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Seisuke Okubo - One of the best experts on this subject based on the ideXlab platform.
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some attempts for estimating Rock Strength and Rock mass classification from cutting force and investigation of optimum operation of tunnel boring machines
Rock Mechanics and Rock Engineering, 2006Co-Authors: Katsunori Fukui, Seisuke OkuboAbstract:Tunnel face and wall collapse are common during excavations performed by tunnel boring machines (TBMs) due to the difficulty of correctly identifying the properties of the excavated Rock. This identification, however, can be simplified by using the cutting force to estimate Rock Strength, a method that has already proved quite successful in Japanese tunnel excavations. This paper summarizes knowledge relating to the cutting force obtained through tunnel excavation experience, and the relationship between Rock Strength and TBM operation is discussed. Although TBM operators rely on intuition to set the cutter head speed appropriately, this decision process represents a logical method of operation that takes advantage of the variable speed capability of the cutter head. Selection of appropriate support methods for the excavated face is also a critical issue in tunnel excavation. This selection process is based on the condition of the Rock, which is difficult to determine quickly and accurately during tunnel excavation. The present paper uses the excavation of two tunnels to demonstrate that it is possible to assign Rock mass classifications accurately based on Rock Strength when boring a uniform Rock type. It is also shown that the Rock mass can be classified from the Rock Strength normalized by the uniaxial compressive Strength when boring through mixed Rock types.
Hirokazu Karasawa - One of the best experts on this subject based on the ideXlab platform.
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Proposed Practical Methods to Estimate Rock Strength and Tooth Wear While Drilling With Roller-Cone Bits
Journal of Energy Resources Technology-transactions of The Asme, 2004Co-Authors: Tetsuji Ohno, Masayuki Kosugi, Hirokazu Karasawa, J. C. RowleyAbstract:The authors have previously developed and proposed methods to estimate the in situ Rock Strength and tooth wear while drilling with roller-cone bits [Karasawa et al., 2002, ASME J. Energy Resour. Technol. 124, pp. 125-132 (Pt. 1) 133-140 (Pt. 2)]. The purpose of this paper is to provide a follow-up to these two reports and to propose, for both previous methods, alternate techniques that can be more readily implemented in the field than those originally presented. The data presented in Part I of the previously mentioned work [1] were reanalyzed in order to find a new and simple parameter that can be used to estimate Rock Strength. This parameter uses only one set of data that consists of bit weight, torque, penetration rate, rotary speed, and bit diameter. It was also demonstrated that the effect of tooth wear on this new parameter is small. In addition, more practical methods, which employ two parameters, are derived and proposed to evaluate the tooth wear of roller-cone bits.
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Methods to Estimate the Rock Strength and Tooth Wear While Drilling With Roller-Bits—Part 2: Insert Bits
Journal of Energy Resources Technology, 2002Co-Authors: Hirokazu Karasawa, Masayuki Kosugi, Tetsuji Ohno, J. C. RowleyAbstract:This paper proposes new methods to estimate both the Rock Strength and tooth wear while drilling with roller-bits. Laboratory drilling tests were conducted to obtain the penetration rate, bit weight and torque using milled-tooth bits with different tooth wear (TO, T4, T7). Drilling media used for the tests were soft to medium-hard Rocks whose uniaxiul compressive Strength ranged from 14 to 118 MPa. Based on the test results, a parameter, which presents the Rock Strength independent of the tooth wear, was first investigated. The investigation revealed that a parameter related to the axial energy and the rotary energy required to drill Rock is effective to estimate the Rock Strength independent of the tooth wear. Second, methods to estimate the tooth wear were studied based on the same parameter that represents the Rock Strength. From the results of this study, methods to measure the tooth wear are proposed.
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Methods to Estimate the Rock Strength and Tooth Wear While Drilling With Roller-Bits—Part 1: Milled-Tooth Bits
Journal of Energy Resources Technology, 2002Co-Authors: Hirokazu Karasawa, Masayuki Kosugi, Tetsuji Ohno, J. C. RowleyAbstract:This paper proposes new methods to estimate both the Rock Strength and tooth wear while drilling with roller-bits. Laboratory drilling tests were conducted to obtain the penetration rate, bit weight and torque using milled-tooth bits with different tooth wear (T0, T4, T7). Drilling media used for the tests were soft to medium-hard Rocks whose uniaxial compressive Strength ranged from 14 to 118 MPa. Based on the test results, a parameter, which presents the Rock Strength independent of the tooth wear, was first investigated. The investigation revealed that a parameter related to the axial energy and the rotary energy required to drill Rock is effective to estimate the Rock Strength independent of the tooth wear. Second, methods to estimate the tooth wear were studied based on the same parameter that represents the Rock Strength. From the results of this study, methods to measure the tooth wear are proposed.
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Study on analytical technique for downhole information (3rd Report). Applicability of Methods for Estimation of Rock Strength and Tooth Wear to Insert Bits.
