A brownfield located in the southwest region of Colombia, in the Upper Magdalena Valley Basin, produces from shallow marine sandstones of the Upper Cretaceous-aged Monserrate Formation. Net pay varies from 50 to 150 ft, with porosity between 17 and 22%, and permeability of 80 to 360 mD. The wells in this field, which has been under water injection since 1997, produce with a high water-cut, which in most cases exceeds 90%.
Water injection has led to inorganic scale, organic scale, asphaltene deposition, fines migration, and the need to treat the wells using hydraulic fracturing and/or matrix acidizing techniques. Conventional matrix stimulation treatments require the use of straddle packers to ensure complete zonal coverage and frequently result in increased water production with no significant increase in oil production, making the treatments uneconomical.
To reduce the cost of and increase the success rate of matrix treatments, a Combined Diverter and Conformance Control (CDCC) fluid was introduced. This allowed the stimulation to be performed when mechanical diversion was not possible due to wellbore restrictions. The CDCC fluid is pumped in alternating stages with the acid system to divert the treating fluid and provide water conformance control.
A recent stimulation campaign, using the CDCC fluid in this field, resulted in a 30% increase in oil production while reducing the water cut by 10%. The average cost of the treatments was reduced by 27%, when compared to conventional treatments. This has led to a reassessment of the economics of the field, with the possibility of recovering an additional ~3% of the reserves in place. The plan is to treat routinely underperforming wells, irrespective of the water cut.
The ability to increase economically the oil production in this marginal field has led to a reassessment of other similar fields approaching their economic limit.