Design and Field Test of Surface Monitoring System for Directional Wells Anti-Collision

With the deepening of exploration and development of onshore and offshore oilfields,cluster wells and infill wells are more and more popular.It will greatly increase the possibility of well collision during the drilling and would have great harm to drilling and the production of oilfield.According to the law of vibration wave propagation,an anti-collision method was put forward.A surface monitoring and warning system for directional wells anti-collision was designed.The components of the system and field test plan were introduced.In the field test in an offshore block in Bohai Oilfield,the center to center distances between the drilling wells and neighboring wells were acquired based on the design data and MWD data of directional wells with Compass software.Besides,the risky intervals were also monitored.The distances between the drill bit and the neighboring wells were analyzed according to the vibration waves of bit.The field application results showed that,the vibration signals at the drilling casing head were very strong when cement plug was drilled; this system could judge whether bit was close to or drilled cement ring and casing of neighboring wells via bit vibration signals; the amplitude of bit vibration waves acquired at casing head of neighboring well declined with the increase of center to center distance between positive drilling well and neighboring well.This declining relationship and separation factor could be used to judge the risk of wellbore collision.