After winning an Alexander von Humboldt fellowship by Dr. Sadeghnejad, the collaboration of PermLab with the Institut für Geowissenschaften at the Johannes Gutenberg University of Mainz (JGU), Germany has been finally started in early 2020.
The idea of this research collaboration is to define several joint MSc and Ph.D. theses and dissertations on Digital Core Analysis and Deep Learning applications in petroleum engineering and publishing joint papers. One cosupervisor/advisor will be assigned to theses and dissertations from both sides and PermLab’s members will access the HPC infrastructure of JGU during this period.
Nader Faramarzi could defend his MSc thesis with a successful grade. Also, he could recently publish his findings in the “Journal of Natural gas Science & Engineering“. Congrats Nader for his achievements and wish him the best.
The response of gas condensate reservoirs is directly influenced by heterogeneity. In such reservoirs, condensate is created around wellbore areas, when the reservoir pressure falls below the dew point pressure. Consequently, the distribution of this condensate bank makes fluid flow in the reservoir even more complicated by changing rock-fluid properties (e.g., relative permeability). This alteration can be assumed as a new heterogeneity, called fluid heterogeneity.
The separation of fluid heterogeneity from rock heterogeneity is a challenging task. The main idea of this study was to investigate the transient pressure responses of a gas condensate reservoir to separate rock and fluid heterogeneities. Different homogeneous and heterogeneous reservoir models of a reservoir were constructed by the geostatistical approach. A commercial reservoir simulator was used to simulate the behavior of different drawdown and buildup scenarios. The fluid was a lean gas condensate selected from one of the Middle East formations. The wavelet transform (WT) approach was implemented to characterize the behavior of condensate banks for both homogeneous and heterogeneous models.
Analyzing the wavelet approximate and detail coefficients of the pressure-transient responses enabled us to distinguish the rock and fluid heterogeneities. The results showed that the wavelet detail coefficient could be a good indicator of reservoir heterogeneity. Moreover, the WT could be successfully used to distinguish different regions of a condensate bank inside the reservoir under study.
Alireza Teimory during his MSc. thesis could design and manufacture a transparent micro model to study reactive flow in porous media. Congrats Alireza for his success. The cell of this study has two characteristics. First, it enables us to work on a real rock sample to investigate geochemical reactions by incorporating actual rocks. Second, it provides a visual observation capability to monitor the behavior of fluid injection into rocks. The transparent cell consists of two transparent Plexiglass plates. A square pocket was precisely machined at the center of the bottom plate to provide a holder for a slabbed rock to be installed in the cell. Bolts and nuts were used to stitch both plates together. An opaque silicon rubber O-ring was used between the plates to prevent any fluid leakage during the experiments. The designed cell was hydraulically tested up to 120 psi before the main experiments.
In the first application, we implemented the manufactured setup to investigate weak acid injection on fracture opening in calcite and dolomite reservoirs. The results were published in the “Petroleum Research” Journal.
In the second study, we investigated acid pre-flushing and pH-sensitive microgel injection in fractured carbonate rocks for conformance control purposes. First, the dependency of fracture aperture changes to the acid pre-flush flow rate was examined. Then, we investigated the effect of pH-sensitive microgel concentration on its resistance to block fractures during post-water flooding by studying the gel failure mechanisms (e.g., adhesive separation, cohesive failure). Finally, the effect of an initial aperture of fracture was examined on microgel washout when water injection is resumed. The results showed that both decreasing the acid flow rate and lowering the initial aperture could increase the rate of aperture changes. Moreover, the microgel solution with a concentration of 1 wt.% showed the highest resistance (98.2 psi/ft) against post-water injection. Additionally, this microgel concentration had the highest permeability reduction factor. Meanwhile, the smaller initial aperture of fracture contributed to a higher microgel resistance. The results were published in “Oil & Gas Science and Technology – Rev. IFP Energies Nouvelles“.
Permlab wishes Alireza the best in the next phase of his life.