Cantarell, which is an offshore complex of fields in the Bay of Campeche, is the most important complex in Mexico and is the second-largest producing field in the world. It is comprised of five fields, with the main pay zones consisting of highly fractured, vuggy carbonate formations from Jurassic, Cretaceous and Lower Paleocene geological ages. Matrix acidizing has always been the main stimulation process used to improve production from these carbonate reservoirs and this is especially the case now that this mature complex has reached its production peak. As with all acidizing programs, a critical factor for success of the treatments is distribution of the acid between all productive zones. Since most producing wells are not homogeneous and contain layers of varying permeability, even distribution of the acid is a difficult task. In addition, the water saturation of the various zones has a major effect on the acid distribution. Since acid is an aqueous fluid, it will tend to predominantly enter the zones with the highest water saturation, in many cases resulting in increased water production. This brings with it the multitude of problems associated with high water production. This paper will present the results of approximately 55 high permeability wells ranging from 1,000 to 6,000 md, which have been acidized using a novel acid diverter based on associative polymer technology (APT). This polymer inherently reduces the formation permeability to water with little or no effect on the permeability to hydrocarbon. Data from production logs from several of the treated wells will be presented, which show excellent oil production distribution along the perforated intervals. In addition, production logs will also be shown for wells acidized with other diverters, such as foams and in-situ crosslinked acid, which showed poorer results. Introduction Cantarell Field The Cantarell field is the second-largest oilfield in the world behind the Ghawar field in Saudi Arabia. It is located offshore in the Gulf of Mexico, 47 miles northeast of Ciudad del Carmen, Campeche. The main hydrocarbon zones in Cantarell are highly fractured carbonate formations from the Jurassic, Cretaceous and Lower Paleocene geological ages (Fig. 1). The field is made up of a number of subfields or fault blocks, with the main fields being Akal, Chac, Kutz, and Nohoch. Production started in 1979 and reached a peak of 1.1 million B/D in 1981 from 40 oil wells. By 1994 the production was down to 890,000 B/D. One year later it was producing 1 million B/D due to the addition of new platforms and wells and a nitrogen injection program. This program was capable of injecting a billion ft3/day of nitrogen to maintain reservoir pressure. By 1996 the field was producing 2.1 million B/D.
This paper presents a case history of a well in the Ku Field, Gulf of Mexico (Fig. 1) where, for the first time, a water-control treatment combined the use of a relative-permeability modifier (RPM) and a hydrocarbon (HC)-based ultrafine cement slurry. The challenge was to activate the HC-based ultrafine cement before it was lost into a highly conductive channel in a reservoir with high porosity and natural fractures. The HC-based ultrafine cement is mixed to form pumpable slurry, which is inactive until contact with water. On contact with water, the slurry remains pumpable for a period of time before forming a dense, hard set. The system is applicable for high temperatures up to 400°F. The RPM additives are basically solutions of polymers that act because of their adsorption on the walls of the pores, achieving a reduction in water permeability without damaging the oil permeability. This paper documents the pumping technique used in the first well in the offshore Mexico region where the water inlet was controlled with a combination of RPMs and HC-based ultrafine cement. After the treatment was applied, water production was cut from 8 to 0%, which has been maintained for more than 3 years. The benefits to the operator are summarized as follows: Because oil from the Ku field goes directly to sales, quality standards are quite strict and wells with water cuts similar to those presented in this study cannot be produced. Applying the water-control treatments outlined in this study has decreased the water cut and thus allowed the wells to continue production.Production could be maintained at a good pace because the choke had to be reduced to control the flow of water.Application of the documented water-control treatment was a lower cost to the operator than repairs using interventions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.