The complete paper describes the test procedures adopted for evaluating various filter cake breaker formulations and the work conducted to develop the systems to be ready for use in two North Sea fields (Field A and Field B). Water injection wells were planned to provide pressure support to oil producers in the two fields, and water-based drilling fluids were selected to drill the reservoir sections for both. The average permeability is 1000 md for Field A and 50–100 md for Field B. A laboratory study was commissioned to evaluate and optimize filter cake breaker systems for use in water injectors to efficiently remove external and internal filter cake to attain matrix injection without the need for backflow to clean the sandface.
Introduction
Field A was commissioned to drill 18 producers and seven water injectors from a semisubmersible drilling rig. Most of the injector wells are high-inclination, long openhole sections. Fluid density of 1.24–1.48 specific gravity (SG) (10.3–12.3 ppg) was required for wellbore stability.
The Field B development plan included drilling 26 producers and 10 water injectors with an average injection rate target of 40,000 B/D of treated, produced water per well.
