Injection Fluids

Stimulation treatments with no polymer in the base fluid are rare. Even slickwater treatments will have small polymer loading to minimize tubular friction. Produced water typically has dilute concentrations of solid particulate matter, droplets of oil (since this water has come from the production stream), and carried-over production chemicals. Many operators no longer do extensive filtering on injection water as it is anticipated that hydraulic fracturing will occur and that fractures will be able to accommodate the particulate material. The particles can be organic (bacteria, plankton, etc.) or inorganic (e.g., clay minerals, quartz, amorphous silica, feldspar, mica, carbonates, etc.). Additives to produced water injection streams will characteris-tically include biocides, scale inhibitors and sometimes drag reducers although the price of the latter can sometimes be prohibitive. The viscosity of heated water represents the viscosity, since the re-injected water will likely be hot. The reverse will be true if seawater is injected.