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Collaboration of PermLab with Johannes Gutenberg University of Mainz, Germany

Category : Achivements , Uncategorized

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.

Tarbiat Modares University - Tarbiat Modares University
Datei:Johannes Gutenberg-Universität Mainz logo.svg – Wikipedia

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.

More good news is underway…

Campus Mainz: Die Uni Mainz in Bildern - damals und heute

Congrats Nader for his first publication

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.

Fig. 1: Schematic of the condensate bank around a wellbore with three regions. In Region 3, there is only single-phase gas. In Region 2, gas and immobile condensate coexists. Region 1 contains both mobile condensate and gas phases.

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.

Fig. 2: Schematic of the DWT (i.e., applying high- and low-pass filters) on the pressure-transient data. Approximates and details are created at each level of WT as the outputs.

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.

Fig. 3: Detail WTC of pressure-transient responses for a) scenario 1 (Pres>Pdew) and b) scenario 2 (Pres=Pdew). Peaks I and II are related to shutting in and opening the well, respectively. Peaks A and B are because of condensate bank creation during the buildup test. Peaks A’ and B’ appear as a result of the condensate bank during the drawdown test

Designing transparent rock micromodel in Permlab for reaction flow studies

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.

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Matrix acidizing of sandstones

Hossein Younesian-Farid published his 2nd paper in the JPSE.  In this study, the interaction of citric acid, as a weak acid, with a sandstone core containing ankerite cement was investigated during matrix acidizing. The model, developed in Python, implemented a global implicit numerical approach to consider acid-rock geochemical interactions. The effect of multi-step dissociation of citric acid on lowering rock pH was investigated. The sugar-lump approach was used to estimate the behavior of the ions concentration originated from the variation of the reactive surface area (RSA). Moreover, the model outputs were validated against matrix sandstone acidizing experiments from the literature.

The concentration of non-ionized acetic acid across the core during the injection of citric acid.

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Speed-up of Soxhlet Core Cleaning in RCAL

Pouya Soltani has published his first paper at PermLab in the SPE Reservoir Evaluation & Engineering Journal. The main idea of this paper is to introduce a methodology of measuring the cleaning time that can be implemented as a routine screening tool in RCAL projects to nominate the proper solvent, which can reduce the Soxhlet cleaning time.

The process of running core analysis experiments (in both RCAL and SCAL) is very time-consuming. As all plug samples should be cleaned during the RCAL phase; therefore, finding of a solvent that can speed-up this process is necessary. The cleanliness of a core sample during Soxhlet extraction is usually determined by monitoring the color of solvents, qualitatively. The main contribution of this study was to propose a methodology during RCAL to nominate the best solvent during the Soxhlet cleaning experiments. By introducing a state-of-the-art quantitative method, the cleaning time of different solvents (i.e., tetrachloroethene, acetone, toluene, chloroform, xylene, and n-hexane) was investigated. This quantitative method is based on turbidity measurement of the solvent that siphons periodically from the Soxhlet extractor. Moreover, the wettability alteration of the implemented solvents was monitored by contact angle measurements.

Designed Soxhlet setup. a) Heater, b) Round-bottom flask, c) Two-neck extractor, d) Condenser, e) Sampling Syringe. The solvent samples are taken from part e by a needle syringe.

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Collaboration between PermLab and PMEAL

Category : Achivements , Uncategorized

The close collaboration between PermLab at Tarbiat Modares University and PMEAL at the University of Waterloo is continuing. By assigning joint-supervisors for the PermLab members, this collaboration is being expanded. At PermLab, our area of interest is characterizing carbonate reservoirs at pore-scale using OpenPNM, an open-source software package developed by PMEAL under the leadership of Prof. Jeff. Gostick at the University of Waterloo.

Recently, a new joint paper was accepted in theSPE Journal and we hope for more new outputs from this collaboration in the next future. This paper deals with reconstruction of vuggy carbonates by pore network modeling and image-based technique. The source code of this code can be downloaded from here.

Farhoodi did great in JNGSE

Shahab Farhoodi, did great and published a very good paper (here) in Journal of Natural Gas Science & Engineering (JNGSE). We in this study payed attention to the analysis of the combined effect of geological heterogeneity and condensate drop out in condensate reservcoirs. A geostatistical approach was used to build reservoir models with different amount of heterogeneity. These models were simulated by a compositional reservoir simulator to generate pseudo-pressure data versus time of these heterogeneous models.

Condensate saturation, Scond, and pressure profile versus the radius from the wellbore, r, for a gas condensate reservoir. Different flow regimes are depicted during the production.

It was revealed that the intensity of the condensate formation around the wellbore is a strong function of the reservoir heterogeneity. The results showed that increasing of the model heterogeneity can entirely complicate the well-test responses when condensate drops near the wellbore region.

Bottomhole pressure and rate history of 10 days. The flowing and shut-in period is one day each.

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Azimi published her 1st paper in PermLab

Category : Uncategorized

Congrates Zahra Azimi for her first publication in PermLab team. Zahra investigated  cross-linked polymer gels as a temporary plugging agent to control the leakage of fluid during drilling, completion, and workover operations. In this study, various concentrations and size of silica nanoparticles are introduced into the sulfonated polyacrylamide (SPAM)/chromium (III) acetate system to produce a nanocomposite with enhanced mechanical properties. First, the rheological behavior of gelant and viscoelastic properties of synthesized nanocomposites are investigated. Then, the surface chemistry and morphology of the synthesized gels is evaluated by Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM), respectively. Finally, the maximum sealing differential pressure for gels for temporary plugging of a wellbore is measured by applying differential pressure across the nanocomposite gel in a designed set-up. The results showed that the precrosslinking reaction and the gelant viscosity are directly related to the size and concentration of the silica nanoparticles as well as the wellbore temperature. Moreover, it is demonstrated that nanocomposites containing 20-30 nm sized particles have a higher mechanical strength and plugging capability in comparison to composites containing silica particles with sizes of 7-10 nm and 60-70 nm.


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Modeling reaction flow in porous media

Category : Uncategorized

Congratulations to Hossein Younesian-Farid, Msc student of petroleum engineering, for his recently published work about reaction flow of pH-sensitive polymer flooding in Petroleum Science & Engineering.


In this study, he developed a mathematical model to predict the acid pre-flush behavior before pH-triggered polymer flooding. Convection, diffusion, and homogeneous/heterogeneous geochemical reactions for a slightly compressible fluid flow in porous media was formulated.  The introduced model was validated against the experimental data. He simulated the injection of several acids (strong and weak acids) into a carbonate rock under different flow conditions (i.e., different Damkohler numbers). The obtained pH values reveal that weak acids can provide better results for acid pre-flushing in carbonate formations.

Figure: Different steps of pH-triggered polymer flooding. a) Water breakthrough during conventional water flooding process because of its flowing through high permeability areas; b) acid pre-flush in order to decrease the pH of the high permeable areas; c) Injection of pH-triggered polymer that has low viscosity in an acidic environment; d) Post water flooding with the  higher sweep efficiency in comparison to (a).