Formation-damaging characteristics of mixed metal hydroxide drill-in fluids and a comparison with polymer-base fluids

Horizontal wells are commonly completed without casing and the fluids used to drill said sections can have a significant effect on the production outc ome. Mixed metal hydroxide (MMH)/ bentonite-based fluids are compared to tw o commonly used reservoir drill-in fluids (DIFs) with respect to filter-cak e characteristics and regain in permeability. The MMH fluids are found to p roduce filter cakes with unique features which result in efficient backflow without need for chemical treatment. Return permeability results which equ al or exceed those for more commonly used DIFs raise questions over the con ventional view that bentonite-containing DIFs are harmful to reservoirs.