Filtercake Integrity and Reservoir Damage

Abstract

Abstract Filtercake performance is of particular importance in openhole completions where formation impairment cannot be bypassed by perforation. Emphasis is placed on producing a thin, tough and highly impermeable cake to seal the wellbore during drilling. Once completed and the well is brought onstream, the filtercake is required to break down without the need for expensive clean up treatments. Filtercake integrity can then play an important role in the cleanup of a reservoir. Back production is assumed to cause the cake either to detach from the formation or rupture. Cake-rock adhesion and inherent filtercake strength are therefore important in determining how the cake breaks down to allow oil flow. If the cake-rock adhesion is strong compared to the internal strength of the cake, the cake may pinhole, or blister to allow flow. If it is relatively weak the entire cake may lift off cleanly. This latter case may cause further production problems if the cake subsequently seals the completion hardware. This paper presents laboratory data on filtercake strength and its relation to cleanup by back-production for typical reservoir drilling fluids. Critical components are identified. The role of bridging solids particle size in determining the balance between adhesion and rupture strength will be demonstrated. Filtercake design to optimize removal through the exploitation of functional weak links will be discussed. P. 111