At present, the main technology for horizontal well drilling is MWD, and the technology 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, downhole recording device and surface detection and processing equipment. The while drilling system uses sensors near the upper part of the bit to measure drilling parameters and formation parameters. The data measured during drilling is transmitted to the surface in real time. MWD can generally measure well deviation, azimuth and tool face direction.
In addition to the above, LWD can also measure formation parameters such as resistivity, natural gamma, lithological density, neutrons, and acoustic waves. In addition, drilling tool vibration analysis technology can also be used to guide directional drilling. The basis for successful horizontal well drilling is the logging while drilling data and the direction logging while drilling data. The information provided by the LWD tool can evaluate the strata in the borehole. This data determines 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 of geophysical measurement, logging data model, near-bit sensor and measurement transmission motor, and detailed structure drawing 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, transmitted to the receiving end section) + geosteering tool acceptance end section (Used to receive data from steering system, LWD logging quality, resistivity and Gamma data) + MWD inclinometer (the core of measurement, power inclinometer and data transmission) + non-magnetic drill collar (used to minimize MWD Or install LWD neutron porosimeter) + drill pipe.
