Method of controlling fluid loss in a permeable formation

摘要

Fluid loss in a permeable formation penetrated by a wellbore is controlled by; (a) mixing an aq. fluid (A) with a polysaccharide polymer (B) to viscosity (A), and a crosslinking agent (C) to form a crosslinked gel in (A); (C) comprises borate, Ti4+ ions, Zr4+ ions, Al3+ ions and/or Sb5+ ions; it may alternatively comprise, in a specific case, (see embodiment) a base; (b) shearing the gel to form particles of average dia. 1-10 mm; (c) slurrying the particles with an aq. fluid (D) of density similar to that of the particles; (d) introducing the resultant suspension into the wellbore in contact with a face of the formation; and (e) producing a filter cake on the face, thereby reducing fluid loss to the formation.