The forming of scale or the migration and intrusion of formation fines and sand into the proppant pack often drastically diminishes the conductivity of frac-packs and propped fractures which can negatively impact well production. This paper describes the development of a new surface modification agent (SMA) that can be applied during frac-packing operations or the remedial treatments of propped fractures or near-wellbore (NWB) formations. Studies were conducted to demonstrate the mechanisms by which this SMA simultaneously inhibits scale formation in the proppant pack while also controlling migration and intrusion of formation sand and fines.
Once coated on the proppant as part of hydraulic fracturing, frac-packing, or gravel pack treatment, or when injected into the proppant pack and formation matrix, this SMA forms a thin film on the particulates, covering the fines and anchoring the particulates in place. The SMA coating also forms a hydrophobic film that encapsulates particulate surfaces, inhibiting chemical reactions that lead to scale formation in pack matrix and subsequent productivity loses.
Experiments using packed beds of proppant, formation sands, and various fines were performed to simulate proppant pack conditions and formation fines before and after remedial treatments. It was observed that SMA treatments formed only a very thin film, which encapsulated proppant or formation particulates and created cohesion between grains, without plugging pore spaces. Additionally, laboratory results demonstrate that SMA treatments can effectively prevent buildup of scale in various sand packs as well as successfully controlling migration of formation fines into proppant packs to maintain fluid flow paths.
In addition to remedial treatments, SMA treatment fluid can be applied while treating formations following a sandstone acidizing treatment, during treatment of formations before a high-rate water pack or frac-pack treatment, or as part of a pad fluid to treat the fracture faces before placement of proppant into a fracture and/or a screen annulus.