Abstract
Bachaquero-01 is one of the biggest heavy oil reservoir (11. 5 °API, 23511 acres and 6621 MMBO of OOIP) that possesses Petroleos de Venezuela (PDVSA) western division in Maracaibo Lake Basin.
Cyclic steam injection as a development strategy in Bachaquero-01 began in 1971, and until November 1998 a total of 344 wells have been stimulated with 1006 cycles.
In Bachaquero-01 reservoir verticals wells are completed in one, two, three or four oil producing zones, in a range between 80 and more than 300 feet, as a consequence gravity override and steam channeling are two reasons that reduce the efficiency of production in cyclic steam injection. In order to reduce these mentioned effects, a surfactant of the linear ionic-alkyl-aryl sulfonate type (LAAS) has been used, which generates a stable foam that has as objective to block the most permeable areas and to achieve a uniform injection profile in order to stimulate efficiently those zones with low permeability and recovery. This effect has allowed obtaining between 15 and 40% more production per cycle.
This technology was evaluated in 1997 in the horizontal and reentry wells completed in the main sand of the reservoir, with the purpose of obtaining a uniform profile of injection along the whole horizontal section. The production obtained after the period of soaking indicates a very good stimulation in this type of wells, for that reason its use is being extending in 1998.
This paper presents the results obtained with the stimulation with steam and surfactant carried out to the vertical and horizontal (new and reentry) wells belonging to the Bachaquero-01 reservoir.
