Directional and horizontal drilling operations are increasingly conducted in all over the world, especially parallel to the growth of the technological developments in the industry. Common application fields for directional and horizontal drilling are in offshore and onshore when there is no way of drilling vertical wells. During directional and horizontal well drilling, many additional challenges occur when compared with vertical well drilling, such as limited weight on bit, harder hole cleaning, trajectory control, etc. This makes even harder to select the proper drilling parameters for increasing the rate of penetration. This study aims to propose a rate of penetration model considering many drilling parameters and conditions. The proposed model is a modified Bourgoyne &amp / Young&rsquo / s model which considers formation compaction, formation pressure, equivalent circulating density, and effective weight on bit, rotation of the bit, bit wear, hole cleaning, inclination, fluid loss properties and bit hydraulics. Also, a bit wear model is developed for roller cones and PDCs. The model performance is tested using field data obtained from several directional and horizontal offshore wells drilled at Persian Gulf. It is observed that the model can estimate rate of penetration with an error of &plusmn / 25 % when compared with the field data.

Semi-circular specimens (SCB) under three point-bending which are commonly used for fracture testing of rocks were used here for fracture mechanics tests. A total of 65 specimens were tested by using Ankara andesite rock. Investigations including the effects of initial notch thickness, different loading span ratios (S/R), flattened loading end, and little dimensional variations when preparing the specimens were carried out. Stress intensity factors for specimens with different geometries were computed individually by using a 3D finite element program ABAQUS. Specimens with a preliminary notch thickness varying from 0.84 to 3.66 mm were tested under three point bending. For a second group of specimens loading span was changed and fracture toughness variation was studied. Another change in the specimen geometry was made by machining a flat loading end at the upper load application point. Fracture toughness values were computed using the stress intensity values computed from numerical modeling and failure loads from the experiments. It was found that up to 2 mm fracture toughness was not affected by variations in the thickness of preliminary notches. Fracture toughness was not affected by changing the loading span. For specimens with flat loading ends, fracture toughness was about 16% lower than the value found from regular SCB type specimens loaded at a point at the top by a steel roller. As a result of about 46 experiments average fracture toughness of Ankara G&ouml / lbasi andesite was found as 1.36 MPa .

Most of the coal properties depend on carbon content and vitrinite reflectance, which are rank dependent parameters. In this study, a new approach was followed by constructing a simulation input database with rank-dependent coal properties published in the literature which are namely cleat spacing, coal porosity, density, and parameters related to strength of coal, shrinkage, swelling, and sorption. Simulations related to enhanced coalbed methane (ECBM) recovery, which is the displacement of adsorbed CH4 in coal matrix with CO2 or CO2/N2 gas injection, were run with respect to different coal properties, operational parameters, shrinkage and swelling effects by using a compositional reservoir simulator of CMG (Computer Modeling Group) /GEM module. Sorption-controlled behavior of coalbeds and interaction of coal media with injected gas mixture, which is called shrinkage and swelling, alter the coal properties controlling gas flow with respect to injection time. Multicomponent shrinkage and swelling effects were modeled with extended Palmer and Mansoori equation. In conclusion, medium-volatile bituminous coal rank, dry coal reservoir type, inverted 5-spot pattern, 100 acre drainage area, cleat permeability from 10 to 25 md, CO2/N2 molar composition between 50/50 % and 75/25 %, and drilling horizontal wells rather than vertical ones are better selections for ECBM recovery. In addition, low-rank coals and dry coal reservoirs are affected more negatively by shrinkage and swelling. Mixing CO2 with N2 prior to its injection leads to a reduction in swelling effect. It has been understood that elastic modulus is the most important parameter controlling shrinkage and swelling with a sensitivity analysis.

