Study on effect of in-situ stress ratio and discontinuities orientation on borehole stability in heavily fractured rocks using discrete element method

Karatela, Ehtesham; Taheri, Abbas; Xu, Chaoshui; Stevenson, Gregor

doi:10.1016/j.petrol.2015.12.016

Cited by 45 publications

(16 citation statements)

References 38 publications

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“…As the research further developed, various failure criteria were studied and compared with each other for a more accurate drilling fluid weight prediction. At the same time, researchers also started to discuss the influence of laminated planes of weakness, pore pressure, and other factors on the borehole stability [3,[17][18][19][20]. In general, the stability analysis of boreholes in rock formations has been well studied and applied in the actual oil and gas industry.…”

Section: Introductionmentioning

confidence: 99%

Stability Analysis in Determining Safety Drilling Fluid Pressure Windows in Ice Drilling Boreholes

et al. 2018

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Borehole stability analysis has been well studied in oil and gas exploration when drilling through rock formations. However, a related analysis of ice borehole stability has never been conducted. This paper proposes an innovative method for estimating the drilling fluid pressure window for safe and sustainable ice drilling, which has never been put forward before. First, stress concentration on a vertical ice borehole wall was calculated, based on the common elastic theory. Then, three failure criteria, the Mogi–Coulomb, teardrop, and Derradji-Aouat criteria, were used to predict the stability of the ice borehole for an unbroken borehole wall. At the same time, fracture mechanics were used to analyze the stable critical pressure for a fissured wall. Combining with examples, our discussion shows how factors like temperature, strain rate, ice fracture toughness, ice friction coefficient, and fracture/crack length affect the stability of the borehole wall. The results indicate that the three failure criteria have similar critical pressures for unbroken borehole stability and that a fissured borehole could significantly decrease the safety drilling fluid pressure window and reduce the stability of the borehole. The proposed method enriches the theory of borehole stability and allows drillers to adjust the drilling fluid density validly in ice drilling engineering, for potential energy exploration in polar regions.

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Section: Introductionmentioning

confidence: 99%

Stability Analysis in Determining Safety Drilling Fluid Pressure Windows in Ice Drilling Boreholes

et al. 2018

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“…In the field of oil and gas exploitation, extensive analytical, experimental and numerical studies have been carried out on surface borehole instability [2][3][4][5][6][7][8][9]. The relevant research has focused on areas as diverse as the mechanism and regularity of borehole failure due to pre-existing rock fractures, crustal stress, as well as soft or unconsolidated rock formations, the rock failure criteria for predicting borehole shear failure and the drilling technique and method of improving the borehole stability, etc.…”

Section: Introductionmentioning

confidence: 99%

“…The relevant research has focused on areas as diverse as the mechanism and regularity of borehole failure due to pre-existing rock fractures, crustal stress, as well as soft or unconsolidated rock formations, the rock failure criteria for predicting borehole shear failure and the drilling technique and method of improving the borehole stability, etc. For example, Karatela et al [2] indicated that the drilling-induced stresses led to the development of a yielded zone around a borehole, and when the initial rock stress ratio increased the rock blocks at the borehole wall tended to move towards the centre of the borehole. As a result, the yielded zone increased around the borehole.…”

Section: Introductionmentioning

confidence: 99%

“…where, δ is the limiting opening of the fissure edge, r p is the plastic rotation factor; when D reaches 0.9-1.0, it is suggested that the fissure is conductive and the stratum is located within the water conductivity fracture zone. Therefore, whether the fissure is conductive or not can be examined by the dislocation of the borehole wall according to Equations (2) and 3. Take the dislocation of the borehole wall at depth 361.3 m in Figure 5b for instance, the dislocation should result from the rotation of the 2.5-m-thick medium grained sandstone located at the bottom interface of SKS 5.…”

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confidence: 99%

“…Take the dislocation of the borehole wall at depth 361.3 m in Figure 5b for instance, the dislocation should result from the rotation of the 2.5-m-thick medium grained sandstone located at the bottom interface of SKS 5. The minimal dislocation of the borehole wall, ∆ is estimated as the borehole diameter of 108 mm, then the rotation angle is no less than 2.5 • according to Equation (2). Thus, D minimizes at 0.94 since δ is roughly equal to 3 mm and r p is 0.46 [21].…”

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confidence: 99%

See 2 more Smart Citations

A Case Study of Surface Borehole Wall Dislocation Induced by Top-Coal Longwall Mining

2017

Energies

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Underground coal extraction causes failure and movement of overlying strata, which could also result in the dislocation of vertical surface boreholes. Investigating the correlation between the dislocation of surface boreholes and the broken of overlying strata is of great significance in deducing the mining-induced dynamic movement of overlying strata, which cannot be seen inside the 'black box'. Field measurement, laboratory experiment and theoretical analysis were employed to study the mechanism of the mining-induced dislocation of surface boreholes, and its relationship with the movement of overlying strata. Due to different deflection angles of adjacent strata, the horizontal movement of strata varies, and this contributes primarily to the dislocation of borehole wall. As the development of strata movement from the mining level towards surface, the position of borehole dislocation also occurred upwards, and the highest borehole dislocation occurred at the same position of overlying Key Stratum (KS). In other words, when a KS breaks, borehole dislocation will occur and develop from the bottom of this KS until the bottom of an upper KS. These key findings can provide a theoretical basis for deducing the mining-induced movement of overlying strata, determining the KS position and assessing the water conductivity of broken strata.

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An Empirical Study on Water-Induced Shear Weakening Behaviors of Rough-Walled Sandstone Joints

Zhang

Zou

et al. 2023

Rock Mech Rock Eng

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Study on effect of in-situ stress ratio and discontinuities orientation on borehole stability in heavily fractured rocks using discrete element method

Cited by 45 publications

References 38 publications

Stability Analysis in Determining Safety Drilling Fluid Pressure Windows in Ice Drilling Boreholes

Stability Analysis in Determining Safety Drilling Fluid Pressure Windows in Ice Drilling Boreholes

A Case Study of Surface Borehole Wall Dislocation Induced by Top-Coal Longwall Mining

An Empirical Study on Water-Induced Shear Weakening Behaviors of Rough-Walled Sandstone Joints

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