救援井在穿越井段提高测量精度的计算方法研究

Study on Calculation Method for Improving Measurement Accuracy in Relief Well′s Pass-by Section

在救援井工程中,为确保救援井与事故井在设计连通点处精准连通并压稳地层,需要使用磁测距工具直接测量救援井与事故井的相对距离。受限于磁测距工具的测量精度,为避免提前碰撞并提高连通的可能性,在救援井轨道设计时需要增加穿越井段以提高测量精度。一般认为通过穿越井段可以将相对距离测量误差由20%减小到10%,但由于相关理论模型未见报道,目前仍缺乏具体的定量分析方法。为实现穿越井段前后测量误差的定量分析,基于救援井工程实际、测量平差理论及测距误差模型,本文建立了两种在穿越井段提高测量精度的计算模型。基于该计算模型的数值模拟计算表明:在算例条件下事故井被测点N-E坐标系的初始值由(108.00 m,28.00 m)修正为(110.14 m,29.24m)和(110.07 m,29.23 m),被测点坐标精度(误差椭圆的长半轴)分别提高了19.0%和21.5%。研究结果表明,两种计算模型均能有效提高测距精度,且计算结果相近,计算精度可以基本满足救援井测量需求,所建立的计算模型可以为救援井井眼轨道及测量方案设计提供理论指导。

In the relief well engineering,in order to ensure that the relief well and the accident well are accurately connected at the designed kill point and kill the blowout,the magnetic ranging tools are used to directly measure the relative distance between the relief well and accident well.Due to the limited measurement accuracy of active magnetic ranging tools,it is often necessary to design the pass-by section to improve measurement accuracy in order to avoid premature collision and improve the connection possibility.It is generally believed that this method can reduce the relative distance measurement uncertainty from 20%to 10%.However,since the relevant theoretical models have not been reported,there is still a lack of specific quantitative analysis methods.In order to quantitatively analyze the measurement uncertainty before and after the pass-by section,based on the engineering practice of the relief well,the measurement adjustment theory and the ranging uncertainty model,two mathematical models to improve the measurement accuracy are established.Numerical simulation based on this model shows that:under the example condition,the initial value of the measured point coordinate in the N-E coordinate system is modified from(108.00 m,28.00 m)to(110.14 m,29.24 m)and(110.07 m,29.23 m)by the calculation model,and the accuracies of point coordinates(major half axis)are improved by 19.0%and 21.5%respectively.The results show that the two mathematical models can effectively improve the ranging accuracy.The calculation results of the two models are similar and the calculation accuracy can meet the engineering requirements.The established mathematical models can provide theoretical guidance for the trajectory design and ranging plan of the relief well.