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Experimental study on hydraulic fracturing properties of elliptical boreholes
Abstract Subsurface rocks are in the in situ stress state prior to drilling. The original and intact borehole subjected to stress redistribution can be deformed during field operations, and elliptical boreholes will be generated. Most laboratory scale hydraulic fracturing experimental specimens were predrilled in the center without considering lateral and axial pressure. In order to investigate the hydraulic fracturing characteristics of boreholes with non-circular appearance commonly seen in the field, hydraulic fracturing experiments were performed on boreholes with elliptical morphology. These experiments provide a comparison of elliptical and circular boreholes, and indicated that the horizontal in situ stress difference and borehole shape affect the breakdown pressure together. When the horizontal stress difference exists, the breakdown pressure reduces with the increase of the short-axis of elliptical boreholes. At zero horizontal stress difference, the situation is just the opposite. The analytic solutions of the stress fields near the elliptical borehole were obtained by employing the complex variable function. The fracture initiation conforms to the maximum tensile stress criterion. Whether the borehole is elliptical or circular, the damage process during hydraulic fracturing will cause fractures to eventually curve to the major stress direction.
Experimental study on hydraulic fracturing properties of elliptical boreholes
Abstract Subsurface rocks are in the in situ stress state prior to drilling. The original and intact borehole subjected to stress redistribution can be deformed during field operations, and elliptical boreholes will be generated. Most laboratory scale hydraulic fracturing experimental specimens were predrilled in the center without considering lateral and axial pressure. In order to investigate the hydraulic fracturing characteristics of boreholes with non-circular appearance commonly seen in the field, hydraulic fracturing experiments were performed on boreholes with elliptical morphology. These experiments provide a comparison of elliptical and circular boreholes, and indicated that the horizontal in situ stress difference and borehole shape affect the breakdown pressure together. When the horizontal stress difference exists, the breakdown pressure reduces with the increase of the short-axis of elliptical boreholes. At zero horizontal stress difference, the situation is just the opposite. The analytic solutions of the stress fields near the elliptical borehole were obtained by employing the complex variable function. The fracture initiation conforms to the maximum tensile stress criterion. Whether the borehole is elliptical or circular, the damage process during hydraulic fracturing will cause fractures to eventually curve to the major stress direction.
Experimental study on hydraulic fracturing properties of elliptical boreholes
Liu, Chao (author) / Zhang, Dongming (author) / Zhao, Honggang (author) / Li, Minghui (author) / Song, Zhenlong (author)
2021
Article (Journal)
Electronic Resource
English
BKL:
56.00$jBauwesen: Allgemeines
/
38.58
Geomechanik
/
38.58$jGeomechanik
/
56.20
Ingenieurgeologie, Bodenmechanik
/
56.00
Bauwesen: Allgemeines
/
56.20$jIngenieurgeologie$jBodenmechanik
RVK:
ELIB18
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Evaluation of hydraulic fracturing efficiency according to data on uninterrupted study of boreholes
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Mechanics of rock fracturing around boreholes
| British Library Conference Proceedings | 1998