Guidon AGS™ Service Helped Extend the Decline Curve for PEMEX Assets

Overview 

In offshore Mexico, PEMEX tried to increase production from mature wells past their production peak. PEMEX wanted to increase oil production in one field without increasing water flow. For the other asset, PEMEX needed a way to divert acid effectively due to extremely high permeability contrasts. 

PEMEX turned to Halliburton, which recommended using its Guidon AGS℠ acid guidance system for both fields. The Guidon AGS service diverts acid from highly permeable zones to less permeable ones. The service can increase oil production with the potential to actually decrease water production in some wells. This marked the first time the Guidon AGS service was used offshore, helping PEMEX overcome the challenges in both assets and increase oil production.

Challenge: PEMEX Wanted to Increase Production in Offshore Fields 

Two mature assets in offshore Mexico owned by PEMEX had passed their production peak. One asset included more than 30 wells. Most standard acid treatments in this field resulted in increased hydrocarbon and water production. The acid treatment is very likely to enter the zones already producing water and increase the water production and reduce oil production. PEMEX wanted to increase hydrocarbon production without increasing water production in these wells. 

Solution: Guidon AGS Service Used for First Time Offshore 

PEMEX turned to Halliburton to help solve these challenges. Halliburton recommended its Guidon AGS acid guidance system. This marked the first time Halliburton used the Guidon AGS agent to stimulate production in offshore reservoirs. PEMEX and Halliburton believed this novel acid diverter could successfully redirect acid away from higher water saturation zones, allowing other zones to get the acid treatment and increase oil production. 

The Guidon AGS agent provides highly effective acid diversion without gelling or setting up. It selectively reduces the formation’s permeability to aqueous fluids with minimal effect on oil or gas production. The Guidon AGS agent successfully diverted acid from predominantly water-saturated zones to predominantly oil-saturated zones in these naturally fractured carbonate formations. 

Acid Diverter Eliminated Need for Zonal Isolation 

In previous attempts to achieve uniform placement of acid across all layers, different techniques were used. The most reliable method was the use of mechanical isolation devices, such as straddle packers. This method allowed injection into individual zones. However, this method is not cost-effective and is time-consuming because each zone is treated individually until an entire interval is completed. The Guidon AGS agent is easy to use and cost-effective because it does not require zonal isolation. 

Results: Guidon AGS Service Diverted Acid and Increased Production 

Halliburton treated 30 PEMEX wells with the Guidon AGS agent. The agent increased oil production in all wells treated with the agent, and either maintained or even reduced the water cut in the wells treated with the agent. The average percent increase in oil production was 231%. In addition, 22% showed a decrease in water cut and 67% showed no change.

Overview: Guidon AGS Service Used in Mature Offshore Producing Field 

Halliburton also used the Guidon AGS service in the Abkatun-Pol-Chuck field in the Bay of Campeche that was one of PEMEX’s most important assets in Mexico. PEMEX wanted a way to extend the decline curve and increase production in these wells. 

Challenge: PEMEX Needed a Way to Keep Acid Out of Highly Fractured Zones 

As with all acidizing programs, a critical factor in the success of the treatments is even distribution of the acid among all productive zones. However, this is difficult because most producing wells have layers of varying permeability. Acid tends to enter zones with the highest permeability. PEMEX’s complex in the Bay of Campeche had a huge permeability contrast and other diversion methods were not performing. The Guidon AGS agent effectively diverted acid treatment from highly fractured zones where acid was not needed to other areas where the acid was more effective. The agent adsorbed to the formation, reducing its permeability to aqueous fluids like acid and diverting it to targeted zones. 

Solution: Guidon AGS Service More Effective Than Other Methods 

Halliburton treated 55 PEMEX wells in offshore fields in the Bay of Campeche with the Guidon AGS service and other diverters. To compare the effectiveness of this new method against other options, PEMEX conducted a comparative test. Other wells in the complex were treated with a foam or a gel to divert acid. Production on the wells treated with the Guidon AGS service increased to more than 11,000 barrels of oil per day in some cases. In addition, wells treated with the Guidon AGS agent had an average productivity index (barrels of fluid per day per psi of drawdown) of 349, almost double that of the other acid diversion methods. 

Results: Success of Service Led to Expansion of Guidon AGS Service 

The success of the Guidon AGS acid guidance system in both fields convinced PEMEX of its effectiveness and led to dozens of other projects with the client. They proved so successful, reliable and cost effective that Halliburton has now expanded the use of the Guidon AGS service worldwide.