Optimizing matrix acidizing treatment

A method tier matrix acidizing, comprising:

• performing first and second cycles of a step up rate test on a formation to be acidized at first and second test temperatures, respectively, wherein the second test temperature is different from the first test temperature;
• determining, from the first cycle of the step up rate test, a first fracture pressure value for the formation associated with the first test temperature;
• determining, from the second cycle of the step up rate test, a second fracture pressure value for the formation associated with the second test temperature;
• determining, from the first and second fracture pressure values, a mathematical relationship for fracture pressure of the formation as a function of bottom hole temperature;
• integrating the mathematical relationship into a fluid placement simulator;
• simulating by the fluid placement simulator a design matrix acidizing treatment plan for the formation accounting for an effect of bottom hole temperature on fracture gradient;
• and
• performing matrix acidizing treatment of the formation according to the design matrix acidizing treatment plan.