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South Kalimantan
Characterization of the Distribution of Physical and Mechanical Properties of Rocks at the Tutupan Coal Mine, South Kalimantan, Indonesia
Azizi, M. A. (Mining Engineering Department, Institut Teknologi Bandung) | Kramadibrata, S. (Mining Engineering Department, Trisakti University) | Wattimena, R. K. (Mining Engineering Department, Institut Teknologi Bandung) | Sidi, I. D. (Mining Engineering Department, Institut Teknologi Bandung)
Abstract Uncertainties of factors that influence slope stability have been acknowledged by many geotechnical engineers, and these are drawn from the characterization of the geotechnical parameters of the slope. The characterization is associated with a process of identifying the distribution of random variable values used in the design of a single slope of an open mine, and also part of the probabilistic method which is an alternative approach in estimating the stability of a slope with a Failure Probability value (FP). This paper explains the characterization process using the Kolmogorov-Smirnov (K-S) method, which will determine the most appropriate function for the distribution of the random variable. The characterization results can be used in determining the Safety Factor including the level of confidence and Probability of Failure based on the best fitting function. 1 Introduction Slope design has over the years become the domain of geotechnical engineers. While this has benefited the technology of the slope design processes, it has also separated the the mine design engineers from the responsibility of the risk versus reward relationship. Given the uncertainties that prevail within the geotechnical discipline, there always exists a probability that a slope may not perform as predicted, and in the worst case can result in a catastrophic failure. The rock slope stability analysis affected by the random input parameters such as internal friction angle, cohesion, water pressure, seismic acceleration and density, which cannot be properly represented by a single value as input parameters in slope stability analysis. The uncertainty in the values of rock mass properties is a major factor in slope stability analysis. Each input parameter has a certain distribution function. There are several methods used in characterizing a data distribution, namely: Chi-Square Method, Kolmogorov-Smirnov method, and the method of Anderson Darling. This paper uses the Kolmogorov- Smirnov method. The principle of this method is based on a comparison between the experimental cumulative distribution function and cumulative distribution theoretical assumptions. The 4 assumptions of the cumulative distribution function will be compared with the empirical distribution functions, namely: normal, lognormal, beta, gamma. The results of the characterization process will be used for the calculation of the safety factor and failure probability of slopes, and the distribution data are obtained from Tutupan Coal Mine, South Kalimantan, Indonesia.
- Asia > Indonesia > South Kalimantan (0.62)
- Asia > Indonesia > Kalimantan (0.62)
- Geology > Rock Type > Sedimentary Rock > Organic-Rich Rock > Coal (0.71)
- Geology > Geological Subdiscipline > Geomechanics (0.65)
ABSTRACT It has been well known that the stability of slopes in the open pit coal mines in Indonesia does not remain constant over long periods of time. This has been mainly attributed to the weathering process that intensively occurs in the tropical regions. It is therefore appropriate to carry out a research of shear strength characteristics on rock samples of the predominant coal bearing strata such as sandstone which are obtained from Tutupan coal mines in South Kalimantan, Indonesia. The research includes the shear creep test with Generalized Kelvin model rheology approach with 15 × 15 cm and 25 × 25 cm sandstone samples size respectively. The research reveals that the long term strength of that sandstone is significantly lower than their peak strengths. It is also found that the Generalized Kelvin rheology model does fit to the rheology of these rock samples.
- Asia > Indonesia > Kalimantan (0.61)
- Asia > Indonesia > South Kalimantan (0.61)
- Geology > Rock Type > Sedimentary Rock > Organic-Rich Rock > Coal (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (1.00)
Mechanical Earth Model (MEM): An Integrated Study in Low-Fracture-Gradient and Depleted Fields to Improved Cementation (Case Study)
Sondang, Jaka (PERTAMINA EP) | Irawan, Gondo (PERTAMINA EP) | Sehang, Andry (PERTAMINA EP) | Permana, Dian (PERTAMINA EP) | Wibowo, Satrio (Schlumberger) | Wisanti, Lia (Schlumberger)
Abstract A depleted reservoir in the Tapian Timur field in South Kalimantan, Indonesia, is located at 1,400-mTVD with a 400-psi formation pressure. Drilling through it presents potential threats to operations, including lost circulation during drilling and cementing and borehole instability. Two wells previously drilled and completed in the area suffered long NPT due to stuck pipe and bad cement bond quality. Even though the field has been explored and developed for 43 years, a thorough study of the reservoir characteristics was never done. Improper knowledge of a reservoir like this one cause’s unnecessary lost time during drilling and poor zonal isolation of the target zone, can potentially jeopardize the economic feasibility of a project. For this reservoir, a geomechanical study was applied, and a mechanical earth model (MEM) was built. The model utilized multidisciplinary data across the field (drilling and logging data, core, pressure history) to evaluate wellbore stability and improve drilling practices. The MEM study provided key recommendations for the drilling process and cementing operation. Decisions made based on the study include changes in casing point, mud-weight optimization, and utilization of high-performance lightweight slurry with fiber. A subsequent well drilled in the area applying the recommendation from the study was drilled and completed faster. Cement bond logs from the section also indicated excellent zonal isolation across the reservoir. The recommendations from the study are currently integrated into the standard operation procedures.
- Asia > Indonesia > Kalimantan (0.36)
- Asia > Indonesia > South Kalimantan (0.25)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.71)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Pressure Management > Well control (1.00)
- Well Drilling > Drilling Operations (1.00)
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