Improved Heavy Oil Recovery by Drilling Horizontal Wells in Rubiales Field, Colombia

Abstract

Abstract The purpose of this paper is to report the methods used and results of the Rubiales Field development, located onshore in "Los Llanos" Basin in Colombia. Horizontal well technology was used to drill through unconsolidated sandstones with an active and strong aquifer, under primary heavy oil depletion with an oil gravity ranging from 11.3 to 14.4 °API. Horizontal wells allow oil production rate increases, water production delays, oil recovery factor increases, and sand production decreases. The Rubiales Field has an OOIP of 4,608 million STB oil, and a wide reserves volume of 385 million STB oil was certified in June 2011 with horizontal well technology. On 31 December 2011, the cumulative oil production of the field was 163 million STB oil (3.7% recovery factor). Currently, the oil production rate is 180.3 thousand BOPD, of which 159.6 thousand BOPD (88.5%) come from horizontal wells. The actual operator company has implemented an aggressive campaign, drilling over 296 horizontal wells from 2006 to 2011. Since 1981, 202 vertical wells and 7 deviated wells have been drilled. In Areniscas Basales Unit, the average production rate reached a peak of over 2,000 BOPD for each completed horizontal well. This production rate is almost 7 times that of the neighboring vertical wells production. The placement of the producer horizontal wells has been optimized in the Rubiales Field in locations where the net pay is less than 30 feet by implementing the use of the azimuthal resistivity log, which allows for real-time mapping while drilling up to a distance of 20 feet. In December 2011, 27 horizontal wells were drilled using this technology. The global production rate for these wells is currently 17.5 thousand BOPD. Because of the success of these horizontal wells, the operator company also implemented this technology at the Quifa Field, discovered in 2008, which is an extension of the Rubiales Field. The oil production rate at the Quifa Field in December 2011 was 39.4 thousand BOPD.