概率分布模型在井眼轨迹不确定性中的应用探讨

DISCUSSION ON THE APPLICATION OF PROBABILITY DISTRIBUTION MODEL IN WELLBORE TRAJECTORY UNCERTAINTY

井眼轨迹在空间中存在不确定性,由多种误差来源累加决定,每种误差来源是一种相互独立的概率事件,导致误差椭圆半径的出现具有随机性和不确定性,理论上可以看作随机出现的事件。通常工程上讨论的误差椭圆半径是基于一定置信水平上的统计概念,但是服从哪种统计分布模型至今没有一个定论。文章以某油田水平井为例,采用三种连续概率模型正态分布、指数分布及均匀分布模型进行误差椭圆半径概率密度及累计概率计算,定量化描述该井与老井碰撞的概率,并对三种模型在油田开发不同阶段的适用性进行探讨。

Wellbore trajectory is uncertain in space,which is determined by the accumulation of various error sources,each of which is an independent probability event.As a result,the radius of the error ellipse has randomness and uncertainty,which can be regarded as a random event in theory.Usually,the error ellipse radius discussed in engineering is based on the statistical concept at a certain confidence level,but there is no conclusion about which statistical distribution model is subject to.This paper takes a horizontal well in an oilfield as an example,and uses three continuous probability models—normal distribution,exponential distribution and uniform distribution—to calculate the probability density and cumulative probability of error ellipse radius,to quantitatively describe the probability of collision between the well and the old well,and to discuss the applicability of the three models in different stages of oilfield development.