Research And Application Of Intersection Probability Based On Well Trajectory Uncertainty

With the rapid development of petroleum industry, easy development and large areareservoir of oilfields gradually reduce. As a result, the developments for small fault blockreservoir, special geology reservoir and thin reservoir are more and more important, whichmakes infill well, sidetrack well, cluster well and platform well required for producer. In theprocess of building well, it is necessary to consider whether there exists the intersectionbetween new well and old well or adjacent well, so the uncertainty of well location arises ourattention. In order to solve this problem, this paper conducted the analysis and research onwell intersection probability based on the well location uncertainty.The error of well location uncertainty mainly derives from survey calculation andmeasuring instrument. This paper optimized survey calculation and cylinder helixinterpolation model in the survey calculation. The calculation error compared withmeasurement error could be ignored, therefore, this study mainly analyzed measurement error,and indicated measurement error is not random but systematic. Through the introduction andtheoretical analysis of measuring instrument, the effects of several factors on well locationuncertainty were determined, also, magnetic compass error, gyrocompass error, depthmeasurement error were systematically introduced. The covariance matrix was applied toconduct the reasonable quantization on well location uncertainty, and a error model of welllocation uncertainty was eventually established. The model was introduced into the analysisof well intersection probability to determine whether there exists the intersection between twowells and predict the intersection probability. These researches can provide an importantguideline for field anticollision.