Wellbore temperature assessment for generic deepwater well in Blacksea and mitigation of hydrate dissociation risk

Öztürk, M Tarık
Drilling operation expanded through deep water environments starting from mid-1980. As water depth increased, hydrate bearing formation in the shallow ocean floor is observed and that started to cause problems during drilling and production operations. Problems due to hydrate dissociation and forming during operations are also reported by the companies working in those environments many times. Although there are several factors affect the dissociation of shallow hydrate bearing sediments, heat flux from deeper sections of the well through shallower section during the operation is the major one. In order to mitigate that risk in this study, Black Sea is taken as a reference drilling environment. Hydrate phase boundary of the region is calculated via using actual temperature and pressure data gathered during drilling operations. Generic wellbore is defined and common drilling operation sequence is simulated in this defined wellbore. Heat transfer from section target depths to the shallow wellbore section is observed during simulations. Reducing effect of low inlet temperatures and a low circulation rate on wellbore temperatures are determined. In addition positive effect of riser boosting on depressing wellbore temperature in the well head is determined. Black Sea deep water hydrate stability zone is determined between 2210-2275m. Target depth limitation for generic well designed in drilling operations is determined as 4600m.


Economical impact of a dual gradient drilling system
Peker, Merter; Parlaktuna, Mahmut; Department of Petroleum and Natural Gas Engineering (2012)
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 ...
Determination of cuttings transport properties of gasified drilling fluids
Ettehadi Osgouei, Reza; Mehmetoğlu, Mustafa Tanju; Özbayoğlu, Mehmet Evren; Department of Petroleum and Natural Gas Engineering (2010)
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 ...
Experimental investigation of cuttings transport in horizontal wells using aerated drilling fluid
Gül, Sercan; Parlaktuna, Mahmut; Kuru, Ergün; Department of Petroleum and Natural Gas Engineering (2017)
A new experimental approach has been introduced in this thesis for the cuttings transport in horizontal wellbores with the introduction of drag reducers into the aerated drilling fluids. Advanced Flow Loop System (annular test section of 21 ft. long 2.91-in. ID transparent casing and 1.85 in. OD inner drill pipe) in Middle East Technical University Petroleum and Natural Gas Engineering Department have been used for the experiments. The liquid phase has been water and water-PHPA copolymer mixture where the g...
Trajectory estimation in directional drilling using bottom hole assembly(bha) analysis
Doğay, Serkan; Kök, Mustafa Verşan; Department of Petroleum and Natural Gas Engineering (2007)
The aim of this study is to combine the basic concepts of mechanics on drill string which are related to directional drilling, thus finding a less complicated and more economical way for drilling directional wells. Slick BHA, which has no stabilizers attached and single stabilizer BHA are analyzed through previously derived formulas gathered from the literature that are rearranged for this study. An actual directional well is redrilled theoretically with a slick BHA and a computer program is assembled for c...
Real-time-optimization of drilling parameters during drilling operations
Eren, Tuna; Özbayoğlu, Mehmet Evren; Department of Petroleum and Natural Gas Engineering (2010)
Real-time optimization of drilling parameters during drilling operations aims to optimize weight on bit, bit rotation speed for obtaining maximum drilling rate as well as minimizing the drilling cost. The process is considered to be formation specific. A statistical method such as multiple linear regression technique has been used for the drilling optimization. An extensive literature survey on drilling optimization was conducted for this research study. A model is developed for this purpose using actual fi...
Citation Formats
M. T. Öztürk, “Wellbore temperature assessment for generic deepwater well in Blacksea and mitigation of hydrate dissociation risk,” M.S. - Master of Science, Middle East Technical University, 2011.