Fracture termination and step-over at bedding interfaces due to frictional slip and interface opening

Cooke, Michele L.; Underwood, Chad A.

doi:10.1016/s0191-8141(00)00092-4

Cited by 273 publications

(109 citation statements)

References 30 publications

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“…For example, some calcite veins in marly shale layers are offset (with very thin connections between the segments) at bedding contacts ( Figure 13B). Similar offsets can be observed for many joints ( Figure 13C; Helgeson and Aydin, 1991;Cooke and Underwood, 2001;Rijken and Cooke, 2001;Larsen et al, 2008). These and other field observations indicate that the arrest or, more generally, offset of hydrofractures at contacts in mechanically layered rocks is very common.…”

Section: Field Observations and Numerical Model On Hydrofracture Emplsupporting

confidence: 60%

“…Some fractures are also arrested by slip at contacts (interfaces). There is some field evidence for slickensides along bedding planes in sedimentary rocks (Renshaw and Pollard, 1994), and Cooke and Underwood (2001) propose that when slip occurs, crack-tip tensile stresses cannot be transmitted across the interface so that the tip becomes arrested.…”

Section: Field Observations and Numerical Model On Hydrofracture Emplmentioning

confidence: 99%

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Effects of mechanical layering on hydrofracture emplacement and fluid transport in reservoirs

2013

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Fractures generated by internal fluid pressure, for example, dykes, mineral veins, many joints and man-made hydraulic fractures, are referred to as hydrofractures. Together with shear fractures, they contribute significantly to the permeability of fluid reservoirs such as those of petroleum, geothermal water, and groundwater. Analytical and numerical models show that-in homogeneous host rocks-any significant overpressure in hydrofractures theoretically generates very high crack tip tensile stresses. Consequently, overpressured hydrofractures should propagate and help to form interconnected fracture systems that would then contribute to the permeability of fluid reservoirs. Field observations, however, show that in heterogeneous and anisotropic, e.g., layered, rocks many hydrofractures become arrested or offset at layer contacts and do not form vertically interconnected networks. The most important factors that contribute to hydrofracture arrest are discontinuities (including contacts), stiffness changes between layers, and stress barriers, where the local stress field is unfavorable to hydrofracture propagation. A necessary condition for a hydrofracture to propagate to the surface is that the stress field along its potential path is everywhere favorable to extension-fracture formation so that the probability of hydrofracture arrest is minimized. Mechanical layering and the resulting heterogeneous stress field largely control whether evolving hydrofractures become confined to single layers (stratabound fractures) or not (non-stratabound fractures) and, therefore, if a vertically interconnected fracture system forms. Non-stratabound hydrofractures may propagate through many layers and generate interconnected fracture systems. Such systems commonly reach the percolation threshold and largely control the overall permeability of the fluid reservoirs within which they develop.

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Section: Field Observations and Numerical Model On Hydrofracture Emplsupporting

confidence: 60%

Section: Field Observations and Numerical Model On Hydrofracture Emplmentioning

confidence: 99%

Effects of mechanical layering on hydrofracture emplacement and fluid transport in reservoirs

2013

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“…Reasons for fracture arrest are the weakness of the interface or the stiffness contrast between layers (e.g. Pollard and Aydin 1988;Helgeson and Aydin 1991;Cooke and Underwood 2001). Once again, however, there is a difference between both joint sets.…”

Section: Fracture Network Generationmentioning

confidence: 99%

Evaluation of the representative elementary volume (REV) of a fractured geothermal sandstone reservoir

2010

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The objective of this study is to evaluate a representative elementary volume (REV) in a fractured geothermal sandstone reservoir in Germany using the discrete fracture network (DFN) model approach. Due to the lack of in situ data from the deep geothermal reservoir, field measurements of outcrop reservoir analogues were conducted to get a quantitative description of the DFN. Field measurements reveal that the geometry of the DFN is largely influenced by the lithological layering (e.g. relationship between joint spacing and bed thickness). Thus, DFN models have to be completed individually for each layer since each bed is distinct compared to its neighbouring beds. Various DFNs were generated using statistical-derived fracture input data. The two-dimensional universal distinct element code UDEC was used for fracture flow simulations. In order to determine the minimum REV, the equivalent average conductivity tensors were obtained with increasing block size. Plots of conductivity tensor coefficients versus block size exhibit only minor variation of the hydraulic properties with increasing block size. Hence, an REV size of 10 m 9 10 m could be determined for all studied stochastically derived discrete fracture networks.

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“…또한 셰일저류층 내에 자연균열이 존재하는 경우 에는 이 자연균열 내 응력분포나 균열면의 마찰계수 등의 특성이 파쇄균열 전파에 상당한 영향을 미친다 [8]. 이에 자연균열과 파쇄균열 간의 상호작용에 대 해 실험 연구 [9][10][11]와 수치해석 연구가 폭넓게 진행 되어 왔다 [12][13][14].…”

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Modeling of Multi-Stage Hydraulic Fracture Propagation

장영호¹,

성원모²

2015

Journal of the Korean Institute of Gas

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-This paper presents a hydraulic fracture propagation model to describe propagation more realistically. In propagating the hydraulic fractures, we have used two criteria: maximum tangential stress to determine the fracture initiation angle and whether a hydraulic fracture intersects a natural fracture. The model was validated for the parameters relevant to fracture propagation, such as initiation angle and crossing ability through natural fracture. In order to check whether a hydraulic fracture crosses a natural fracture, the model results on crossing state excellently matched with the experimental data. In the sensitivity analysis for direction of maximum horizontal stress, frictional coefficient of fracture interface, and natural fracture orientation, the results show that hydraulic fracture intersects natural fracture, and then, propagated suitably with theoretical results according to fracture interaction criterion. In comparison of this model against vertical fracture approach, it was ascertained that there are discrepancies in fracture connectivity and stimulated reservoir volume.

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Fracture termination and step-over at bedding interfaces due to frictional slip and interface opening

Cited by 273 publications

References 30 publications

Effects of mechanical layering on hydrofracture emplacement and fluid transport in reservoirs

Effects of mechanical layering on hydrofracture emplacement and fluid transport in reservoirs

Evaluation of the representative elementary volume (REV) of a fractured geothermal sandstone reservoir

Modeling of Multi-Stage Hydraulic Fracture Propagation

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