A solvent-based surface modification agent (SMA) has been very successful in precoating proppants to improve their performance in fracture stimulation treatments. To a far lesser degree, it was also used as an aggregating agent applied to formations and/or proppant packs to stabilize fines in a remedial method. However, its incompatibility with some aqueous wellbore fluids and the safety concerns due to the solvent base has limited its field applications. This paper presents the development of a new formulation of an SMA-aggregating agent that is aqueous-based, and includes results obtained from extensive laboratory studies. The new aqueous-based surface-modification agent (ASMA) provides significant improvements in health, safety, and ease of operation for the treatment of proppant, formation surfaces, and unconsolidated formations to control proppant and fines aggregation. Additionally, this ASMA will function to moderate undesirable diagenetic reactions that effect proppant strength, proppant pack permeability and formation permeability.
A unique property of this ASMA is that the rate of release of the active SMA ingredient can be controlled allowing it to be used for primary fracturing treatments or as a remedial treatment of damaged proppant packs or inhibiting continued formation fines production. This means the ASMA can be added directly to frac fluid during a treatment to coat proppant, to a fracture stimulation treatment prepad to treat the formation face, or at a later time as a remedial treatment.
As a remediation application, once injected into the proppant pack and formation matrix, the ASMA forms a thin film on the particulates, covering the fines and anchoring the particulates in place. In addition to controlling fines, ASMA coating forms a hydrophobic film that encapsulates the particulate surfaces, inhibiting the chemical reactions that lead to scale formation in the pack matrix and subsequent productivity loses.
Experimental testing using packed beds of proppant, formation sands, and various fines were used to simulate proppant pack conditions and formation fines before and after remedial treatments. It was observed that only a very thin film was formed, which encapsulated the proppant or formation particulates and created cohesion between grains without plugging the pore spaces. Additionally, laboratory results show that ASMA treatments effectively mitigate the buildup of scale in various sand packs as well as successfully control the migration of formation fines into proppant packs to maintain fluid flow paths.