Combining Sonic Velocity and Characterization of Pore Architecture to Develop a Proxy for Reservoir Permeability in Unconventional Carbonates: An Example from the Mid-Continent Mississippian Limestone

Berg, Beth Vanden; Grammer, G. Michael

doi:10.15530/urtec-2014-1927131

Cited by 1 publication

(1 citation statement)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A combination of color and extinction behavior during rotation under cross-polarized light was used to segment the images into pore space and rock prior to calculate a variety of different geometrical parameters (see [9] for more details on this method). A variety of previous studies have shown that differences in pore geometry can be most adequately captured by the quantitative pore shape parameters perimeter over area (PoA) and dominant pore size (DomSize) [34,[39][40][41][42].…”

Section: Digital Image Analysismentioning

confidence: 99%

Significance of Sonic Velocities in Limestones and Dolostones: A Comprehensive Study Revealing Limited Impact of Mineralogy

Weger,

Baechle,

Shen

et al. 2024

Minerals

View full text Add to dashboard Cite

Seismic reflection data and implicitly sonic velocity are undoubtedly the most important source of information for large-scale subsurface characterization. Yet, deriving reservoir and fluid flow properties from acoustic data is still challenging in carbonates, which display large acoustic velocity variations that contest many of the conventional assumptions regarding wave propagation in porous media. In this comprehensive study on 370 carbonate samples (247 limestones and 123 dolomites), we re-evaluate the impact of mineral velocity on bulk rock acoustic properties of dolomite and limestone by assessing the link between sonic velocity and the rock’s pore geometry. We quantify pore size and pore network complexity using parameters from both digital image analysis (DIA) and the extended Biot theory (EBT). We then compare DIA and EBT parameters to assess the impact of pore network geometry versus mineral velocity on the acoustic velocity of carbonate rocks. We explore the usefulness of EBT parameter γk in improving permeability estimates. Published values of velocity indicate that dolomites exhibit higher velocities than limestones at any given porosity. Our laboratory measurements of acoustic velocity, however, reveal that both dolomites and limestones show extreme variations in sonic velocities where samples with compressional velocity of ~5000 m/s may range in porosity from 5% to 25% and samples with porosity of ~20% may range in velocity from ~4000 m/s to 5700 m/s. Through the quantitative assessment of the pore network in our samples we document that pore network geometry has much more impact on the acoustic velocity of carbonates than variations in mineralogy, in this case dolomite and calcite. Most of the dolostone samples studied are dominated by small pores, resulting in relatively low velocities for their given porosity, while limestones with similar velocity–porosity values often possess simpler pore networks with larger pores. This pore size difference offsets the faster velocity of dolomite. The extended Biot theory parameter γk, captures this variation in pore size and internal geometry and exhibits a strong correlation to specific surface. Moreover, γk captures the impact of internal pore geometry on acoustic velocity, providing the basis for challenging existing assumptions regarding the importance of mineral velocity. By quantifying internal geometry, γk can improve permeability estimates in reservoir characterization and enhance evaluations of producibility and injectability. With that, it has direct implications on general geophysics, hydrocarbon exploration, and CCS initiatives.

show abstract