| Along with the increase of strength of offshore oil and gas field development, number ofplatform wellbore tends to be intensive. There are more and more offshore productionplatforms while well spacing continues to decrease. For example, well pattern changes from2m x2m to1.5m x1.7m and the platform spacing can be just30~40m in some Bohai oilfields. This leads to a result that drilling workers should be alert to collisions with not only theadjacent wellbore of their platform but also the wellbore of adjacent production platforms.Multi-platform wellbore collision becomes more prominent.According to operating difficulties of wired data transmission between platforms, this paperproposed an offshore multi-platform wellbore anti-collision method based on wireless datatransmission. Acceleration sensors are installed in the wellbore casing head of multi-platform.They acquire the vibration signal generated by drill bit drilling rock. Wireless transmissionequipment transfers vibration signal to computer. Vibration signal is analyzed by multiple IPanti-collision software. When the signal characteristic value exceeds anti-collision alarmthreshold, alarm information will be sent out by system software. Multi-platformanti-collision monitoring system realizes the judgment of bit approaching and the collisionwarning of adjacent platform risk well casing.The current situation of well anti-collision and wireless data transmission is investigated inthis paper. Marine platform environment influences on the electromagnetic wave transmissionand wireless transmission equipment are analyzed theoretically. The propagation losscalculating method of sea surface line-of-sight transmission is obtained. Wireless devices areselected with anti-explosion design. Through experiments, three kinds of wireless transmission equipment were compared bychanges of signal intensity with distance and one of them was selected as the multi-platformanti-collision monitoring wireless transmission equipment. The time domain and frequencyspectrum characteristic of vibration signal of simulated wellbore and rock transferred bywired and wireless transmission were analyzed. The rain attenuation at short range andequipment reliability of the complex climate were verified. Through the detection of SNR andRSSI of wireless transmission equipment, propagation loss of sea surface line-of-sighttransmission was verified. It showed that wireless data transmission is feasible inmulti-platform wellbore anti-collision. |
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