The Influence of Drilling Fluid Contamination on Logging and Countermeasures
Drilling fluid, known as the “blood” in drilling engineering, has the functions to carry cuttings, protection wall, balance formation pressure and reduce drilling tool wear. In the petroleum drilling process, the varieties and quantities of drilling fluid additives are increased, so as to reduce downhole complex conditions or deal effectively with engineering accidents. The contamination of organic additives on debris at the bottom of reservoir has caused a certain difficulty to identify oil and gas shows. In this paper, the impact of organic additives in drilling fluid on the comprehensive logging is discussed. Besides, the analysis of comprehensive logging data and the study on interpretation and evaluation methods are conducted. The study results provide a scientific basis for the recognition of oil and gas show in logging work under the conditions of the mixing of crude oil or organic additives in drilling fluid, and for the identification of lithology and the interpretation and evaluation of hydrocarbon reservoir.