The simulation and analysis of array lateral log response of fracture in coal bed methane reservoir

Fracture is the important seepage channel of fluid in the coal bed methane reservoir.The fracture is very important for the formation of the effective strorage block of hydrocarbon.The study of log responses of fracture is the key to determining the fracture parameters.The fracture is usually developed in the form of fracture zone.Based on the fracture group model, a three-dimensional finite element method is used to simulate the responses of the array laterolog in fractured formation.The results show that conductivitites of array latero log are primarily linearly related to the porosity of fracture and the conductivity of pore fluid.With dip angle increasing, the array log apparent resistivity increases.With block resistivity increasing, the array log apparent resistivity increases too.Apparent resistivity is positive in the high-angle fractured formation and may be negative in the low-angle fractured formation with high block resistivity.Apparent resistivity increases gradually with fracture density increasing under the same porosity of fracture.If fracture density is large enough, the log response will not vary with essential fracture density.Log response of crossing fracture is apparently different from that of the parallel fracture group, and log response of crossing fracture is different under different dip grouping system.