Types, characteristics and effects of natural fluid pressure fractures in shale: A case study of the Paleogene strata in Eastern China

Ma, Cunfei; Dong, Chunmei; Luan, Guoqiang; Lin, Chengyan; Liu, Xiaocen; Elsworth, Derek

doi:10.1016/s1876-3804(16)30074-x

Cited by 28 publications

(11 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…7A), so small differences in A and B may be exacerbated. The veinlets are similar in shape to many wing cracks formed by fluid expulsion (e.g., Mutlu and Pollard, 2008;Kobchenko et al, 2014;Ma et al, 2016) and modeled by Willemse and Pollard (1998), Lee et al (2016), and others. This suggests that fluid overpressure during compaction (vertical uniaxial stress) and diagenesis may have been sufficient to fracture already cemented shale, and that the fluids were probably internally sourced.…”

Section: Veinlet Heterogeneity and Possible Fracturing Mechanismsmentioning

confidence: 74%

The transition from planar to en echelon morphology in a single vein in shale: Insights from X-ray computed tomography scanning

et al. 2020

View full text Add to dashboard Cite

En echelon fractures and veins are among the most common and distinctive geological structures, yet their three-dimensional forms and relationships to surrounding structures are commonly unclear. X-ray computed tomography (CT) offers an unrivaled ability to examine structures within rocks in three dimensions, and it is applied here to a sample of drill core from the Marcellus Shale of southwestern Pennsylvania (USA). CT images yield qualitative and quantitative data on the transition from a pyrite-rich planar vein to an en echelon veinlet array, and on the heterogeneity of veinlets within the array. Using a combination of three- and two-dimensional images, geometric data, and traditional petrography, we identify a range of veinlet shapes consistent with deformation during formation of an antitaxial graphite-calcite-pyrite vein system. Each of the veinlets is rooted in the underlying planar vein where it is narrowest. The transition from planar vein to en echelon array coincides with a change in bedding, suggesting that competency contrasts between adjacent beds controlled the fracture morphology. Veinlets initiated as short, lenticular fractures at ∼45° to the planar vein before lengthening, dilating, and rotating. None of the veinlets are strongly sigmoidal, nor is there measurable offset across the margins of the planar vein; therefore, finite non-shear strain was very limited, and fluid overpressure–induced fracturing during burial and diagenesis is probably the most likely process for fracturing and vein formation.

show abstract

Section: Veinlet Heterogeneity and Possible Fracturing Mechanismsmentioning

confidence: 74%

The transition from planar to en echelon morphology in a single vein in shale: Insights from X-ray computed tomography scanning

et al. 2020

View full text Add to dashboard Cite

show abstract

“…These are the most commonly encountered structures in shales than in limestones in sedimentary basins around the globe (Chen, Steele‐MacInnis, Ge, Zhou, & Zhou, 2016; Cobbold, Zanella, Rodrigues, & Loseth, 2013). Previously, it was suggested that tectonics is responsible for the formation of fractures, in which the fibrous calcite veins are formed (e.g., Ma, Dong et al, 2016; M. Wang et al, 2018, 2020; Worden, Benshatwan, Potts, & Elgarmadi, 2015). While some authors argued that hydrocarbon generation is a key mechanism in the formation of fibrous sparry calcite (Cobbold et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Tracing forming mechanism of the sparry calcite growth in the lacustrine shale of east China: A glimpse into the role of organic matter in calcite transformation