The Mining and Materials Processing Institute of Japan, 1996Co-Authors: Hirokazu Karasawa, Tetsuji Ohno, Masayuki KosugiAbstract:The main objectives of this report are to confirm the applicability of the methods for the estimation of Rock Strength and tooth wear to insert bits. These methods were obtained from the test results of the milled tooth bits with different tooth wear as described in the 2nd report. Therefore, drilling tests were conducted using 101.6mm-dia insert bits with different tooth wear. The main results obtained from the tests are as follows: 1. The relation between the effective axial energy per revolution divided by bit diameter (Feu/Nd) and the effective rotary energy per revolution divided by cross-sectional area of bit squared ((8Te/d2)2), is the information which shows the Rock Strength independent of tooth wear. The drilling Strength of Rock (Ds) can be obtained from the relation between them.2. The relations between Ds and the penetration Strength of Rock (Is), Ds and the specific energy calculated from the effective rotary energy (Se), Ds and the threshold weight per unit length of bit diameter (Fc/d), are effective information to estimate the tooth wear quantitatively.From these results, it became clear that the methods for the estimation of Rock Strength and tooth wear obtained from the milled tooth bits are applicable to the insert bits.
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Study on analytical technique for downhole information (1st Report). Estimation of Rock Strength by Bit Vibration.
Shigen-to-Sozai, 1994Co-Authors: Hirokazu Karasawa, Tetsuji Ohno, Shigeo MisawaAbstract:Drilling tests for several types of Rock were conducted to investigate the relationship between bit vibration and Rock Strength. An insert bit, a tooth bit and a PDC bit of 3-7/8 in. diameter were used for the tests. Rocks drilled are tuff, sandstone, granite and two types of andesite whose uniaxial compressive Strength ranges from 16.5 to 167 MPa. The bit vibration while drilling was measured by two accelerometers for horizontal and vertical directions set in a rod above the bit. The magnitude of the bit vibration was obtained by the calculation of RMS (root mean square) value of acceleration. The bit weight, penetration rate, torque and rotary speed were also measured while drilling, in addition to the bit vibration.From the results of tests, it became obvious that the bit vibration reflects well the change of Rock Strength. Moreover, the bit vibration, penetration rate and torque at the same bit weight were compared to understand the feature of the bit vibration. The comparison revealed that the change of the bit vibration and penetration rate with the change of Rock Strength are larger as compared to that of the torque in two types of roller cone bit. It also revealed that the increase and decrease of bit vibration for the change of Rock Strength are opposite to those of the penetration rate in the roller cone bits.
J. C. Rowley - One of the best experts on this subject based on the ideXlab platform.
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Proposed Practical Methods to Estimate Rock Strength and Tooth Wear While Drilling With Roller-Cone Bits
Journal of Energy Resources Technology-transactions of The Asme, 2004Co-Authors: Tetsuji Ohno, Masayuki Kosugi, Hirokazu Karasawa, J. C. RowleyAbstract:The authors have previously developed and proposed methods to estimate the in situ Rock Strength and tooth wear while drilling with roller-cone bits [Karasawa et al., 2002, ASME J. Energy Resour. Technol. 124, pp. 125-132 (Pt. 1) 133-140 (Pt. 2)]. The purpose of this paper is to provide a follow-up to these two reports and to propose, for both previous methods, alternate techniques that can be more readily implemented in the field than those originally presented. The data presented in Part I of the previously mentioned work [1] were reanalyzed in order to find a new and simple parameter that can be used to estimate Rock Strength. This parameter uses only one set of data that consists of bit weight, torque, penetration rate, rotary speed, and bit diameter. It was also demonstrated that the effect of tooth wear on this new parameter is small. In addition, more practical methods, which employ two parameters, are derived and proposed to evaluate the tooth wear of roller-cone bits.
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Methods to Estimate the Rock Strength and Tooth Wear While Drilling With Roller-Bits—Part 2: Insert Bits
Journal of Energy Resources Technology, 2002Co-Authors: Hirokazu Karasawa, Masayuki Kosugi, Tetsuji Ohno, J. C. RowleyAbstract:This paper proposes new methods to estimate both the Rock Strength and tooth wear while drilling with roller-bits. Laboratory drilling tests were conducted to obtain the penetration rate, bit weight and torque using milled-tooth bits with different tooth wear (TO, T4, T7). Drilling media used for the tests were soft to medium-hard Rocks whose uniaxiul compressive Strength ranged from 14 to 118 MPa. Based on the test results, a parameter, which presents the Rock Strength independent of the tooth wear, was first investigated. The investigation revealed that a parameter related to the axial energy and the rotary energy required to drill Rock is effective to estimate the Rock Strength independent of the tooth wear. Second, methods to estimate the tooth wear were studied based on the same parameter that represents the Rock Strength. From the results of this study, methods to measure the tooth wear are proposed.
