Rock Property Inversion in Organic-Rich Shale: Uncertainties, Ambiguities, and Pitfalls

Bandyopadhyay, Kaushik; Sain, Ratnanabha; Liu, Enru; Harris, Chris; Martinez, Alex; Payne, Michael A.; Zhu, Yongmei

doi:10.1190/segam2012-0932.1

Cited by 22 publications

(5 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hu et al (2015) map organic richness of the Eagle Ford Shale from inversion data of acoustic impedance and shear impedance combined, based on rock-physics models. Bandyopadhyay et al (2012) demonstrate the ambiguities and uncertainties when characterizing organicrich shales, and they also include V P /V S and anisotropy to better quantify TOC from rock-physics models. Qin et al (2014) investigate the effect of maturation on the rock-physics properties of organic-rich shales.…”

Section: Introductionmentioning

confidence: 97%

Rock-physics analysis of clay-rich source rocks on the Norwegian Shelf

Avseth¹,

Carcione

2015

The Leading Edge

View full text Add to dashboard Cite

Rock-physics trends and properties of clay-rich source rocks are investigated in selected wells in the North Sea and Norwegian Sea. Properties can vary significantly because of burial compaction, composition, diagenesis, organic richness, and maturation. The many competing effects can be difficult to disentangle in traditional rock-physics crossplots. However, nearly all the sourcerock data in the study are bounded nicely by linear trends that are based on rock-physics models, in acoustic-impedance (AI) versus shear-impedance (SI) crossplots. These reference models serve as a nice screening tool for organic richness and/or maturation level (i.e., hydrocarbon generation and expulsion), regardless of burial depth. The use of rock-physics templates for the early mature to mature stage of clay-rich source rocks is demonstrated by combining a simple basin-modeling approach with a rock-physics model using Backus average in which the organic-rich shale is represented by a transverse isotropic mixture of clays, kerogen, and hydrocarbons. The resulting templates are bounded nicely by reference trends and explain some of the observed trends in the data. However, the local presence of carbonaceous material and diagenesis within the source rock, which have not been accounted for in the rock-physics modeling, might explain why some of the data points have higher impedances and lower V P /V S than the template models. Finally, source rocks with hydrocarbon saturation can cause AVO signatures similar to hydrocarbon-filled sands and therefore represent false positives in exploration.

show abstract

Section: Introductionmentioning

confidence: 97%

Rock-physics analysis of clay-rich source rocks on the Norwegian Shelf

Avseth¹,

Carcione

2015

The Leading Edge

View full text Add to dashboard Cite

show abstract

“…Problems related to the non-uniqueness of rock property inversion for organic rich shales are also highlighted in Bandyopadhyay et al (2012), who show how incorporating V p /V s in addition to AI reduces error (ambiguity due to combinations of clay volume, TOC and porosity) and produces better constrained results. Therefore, we investigate if incorporating additional seismic properties will result in equivalent or better TOC prediction, and potential for evaluating maturity and hydrocarbon presence.…”

Section: Variation In Acoustic Impedance and The Link To Rock Propertiesmentioning

confidence: 99%

Organic content and maturation effects on elastic properties of source rock shales in the Central North Sea

2019

View full text Add to dashboard Cite

We have investigated the effects of organic content and maturation on the elastic properties of source rock shales, mainly through integration of a well-log database from the Central North Sea and associated geochemical data. Our aim is to improve the understanding of how seismic properties change in source rock shales due to geologic variations and how these might manifest on seismic data in deeper, undrilled parts of basins in the area. The Tau and Draupne Formations (Kimmeridge shale equivalents) in immature to early mature stages exhibit variation mainly related to compaction and total organic carbon (TOC) content. We assess the link between depth, acoustic impedance (AI), and TOC in this setting, and we express it as an empirical relation for TOC prediction. In addition, where S-wave information is available, we combine two seismic properties and infer rock-physics trends for semiquantitative prediction of TOC from [Formula: see text] and AI. Furthermore, data from one reference well penetrating mature source rock in the southern Viking Graben indicate that a notable hydrocarbon effect can be observed as an addition to the inherently low kerogen-related velocity and density. Published Kimmeridge shale ultrasonic measurements from 3.85 to 4.02 km depth closely coincide with well-log measurements in the mature shale, indicating that upscaled log data are reasonably capturing variations in the actual rock properties. Amplitude variation with offset inversion attributes should in theory be interpreted successively in terms of compaction, TOC, and maturation with associated generation of hydrocarbons. Our compaction-consistent decomposition of these effects can be of aid in such interpretations.

