Abstract

This paper describes the application of openhole Multi-Stage Fracturing completions with swelling packers and sliding sleeves in the carbonate formation of the Karachaganak field, Kazakhstan. It focuses on the benefit brought to the field by the new completion concept. It also explains the methodology and strategies adopted for executing fracturing stimulation within the limited capacity of material supply and logistic challenges in a harsh environment and remote location.

The completion strategy in the Karachaganak field has been evolving from simple vertical (cased hole / openhole) completions, to selective and non-selective multilateral wells, and most recently to extended horizontal wells. Acid stimulation, both matrix and fracturing, are the common method to improve well productivity in this highly heterogeneous formation. Multi-stage acid fracturing was identified as a potential technique to achieve the objective of unlocking production from extended horizontal openhole section in the low permeability regions of the field.

The new completion technology combines the use of swelling packers and ball activated stimulation sliding sleeves (with a mechanical shift option) to achieve intervention-free multi-stage fracturing in the openhole. The swelling packer and stimulation sliding sleeve provide a reliable isolation and fracturing point respectively for a selected fracturing zone.

Post-stimulation inflow profile indicated contribution from almost all the treated zones as a result of diversion effectiveness. The first application of this technology in one of the Karachaganak wells resulted in a significant initial production and the well was recorded as one of the best Object 3 oil producers in the field. Ten (10) subsequent completions were deployed after the first installation. The stimulations performed to date have shown that Swelling Packers are reliable for zonal isolation and allow a good coverage of the entire horizontal section.

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