Abstract: The invention relates to a system and method for separating, and safely monitoring and sampling flow back fluid returns from coiled tubing operations in oil and natural gas wells. The system comprises a flow back tank; one or more gas diffusers; one or more shale shakers; and a chute, which diverts flow from the gas diffusers to a sampling site positioned near the perimeter of the flow back tank. The system also has a volume level indicator on or near the perimeter of the flow back tank. The method comprises piping fluid returns from a wellbore, separating the trapped gases from the fluid returns, directing the degassed fluids to a shale shaker to separate the solids and directing the separated solids and liquids into separate tanks for analysis and reconditioning, if necessary. Cleaned liquids may be recirculated back to the wellbore.

Abstract: The non-damaging use of relatively high density calcium halide-containing brine compositions as kill weight workover fluids in high pressure water injection wells is rendered practicable via the use of an aqueous preflush composition containing an effective amount of a scale inhibitor material. In those instances where the scale inhibitor material is relatively strongly acidic in character (such as, for example, in the case of phosphonic acid materials, and the like), remarkable improvements in the injectivity of wells treated with said acidic aqueous preflush composition has also been obtained.