Wellbore stability problems make up huge over-costs worldwide. Since in recent years declining resource volumes and favorable oil prices are encouraging operators to drill deeper, more complex well trajectories drilling for hydrocarbons have turn into a much more challenging task. Furthermore, the complexity and variations of those wells have added the weight to planning and problem anticipation at both drilling and production stages. The thesis will describe the geomechanical wellbore stability analysis of Sayindere, Karabogaz and Karababa formations drilled in X field, Adiyaman. The analysis assumes validity of linear elastic theory for porous media and requires drilling reports, well logs, laboratory tests and core analysis. It was observed that with the assessment of geomechanical wellbore stability analysis mud weight window, which includes minimum mud weight and maximum mud weight can be determined for the studied formations.

This study derives a method that seeks a possible relationship between settlement site locations and sunrise-sunset times of those locations using Geographical Information Systems. The method is applied to &Ccedil / ankiri province, which is located at northeast of Ankara and covers approximately an area of 8380 km2. Three main data sets of the study area are used in this thesis: 1) Settlement data containing the coordinates, IDs and names of the 891 settlement points, 2) Topographic data containing the coordinates and digital elevation values of all raster pixels 3) Bright sunshine duration data (BSD) composed of the difference between sunset and sunrise times for all raster pixels. In the first step of this study, sunrise and sunset times of the study area are calculated with an algorithm that uses Digital Elevation Model. This algorithm is developed specifically for computing those times over a topographic surface which may delay the sunrise time or bring forward the sunset time, thus reducing the BSD. In the second step, unsuitable landforms for settlement are clipped out from the study area based on the thresholds derived from elevation, slope and aspect parameters. Then, BSD histograms and statistics of the settlements and study area are compared for each of the 12 months and for the average of 12 months. Finally, neighborhood analysis on settlements is carried out by comparing the BSD values of each settlement with the BSD characteristics of circular buffer surrounding the settlement. The main conclusion derived from above mentioned analysis is that the BSD does not directly affect the selection of the settlement sites.

Due to rapidly growing population of Ankara city (Turkey) and traffic load, it is required to widen some of the existing highways. One of them is Ankara-EskiSehir (E-90) highway that connects highly populated areas to the city center. During widening, several cut slopes were formed along the highway route. However, some instability problems such as small-sized rock falls and rock detachments have occurred along a cut slope in highly jointed, folded and sheared limestone. They caused local degradation of the cut slope. The cut slope has a slope angle varying from 71&deg / to 84&deg / and contains several shear zones. In this study, the relationships between the existing detachment zones and various parameters (e.g. block size, point load strength index, weathering, shear zone, daylight zone) considered to be important for slope instability were investigated using GIS-based statistical landslide susceptibility analyses in order to predict the further aerial extension of the detachment zones with time. During the overlay analyses, statistical index and weighting factor methods were used by means of TNT-MIPS software. The outcomes of the analyses using both methods are compared and evaluated together with the field observations to check the reliability of the methods and to assess the detachment zones that may develop in the future. Additionally, limit equilibrium analyses were also carried out for the determination of the possible large scale mass failures. The overlay analyses indicate some risky zones where detachments are likely to occur in the future. On the other hand, the limit equilibrium analysis of the rock mass using Bishop simplified method shows that except one section no mass failure is expected in the cut slope. Suitable remediation measures which include the use of wire mesh, shotcrete, toe support, and concrete barrier blocks or catch/barrier fences are recommended for these zones.

Bentonite is a smectite type clay mineral and swells in water. In this thesis, the effect of acetone, methyl-ethyl ketone, n-hexane on the properties of bentonite was determined by thermal analysis and water absorption tests. The tests indicated no significant change with treating bentonite with organic liquids. Because of the swelling property, only small amount of bentonite can be suspended in water. This may limit certain applications of bentonite. In this thesis, feasibility of suspending large quantities of bentonite in a non-aqueous media was studied. The concentrations for a pumpable high solid bentonite slurry were determined. As aqueous slurry showed pumpable properties up to 30-35 pounds/barrel, this concentration was as high as 125-150 pounds/barrel for acetone, 175-200 pounds/barrel for methyl-ethyl ketone and 325-350 pounds/barrel for n-hexane. Bentonite deposite has a complicated composition, containing free silica minerals, such as quartz, cristobalite, and opal / silicate minerals, such as feldspar, mica, and zeolite / carbonates or sulfates of alkaline earth metals, such as calcite, dolomite, and gypsum / and, in addition, iron compounds and humus. As mined it is primarily broken and dried and then pulverized by means of an attrition grinding machine. In this study dispersion of raw bentonite by high shear blending and shaking forces in the presence of acetone, methyl-ethyl ketone and n-hexane and eliminating the non-clay impurities by screening were studied. Many attempts have been made to provide a bentonite composition retaining the full swelling properties of the bentonite by the addition of non-aqueous liquids for obtaining a flexible waterproofing sheet. In this research the possible method for deposition of bentonite in a sponge by saturating the sponge with bentonite using organic liquids was investigated.

