Rock strength properties and their measurement

2017 ◽  
pp. 117-162
Author(s):  
Duncan C. Wyllie
Keyword(s):  
Rock Strength ◽  
Strength Properties

scholarly journals Rock strength properties of granitic rocks in Yosemite Valley, Yosemite National Park, California

Data Series ◽  
2020 ◽  
Author(s):  
Brian D. Collins ◽  
Federica Sandrone ◽  
Laurent Gastaldo ◽  
Greg M. Stock ◽  
Michel Jaboyedoff
Keyword(s):  
National Park ◽  
Rock Strength ◽  
Strength Properties ◽  
Granitic Rocks ◽  
Yosemite National Park ◽  
Yosemite Valley

scholarly journals Soil and rock strength parameters of the Shiraidake Landslide, Japan

2001 ◽  
Vol 23 ◽  
Author(s):  
Robert Jelinek ◽  
Prem Prasad Paudel ◽  
Hiroshi Omura
Keyword(s):  
Rock Strength ◽  
Sedimentary Rocks ◽  
Strength Properties ◽  
Triaxial Tests ◽  
Dry Density ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Strength Parameters ◽  
Consolidation Pressure ◽  
Early Tertiary

The Shiraidake area of northwest Kyushu has an extensive distribution of landslides. A series of undrained triaxial tests and unconfined compression tests were carried out to investigate the variation of strength properties in a selected borehole from the Shiraidake Landslide. It is a translational landslide (called the Hokusho-type in Japan) and is composed of the Early Tertiary and Quaternary sedimentary rocks that are prone to rapid weathering. Core rock samples and recompacted soil samples were used for the study. The results provided the fundamental characteristics of soil and rock under the triaxial and uniaxial tests, and indicated that the undrained behaviour of tested soils generally depends on the pre-shear consolidation pressure and dry density. In addition, the type of material used and the tests performed are important factors that influence the soil and rock strength.

scholarly journals The control of composition, texture and weathering on the physical and strength properties of selected intrusive igneous rocks from North Pakistan

2021 ◽  
Author(s):  
Muhammad Yasir ◽  
Waqas Ahmed ◽  
Muhammad Sajid
Keyword(s):  
Compressive Strength ◽  
Specific Gravity ◽  
Rock Strength ◽  
Grain Shape ◽  
Strength Properties ◽  
Igneous Rocks ◽  
Grain Sizes ◽  
North Pakistan ◽  
R Value ◽  
Weathering Grades

Abstract This work characterizes intrusive igneous rocks from north Pakistan in terms of their mineralogy, texture and weathering grades and their effect on the physical and strength properties. The mafic and intermediate rocks showed a low cumulative percentage of quartz, feldspar and plagioclase with high specific gravity, strength (i.e. UCS and R-value) and UPV values compared to the felsic rocks. Likewise, samples with anhedral grain shape, irregular boundaries, fine to medium grain size (UD, ANS, CGN) showed higher strength values, that is, 121, 118 and 91 MPa compressive strength and 11, 9, and 12 MPa tensile strengths, respectively. The weathering grades assigned to the investigated samples, such as fresh (WG-I), slightly weathered (WG-II) and highly weathered (WG-III) corresponded well with the physical and strength properties, that is, as the grade increased from WG-I to WG-III, the porosity and water absorption increased (0.28% and 0.72% respectively), whereas the specific gravity, compressive strength and tensile strength decreased (2.04, 20 MPa and 2.5 MPa, respectively, for CGA). The presence of quartz affects rock strength; however, no significant correlation was observed for strength and maximum and mean grain sizes of different minerals.

Wellbore Stability Beyond Mud Weight

2021 ◽  
Author(s):  
Khaqan Khan ◽  
Mohammad Altwaijri ◽  
Sajjad Ahmed
Keyword(s):  
Oil And Gas ◽  
Rock Strength ◽  
Tectonic Stress ◽  
Strength Properties ◽  
Wellbore Stability ◽  
Drilling Mud ◽  
Stress Regime ◽  
Drilling Parameters ◽  
Well Trajectory ◽  
Formation Pore Pressure

Abstract Drilling oil and gas wells with stable and good quality wellbores is essential to minimize drilling difficulties, acquire reliable openhole logs data, run completions and ensure well integrity during stimulation. Stress-induced compressive rock failure leading to enlarged wellbore is a common form of wellbore instability especially in tectonic stress regime. For a particular well trajectory, wellbore stability is generally considered a result of an interplay between drilling mud density (i.e., mud weight) and subsurface geomechanical parameters including in-situ earth stresses, formation pore pressure and rock strength properties. While role of mud system and chemistry can also be important for water sensitive formations, mud weight is always a fundamental component of wellbore stability analysis. Hence, when a wellbore is unstable (over-gauge), it is believed that effective mud support was insufficient to counter stress concentration around wellbore wall. Therefore, increasing mud weight based on model validation and calibration using offset wells data is a common approach to keep wellbore stable. However, a limited number of research articles show that wellbore stability is a more complex phenomenon affected not only by geomechanics but also strongly influenced by downhole forces exerted by drillstring vibrations and high mud flow rates. Authors of this paper also observed that some wells drilled with higher mud weight exhibit more unstable wellbore in comparison with offset wells which contradicts the conventional approach of linking wellbore stability to stresses and rock strength properties alone. Therefore, the objective of this paper is to analyze wellbore stability considering both geomechanical and drilling parameters to explain observed anomalous wellbore enlargements in two vertical wells drilled in the same field and reservoir. The analysis showed that the well drilled with 18% higher mud weight compared with its offset well and yet showing more unstable wellbore was, in fact, drilled with more aggressive drilling parameters. The aggressive drilling parameters induce additional mechanical disturbance to the wellbore wall causing more severe wellbore enlargements. We devised a new approach of wellbore stability management using two-pronged strategy. It focuses on designing an optimum weight design using geomechanics to address stress-induced wellbore failure together with specifying safe limits of drilling parameters to minimize wellbore damage due to excessive downhole drillstring vibrations. The findings helped achieve more stable wellbore in subsequent wells with hole condition meeting logging and completion requirements as well as avoiding drilling problems.

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