Surface modification agents (SMAs) were developed more than fifteen years ago to agglomerate proppant to reduce proppant flowback, prevent fines invasion and migration, and improve fracture conductivity. The instant onset of extreme tackiness and insolubility of SMAs can present operational challenges with respect to maintaining and cleaning fracturing equipment. This paper presents the laboratory development and field implementation of a new, aqueous-based surface modification agent (ASMA) that addresses operational challenges and provides superior economic benefits with low health and environmental risk. New potential uses resulting from slow onset of tackiness are also presented.
An ASMA is a water external emulsion having an SMA contained within the internal phase. This ASMA is applicable for all of the same uses as solvent-based SMAs, such as on-the-fly coating of proppant during fracturing, frac-packing, or gravel-packing. One new application made possible by emulsion delivery is the inclusion of the ASMA in the first fluid injected into a fracture, which coats the fracture face with a hydrophobic film. This film provides stability to soft formations, inhibits water invasion, minimizes damage attributed to formation spalling, and improves proppant distribution by causing proppant to adhere to the frac face.
ASMA is aqueous based, and can be diluted in brine for deep injection into existing proppant packs. This enables its use for remedial treatments to repair fines-damaged frac-packs where frequent acid treatments are required to maintain acceptable production. Laboratory optimization of acid stimulation and remedial fines-control treatment designs are presented.
New emulsion technology allows SMA release to be delayed so that the extreme tackiness and insolubility does not damage mixing equipment, and can be easily cleaned. In addition, the delayed delivery of the SMA permits direct injection into proppant packs and the formation matrix to provide for remedial fines treatments, resulting in longer lasting acid stimulation of frac-pack completions.