Numerical simulation of formation resistivity variation in water drive process and analysis of influence factors of inflection point

Key words:  well logging  water drive  water saturation of inflection point  injection water multiple  resistivity of mixed fluid

Abstract:

A theoretical simulation material balance method of variable multiple injected water was proposed to confirm the relationship between formation resistivity and water saturation. Through the theoretical simulation method, the influence factors of formation resistivity and water saturation of inflection point were analyzed. Comparison with the data of core displacement experiment proved that the numerical simulation method has high precision. The better the formation physical property or the bigger resistivity ratio of injected water to original water, the lower the water saturation of inflection point, the faster the process of water drive. The higher the irreducible water saturation, the lower the irreducible oil saturation or the bigger the saturation exponent, the higher the water saturation of inflection point, the slower the process of water drive. The inflection point usually appears when the injection water multiple is 1.4-2.0. The smaller the porosity, the higher the irreducible oil saturation or the bigger salinity ratio of injected water to original water, the bigger the waterflooded formation resistivity. And the waterflooded formation resistivity is even bigger than the reservoir resistivity.