Candidate Selection

Criteria to qualify a well for treatment includes:

Wells that exhibit a high producing fluid level, limited by equipment, and are not pumped off, even at high total fluid rates.
A high water-oil ratio, or (WOR).
An indication of good remaining oil column or mobile oil saturation. A well which has oil buildup behind the tubing which can be flushed out by circulating the well is an excellent candidate.
The well should be relatively high on structure.
The well should have had a relatively high initial production rate, and a good cumulative production history, demonstrating a significant amount of original oil in place.

Ideal Formation Characteristics
Carbonates (Dolomites & Limestones)
Highly fractured (Naturally)
High permeability contrast within produced interval
Bottom water drive
Required Information for Treatment Design
Production data (Current)
Completion data (Open Hole or Perforated)
Lithology (Carbonate or Sandstone?) (Naturally fractured) (Degree of permeability variation) (Contrast)
Logs and core analysis if available
Water analysis (Produced water)
Reservoir temperature
Preparation for Treatment
Proper cleanup is critical for success. (Acidize, Swab, Clean out Wellbore)
Pull rods and tubing
Test tubing (Steam clean if necessary)
Run and set tension packer +/-1 joint above interval to be treated
Acid job to clean up iron sulfide, scale, etc. (This step is critical to assure polymer injectivity into water-bearing zone)
Pre-treatment gel scan with mixing water to determine chemical formulation
Treatment Procedure
Injectivity Test - usually 2% Kcl water with premium biocide and surfactants
Calibration of metering systems to deliver proper chemical formulation
Start polymer injection-correlation of mixing systems
Periodic sampling of mixture during treatment/quality control/determine gel times
Treatment log-modified Hall plot-Monitor injection rate and pressure
Moderate pressure buildup throughout treatment is desirable
Excessive or rapid pressure response indicates plugging action (Reduce injection rates or terminate treatment)
Oil post-flush with oil-soluble corrosion inhibitors and emulsion preventers
Shut well in 3-5 days to assure maximum development of gel strength