InterPore2025

Large-Scale Porous Systems and Their Controls on Permeability in Pre-salt Karstified Reservoirs

22 May 2025, 10:05

15m

Oral Presentation (MS09) Pore-scale modelling MS09

Speaker

Ms Candida Menezes De Jesus (Heriot-Watt University)

Description

Large-scale pore systems in karstified carbonate reservoirs impact the efficiency of several processes, from drilling and completion to flow modeling and history matching. Despite the efforts to use the full potential of the available well data and integrate it with drill stem test data (DST), predicting the permeability of such reservoirs continues to be challenging.

One of the main difficulties is that the pore network in a karstified reservoir can comprise geometric elements of different sizes, generating heterogeneities
that impact reservoir productivity. Characterizing these elements is complex, since their representative elementary volume may reside on intermediate scales between rock samples, well logs, and seismic data. Therefore, it is still a technological challenge to measure the full extent of those structures with the available subsurface data.

This raises several questions regarding the key elements that govern system connectivity and the methodologies required for their characterization. A network of vuggy conduits likely plays a significant part in this connectivity; however, microfractures may also be present and have a relevant role. Furthermore, high-permeability pathways are expected to influence the residual oil saturation following water injection. Additionally, it is necessary to assess whether the scale of the core data is adequate to address these uncertainties.

In this work, we will use absolute permeability tests of centimeter-scale karstified carbonate samples (whole cores) and tomographic images of these rocks to identify the connected porous elements that determine the connectivity of karstified rocks at the whole core scale. We intend to characterize the geometry of porous elements that overprint the original rock matrix to define upscaling parameters to evaluate the impact that those systems have on hydrocarbon recovery and CO${}_2$ trapping. Such a thorough characterization will enable the petrophysical models to be more robust, improving the predictability of the karstified reservoir behavior.