show abstract

“…The enormous energy demands throughout the world can be met by getting such fuel from unconventional sources. Shale is the most prevalent type of clastic sedimentary rock on earth which is primarily composed of fine-grained particle created by compacting clay and silt. − Shale rocks have the dual capability of serving as both reservoirs and sources of rock. As shale has low to ultralow permeability, generally at the nanoscale, and low porosity, it limits the extraction of oil and gas using conventional methods. ,− To overcome these challenges, horizontal drilling followed by the multistage hydraulic fracturing have become the primary technologies for developing shale gas reservoirs. − Notably, the advancements in horizontal drilling and multistage hydraulic fracturing have had a significant impact on the U.S. natural gas and energy markets, leading to remarkable success in shale gas production. − …”

Section: Introductionmentioning

confidence: 99%

Supercritical Carbon Dioxide Utilization for Hydraulic Fracturing of Shale Reservoir, and Geo-Storage: A Review

Gupta,

Verma

2023

Energy Fuels

View full text Add to dashboard Cite

Hydraulic fracturing has completely revolutionized how shale resources are exploited to extracthydrocarbons. However, sustainability and environmental issues have fueled the desire for alternate fracturing technologies. Supercritical carbon dioxide (Sc-CO2) fracturing is a new method that uses high-pressure, high-temperature CO2 in its supercritical state (7.38 MPa and 31.1 °C) to generate fractures in shale formations, thereby increasing reservoir permeability. This Review thoroughly analyzes the effects of Sc-CO2 on shale reservoirs during the fracturing process, including the factors that affect fracture breakdown pressure and the complexity and roughness of fracture induced by Sc-CO2. Sc-CO2 can fracture rock at a fracturing pressure lower than that of slick water. CO2, in its supercritical state, shows strong permeability, low viscosity, and extremely low surface tension, like gas, because of which it can infiltrate any space larger than its kinetic diameter (0.330 nm). Many research investigations illustrate how Sc-CO2 affects shales with diverse pore structures, mineral compositions, and mechanical properties when exposed to Sc-CO2 for several hours to days. It is challenging to effectively store CO2 in shale gas reservoirs due to their low permeability and limited storage capacity. To improve the effectiveness of CO2 storage, shale can be fractured to increase the pore space and surface area in reservoirs. Thereby, a certain amount of the CO2 pumped for shale gas production can be securely stored in shale formations, reducing carbon emissions and allowing for a zero-carbon footprint. This paper discusses the pathway and different chemical reactions involved in the storage of CO2 after fracturing over a period. However, fully understanding the interactions between Sc-CO2 and shale rock and the possibility of long-term storage of CO2 in shale formations is quite challenging. It is because of a lack of research and limited knowledge in the above field. Hence, more investigation and development are required in the research area of Sc-CO2 fracturing and the interaction of CO2 with shale rock.

show abstract

Rock Property Inversion in Organic-Rich Shale: Uncertainties, Ambiguities, and Pitfalls

Cited by 22 publications

References 8 publications

Rock-physics analysis of clay-rich source rocks on the Norwegian Shelf

Rock-physics analysis of clay-rich source rocks on the Norwegian Shelf

Organic content and maturation effects on elastic properties of source rock shales in the Central North Sea

Supercritical Carbon Dioxide Utilization for Hydraulic Fracturing of Shale Reservoir, and Geo-Storage: A Review

Contact Info

Product

Resources

About