Accurate communication, both written and oral, is the key to avoiding convergence errors. This function can generally be divided into two or three groups depending on the size of the organization and the complexity of the project.
The initial group will normally consist of seismic crews, geophysical and geology departments, who will be responsible for developing structure maps and choosing targets with respect to a common coordinate system. The next group might be land/hydrographic survey crews, geology, drilling engineering, and a directional service company who might be responsible for developing well plans to the proposed targets from selected surface locations. At this point the grid convergence and magnetic declination angle should be computed, cross checked, and documented on the well prognosis and directional maps using a polar grid convergence diagram. All groups should be in agreement with these values before release to operations. The final group might consist of drilling engineering, operations drilling foremen, and directional drillers who will be responsible for drilling the well to target as planned. This is the stage where most errors and miscommunication are likely to occur. Never assume the man on the rig will understand your written communications. A meeting should be held, at the rig site if necessary, to assure that all parties understand the map azimuth reference and the magnitude and sense of necessary correction angles.
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