Polymer Treatment Controls Fluid Loss While Maintaining Hydrocarbon Flow

Abstract

Technology Update The loss of pumped fluids that are circulated from surface to total depth (TD) and back during various drilling, completion, and intervention operations poses numerous problems affecting wells and reservoirs. Fluid loss (FL) to the formation is costly not only in terms of the fluid itself, diverted from its task, but in the time and expense required to mitigate the problem. Well control can be compromised, wellbore cleanouts impaired, and reservoirs damaged, sometimes permanently, as a result of fluids entering the formation. A low-viscosity, solids-free FL treatment can help (1) cure lost circulation, (2) prevent loss of expensive drill-in fluid during workovers, (3) improve well control by maintaining a hydrostatic column, and (4) provide FL control in vertical- and horizontal-well gravel-packing operations. The treatment technology, developed by Halliburton as the LO-Gard fluid-loss-control system, relies on an associative polymer to decrease matrix permeability to aqueous fluids, limiting leakoff into treated zones. A significant property of the treating fluid is that it causes little or no damage to the flow of hydrocarbons. The treatment fluid may be used in various applications.Well intervention cleanouts by coiled tubing and hydraulic workoverGravel packingMost lost-circulation events occurring during cementing, fracturing, and drillingAfter tubing-conveyed perforating (TCP) operationsFL control before, during, and after gravel packingElectrical submersible pump (ESP) replacement operationsCirculation maintenance in horizontal openhole completions across unconsolidated sands (Fig. 1)Formation permeability reduction inHigh-permeability streaksThinned or eroded drill-in fluid wall cakeBreeched or fractured wall cakeNatural- or hydraulic-fracture networks FL Problems and Causes During workovers, gravel-pack completions, ESP replacement, underbalanced TCP (UTCP), and other applications, aqueous well fluids are usually circulated continuously between the surface and TD. Maintenance of a hydrostatic column is necessary for well control and to enable treatment fluids to be injected into the targeted intervals downhole, without fear of overdisplacing the treatment fluids.