Abstract: Boron injection neutron lifetime logging (NLL) is a new NLL technology that has been developed to solve the logging problems in mature oilfields where part of the pay zones are strongly watered out. Boron injection NLL technology uses boron element as tracer and performs " log -inject- log" operation by using neutron lifetime. It directly evaluates the water out behaviors of formations in perforated intervals and identifies water yield zones and potential pay zones according to amplitude variations between the two logs.