Congrats Nader for his first publication

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