Technology Behind the Turnaround at CantarellTue, 01/22/2013 - 14:07
“2012 has been the first year with increasing production for the Cantarell complex since 2004,” says Miguel Ángel Lozada Aguilar, Cantarell Administrator. “This was achieved through the application of new technologies that have not only increased production but also the recovery factors of the fields.” Three multidisciplinary teams were put together with the sole objective of optimizing recovery factors and production rates by using new technologies, implementing best practices available in the industry, and utilizing sound reservoir management policies at the ten fields that belong to the Cantarell Complex. These groups are focused on three different field types, divided by field qualities and specifications: the mature field Akal, the largest and most important field with 2.45 billion bbl of remaining 2P reserves and average production of 234,200 b/d in 2012; developing fields such as Sihil and Ixtoc, which produced 133,300 b/d in 2012; and the mature field of Ek- Balam, which have a proven 2P reserve of 550 million bbl and average production of 49,600 b/d last year.
New technologies and methodologies have been implemented systematically in exploitation processes from geological and dynamic characterization, to drilling and well completion. One of the most successful technologies introduced at Akal is Double Displacement Process (DDP). “When you begin producing, well pressure is very high and water levels are low; however, after removing a substantial amount of oil from a reservoir, a gas cap is created and water levels rise,” explains Lozada Aguilar. DDP reduces water levels that have risen to over 600m above their original level and will help produce an additional 400 million bbl. “We are expecting the gas-oil and water-oil contact to move down at a 15m/year rate, which means that we will be producing 500,000 b/d of water and will be drilling 40 new water producing wells,” Lozada Aguilar explains.
In order to decrease water levels in the Akal field, it is necessary to first install production infrastructure, water treatment plants, gas management and reinjection mechanisms and increase dehydration capacity from 100,000 b/d to 500,000 b/d. Even though this technology is not new to the oil and gas industry, since it has been used effectively around the world to optimize production, it has never been used in a massive complex such as Cantarell.
To increase production in the different fields, engineers are taking advantage of their geologic features and utilizing gravity drainage to naturally allow oil to slip to the bottom of the well and facilitate its extraction. “This strategy has been extremely important because it will allow us to extract as much oil as possible without decreasing the recovery rate. Actually, due to the nature of this process, it would even allow us to increase the recovery rate of fields like Akal because of the resulting decrease in water levels,” Lozada Aguilar details. In order to take advantage of the gravity drainage mechanism in Akal, it will also be necessary to drill up to of 150 new wells, 40% of which will be non-conventional wells, either horizontal or long extended reach wells. There is also a surveillance plan for monitoring the gas-oil and water-oil contact to maintain an optimal oil exploitation window.
Lozada Aguilar explains that in the near future an enhanced oil recovery pilot test will be performed in the Akal field. The technology to be implemented has been developed by Pemex, together with IMP specialists and top petroleum universities from the US. The main purpose of this new enhanced oil recovery technology is to reduce the capillary forces using foams with surfactants. The surfactant has been already designed, as well as the pilot test using laboratory tests and the STARS reservoir simulator. Besides gravity drainage, double displacement techniques, and the creation of multidisciplinary groups as a means to increase production and recovery factors at Cantarell fields, Lozada Aguilar believes that past secondary oil recovery processes with nitrogen injection in the Akal field have not only maintained the reservoir pressure and increased production, but allowed field operators to increase the final recovery factor. “Critics claim that nitrogen injection techniques used at the complex have damaged the reservoirs and decreased recovery rates; however, this is a myth, since there is no evidence of any damage,” he concludes.