Schlumberger

Case Study: PURE System Increases Saudi Gas Well’s Injectivity

Dynamic underbalance and clean perforations decrease skin value to almost zero

Challenge: Maximize injectivity in gas well with dual casing to allow hydraulic fracture treatment while keeping fracture pressure below 17,000 psi.

Solution: Use PURE clean perforations system to improve injectivity and lower injection pressure.

Result: Increased injectivity from less than 2 bbl/min to 24.6 bbl/min; reduced skin value from a predicted 7 with conventional perforating systems to nearly zero.

Conventional injection technique yields low output

An operator was planning an injectivity test prior to fracturing one of its gas wells. The fracture gradient was high at between 0.91 and 0.96 psi/ft—almost reaching the completion limit of 17,000 psi. The well had dual casing and was initially perforated with a 33⁄8-in perforating gun.

After a total of 20 ft was perforated, an injectivity test confirmed that less than 2 bbl/min could be injected before maxing out the bottomhole pressure. The operator began looking for a solution to maximize the well’s injectivity to allow hydraulic fracture treatment to optimize production.

Dynamic underbalance of PURE system selected as injectivity solution

After consulting with Schlumberger, the operator chose to deploy the PURE system to create dynamic underbalance conditions and to maximize perforation cleanup. Along with the PURE system, SPAN Schlumberger perforating analysis was used to analyze the well and reservoir conditions. The SPAN analysis results suggested the skin factor could be reduced from 7 with standard perforating systems to a value very close to zero with the PURE perforating system.

Injectivity results exceed operator’s expectations

After perforating with the newly configured gunstring, the injection rate increased to 24.6 bbl/min, exceeding expectations.


Download: PURE System Increases Saudi Gas Well's Injectivity (0.14 MB PDF)

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Reconfigured Gunstring Increases Injection Rate to 24.6bbl/min

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PURE Perforating System for Clean Perforations
The PURE system creates clean perforations by optimizing the dynamic underbalance that occurs after charge detonation. Visit PURE System page