Gomez, Max (Pacific Rubiales Energy) | Florez Anaya, Alberto (Pacific Rubiales Energy) | Araujo, Ysidro Enrique (Pacific Rubiales Energy) | Parra Moreno, Wilson (Pacific Rubiales Energy) | Bolanos, Viviana (Pacific Rubiales Energy) | Landaeta, Libia (Pacific Rubiales Energy)
Rubiales and Quifa are the Colombia’s major heavy oilfields (oil gravity ranges from 11.3 to 14.4 °API) with a current oil production of more than 260 MSTB with an oil viscosity ranges from 370 to 730 centipoises. Horizontal well technology is used to drill through unconsolidated sandstones with an active and strong aquifer, under primary depletion. Since 2006, 604 horizontal producer wells have been drilled and completed using slotted liner in open hole.
The high water production rate from the beginning of the operation in the horizontal wells is the main problem to be controlled in the Rubiales and Quifa fields, due to the high cost of produced water treatment and other factors. Water production is inevitably associated with the oil production; however one of the biggest challenges is to delay the water production as much longer as possible.
Rubiales and Quifa actually have a large number of closed wells that have reached its economic limits, mainly by high water production. This production imbalance is being addressed in the new horizontal wells, using inflow control devices (ICDs). The ICDs is placed in each screen joint to balance the production influx profile across the entire lateral length and compensate the permeability variation and therefore the productivity of each zone.
In 2012, a pilot test has been designed and implemented in Rubiales field with three horizontal wells using passive ICDs completion. The performance of the ICD’s is found to reach the highest cumulative oil production compared to neighboring wells. The main purpose of this paper is to detail the selection process design and results evaluation for the use of the passive ICDs in horizontal wells at Rubiales and Quifa Fields, heavy oil reservoirs.
Rubiales and Quifa fields are the major oilfield in Colombia; two heavy oil reservoirs (API in the range 11.3° to14.4°) with unconsolidated sandstone formation with high permeability, however, there is low productivity in vertical and deviated wells, caused by formation damage from drilling fluids, and cased gravel packing completion.
These two formation damages have been mitigated by applying a successful gravel packing technique in both vertical and deviated wells. On June 30, 2014, the oil production rate was 186 thousand BOPD, of which 14.5 thousand BOPD (7%) came from 162 vertical and deviated wells with the successful gravel packing technique.
The successful gravel packing technique consists on first running a standard cemented 7 inches casing and then cutting the casing in the production zone and enlarge the open hole section from 8.5 inches to 13 or 16 inches diameter to remove cement bond overpassing the washout. Finally, the enlarged open hole section is gravel packed with mesh 20-40.
The completion technology purpose is to increase the well productivity, isolating high water saturation intervals on both top and bottom of the oil zone, reducing the skin damage. Before 2007, 30 wells were completed with conventional cased hole gravel packing. Most of these wells were damaged having to be frequently stimulated with organic treatment; 14 of these wells have been re-completed using gravel packing technique. The results show an increase in the productivity index from 2 to 5 times, compared to conventional completion and showing a maximum increase in total fluid rate from 600 BFPD to 3000 BFPD.
Finally, some examples are presented comparing gravel packing using this technique and the cased hole completion method. Operation procedures, advantages, limitations, and production results are presented in individual well performance comparisons. The successful application of this technology has contributed to increase oil production in Tubiales and Quifa fields development and it has also been extended to other analogue fields.
Florez Anaya, Alberto (Pacific Rubiales Energy) | Araujo, Ysidro Enrique (Pacific Rubiales Energy) | Uzcategui Rivas, Myriam Elizabeth (Pacific Rubiales Energy) | Parra Moreno, Wilson (Pacific Rubiales Energy) | Lavado Quinones, Rosa (Pacific Rubiales Energy)
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.