Abstract: Aiming at the attributes of Budate reservoir, finite-difference method based on resistor network is applied to modeling of dual laterolog for igneous reservoirs with parallel fractures and net-fractures. The dual laterolog responses was calculated for the reservoirs in case of a series of parallel fractures, two series of parallel fractures in different angle, and net-fractures with invasion. The log characteristics are summarized for the parallel fractures and net-fracture system: high dip parallel fractures induce positive difference on dual laterolog, and low dip corresponds to negative difference. Both dip and angle of two series of parallel fractures that form a netfracture system influence the response. If the angle is small, the laterolog response tends to that of a series of parallel fractures. As the angle grows, the resistivity drops down and the influence of dip tends to diminish. The existence of mud invasion leads to positive difference on dual laterolog, and makes the effect of dip and angle vaguer. The results will provide theoretical basis for the identification and evaluation of reservoirs of these types.

Key words: igneous rocks, netfracture, logging response, dual laterolog, logging