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245	0	0	_aLowering the viscosity of Doba - Chad heavy crude oil for pipeline transportation _bThe hydrovisbreaking approach
270			_a19/11/2008 ; 21/04/2005
300			_a13 p.
520			_aTranscripción del resumen publicado por el autor: This study was instigated in view of the recent commercial exploitation of the Doba oil field in landlocked Chad, which is a region from which crude oil is extracted and expected to be routed to the Atlantic shore through pipeline transportation. Thus, nonisothermal kinetic hydrovisbreaking tests of Doba crude oil were conducted in a mechanically stirred baffled autoclave reactor under various conditions to alter the rheological properties of the treated crude. The crude hydrovisbreaking kinetics was modeled based on the four-parameter reaction severity concept ( , y, E, ßo), as a function of the conversion in polyaromatics and polar maltenic subfractions. The hydrovisbreaking of Doba crude was observed to be a pseudo-first-order reaction (i.e., in excess of H2), with respect to the polyaromatics and polar maltenic conversion. The following assortment of kinetic parameters was identified under noncatalytic hydrovisbreaking conditions: heterogeneity coefficient, y = 1; characteristic temperature, = 29.95 K; and activation energy, E = 140.9 kJ/mol. Four viscosity mitigation scenarios involving catalytic (FeS, MoS2) and noncatalytic hydrovisbreaking of Doba heavy crude oil were investigated. It was found that the minor proportions of the fractions that distilled before 250 °C and the small asphaltene yields marginally affected the crude viscosity. It was therefore determined that it is possible to meet the viscosity specification for pipeline transportation via (noncatalytic) hydrovisbreaking, which requires neither predistillation (topping) nor post-deasphalting units. The treated crudes and the syncrudes (mixtures of untreated and treated crudes) were observed to exhibit nonelastic viscous Newtonian behavior over the temperature range typical of crude transportation via pipeline. Treated crudes at 440 °C for 25 min and syncrudes that were the result of mixing 50 wt % of untreated crudes with crudes treated at 460 °C for 15 min yielded kinematic viscosities within the pumping specifications (i.e., = 25cSt @ 50 °C). The use of catalysts led to even lessviscous maltenes subfractions; however, post-deasphalting was required, because the catalyst-coke mixture, as well as asphaltenes, inflated the viscosity above the norm. An iron sulfide catalyst outperformed a molybdenum sulfide catalyst, in terms of the deasphalted crude viscosity. Aging tests over two-month periods indicated that the higher the treatment severity, the more stable the viscosity of the Doba treated crudes, which is potentially compatible with the residence times of syncrudes within the 1050-km-long transportation pipeline between Chad and Cameroon.
773	0		_tEnergy & fuels _gVol. 18, no. 4 (jul./agos. 2004) ; p. 1156-1168
942			_cARTICULO
100	1		_aDehkissia, Soumaine _934503
100	1		_aLarachi, Faical _934502
650		0	_aCrudos pesados _936040
650		0	_aPetróleos pesados _922736
650		0	_aTratamiento de petróleos pesados _94907
650		0	_aViscosidad _91954
650		0	_aViscosity breaking _936041
650		0	_aHidrocraqueo _91968
650		0	_aHidrogenación _92779
650		0	_aTransporte de petróleos pesados _910594
650		0	_aOleoductos _9209
650		0	_aDinámica de fluidos _960
700	1		_aLarachi, Faical _934502
999			_c164364 _d164364