Optimizing Proppant Surface Properties to Improve Formation Flow in Offshore Frac-Packs

Abstract

The objective of this study is to introduce a new neutral wettability proppant that improves flow and cleanup of the proppant pack. It is known that the proppant pack permeability is the primary factor that affects the productivity of a fractured well. In such operations, fracturing fluid (cross-linked or linear) is used to deposit the proppant. In order to transport proppant within the fracture, fracturing fluid rheological properties must be attained based on fracture type, job design metrics, formation characteristics, proppant properties and proppant loading. These fluid properties are typically adjusted by using gelling agents and other chemical additives to ensure transport capability. The types and concentration of gelling agents, cross-linkers, and breakers, are known to affect the permeability of the pack. If these fluids are not removed, they build up in the proppant pack. This fluid retention leads to decreased permeability and reduced effective half-length of the fracture. In this paper a neutral wettability proppant that is neither oil wet nor water wet was used to (1) eliminate capillary pressure within the proppant pack and (2) alter the interaction between aqueous/organic (hydrocarbons) and the proppant surfaces by decreasing the intra-molecular interactions between the fluids and the proppant surfaces thus resulting in improved flow compared to native surfaces. Light weight ceramic proppant was permanently surface modified to a neutral wettability state. This new proppant was evaluated in the laboratory and in the field for compatibility with the fracturing fluid, clean-up properties through the proppant pack and recorded flow back of treatment fluids after a frac-pack operation. Results indicated that the new proppant surfaces not only reduced water saturation but also improved oil mobility. These observations showed the promises of permanently modifying surfaces as next-generation products for improved flow and decreasing the risk of formation damage due to the fracturing fluids left behind after treatment. When this proppant was applied in a frac-pack completion, flow back was efficient with rapid recovery of all pumped fluids. In this case the surface of the proppant reduced the intra-molecular forces between the proppant and the fracturing fluid, eliminating capillary pressure within the frac-pack and leading to a more efficient and quicker fracturing fluid flow back compared to using proppant in its native state. First oil breakthrough was earlier than other wells in the same area.

Technologist in Residence for Advanced Manufacturing and Materials in Unconventional Oil and Gas Equipment and Infrastructure

“…A self-assembled monolayer can provide a surface with permanent non-native wettability properties (from Bestaoui-Spurr et al, 2017a). Bestaoui-Spurr et al (2017b) reported some results of using the coated proppant reported by Bestaoui-Spurr et al (2017a) at several completions in the Gulf of Mexico, as well as in the laboratory. This was a light-weight ceramic proppant with a permanently modified neutrally wet surface.…”