Shear strength characterization of discontinuities is an important concept for slope design in discontinuous rocks. This study presents the development of a methodology for implementing Barton-Bandis empirical shear strength failure criterion in three dimensional distinct element code, 3DEC, and verification of this methodology. Normal and shear deformation characteristics of discontinuities and their relations to the discontinuity surface characteristics have been reviewed in detail. First, a C++ dynamic link library (DLL) file was coded and embedded into 3DEC for modelling the Barton-Bandis shear strength criterion. Then, a numerically developed direct shear test model was used to verify the normal and shear deformation behaviour with respect to empirical results of the Barton-Bandis shear strength criterion. A three dimensional simple discontinuous rock slope was modelled in 3DEC based on Barton-Bandis shear strength criterion. The slope model was first utilized by Mohr-Coulomb failure criterion. Then, with the use of the new model developed here, the effects of the discontinuity surface properties on shear strength were introduced to the slope problem. Applicability of the developed model was verified by three large scale real case studies from different open pit lignite mines of Turkish Coal Enterprises (TKi), namely Bursa Lignites Establishment (BLi) &ndash / 2 cases and &Ccedil / an Lignite Establishment (&Ccedil / Li). The results with the new model option, which allows users to use important discontinuity surface properties like joint roughness coefficient and joint wall compressive strength, compared well with results of previous studies using Mohr-Coulomb failure criterion.

Groundwater can be a critical issue to be considered in civil engineering, mining engineering and interdisciplinary fields. Karstic structures and aquifers enclosing groundwater are potential risks in case they are not studied in detail. Enclosed groundwater can result in floods at pit bottom or can cause instabilities of permanent pit slopes. This study is about analyses of flooding possibility at the pit bottom and possible instabilities of pit slopes in the Elbistan-&Ccedil / &ouml / llolar open cast coal mine due to the presence of a karstic aquifer under the lignite formation. Thickness and permeability of the bottom clay formation under the lignite bed are necessary critical parameters for investigating a possible water rush from a confined aquifer in limestone formation underneath the bottom clay. These parameters were changed, and water flow quantities towards the pit bottom were determined by finite element models. Critical values of these parameters were investigated considering the lack of accurate site investigation information regarding the thickness and permeability of bottom clay. Possible strength loss, fracturing, and thus permeability increase in bottom clay due to a confined aquifer were studied. In flooding and slope stability analyses Phase2 software based on finite element method is used. Results of analyses showed that as reported thickness of bottom clay is around 120 m at the pit bottom and permeability values are in orders of magnitudes of 10-8 m/s, no serious flooding problems are expected to occur unless the thickness of bottom clay layer drops down to around 20 m, and the permeability of this layer reaches an order of magnitude of 10-5 m/s. Mechanical effects of confined aquifer on slopes and bottom clay displacements were investigated, and thus fracturing and failure possibilities of bottom clay and permanent slope were assessed. Slope and pit bottom displacements increased to meter levels for less than 60 m bottom clay thicknesses. Whereas 50-60 m bottom clay thickness can be critical for cracking, 20 m bottom clay thickness was found to be critical for water rush to the pit bottom. With reported bottom clay thickness of 120 m and with 25o slope angle permanent slope factor of safety was found to be 1.2, and this value was not effected unless clay layer thickness drops below 70 m levels. Higher than 32o overall slope angle there will be a risk of slope failure for permanent and production slopes, reflected by safety factors less than one, in the stability analyses.

Kirka Boron Plant in Eski

Fracture toughness is an important rock property for rock fracturing and fragmentation applications. Theory and practice of opening mode (mode I) and shearing mode (mode II) fracture toughness tests are still in a developing stage for the cylindrical rock cores. A new circular plate type test specimen is used for mode II fracture toughness testing on rock cores. This involves a straight edge notched circular plate type core disc geometry under three-point bending load / new method and its associated specimen geometry is referred as straight edge notched disc bend (SNDB) specimen under three-point bending. Mode II fracture toughness results of the tests with this new geometry were compared to the results of the tests commonly employed for mode II fracture toughness testing. Specimen geometries were modeled and mode II stress intensity factors were computed by finite element modeling using ABAQUS program. For comparison purposes, mode II or shearing mode fracture toughness KIIc of two different rock types were determined by different testing methods commonly employed in recent practice. Core specimens of Ankara andesite and Afyon marble rock types were tested with cracked chevron notched Brazilian disc and cracked straight through Brazilian disc specimens under Brazilian type loading, semi-circular bend specimen and straight edge notched disc bending specimen geometries under three-point bending.For all testing groups, cylindrical cores with diameters varying from 7.5 cm to 12.5 cm were prepared with notch lengths changing from 1.5 cm to 2.6 cm. Effect of specimen thickness on mode II fracture toughness was investigated for three different testing methods. Fracture toughness values remained constant when thickness of the specimens was increased for cracked straight through Brazilian disc, semi-circular bend and straight notched disc bend methods. For cracked straight through Brazilian disc method KIIc values of Ankara andesite and Afyon marble were 0.99 MPa&radic / m and 0.86 MPa&radic / m, respectively. Mode II fracture toughness with semi-circular bend specimen was 0.43 MPa&radic / m for andesite and 0.46 MPa&radic / m for marble. When the results of the two three-point bending type tests were compared straight notched disc under three-point bending resulted in higher KIIc values (0.61 MPa&radic / m for andesite and 0.62 MPa&radic / m for marble) than the results found by semi-circular bend tests.

