Low-permeability reservoirs are highly sensitive to water saturation. When filtrate or clear brine is lost into these formations, capillary forces pull the fluid into pore spaces and prevent full displacement upon production. This paper illustrates how effective flowback chemistry reduces water saturation and enhances productivity. The authors initiated a study to evaluate chemistries that can be added to reservoir drill-in fluids, completion brines, and workover fluids to reduce capillary forces, recover invaded brine from the formation, and promote optimal productivity of the well. This paper introduces a unique flowback chemistry that not only provides excellent surface tension reduction and good thermal stability, but fulfills a challenge not met before; i.e., it is completely soluble and compatible with all common types of completion brines. Furthermore, this chemistry is not absorptive to solids in drilling fluids or a porous formation matrix, therefore low surface tension and low capillary pressure are maintained with mud filtrate or brine that is lost to the formation. Simple, low-cost, and innovative methodologies are presented to illustrate capillary pressure reduction and brine recovery in a simulated formation.
Due to the nature of surface activity, flowback treatments containing surfactants invariably generate strong and long-lived foam. If not controlled, foam can cause difficulties or even catastrophic outcomes for well service jobs including fluid transportation, well circulation, and brine reclamation. The flowback chemistry presented in this paper includes a new and very effective defoamer (or antifoamer,) which renders the flowback treatment non-foaming. Successful lab tests and field application are presented.