Saudi Arabia: Exceptional depth control critical for accurate placement in seven stage selective stimulation job

Tool in operation:

The candidate well was a recently sidetracked oil producer in the Kingdom of Saudi Arabia (KSA). Due to the abundance of carbonate reservoirs in KSA, selective acid stimulation has the potential to increase production significantly, while simultaneously reducing the treatment fluid volumes and overall stimulation cost.

The Target CHALLENGER™ Straddle Tool was selected for this operation to provide real-time pressure and temperature data and due to the requirement for very accurate downhole tool positioning.

Due to relatively low expected treatment pressures, rates and volumes, the operation utilised conventional 2.0” Coiled Tubing (CT) surface equipment and a CT internal cable resistant to acid.

Several nipple sizes was passed before entering the near horizontal 4.5” liner. Using the casing-collar-perforations-locator (CCPL) all perforation intervals and blank spaces in between were identified. Exceptional depth control was critical for accurate placement of the electric straddle packers, since blank pipe sections in between the perforation intervals were only 2ft long.

During the acid stimulation the tension-compression sub provided real-time information to surface regarding the effective forces acting on the bottom hole assembly (BHA). Being able to keep the electric straddle packers securely in place during the treatment has been contributing to avoiding unintentional BHA movement and hence reduced risk for packer element damage.

Since all functions of the Target CHALLENGER™ Straddle Tool are electric operated, controlled from surface through the CT internal cable, the packers will remain set when pumping is stopped. Several observations periods without pumping confirmed pressure isolation behind the casing, or loss of pressure integrity for other perforation intervals. Pressure sensors are installed above and below the packers of the electric straddle tool, as well as in between. The information gained can contribute towards correct perforation spacing for newly drilled wells and maximising production.

Result

All 7 perforation zones were successfully straddled and acid stimulated in one run