A relatively new fracture toughness testing method called Straight Notched Disc Bending (SNDB) was used before for fracture testing of Ankara Andesite and Afyon Marble cores. In this work to investigate the applicability of the new method to other rock types. With a preliminary notch of 10 mm, straight notched disc type specimens with a diameter of 75 mm were loaded by three-point bending loads. Investigation of effect of specimen height on the stress intensity factor and fracture toughness was carried out. Specimen heights (B) between 18 &ndash / 67 mm were tried for andesite and marble cylindrical specimens. Loading span, that is span/radius (S/R) ratio was changed between 0.6 - 0.9 for andesite specimens. Stress intensity factor for specimens was computed with ABAQUS program. Stress intensity factor was found to increase with increasing specimen diameter for a fixed span/radius ratio. Stress intensity factor decreased with increasing specimen height. Changing span was found to have no significant effect on fracture toughness of andesite. Fracture toughness was significantly lower for specimens with smaller height. The suggested testing height interval for this type of specimens was between height/diameter ratios of 0.49 &ndash / 0.64. Results were compared to the results obtained by a well-known specimen geometry named semi-circular bend specimens (SCB) under three-point bending. SCB tests produced lower values for fracture toughness for both rock types. Fracture toughness was 0.99 MPa&amp / #8730 / m for Ankara Andesite and 0.70 MPa&amp / #8730 / m for Afyon Marble.

The purpose of this study is the characterization and modeling of Ulubey aquifer system which serves as an important water supply for USak province located in inner parts of the Aegean Region in Turkey. In recent years, growing population, accelarating industrial activities and on the contrary decreasing rainfall and contamination of the surface water resources made groundwater indispensable to meet domestic, agricultural and industrial water demands of USak province. All these facts necessitate the development of a groundwater management plan, which this study aims to end up with. For this purpose, every single component of the recharge/discharge mechanisms of the groundwater budget of the aquifer system should conceptually be comprehended. However, due to lack of data, all of the components can not be precisely determined. Hence, a mathematical groundwater flow model successfully calibrated under steady state conditions, is utilized to calculate the missing components of the groundwater budget and also to test the effects of increased pumping rates for irrigational and domestic uses to supply the increasing demand in the future. For this purpose, three management scenarios are set up under transient conditions over a planning period of 20 years. Drawdown maps, groundwater budgets and groundwater level hydrographs are utilized to observe the effects. The results of these simulations proved that neither of the tested management scenarios creates significant drawdowns or change in groundwater reserve of the Ulubey aquifer system.

The New Ulus Tunnel will be constructed within the andesitic terrain at Hidirliktepe (Ankara). Excavation of the tunnel will be accomplished through blast and drill method. Emprical methods will be consulted during the design of the support systems as well as the slope of the portal rock face. Therefore it is essential to perform detailed rock mass characterization studies. In this thesis it is aimed to determine the rock mass characteristics in order to design the rock slope of the portals and to assess the reliable support systems for the tunnel. For this purpose laboratory tests and field investigations were conducted. Field investigations involved detailed discontinuity measurements and borehole drillings. In respect of laboratory tests / point load index, unit weight and uniaxial compression strength tests were used. The field and laboratory test results were utilized in the Rock Mass Classification Systems (RMR, Q-system) in order to ascertain the rock mass characteristics. By all accounts, necessary tunnel support systems were determined. As for the portal areas, the rock face design was accomplished through kinematical analyses. Consequently, no failure is expected at the portal rock slopes.

Expansive soils are a worldwide problem that poses several challenges for civil engineers. Such soils swell when given an access to water and shrink when they dry out. The most common and economical method for stabilizing these soils is using admixtures that prevent volume changes. In this study the effect of using Bigadic zeolite (boron by-product) in reducing the swelling potential is examined. The expansive soil is prepared in the laboratory by mixturing kaolinite and bentonite. Bigadic zeolite (boron by-product) is added to the soil at 0 to 25 percent by weight. Grain size distribution, Atterberg limits and swell percent and rate of swell of the mixtures are determined. Specimens are cured for 7 and 28 days. As a result of the experimental study, it was seen that addition of Bigadic zeolite (boronby-product) decreased swelling potential and rate of swell of the artificially prepared expansive soil specimen at laboratory conditions. The swell percentage and rate of swell of the stabilized specimens are affected positively by curing.

Niksar (Tokat), is an urban area located in a seismically active zone of Turkey. The aim of this thesis is to prepare GIS-based microzonation map of Niksar settlement area for the purpose of urban planning. Liquefaction, activity, slope, aspect, fault proximity, ground amplification and lithology are considered during the overlay analysis by using Multicriteria Decision Making Analysis (MCDA) of Simple Additive Weighing (SAW) and Analytical Hierarchical Process (AHP) methods. Based on the evaluations, the study area is divided into four different zones, namely, (1) areas suitable for settlement / (2) provisional settlement areas / (3) areas requiring detailed geotechnical investigation / (4) unsuitable areas. Two microzonation maps obtained from analyses are compared. Maps prepared by SAW and AHP methods are found to be consistent with each other. However, the microzonation map prepared by AHP method is recommended for the purpose of urban planning because it has the ability to check consistency itself.

Groningen Gas Field is located within the southern part of the South Permian Basin in the northeast Netherlands. Since several wells have been producing from the Carboniferous-Permian Petroleum System, the field is considered as mature for hydrocarbon exploration. More detailed work is necessary to evaluate further exploration and development opportunities. Thus, evaluation of the subsurface has been carried out as part of the petroleum system concept by using the basin modeling. In this study, seismic interpretation was performed by using 3-dimensional seismic and borehole data with Petrel software in order to understand stratigraphy and structural settings of the area. PetroMod basin analysis software has been used for 1-dimensional and 2-dimensional basin modeling study by integrating interpreted geophysical, geological and geochemical data. Results show that the most recognized traps were formed during pre-Zechstein, and the major generation-migration and accumulation of hydrocarbon commenced during Middle Jurassic and continues to the present time. Since the timing of main hydrocarbon generation varies spatially and has begun after trap formation, both early and late migration enhances the potential of the porous Upper Rotliegend reservoirs. Prospective hydrocarbon traps may occur in the southwestern regions of the basin due to shallower depth of burial. On the other hand, all local structural highs that formed as a result of salt movement create potential traps in the region.