From the experimental results, the U-shaped curves were more obvious and of longer duration in the case of greater outlet pressure. The transition from the initial to the final steady state condition occurred rapidly in all the cases shown here, with the U-shaped pressure profile appearing only over a relatively short time (at the small scale and low pressures tested in this study).

• Item Type: Conference Proceedings
• Additional Information: The authors would like to thank the sponsors of the Joint Industry Project on “Liquid Loading in the Operation of Gas Fields: Mechanisms, Prediction and Reservoir Response” and RWE Dea for supporting this work.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Falcone, Professor Gioia and Liu, Dr Xiaolei
• Authors: Liu, X., Limpasurat, A., Falcone, G., and Teodoriu, C.
• College/School: College of Science and Engineering > School of Engineering > Systems Power and Energy
• ISBN: 9780791845455