As development of unconventional resources typically requires deeper and usually longer wells, operators around the world find themselves working in increasingly challenging environments. Two technologies in particular—ball-activated limited entry and HP/HT systems—are being increasingly deployed in the Middle East to help operators boost production from existing fields and access new reservoirs.

Ball-activated limited entry systems

Identifying technologies that can both increase production and improve efficiency to reduce costs is a key step in turning a contingent resource into a proven commercially recoverable reserve.

Acid stimulation is one method to increase hydrocarbon production and long-term reservoir drainage from tight carbonate reservoirs; however, the stimulation treatment is only as effective as the placement method. Packers Plus’ QuickFRAC multistage completion system combines the limited entry aspect of cemented liner completions with the efficiency of a ball-drop system.

A configuration of RockSEAL H2 packers and several QuickPORT V sleeves allows multiple individually isolated stages to be grouped together in a single treatment zone. Using a designed pump rate to maintain the desired pressure differential, the system evenly distributes batch fractures to the select zone. After stimulation, the well can be immediately flowed back and put on production.

An early success with the system occurred in Turkey as part of a pilot project to shift development from vertical to horizontal wells. Two of the four wells in the pilot project used the QuickFRAC system to deliver the matrix acidizing completion. All stimulations used three concurrent sub-stages of 15% hydrochloric (HCl) slick acid, 15% HCl gelled acid, 15% HCl self-diverting acid and 2% potassium chloride spacers. The combined volumes of these sub-stages were successively increased throughout the job. Maximum treating pressures were calculated using an estimated formation breakdown gradient of 1 psi/ft, fluid hydrostatics calculated for stimulation fluids and estimated friction pressures.

Results of the pilot project indicated a successful stimulation and a significant increase in production from all four horizontal wells compared to offset vertical wells.

HP/HT systems

The Packers Plus Titanium XV line of products is specially designed for differential pressure treatments up to 15,000 psi and has been run in several HP/HT formations around the world.

Two recent wells in Oman pushed these HP/ HT capabilities to their limit and required a customized solution with a working differential pressure of 15,000 psi (max design pressure rated to 18,000 psi). Having used cased-hole plug-and-perf systems previously, the operator wanted to trial an uncemented openhole system that would increase near-wellbore conductivity, reduce treating pressures and be robust enough to function in temperatures up to 176 C (350 F).

Following a successful installation of a six-stage system on the first well, the first three stages were stimulated, and the well was flowed back. IP from those stages surpassed expectations and prompted the operator to forego the remaining three stages in the first well. Best practices from the first installation were transferred to the second completion, leading to significant improvement of installing and stimulating the four-stage openhole multistage lower completion.

The specially designed Titanium XV RockSEAL packers deployed for these jobs maintained zonal isolation throughout the stimulation despite the harsh conditions. The effectiveness of the packers was verified with radioactive tracers.

By delivering the planned stimulation program in challenging formations, high-efficiency HP/HT completion systems are helping operators deliver some of the top performing wells in their fields.

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