Polymer-enhanced surfactant flooding for permeable carbonates

A process for recovering hydrocarbons in a carbonate reservoir, the process comprising the steps of:

• a. introducing a first saline solution into the carbonate reservoir, wherein the first saline solution comprises water, salt, and an absence of a surfactant;
• b. recovering an amount of hydrocarbon from the carbonate reservoir;
• c. introducing a second saline solution into the carbonate reservoir, wherein the second saline solution has a salt concentration in a range of 35,000-80,000 ppm, and wherein the second saline solution comprises water, salt, a betaine surfactant comprising ethylene glycol mono butyl ether as a co-surfactant, and a saline soluble polymer comprising xanthan gum without a pyruvylate group exhibiting viscosity retention at 95° C. for at least 6 months at a concentration range from 0.05 weight percent to 0.1 weight percent, and wherein the second saline solution has a density of 1.008 g/cm3 and a viscosity of 4.13 centipoise at 95° C.;
• and
• d. recovering a second amount of hydrocarbon from the carbonate reservoir.