Squeezing is routinely employed by Statoil as a means of maintaining well productivity and avoiding safety issues related to downhole safety valve scaling. In the majority of cases, squeezing maintains well production through minimisation of scale related downtime. However, it has been observed occasionally by Statoil that the benefits of scale prevention by squeezing can be outweighed by the detrimental impact on well productivity. While there have been several articles covering specific elements of a squeeze operation that have affected well productivity, little has been published that attempts to completely describe squeeze related, production impairment mechanisms. This paper will aim to address this gap by demonstrating how squeezing, in some cases, can have an adverse impact on well productivity and highlight the remedial or preventative methods that have been utilised.

A review of the squeeze related, production impairment mechanisms from Statoil operated fields show that they can be related to near wellbore formation, alteration in the reservoir production characteristics or completion design. Physical formation damage mechanisms include

  • Squeezing of sensitive reservoirs (fines mobilisation and clay swelling)

  • Scaling of production intervals due to incorrect inhibitor placement

  • Viscosified inhibitor formation damage

  • Damage related to precipitation squeezes

  • Increased sand production after squeezing

Liquid formation damage mechanisms include

  • Squeeze related relative permeability alteration causing increased water cut and reduced oil rates.

  • Water blocks and emulsion formation due to squeezing of an aqueous treatment into an oil producing or water sensitive interval.

Other examples of squeeze related productivity impairment are screen and gravelpack blockage while an indirect effect are lift problems after squeezing in wells with depleted reservoir pressure. In all instances, the economic costs of lost production can far exceed those of actually performing the squeeze. Case histories will be used to illustrate the productivity impairment mechanisms and methods used to overcome these along with lessons learned.

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