Abstract: In order to overcome technical difficulties in Well Wei 68-FP1,such as slim-hole drilling in horizontal section,high friction and drag,difficult to control well trajectory,etc.,drilling technology for horizontal wells has been studied.The well path was optimized to reduce torque and drag by analyzing the data of torque and drag with different curvatures collected from adjacent wells.Combined with the early practice of horizontal wells for unconventional oil and gas reservoir,small angle PDM and undergauge bi-stabilizer assembly had been used,and optimized PDM angle and the size of stabilizers to improve precision of well trajectory control.Oil-based drilling fluids were applied and reasonable density was determined to maintain hole stabilization at horizontal section."C1+GAMMA" geo-steering technique was employed to ensure the horizontal section inside reservoir.The measures of safe drilling were adopted to ensure downhole safety.The technical application showed that reasonable well path could reduce drag in drilling,small angle PDM and undergauge bi-stabilizer" assembly were the key factors in controlling trajectory,and it could also improve the ratio of rotary drilling."C1+GAMMA" geo-steering technique could keep the well trajectory inside the reservoir.The success of Well Wei68-FP1 will provide the reference for horizontal drilling in shale reservoirs.