Dynamic HDIL Responses While Saline Drilling Mud Invading Reservoirs

Abstract

Abstract.A high definition induction log (HDIL) device provides six resistivity responses with various radial detective depths. Its responses were influenced by saline mud filtrate invading into the reservoir dynamically after the formation was opened while drilling. The dynamic invasion process results in the time dependent formation-resistivity profiles, thus the responses of HDIL are time dependent. The measurement results deviate from the true-formation resistivity, so that errors and wrong estimation would be introduced. The effects of saline mud on dynamic responses of HDIL devices were calculated from the dynamic invasion theory for oil bearing reservoir, water zone and oil/water formation. The shallow detective HDIL arrays are influenced by the invasion process strongly. The logging time must be regarded as an important parameter to estimate the true-formation resistivity while evaluating the reservoirs and understanding the dynamic invasion process physically. Well logging was suggested to be performed at the early stage when the formation was opened for less effects of invasion.