The invention discloses a multivariable inversion method for measuring the
neutron porosity of a buried hill reservoir, and belongs to the technical field of nuclear
logging. The multivariable inversion method specifically comprises the following steps: constructing a
neutron logging instrument array
detector, measuring the buried hill reservoir, calculating a counting ratio R, and defining R1 and R2; constructing a multivariable inversion model, and performing inversion to obtain Por, Por1, Por2, cal and OFFSET; and the relative eccentricity OFFSETRE is defined, iteration inversion is conducted on the OFFSETRE through a dichotomy method, and the well
diameter, the relative eccentricity and the
porosity are output to serve as inversion results. The method can effectively reduce the negative influence of dual environment effects generated by well
diameter fluctuation and instrument eccentric distance change on a
logging result, remarkably alleviates the complexity and difficulty of environment correction, greatly improves the accuracy and reliability of
neutron porosity measurement of the buried hill reservoir, and has a great significance in improving the oil-gas exploration and development efficiency. And the
reservoir evaluation precision is optimized, and the method has extremely important practical significance and application value.