A decade of oriented perforating for sand control

A decade of use on the Norwegian shelf confirms the method’s effectiveness in suitable fields, and offers insight into the shelf’s in situ stress conditions.

Jamie Stuart Andrews, Håvard Jøranson and Arne Marius Raaen, StatoilHydro

Oriented perforation has been used to prevent sand production on many of StatoilHydro�s fields on the Norwegian Continental Shelf (NCS) during the last decade. As an alternative to mechanical sand control measures, the operator has chosen oriented perforating in several platform and subsea developments, mature fields and HPHT reservoirs.

Before 2000 the tool design for passive orientation was generally inadequate, and misalignment of perforations was common. However, collaboration between operators and service companies has led to significant improvements in orientation systems. Several suppliers now offer orientated Tubing-Conveyed Perforation (TCP) systems that are qualified for use by StatoilHydro. Some of these include devices for accurately measuring orientation while perforating.

Several years� experience confirms that good orientation accuracy can be achieved and designed for. Oriented TCP service has shown a good track record even in well sections with sharp doglegs or modest inclination. A large body of production experience from several fields, including fields with over 5,000-psi depletion, confirms that oriented perforating can be a good sand prevention measure in suitable fields. The operator suggests that the field data is an excellent confirmation of its sand prediction models and, more generally, of the in situ stress conditions prevalent on the NCS. Furthermore, the success of oriented perforations indicates a normal faulting pattern on the NCS, in contrast to data that other parties have published regarding the shelf.

BACKGROUND

Despite a very good success rate with mechanical sand control, a guiding strategy in Statoil has been to avoid such completions whenever possible. This is due in part to cost and logistical issues but also to the plugging and productivity decline potential inherent in sand control completions.