In recent years increasing growth rate of all industrial fields generated an emerging energy demand and consequent environmental problems worldwide. Defining environmental profiles of products and systems using environmental tools, such as Life Cycle Assessment (LCA), is a critical issue for sustainable mining. In order to tackle the increasing environmental challenges and air emissions induced by surface coal mining, alternative material handling options are needed to be evaluated. This research study aims to provide a robust LCA model in selection of the alternative material haulage systems as a decision support system. The main objectives of this thesis study are: i) contributing to the national archived data by gathering data about haulage systems from an open pit coal mine, ii) constructing life cycle inventory from the acquired environmental data, iii) performing life cycle assessment of both material haulage systems in an open pit coal mine according to their environmental burdens, iv) conducting uncertainty assessment, and v) suggesting improvement in stages where emissions are critical. In order to accomplish these objectives, comparative LCA from cradle-to-grave was carried out in SIMAPRO 7.3 to determine life cycle environmental impacts of off-highway mining trucks and belt conveyors in coal transportation. Climate change and acidification were selected as major impact categories considered to be major concerns in mining industry. The results of this study revealed that off-highway trucks had 1.9 times greater impact on acidification category than belt conveyors, on the other hand, belt conveyors had 1.6 times greater impact on climate change. NOx emissions caused 96 percent of the acidification impact. CO2 emissions from fossil fuel combustion led to 95 percent of the climate change effect. The obtained results also indicated that the highest impact on all selected impact categories were generated from the utilization stage of the trucks operated by diesel oil and utilization of belt conveyor systems operated by electricity. The main novelty of this study is that it is one of the first LCA studies in the Turkish mining industry where considerable amount of emissions occur due to material handling. This study also advances the current knowledge about environmentally critical processes in material handling systems and places recommendations for both alternatives aiming better decision making. The results of the study are expected to provide a decision support system for the mining industry.

The aim of this study was to determine the adsorption capacity of activated carbon and organo-zeolites for removal of pesticides in water. In order to prepare organo-zeolite, two kinds of cationic surfactants, namely, hexadecyltrimethyl ammonium bromide (HTAB) and dodecyltrimethyl ammonium bromide (DTAB) were used. Adsorption studies of cationic surfactant on zeolite were investigated in respect to initial concentration of cationic surfactant, time, and temperature. It has been found that the best fitted isotherm equation was Langmuir equation. The observed adsorption rates were found to be equal to the second order kinetic model. The activation energies of cationic surfactant adsorption was determined by using Arrhenius equation.

Dual Gradient Drilling (DGD) system is a promising technology that was developed to overcome the deep water drilling problems occurred due to narrow operating window between pore pressure and fracture pressure. In conventional drilling practice, single mud weight exists from drilling unit to TVD (True Vertical Depth) which creates big hydrostatic pressure in bottom hole ,moreover, minor changes in mud weight results a big pressure changes proportional to the length of hydrostatic column increase with water depth. On the other hand, DGD allows using two different mud weights to get same bottom hole pressure / low gradient drilling fluid from drilling unit to the sea floor and high gradient drilling fluid form the sea floor to TVD, to decrease the effect of water column on mud hydrostatic pressure in TVD. In this thesis, a conventionally drilled deepwater well was redesigned considering the DGD system and drilled virtually to determine the changes of cost of services and materials on total operation budget to prove the positive impact of system on total operation cost. This study not only proved the technical advantages of the DGD system, but also showed economical impact of the system on total drilling cost, by decreasing around 19%.