At present, the main technology in horizontal well drilling is MWD (ie, logging while drilling), and the one used for formation evaluation is called LWD (logging while drilling or FEMWD—measurement while drilling system for formation evaluation). The measurement while drilling system is composed of downhole sensor components, data transmission or downhole recording devices and surface detection and processing equipment. All while drilling systems use sensors close to the upper part of the bit to measure drilling parameters and formation parameters. The data measured during drilling is transmitted to the ground in real time. MWD can generally measure well deviation, azimuth and tool face direction. In addition to the above, LWD can also measure resistivity, natural gamma, lithological density, neutron, acoustic wave and other formation parameters. In addition, drilling tool vibration analysis technology can also be used to guide directional drilling. The basis for successful horizontal well drilling is LWD data and MWD direction data. LWD tools provide information that can evaluate the formations drilled in the borehole. These data determine how to change the direction of the borehole to achieve the desired goal. This method is called “geosteering”.
Geosteering technology includes reliable steering system (MWD), improved new-type stratum physical measurement, logging data model, near-bit sensor and measurement transmission motor, and detailed structure map with three-dimensional seismic processing. The following are typical bottom hole combinations and drill string combinations used in geosteering drilling: drill bit + geosteering system (measurement motor, near-bit resistivity, gamma and well deviation, launched to the receiving end section) + geo-steering tool acceptance End section (used to receive data from the steering system, LWD logging quality, resistivity and Gamma data) + MWD inclinometer (the heart of measurement, power supply inclinometer and data transmission) + non-magnetic drill collar (for Minimize the azimuth error of MWD or install LWD neutron porosity instrument)+ drill pipe.
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