Unravelling the pore network and its behaviour: An integrated NMR, MICP, XCT and petrographical study of continental spring carbonates from the Ballık area, SW Turkey

Abstract

Applying an integrated methodology, including petrography, mercury injection capillary pressure, laboratory nuclear magnetic resonance and X‐ray computed tomography, on continental spring carbonate reservoir analogue samples is a prerequisite to understand plug scale porosity and permeability heterogeneities. Depending on the dominant pore type in a sample, the orientation and distribution of the pores, pore network connectivity varies from poor to excellent in these continental spring carbonates. The latter exhibit large‐scale ranges for both porosity (3%–25%) and permeability (0.004–3,675 mD). Facies classification alone proved insufficient to link porosity and permeability, due to intrafacies pore network variability. Better assessment of reservoir properties can be achieved by subdividing facies into lithotype and pore type classes. Obtained pore network data addresses the pore types, pore (throat) sizes, number of pore compartments, and allow a subdivision of the pore size distributions into unimodal, bimodal and atypical types. There is no micropore compartment present in samples with unimodal mercury injection capillary pressure and nuclear magnetic resonance distributions. Decoupled micropore compartments are observed in samples with bimodal mercury injection capillary pressure and nuclear magnetic resonance distributions, which show isolating calcite rims, and have limited permeabilities. The cement rims decrease the macropore connectivity and decouple the micropore compartments, which reside in micritic dendrites. The micropore compartment (r < 1 µm) is coupled with the mesopore (r = 1–15 µm) and macropore compartment (r > 15 µm) for atypical samples which lack pore‐lining calcite rims.

Pore Size Distribution Characterization by Joint Interpretation of MICP and NMR: A Case Study of Chang 7 Tight Sandstone in the Ordos Basin

“…Fluid flow in a porous media is mainly controlled by PSD, interfacial tension, and wettability [6,28,36]. For porous reservoirs, the interfacial tension and wettability changes would significantly affect oil migration and recovery [54][55][56][57].…”

“…This technique was widely used in the evaluation of various petroleum reservoirs, such as clastic rocks, carbonate rocks, and volcanic rocks, for nearly five decades [11,[22][23][24][25]. In recent years, it has become an indispensable tool for characterizing reservoir properties, such as PSD, porosity, permeability, wettability, fluid movability, and saturation, due to the nondestructive feature, convenience in sample processing, and short test time [6,[26][27][28][29].…”

Non‐marine carbonate: Wherefore art thou?

“…For instance, great attention has been addressed to their petrophysical properties and reservoir potential in consideration of recent South Atlantic subsurface hydrocarbon discoveries (Carminatti et al, 2008). In this view, the study by Soete et al (2021) concerns a travertine spring carbonate reservoir analogue applying petrophysical characteristics to understand plug scale porosity and permeability heterogeneities utilising an integrated methodology, including petrography, Mercury Injection Capillary Pressure, laboratory Nuclear Magnetic Resonance and X-ray Computed Tomography. Also the manuscript by Reijmer et al (2021) aims to determine variations in petrophysical properties within a Miocene mixed alluvial to lacustrine carbonate system (Madrid Basin, Central Spain) and highlights how travertine deposits are dominated by larger Equivalent Pore Aspect ratios compared to the lacustrine and full-marine carbonate deposits.…”

Estimating Permeability in a Limestone Geothermal Reservoir from Nmr Laboratory Experiments

“…Hence the standard NMR-porosity-T2 relationship should be carefully applied and/or calibrated with the testing of core samples. Once completed and an adequate understanding of the depositional environment and the geological context have been gained, it can be applied safely to other wells for which NMR logs are available (Duan et al, 2018;Moss, 2000;Müller-Huber et al, 2016Soete et al, 2021;Tian et al, 2018;Vincent et al, 2011). A previous study in which cores were recovered from a Paris Basin geothermal reservoir (Bathonian) dates from 1981 at the Aulnay-sous-Bois doublet (Giot and Rojas, 1981).…”