Black Mudrocks: Lessons and Questions from the Mississippian Barnett Shale in the Southern Midcontinent

Ruppel, Stephen C.; Loucks, Robert G.; Furbish, David Jon

doi:10.2110/sedred.2008.2.4

Cited by 64 publications

(21 citation statements)

References 5 publications

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“…The single pore volume is not large, ranging from several nm to 300 -500 nm ( Figure 5a). Organic matter pores are irregular pores present within organic matter (Ruppel and Loucks, 2008;Loucks et al, 2009Loucks et al, , 2012Loucks and Reed, 2014). Inorganic mineral pores are mainly composed of inter-particle pores, charged with liquid petroleum during the oil generation stage.…”

Section: Organic Matter (Om) Pores Are the Main Reservoir Space For Smentioning

confidence: 99%

Shorten the Learning Curve Through Technological Innovation: A Case Study of the Fuling Shale Gas Discovery in Sichuan Basin, SW China

Jin¹,

Li²,

Hu³

et al. 2015

Unconventional Resources Technology Conference

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Based on a comparison of geological conditions for shale gas in China and those in America, combined with geological properties and surface conditions, we conclude that marine strata in south China having similar properties to those of America are targets for shale gas exploration, and the Sichuan Basin and its surrounding area is a favorable exploration area. Improved geological understanding and technological innovation are among the key factors that have helped Sinopec to shorten the learning curve in shale gas resource exploration and exploitation. After six years of research and exploration, the Fuling Shale Gasfield, which is the first major commercial shale gas play in China, was finally found in the Sichuan Basin in 2012 and successfully developed. Fuling Shale Gasfield is located in the Jiaoshiba structure, a broad box-shaped, faulted anticline. The shale gas producing layers are the Upper Ordovician Wufeng Fm. and Lower Silurian Longmaxi Fm. Comprehensive analysis of the shale gas reservoir indicates that organic matter content is the principal control on shale gas enrichment, the organic micropores are the main reservoir space, horizontal bedding fractures ensure horizontal seepage, and the high siliceous mineral content ensures good fracturing ability. Integration of those four properties in the Wufeng-Longmaxi shales is conducive to enrichment and exploitation of shale gas. The shale gas potential of the Wufeng-Longmaxi formations is mainly controlled by the original depositional environment which determines organic matter content and postdepositional conditions that promote shale preservation and gas retention within the shale after thermal maturation. Deposition and distribution of the shales are controlled by the platform depression environment, while thickness and high TOC content are the primary indicators for play evaluation. The late preservation conditions control the enrichment of shale gas, and the high pressure coefficient in the Sichuan Basin is the basis for evaluation of preservation conditions.

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Section: Organic Matter (Om) Pores Are the Main Reservoir Space For Smentioning

confidence: 99%

Shorten the Learning Curve Through Technological Innovation: A Case Study of the Fuling Shale Gas Discovery in Sichuan Basin, SW China

Jin¹,

Li²,

Hu³

et al. 2015

Unconventional Resources Technology Conference

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“…Reed & Loucks (2007) examined many samples of Barnett and Woodford Shale using SEMbased techniques, some on argon-ion-milled surfaces, in search of microfractures and/or pores, but they saw no evidence of an open microfracture network in these formations. Rather, gas storage is accommodated partly by micro-to nanosized pores (free gas) and partly by sorption of methane and other molecules in organic matter and clay particles (Ruppel & Loucks 2008;Ross & Bustin 2009). The mechanism by which free or sorbed gas can move from its storage location into a hydraulic fracture network remains a challenging problem.…”

Section: Open Microfracturesmentioning

confidence: 99%

Natural fractures in some US shales and their importance for gas production

Gale

Holder

2010

PGC

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Shale gas reservoirs are commonly produced using hydraulic fracture treatments. Microseismic monitoring of hydraulically induced fracture growth shows that hydraulic fractures sometimes propagate away from the present-day maximum horizontal stress direction. One likely cause is that natural opening-mode fractures, which are present in most mudrocks, act as weak planes that reactivate during hydraulic fracturing. Knowledge of the geometry and intensity of the natural fracture system and the likelihood of reactivation is therefore necessary for effective hydraulic fracture treatment design. Changing effective stress and concomitant diagenetic evolution of the host-rock controls fracture initiation and key fracture attributes such as intensity, spatial distribution, openness and strength. Thus, a linked structural-diagenesis approach is needed to predict the fracture types likely to be present, their key attributes and an assessment of whether they will impact hydraulic fracture treatments significantly. Steep (.758), narrow (,0.05 mm), calcite-sealed fractures are described in the Barnett Shale, north-central Texas, the Woodford Formation, west Texas and the New Albany Shale in the Illinois Basin. These fractures are weak because calcite cement grows mostly over non-carbonate grains and there is no crystal bond between cement and wall rock. In bending tests, samples containing natural fractures have half the tensile strength of those without and always break along the fracture plane. By contrast, samples with quartz-sealed fractures do not break along the fracture plane. The subcritical crack index of Barnett Shale is .100, indicating that the fractures are clustered. These fractures, especially where present in clusters, are likely to divert hydraulic fracture strands. Early, sealed, compacted fractures, fractures associated with deformation around concretions and sealed, bedding-parallel fractures also occur in many mudrocks but are unlikely to impact hydraulic fracture treatments significantly because they are not widely developed. There is no evidence of natural open microfractures in the samples studied.

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“…A significant number of studies have been carried out on TOC content, OM type and thermal maturity and their impacts on micropore structure distribution and related MSC of shales (Bust et al, 2012;Bustin, 2007, 2008a;Jarvie et al, 2007;Kang et al, 2010;Ruppel and Loucks, 2008;Schettler et al, 1991). For example, Chalmers and Bustin (2007) considered the TOC content as the primary controlling factor on the amount of methane sorption in shales, while the OM type and maturity play a secondary role.…”

Section: Introductionmentioning

confidence: 99%