Improvements in Downhole Chemical Delivery: Development of Multifunctional Proppants
Ceramic proppants can provide the highest fracture conductivity under most conditions relative to natural frac sand and resin coated sands. However, regardless of proppant type or the state of fracture conductivity at the time of the hydraulic fracturing treatment, the fracture conductivity and well performance can be impaired and jeopardized by production related events including inorganic scaling (i.e. barium sulfate, calcium carbonate, etc.) or hydrocarbon depositions (i.e. paraffin, asphaltenes). Current solutions to these post-hydraulic fracture related production problems include liquid inhibitor additions to the frac fluid, solid inhibitor additives to the proppant slurry, post frac chemical squeezes, downhole chemical injection and periodic clean-outs, among others.
An improved chemical delivery method has been introduced which utilizes porous ceramic proppants to function both as a proppant and chemical delivery system. Standard ceramic proppants are manufactured to eliminate internal pellet porosity to the greatest degree possible as the presence of porosity can reduce pellet strength and thus negatively impact conductivity – the primary purpose for choosing a ceramic proppant in the first place. Previous uses of porous ceramic proppants for chemical delivery have in many cases sacrificed conductivity. However by tailoring the type of substrate and degree of porosity present in the proppant grain, an addition of porous proppant to standard proppant can be achieved that does not negatively impact conductivity. This porous component of the proppant pack can then be infused with a chemical – such as a scale inhibitor – to provide a multi-function proppant that provides both designed conductivity and efficient chemical delivery.
This paper will describe how pellet porosity and substrate type can be tailored to avoid negatively impacting conductivity along with the benefits of using a chemically infused ceramic proppant as a vehicle for downhole chemical delivery relative to other established chemical treatment methods. Types of chemicals that may be considered for use in this fashion include scale, paraffin and asphaltene inhibitors as well as others. The chemically infused proppants are designed to facilitate a slow release of the desired chemical in order to provide long term effective application. This type of delivery system has distinct advantages over other approaches to chemical treatment.
Author(s): Robert J. Duenckel, CARBO Ceramics Inc.; Joshua G. Leasure, CARBO Ceramics Inc.; Terry Palisch, Carbo Ceramics Inc.