Mud invasion and array laterolog responses in horizontal well based on numerical simulation

The initial formation fluid distribution and resistivity around the well will be changed while the mud-filtrate invades the permeable formation. In this paper, a simulation model of the formation is established to study the sensitivity analysis of the mud invasion and array laterolog responses in horizontal wells. According to the dynamic evolution law of water saturation distribution and the characteristics of array laterolog responses, we found that the fluid properties and formation petrophysics have a significant influence on the mud invasion profile. Combined with numerical simulation results and theoretical analysis, some conclusions are drawn that invasion characteristics exist in obvious differences in different permeable formations, filtrate flow forms symmetrical geometry in relative low permeability formation, and it generates quite complex asymmetric invasion geometries around the well in a highly permeable formation. Similarly, the research results show that the characteristics of the array laterolog responses and the differences of apparent resistivity with different investigation depths are influenced by the change of geometrical shape and saturation distribution around the well during the invasion. We can estimate the mud invasion extent according to the different characters of array laterolog. An accurate understanding of the relationship between mud invasion and array laterolog responses can provide a reliable basis for reservoir evaluation and resistivity correction in a horizontal well.