Development of Near-Bit High Precision Imaging Measuring Tool While Drilling

The exploration and development of low-permeability and ultra-low-permeability reservoirs have been focused at home and abroad. Low-permeability oil and gas reserve resources are huge in China. However, difficult problems are available such as low productivity in reservoir drilling and development because of the limitations of existing drilling technologies. Conventional geosteering tools can be used for identifying the overall geological and stratigraphic structure as well as reservoir-related information characteristics at the borehole trajectory direction only. However, low-permeability reservoirs are characterized by strong heterogeneity, poor stratum physical properties, thin reservoirs and complex structures, therefore more precise borehole trajectory control and reservoir evaluation technologies are required accordingly. The near-bit resistivity gamma imaging while drilling is combined with the wireless short transmission technology of electromagnetic waves across the screw in the geosteering system, and the system can be used for accurately obtaining the 360-degree high-resolution image information of borehole walls, and wirelessly transmitting the near-bit reservoir data information to the MWD system on the upper part of the screw motor through electromagnetic wave propagation effect suitable for various drilling fluid systems. The information is supplied to geoscientists for research and judgment. The stratum dip angle is calculated, and the stratum boundary is identified according to the information, thereby controlling the borehole trajectory more accurately, and providing technical tools for the drilling and development of low-permeability and ultra-low-permeability oil and gas reservoirs.