Numerical simulation of a kind of imaging tool responses on fractures in oil-based drilling fluid environment

Key words:  oil-based drilling fluid  electrical imaging tool  3-D finite element method  numerical simulation  fracture

Abstract:

Based on electromagnetic field theory and three dimensional finite element methods, an algorithm for simulating fracture responses of an oil-based drilling fluid electrical imaging tool is presented in detail. This algorithm can be applied to simulate the oil-based drilling fluid imaging tools responses to different types of fractures, including horizontal fractures, inclined fractures and crossed fractures. When the open width of the crack is greater than 1mm, with the decrease of the width, the value of responses declines, and the cracks can be identified perfectly. The ability of the algorithm to identify fractures can be influenced by the resistivity contrast between the background and the fractures. These simulation results clearly reveal the positions and the azimuths of the fractures as well. Fracture dip can also be obtained for inclined fractures through follow-up treatment.