Fluid loss control additives for drilling fluids

A system for drilling a wellbore, the system comprises:

• a drilling fluid comprising:
• an aqueous base fluid,
• a first fluid loss control additive that is a cross-linked polymer comprising N-vinylpyrrolidone as a monomer, and
• a second fluid loss control additive that is a cross-linked copolymer comprising a first comonomer of 2-acrylamido-2-methylpropanesulfonic acid in a first comonomer concentration of at least 70 mol % of the copolymer;
• wherein the second fluid loss control additive additionally comprises a second comonomer comprising an N-vinyl amine-containing monomer, a terminal double bond-containing monomer, or a combination of an N-vinyl amine-containing monomer and a terminal double bond-containing monomer;
• wherein the second comonomer is present in a total second comonomer concentration of 30 mol % or less of the copolymer;
• a zinc brine configured to be introduced into the wellbore after the drilling fluid is introduced into the wellbore;
• mixing equipment configured to mix the aqueous base fluid, the first fluid loss control additive, and the second fluid loss control additive;
• and
• pumping equipment configured to pump the drilling fluid and the zinc brine in the wellbore;
• wherein the zinc brine is pumped after the drilling fluid,
• wherein the drilling fluid forms a filter cake, and wherein the filter cake is capable of controlling fluid loss of the zinc brine for at least 16 hours.