A process of reducing the acidity of a whole acidic crude oil at an on-site production facility near to a wellhead of a petroleum reservoir, comprising the steps of: obtaining a petroleum reservoir supply of whole acidic crude oil having a TAN of at least 0.3; mixing the acidic crude oil with water at a weight ratio of 10:1 to 1:50 to form a crude oil/water mixture; heating the crude oil/water mixture to a crude oil/water temperature in the range of 10°C to 150°C to form a pumpable crude oil/water mixture; pumping the pumpable crude oil/water mixture to a pressure of at least 22.1 MPa to form a pressurized crude oil/water mixture; pre-heating the pressurized crude oil/water mixture to a pressurized temperature in the range of 150°C to 350°C; contacting the pressurized crude oil/water mixture with a ZrO 2 catalyst in a reaction zone, wherein the reaction zone comprises main reactor having an interior portion; heating the pressurized crude oil/water mixture to a reaction temperature range of 400° to 500°C while maintaining the pressure at or above at least 22.1 MPa for a reaction period of time operable to produce a treated crude oil having a significantly reduced TAN in comparison to the TAN of the acidic crude oil; reducing the pressure of the treated crude oil using a pressure regulating device to create a pressure-reduced treated mixture; separating the pressure-reduced treated mixture into a gas portion and a liquid portion; separating the liquid portion into recovered water and low acidity oil; and collecting the low acidity oil wherein the low acidity oil is an upgraded crude oil having reduced amounts of asphaltene, sulfur, nitrogen or metal containing substances as compared to the acidic crude oil. obtaining a petroleum reservoir supply of whole acidic crude oil having a TAN of at least 0.3; mixing the acidic crude oil with water at a weight ratio of 10:1 to 1:50 to form a crude oil/water mixture; heating the crude oil/water mixture to a crude oil/water temperature in the range of 10°C to 150°C to form a pumpable crude oil/water mixture; pumping the pumpable crude oil/water mixture to a pressure of at least 22.1 MPa to form a pressurized crude oil/water mixture; pre-heating the pressurized crude oil/water mixture to a pressurized temperature in the range of 150°C to 350°C; contacting the pressurized crude oil/water mixture with a ZrO 2 catalyst in a reaction zone, wherein the reaction zone comprises main reactor having an interior portion; heating the pressurized crude oil/water mixture to a reaction temperature range of 400° to 500°C while maintaining the pressure at or above at least 22.1 MPa for a reaction period of time operable to produce a treated crude oil having a significantly reduced TAN in comparison to the TAN of the acidic crude oil; reducing the pressure of the treated crude oil using a pressure regulating device to create a pressure-reduced treated mixture; separating the pressure-reduced treated mixture into a gas portion and a liquid portion; separating the liquid portion into recovered water and low acidity oil; and collecting the low acidity oil wherein the low acidity oil is an upgraded crude oil having reduced amounts of asphaltene, sulfur, nitrogen or metal containing substances as compared to the acidic crude oil.