Abstract: The design and practical application of three-dimensional horizontal wells were studied to solve the problem of three-dimensional horizontal well construction using conventional directional equipment and to reduce costs. After analyzing the three-dimensional trajectory design models and comparing their advantages and disadvantages, the optimal constant tool face angle model was selected. Focusing on the six sections that make up a typical well-path (vertical, increasing, twisting, stable, increasing, and horizontal) and starting with the basic equation with the A target as the constraint, an initial azimuth model was established. After obtaining the build-up rate and the tool face angle based on the initial azimuth, the remaining trajectory parameters were calculated to complete the design of the three-dimensional horizontal well trajectory. This method was applied in the JH17P36 well using conventional equipment to obtain the following results:the vector hit the target, the coincidence rate of the actual trajectory and the design trajectory were high, and the technical indicators were excellent. The drilling example results indicated that the calculation model and the design method were accurate, reasonable, and feasible and also demonstrated the superiority of the constant tool face angle model.

Key words: heterogeneous reservoir, constant tool face angle, horizontal well, well-path, target