Analysis on the Second Opening of WFSD-2 Hole and Deviation Correction Construction

Abstract:

WFSD-2 hole of scientific drilling engineering of Wenchuan earthquake fault zone has high quality requirement, and the hole deviation and coring rate are especially important. But the granite, granodionite and metavolcanic rocks in upper part (≤600m) are hard and compact with fracture development, many fracture surfaces and small faults; the big fault dip made deviation easily occur with core blockage. Because of complicated bore hole structure, the deviation was difficult to control by large diameter roller bit drilling. The satisfied effect was received by second opening(47.8～638.01m)construction：in 80～311.39m section, top angle/azimuth angle from 0.7°/202.9°to 5.8°/222.7°; then 5LZ120×7.0L-5 screw motor was used in 317.43～456.12m section, top angle/azimuth angle were corrected from 6.0° /228.3° to 0.9 °/103.7° . The paper summed up and analyzed the construction of deviation correction.