Horizontal Well Placement in Thin Pay Zone and High-Permeability Heavy oil Reservoir in Rubiales and Quifa Field
Florez Anaya, Alberto1; Araujo Paz, Ysidro; Lavado Quiñones, Rosa; Zamora Guevara, Henrry; and Dacol Fuentes, Sergio
Rubiales and Quifa Field, a heavy oil field (API Gravity 12.3) is located in Llanos Orientales basin of Colombia in South America. Field consists of one sandstone reservoirs of Terciary, Carbonera Formation-Areniscas Basales. The reservoir is highly heterogeneous, thinly bedded, unconsolidated with high viscosity and strong aquifer support. The field is on production since July 1981 and the current oil production is 270,000 bpd.
Horizontal wells were considered the best solution for improving the well productivity in those cases with "thinly bedded", heavy oil field with objective for tapping the bypassed oil and delaying the water production while controlling the sand production due to low drawdown pressure and increased exposure to the reservoir. The placement of the producer horizontal wells has been optimized in the Rubiales and Quifa Fields in locations where the geological uncertainty is high due to low correlation between vertical wells, low information density and low bed thickness of the sandstone to drill, by implementing the use of the azimuthal resistivity log, which allows for real-time mapping while drilling up to a distance of 20 feet and drilling pilot hole to plan the horizontal trajectory.
Rubiales and Quifa oil fields present low reservoir thickness, surrounded by a powerful aquifer. The oil sand is a fluvial system with high stratigraphic complexity that comprises shallow channels interconnecting each other and with vertical stacking of multi-storied channel deposits. Lateral migration of main paleodrainage produced high lateral and vertical anisotropy as a consequence of faces changes. Actually, these issues were part of the reasons why in the 80’s and 90’s Rubiales was considered a marginal oilfield (there were only vertical wells in that time). This is not only because those geological features which allow the oil accumulation due to the permeability barriers, but also because the complex compartmentalization needs the implementation of techniques, procedures and technologies that succeed in transforming apparent problems into favorable factors.
AAPG Search and Discovery Article #90166©2013 AAPG International Conference & Exhibition, Cartagena, Colombia, 8-11 September 2013