In the drilling of horizontal Wells and large displacement Wells, the operators realize that one of the most important directional drilling problems is that the actual trajectory is not consistent with the designed trajectory, which is developed by geologists, geophysicists and reservoir engineers.

This inconsistency reduces operational efficiency, increases drilling and lifting costs, and reduces well oil and gas production potential. However, using automatic guided bits can reduce this inconsistency.

In the development of unconventional oil and gas resources, the conventional method is to design certain well spacing and parallel drilling horizontal Wells, which aims to maximize the oil drainage area of the reservoir without excessive investment.
Therefore, horizontal well spacing needs to be designed to ensure that the drainage radius intersects without excessive overlap. If the oil drainage area does not intersect, oil and gas resources cannot be produced. However, due to the limited accuracy of the downhole measurement method and the error of well trajectory, the actual trajectory is often hundreds of feet away from the optimal one. These problems become more apparent as the horizontal segment grows longer.

In 2016, Stefan Maus et al. published a paper entitled “simulation of recovery loss caused by well track error”. An oil and gas recovery simulator is presented to simulate the effect of well path error on reservoir drainage area. The simulator USES input parameters to evaluate different drilling schemes. Input parameters include: length of horizontal section, spacing of horizontal section, borehole orientation, measurement method, and recovery with a function of drainage radius.
Based on the latest error model of shaft measurement accuracy by industry steering committee, a large number of Wells are simulated with the simulator. The simulator evaluates and predicts the remaining oil and gas of the oil field caused by the inaccurate well path. The results of this paper suggest that when directional drilling is performed using traditional standard MWD methods, systematic errors in the well trajectory can cause hydrocarbons of hundreds of thousands of dollars per well to be unrecoverable.

Although directional well engineers try to keep the actual drilling track on the design track to achieve maximum recovery and drill as quickly as possible, they are often unsatisfactory. The field operation changes quickly and there are many variables, such as the change of rotary deflection, the inconsistency of the yield value of mud motor, the deflection of bit, etc., they cannot coordinate these variables. There are too many variables for directional well engineers to consider and respond to in real time, continuously, and predictably.