Numerical methods for the borehole breakout problems using Geo3D

Morita, Nobuo

doi:10.1016/b978-0-323-91112-2.00017-3

Cited by 2 publications

(1 citation statement)

References 15 publications

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“…Uniaxial strength is the maximum that the rock can carry under uniaxial compression. It is also known as the unconfined compressive strength of the material because confining stress is set to zero (Morita, 2021). The approximate compressive strength can be estimated from correlation with indexes obtained with simple field tests, such as the Schmidt hammer test.…”

Section: Introductionmentioning

confidence: 99%

Geostatistical assessment of unconfined compressive strength of rocks in Northeast Jeddah, Saudi Arabia

Alghamdi

2023

Int. j. adv. appl. sci.

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The determination of rock strength holds paramount importance in the field of engineering geology. In this study, we conduct a comprehensive geostatistical evaluation of the unconfined compressive strength (UCS) within a 100 km2 area situated in northeast Jeddah, Saudi Arabia. The UCS values were indirectly estimated using an empirical equation based on the Schmidt hammer rebound method, resulting in a range of strengths from 9.2 to 198.4 MPa. The corresponding mean UCS values vary between 60.3 to 81.7 MPa, with standard deviations ranging from 18.6 to 45.3 MPa. The analysis revealed that, among the sites examined, a specific location exhibited the highest median UCS value of 72.2 MPa, while another site recorded the lowest value of 56.2 MPa. Based on the distribution of UCS values, the study area was classified into five distinct strength categories: very low, low, medium, high, and very high. Notably, the majority of variability in UCS values was confined within the middle 50% range, as evident from the interquartile range (IQR) below 30 MPa. Additionally, certain sites displayed a tighter cluster of UCS values, while an IQR of DEFJ≥60 indicated a more widespread distribution of strength values. Furthermore, two locations were identified as representing the minimum and maximum UCS values within a 95% confidence interval. The UCS in location A was estimated at 60.25±9.14 MPa, whereas in location B, it was 81.72±8.50 MPa. These findings offer valuable insights into the rock strength characteristics of the designated area, providing essential data for engineering and geotechnical applications.

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Section: Introductionmentioning

confidence: 99%

Geostatistical assessment of unconfined compressive strength of rocks in Northeast Jeddah, Saudi Arabia

Alghamdi

2023

Int. j. adv. appl. sci.

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Experimental investigation of the rock cutting process and derivation of the 3D spatial distribution of the formation strength using in-cutter sensing

Koulidis,

Pelfrene,

Ahmed

2023

J Petrol Explor Prod Technol

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Recent advances in downhole measurements allow to accurately measure drilling forces at the drill bit, and estimate the evolution of the rock strength along the well profile. This paper presents an experimental methodology that allows to measure drilling forces, at the cutter scale, with a sensor embedded behind a polycrystalline diamond compact (PDC) cutter, and to infer the 3D spatial distribution of the rock strength. Two experimental campaigns have been performed on a laboratory-scaled drilling rig and complemented with standard mechanical tests to validate rock strength estimations. In the first campaign, homogeneous synthetic rock samples have been prepared. The average rock strength of each sample derived from cutter force measurements and a cutter–rock interaction model, compares well with the one derived from mechanical tests. In the second campaign, heterogeneous synthetic rock samples have been prepared. They are made of two layers of gypsum mixtures of different strengths, separated by a slanted bedding plane. Based on the instrumented cutter measurements, the 3D spatial distribution of the rock strength has been reconstructed along its path. Rock strength estimations are consistent with results obtained from mechanical tests, and the reconstructed geometry of the bedding plane matches well its actual geometry. The experimental methodology and technology presented in this paper lay the foundations for estimating rock properties in 3D, at the drilling stage. It has the potential to provide geoscientists information about complex lithological structures at an early stage, reducing the need for expensive and time-consuming coring and logging operations.

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Numerical methods for the borehole breakout problems using Geo3D

Cited by 2 publications

References 15 publications

Geostatistical assessment of unconfined compressive strength of rocks in Northeast Jeddah, Saudi Arabia

Geostatistical assessment of unconfined compressive strength of rocks in Northeast Jeddah, Saudi Arabia

Experimental investigation of the rock cutting process and derivation of the 3D spatial distribution of the formation strength using in-cutter sensing

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