et al. 2022

View full text Add to dashboard Cite

The formation of sparry calcite is very common in fine‐grained sedimentary rocks worldwide. Sparry calcite is formed from the diagenetic calcite crystals having a grain size > 50 μm. It is also widely distributed in the Es3x shale of the Eocene Shahejie Formation in the Zhanhua Depression, Bohai Bay Basin. The detailed investigations of the Es3x shale show that the sparite crystals start appearing at a burial depth > 3,000 m and the total organic carbon content (TOC) is >3 wt%. It indicates that the sparry calcite formed at high depths and in the most organic‐rich intervals of the studied shale. The presence of organic matter (OM) laminae parallel to the sparry calcite laminae, and sparry calcite along the edges of the OM show a direct physical relationship between sparry calcite and OM. It suggests that the diagenetic system was not influenced by hydrothermal fluids and only the OM is possibly responsible for the formation of sparry calcite in the studied shale. Sparry calcite forms in the thermally mature oil window, and oil generation in the Es3x shale causes the dissolution of micrite, providing the ions source for sparry calcite formation. Therefore, the geothermal gradient, as well as oil generation and kerogen maturation, are responsible for sparry calcite growth in the studied shale. The proposed model shows that the sparry calcite can form in the pores formed by elastic deformation as well as in the microfractures in the study area. In laminated shale, sparry calcite followed three stages of its formation, including (a) formation of laterally discrete calcite crystals, (b) lateral intergrowth of equant calcite crystals and (c) lateral intergrowth of fibrous calcite. Likewise, the genesis of sparry calcite in the non‐laminated shale also followed the same three phases; however, elastic deformation played a dominant and an important role in this variety of shale. Based on the detailed interpretations, we suggest that the OM, microfractures and elastic deformation act as major contributors in the formation and maturation of sparry calcite. We expect that this study also highlights the growth mechanism and maturation of sparry calcite in the Zhanhua Depression as well as other similar rift‐related basins around the globe.

show abstract

“…Bedding-parallel fibrous calcite veins are found in sedimentary rocks from Cambrian to Palaeogene strata in many locations worldwide (Cobbold and Rodrigues, 2007;Cobbold et al, 2013;Heindel et al, 2015;Kershaw and Guo, 2016;Ma et al, 2016;Cabral et al, 2019). Rocks hosting the veins are typically mixed siliciclastic-carbonate rocks, such as calcareous mudstones, argillaceous limestones and lime muds consistently rich in organic matter with low permeabilities (Franks, 1969;Cobbold and Rodrigues, 2007;Rodrigues et al, 2009;Cobbold et al, 2013;Heindel et al, 2015;Meng et al, 2017;Tribovillard et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

The Occurrence of Bedding-Parallel Fibrous Calcite Veins in Permian Siliciclastic and Carbonate Rocks in Central Thailand

et al. 2022

View full text Add to dashboard Cite

Bedding-parallel fibrous calcite veins crop out at two Permian carbonate localities in the Phetchabun area, central Thailand, within the Nam Duk and Khao Khwang Formations. Samples are studied to determine their petrographic, geochemical and isotopic character, depositional and diagenetic associations and controls on the formation of fibrous calcite across the region. Biomarker and non-biomarker parameters are used to interpret organic matter sources in the vein-hosting units, the depositional environment and levels of source rock maturation in order to evaluate source rock potential in the two Formations. Carbon and oxygen isotope values of the veins and the host are determined to discuss the source of carbonates and diagenetic conditions. The petroleum assessment from the Khao Khwang and Nam Duk Formations suggests that both Formations are a petroleum potential source rock with type II/III kerogen deposited in an estuarine environment or a shallow marine environment and a slope-to-basin marine environment or an open marine environment, respectively. The bedding-parallel fibrous calcite veins from the Khao Khwang and Nam Duk Formations are divided into two types: 1) beef and, 2) cone-in-cone veins. The carbon and oxygen isotope compositions from the fibrous calcite veins suggest that the calcite veins could be precipitated from a carbon source generated in the microbial methanogenic zone. The results in this study provide a better understanding of the interrelationship between the bedding-parallel fibrous calcite veins and petroleum source rock potential.

show abstract

Types, characteristics and effects of natural fluid pressure fractures in shale: A case study of the Paleogene strata in Eastern China

Cited by 28 publications

References 21 publications

The transition from planar to en echelon morphology in a single vein in shale: Insights from X-ray computed tomography scanning

The transition from planar to en echelon morphology in a single vein in shale: Insights from X-ray computed tomography scanning

Tracing forming mechanism of the sparry calcite growth in the lacustrine shale of east China: A glimpse into the role of organic matter in calcite transformation

The Occurrence of Bedding-Parallel Fibrous Calcite Veins in Permian Siliciclastic and Carbonate Rocks in Central Thailand

Contact Info

Product

Resources

About