Analysis and application of prediction model for formation fluid sampling time while drilling

Formation sampling while drilling (FSWD) is one of the most advanced formation techniques in world. It characterized by short operation time, shallow mud invasion, and obtained data closer to real situation reservoir. During process, first fluid that suction probe on borehole wall inhales basically filtrate. With increase it gradually mixes into fluid, finally infinitely close 100%. At this very important judge starting time sampling. If too early, percentage samples contaminated filtrate will be higher, which can not meet requirement fidelity. late, stop circulating for long, cause sticking. In paper, prediction method simulate permeability under certain parameters conditions. Based simulated results, model tool established pumping situation, variation content pumped with obtained, is, relationship between contamination rate This great significance field application tools drilling.