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Methods to Estimate the Rock Strength and Tooth Wear While Drilling With Roller-Bits—Part 1: Milled-Tooth Bits
Journal of Energy Resources Technology, 2002Co-Authors: Hirokazu Karasawa, Masayuki Kosugi, Tetsuji Ohno, J. C. RowleyAbstract:This paper proposes new methods to estimate both the Rock Strength and tooth wear while drilling with roller-bits. Laboratory drilling tests were conducted to obtain the penetration rate, bit weight and torque using milled-tooth bits with different tooth wear (T0, T4, T7). Drilling media used for the tests were soft to medium-hard Rocks whose uniaxial compressive Strength ranged from 14 to 118 MPa. Based on the test results, a parameter, which presents the Rock Strength independent of the tooth wear, was first investigated. The investigation revealed that a parameter related to the axial energy and the rotary energy required to drill Rock is effective to estimate the Rock Strength independent of the tooth wear. Second, methods to estimate the tooth wear were studied based on the same parameter that represents the Rock Strength. From the results of this study, methods to measure the tooth wear are proposed.
Stephen Butt - One of the best experts on this subject based on the ideXlab platform.
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Machine Learning Approach to Model Rock Strength: Prediction and Variable Selection with Aid of Log Data
Rock Mechanics and Rock Engineering, 2020Co-Authors: Mohammad Islam Miah, Salim Ahmed, Sohrab Zendehboudi, Stephen ButtAbstract:Comprehensive knowledge and analysis of in situ Rock Strength and geo-mechanical characteristics of Rocks are crucial in hydrocarbon and mineral exploration stage to maximize wellbore performance, maintain wellbore stability, and optimize hydraulic fracturing process. Due to the high cost of laboratory-based measurements of Rock mechanics properties, the log-based prediction is a viable option. Nowadays, the machine learning tools are being used for estimation of the in situ Rock properties using wireline log data. This paper proposes a machine learning approach for Rock Strength (uniaxial compressive Strength) prediction. The main objectives are to investigate the performance of data-driven predictive model in determining this vital parameter and to select features of predictor log variables in the model. The backpropagation multilayer perception (MLP) artificial neural network (ANN) with Levenberg–Marquardt training algorithm as well as the least squares support vector machine (LS-SVM) with coupled simulated annealing (CSA) optimization technique is employed to develop the dynamic data-driven models. Capturing nonlinear, high dimensional, and complex nature of real field log data, the Rock Strength models’ performances are evaluated using statistical criteria to ensure concerning the model reliability and accuracy. The model predictions are compared and validated against the measured values as well as the results obtained from existing log-based correlations. Both the MLP-ANN and the CSA-based LS-SVM connectionist strategies are able to predict the Rock Strength so that there is a very good match between the model results and corresponding measured values. The input log parameters are ranked based on their contributions in prediction performance. The acoustic travel time and gamma ray are found to have the highest relative significance in estimating Rock Strength. New correlations are also developed to obtain the in situ Rock Strength of the siliciclastic sedimentary Rocks using the most important log parameters such as dynamic sonic slowness, formation electron density, and shalyness effect. The developed correlations can be used to obtain quick estimation of dynamic uniaxial compressive Strength profile using wireline logging data, instead of static data from the surface measurements or laboratory data. It is expected that the proposed models and tools will enable oil and gas engineers to better predict Rock Strength and thus enhance wellbore performance.
James E Russell - One of the best experts on this subject based on the ideXlab platform.
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quantifying the effect of Rock Strength criteria on minimum drilling mud weight prediction using polyaxial Rock Strength test data
International Journal of Geomechanics, 2006Co-Authors: Xianjie Yi, James E RussellAbstract:In engineering practice, a linear poroelasticity stress model in combination with a Rock Strength criterion is commonly used to determine a minimum mud weight for stable well drilling. Rock Strength criterion therefore plays a key role in minimum mud weight prediction. There are a variety of Rock Strength criteria available in the literature. It is well known that all those criteria fall into two categories: intermediate principal stress dependent ( σ2 dependent) criteria and intermediate principal stress independent ( σ2 independent) criteria. To identify if a specific Rock failure is σ2 dependent or σ2 independent, a polyaxial (true triaxial) Rock Strength test is essential. Similarly, to study the effect of Rock Strength criteria on wellbore stability and minimum drilling mud weight prediction, polyaxial Rock Strength test data are most useful. In this paper, we present a systematic approach to quantify the effect of three most commonly used Rock Strength criteria on minimum drilling mud weight predict...
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Effect of Rock Strength Criterion on the Predicted Onset of Sand Production
International Journal of Geomechanics, 2005Co-Authors: Peter P. Valko, James E RussellAbstract:The variation of sanding onset prediction results with the selection of one or another Rock Strength criterion is investigated. In this paper, four commonly used Rock Strength criteria in sanding onset prediction and wellbore stability studies are presented. There are Mohr–Coulomb, Hoek–Brown, Drucker–Prager, and modified Lade criteria. In each of the criterion, there are two or more parameters involved. In the literature, a two-step procedure is applied to determine the parameters in the Rock Strength criterion. First, the Mohr–Coulomb parameters like cohesion So and internal friction angle ϕf , are regressed from the laboratory test data. Then, the parameters in other criteria are calculated using the regressed Mohr–Coulomb parameters. It is proposed that the best way to evaluate the parameters in a specific Rock Strength criterion is to perform direct regression of the laboratory test data using that criterion. Using this methodology, it is demonstrated that the effect of various Rock Strength criteria...
