Yönlü ve yatay kuyularda delme hızının tespiti için bir model.

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 & Young’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 ±25 % when compared with the field data.M.S. - Master of Scienc

Gaz-sıvı karışımlı sondaj akışkanlarının kesinti (kırıntı) taşıma özelliklerinin tayini.

The studies conducted on hole cleaning have been started with single phase drilling fluids for vertical holes in 1930’s, and have reached to multiphase drilling fluids for directional and horizontal wells today. The influence of flow rate and hole inclination on cuttings transport has been well understood, and many studies have been conducted on effective hole cleaning either experimentally or theoretically. However, neither the hydraulic behavior nor the hole cleaning mechanism of gasified drilling fluids has been properly understood. The aims of this study are to investigate and analyze the hole cleaning performance of gasified drilling fluids in horizontal, directional and vertical wells experimentally, to identify the drilling parameters those have the major influence on cuttings transport, to define the flow pattern types and boundaries as well as to observe the behavior of cuttings in detail by using digital image processing techniques, and to develop a mechanistic model based on the fundamental principles of physics and mathematics with the help of the experimental observations. A mechanistic model is developed with the help of the obtained experimental data. Developed model is used for estimating optimum flow rates for liquid and gas phases for effective cuttings transport as well as for determining the total pressure losses and void fraction of each phase for a given drilling conditions. The v mechanistic model obtained using the experimental data within the scope of this study will be used to develop the hydraulic program and equipment selection to be used in the field during underbalanced drilling applications.Ph.D. - Doctoral Progra

Pressure drop estimation in horizontal annuli for liquid-gas 2 phase flow: Comparison of mechanistic models and computational intelligence techniques

Frictional pressure loss calculations and estimating the performance of cuttings transport during underbalanced drilling operations are more difficult due to the characteristics of multi-phase fluid flow inside the wellbore. In directional or horizontal wellbores, such calculations are becoming more complicated due to the inclined wellbore sections, since gravitational force components are required to be considered properly. Even though there are numerous studies performed on pressure drop estimation for multiphase flow in inclined pipes, not as many studies have been conducted for multiphase flow in annular geometries with eccentricity. In this study, the frictional pressure losses are examined thoroughly for liquid-gas multiphase flow in horizontal eccentric annulus. Pressure drop measurements for different liquid and gas flow rates are recorded. Using the experimental data, a mechanistic model based on the modification of Lockhart and Martinelli [18] is developed. Additionally, 4 different computational intelligence techniques (nearest neighbor, regression trees, multilayer perceptron and Support Vector Machines - SVM) are modeled and developed for pressure drop estimation. The results indicate that both mechanistic model and computational intelligence techniques estimated the frictional pressure losses successfully for the given flow conditions, when compared with the experimental results. It is also noted that the computational intelligence techniques performed slightly better than the mechanistic model. (C) 2014 Elsevier Ltd. All rights reserved