A Laboratory Investigation of the Effect of Bedding Plane Inclination Angle on Hydro-Fracturing Breakdown Pressure in Stratified Rocks


In this paper, the effect of layer inclination, thickness and physical and mechanical properties of layers on hydraulic breakdown pressure was investigated. To achieve this aim, the model materials composed of kaolinite, cement and water in distinct ratios were used to simulate the laminated blocks like sandstone-shale and limestone-shale interbedded rocks. The fabricated rock blocks were drilled at different dip angles of 0⁰, 30⁰, 45⁰, 60⁰ and 90⁰ with respect to their bedding planes. The prepared laminated cylindrical samples are 54 mm in diameter and 108 mm in length. Then, these specimens were drilled in the center to prepare the hollow cylinder samples. The prepared specimens have two different layer thicknesses designated as low-thickness (t = 1cm) and high-thickness (t=2cm). The laboratory scaled hydraulic fracturing test was performed on thick-walled cylinder samples with different layer thicknesses and bedding plane inclination angles. The results of the study indicated the breakdown pressure is reduced for bedding plane angles ranging from 0⁰ to 45⁰ and increased for bedding plane angles 45⁰ to 90⁰. The minimum breakdown pressure occurred at inclination angle of 45◦. This phenomenon can be expressed as the anisotropy effect on the hydraulic fracturing breakdown pressure.

Meeting Name

53rd U.S. Rock Mechanics/Geomechanics Symposium (2019: Jun. 23-26, Brooklyn, NY)


Mining Engineering

Keywords and Phrases

Cylinders (Shapes); Fracture; Hydraulic Fracturing; Infill Drilling; Kaolinite; Lime; Rock Mechanics; Shale, Anisotropy Effect; Breakdown Pressure; Cylindrical Samples; Hydro-Fracturing; Inclination Angles; Laboratory Investigations; Physical and Mechanical Properties; Thick Walled Cylinders, Pressure Effects

Document Type

Article - Conference proceedings

Document Version


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© 2019 American Rock Mechanics Association (ARMA), All rights reserved.

Publication Date

01 Jun 2019