In-depth profile control step by step method employing equipressure drop gradient

The invention provides an in-depth profile control step by step method employing equipressure drop gradient , which relates to the technical field of deep profile control of a water flooding development oil reservoir. According to the practical condition of a test block, suitable profile control agent is selected, and the breakthrough pressure gradients of profile control agents of different compositions are tested. A stratum is divided into a near wellbore zone, a far wellbore zone and a stratum deep according to the pressure drawdown of the stratum; and the pressure gradients of the zones are different, so that slugs with different strengths are required. According to the principle of equipressure drop gradient, namely, the breakthrough pressure gradient of the profile control agent equals to the pressure gradient of the stratum, the composition of each slug is selected, profile control slugs are combined, and the combined profile control slugs are optimized according to the cost. According to the invention, profile control agents with different strengths can be placed in different positions of the stratum, and overall in-depth fluid diverting step by step of the space of the oil reservoir can be realized through the combination of profile control agents with different strengths, so that the conformance factor can be improved greatly, further the oil recovery efficiency can be improved.