Heavy-Crude-Oil Upgrading With Transition Metals

Abstract

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 107837, "Heavy-Crude-Oil Upgrading With Transition Metals," by H.R. Nares, P. Schacht-Hernandez, M.A. Ramirez-Garnica, and M.C. Cabrera-Reyes, Inst. Mexicano del Petroleo, and L. Noe-Valencia, U. La Salle, Mexico, prepared for the 2007 SPE Latin American and Caribbean Petroleum Engineering Conference, Buenos Aires, 15–18 April. The full-length paper discusses the effects of some metallic oxides used to upgrade heavy-crude-oil properties. The objective is to increase oil mobility in the reservoir by reducing viscosity and improving oil quality by use of alumina-supported transition metals and liquid-phase transition-metals catalysts derived from acetylacetonate or alkylhexanoate compounds. Heavy crude oil from the Gulf of Mexico (GOM) was studied. Oil gravity was increased from 12.5 to 21 to 26°API, asphaltene content was reduced from 26 to 7 wt%, and distillable fraction was increased by 20 to 30 wt%. Introduction Some of the main problems that heavy crude oil presents are:low mobility through the reservoir because of its high viscosity, which affects the wells productivity index (PI);difficult transportation to the refineries and the high cost of that transportation; andthe low processing capacity in the refineries. For these reasons, it is necessary to enhance the heavy crude oil, both above ground and underground. Some of the main processes used are carbon rejection, hydrogen addition, and physical separation. All these processes are focused on converting oil residues into more-valuable products such as gasoline, middle distillate, and fluid-cracking catalytic feedstock. An interesting alternative to recover the heavy and extra heavy crude oil is downhole catalytic upgrading. This alternative presents several advantages compared with its above ground counterpart such as an increase in the well PI, a reduction in the lifting and transportation costs to the refining center, the production of more-valuable products as a result of the decreases in viscosity values, resins, asphaltenes, sulfur, and metal contents. Some of the most important processes that have been studied to enhance heavy and extra heavy crude oil are steam-drive, cyclic steam injection, steam-assisted gravity drainage, fireflood, and downhole catalytic processes. The main objective of these processes is to decrease the viscosity of the heavy crude oil to improve its flow from the reservoir to the producer well. This viscosity reduction can be achieved by increasing the reservoir temperature or by injecting hydrogen-donor compounds. Two ways to improve the quality of heavy crude oil are hydrocracking and hydrotreating such as aromatic hydrogenation and desulfurization. This removal can be achieved by injection of a catalytic solution [organic metallic compounds of molybdenum (Mo), iron (Fe), cobalt (Co), and nickel (Ni)].