Abstract: In accordance with such geological conditions as low reservoir pressure and low permeability in Santanghu Block of Tuha Oilfield in Xinjiang, foam drilling fluid was selected in drilling the horizontal section of well Niu-102, to minimize formation damage and reserve oil and gas reservoir. Horizontal well drilling technologies, and under-balanced drilling technologies with foam drilling fluid were applied, and well trajectory was monitored and controlled with the help of wireless MWD inclinometer and DST tool run through the side-entry sub. The drilling operation was safely and smoothly carried out, and some valuable experience was obtained in drilling this well.