定向井防碰地面监测系统设计及现场试验

随着陆地和海上油气勘探开发程度的不断提高,丛式井和加密井正变得越来越普遍,而受老井网加密调整使井间距离更密、老井测斜数据不完整或不准确、井眼轨迹控制产生误差等因素的影响,钻井过程中易发生井眼碰撞,对钻井和油田的正常生产构成了潜在威胁。根据振动波的传播机理,提出了一种定向井防碰地面监测方法,设计了一套定向井防碰地面监测系统。该系统在渤海某海上油田区块钻井现场进行了试验:借助定向井设计、随钻测量资料,利用Compass软件分析了在钻井与邻井的中心距,并对危险井段进行了监测;根据采集到的钻头振动信号特征,分析了钻头对危险井筒的趋近。现场应用结果表明:钻头钻水泥塞过程中,在钻井套管头处振动信号强度很大,该系统可通过识别钻头振动信号判断钻头靠近或钻遇了邻井水泥环和套管;在邻井套管头采集到的钻头振动信号的振幅,随在钻井和邻井的中心距的增加呈一定的衰减关系,可根据该关系和分离系数判断井眼碰撞的风险。 

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.