Study on Calculation Method for Improving Measurement Accuracy in Relief Well's Pass-by Section
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 or-der 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 im-prove the measurement accuracy are established.Numerical simulation based on this model shows that:under the ex-ample 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 ac-curacies 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.
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