水平井合理长度优化研究

传统油藏工程方法认为水平井长度与产能呈正相关,即随着水平井长度的增加,气井产能也随之增大,基本呈线性关系。而和田河气田MA5-1H井、MA4-H1井物性接近,水平井长度相差3倍,但是两口井产能却相差不大。分析原因认为,传统的油藏工程方法没有考虑气井井筒内摩阻及井底非达西流动对气井产能的影响。针对以上问题,根据气体地下稳定渗流理论及水平井三维渗流特征, 利用水平气井产能公式,在考虑了井筒摩阻和非达西流动因素的情况下,计算气井产量的增加和水平段的长度实际并非呈线性关系,即随着水平段长度的增加,产能增加的幅度越来越小,而在1200m以内摩阻对水平井产量的影响较小,几乎可以忽略。利用此结论,对和田河气田水平井合理长度进行了优化,优化后确定和田河气田水平井合理长度为500~800m左右,该认识对和田河气田下步水平井设计具有重要的参考意义。

Reasonable length optimization of horizontal wells

The traditional reservoir engineering methods indicate that the length of a horizontal well and its production has a linear relationship, that is, gas well capacity increases with the length of horizontal wells. