Geological Survey of Directionally Drilled Rivers

Some problems that develop with the geological survey of directionally drilled river are summarized and analysed. It is pointed out that the amount of work for exploration drilling shall be defined according to specific geologic conditions on the job site, rather than inflexibly following codes and standards. As for the application of exploration means, comprehensive exploration method is recommanded of combining engineering geophysics and geologic drilling, that is to say, the stratigraphy of the section crossed is interpretated with the results of engineering geophysics, and the results, in turn, are checked and reviewed through drilling. By doing this, not only can the cost be held down, field work time shorterned, but the stratigraphy of the crossed sectioin can be interpretated thoroughly and systematically. Attention shall be paid especially to the formations having considerable effects on directional drilling operation, the formations within 7m above and below the proposed design depth, and the formations where the pipeline enters into and exits from ground.