Economical impact of a dual gradient drilling system

Peker, Merter
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%.


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...
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 ...
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...
Wellbore temperature assessment for generic deepwater well in Blacksea and mitigation of hydrate dissociation risk
Öztürk, M Tarık; Parlaktuna, Mahmut; Department of Petroleum and Natural Gas Engineering (2011)
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 dee...
performance analysis of drilling fluid liquid lubricants
Sönmez, Ahmet; Kök, Mustafa Verşan; Department of Petroleum and Natural Gas Engineering (2011)
Excessive torque is one of the most important problems in oil/gas drilling industry. Friction between wellbore/casing and drill string causes excessive torque. This study discusses performance analysis of drilling fluid lubricants, which are used as friction reducers in well-bore. Three different types of commercial chemical lubricants, which are fatty acid and glycerid based, triglycerid and vegetable oil based and polypropylene glycol based, diesel oil, and crude oil, which consists of different API gravi...
Citation Formats
M. Peker, “Economical impact of a dual gradient drilling system,” M.S. - Master of Science, Middle East Technical University, 2012.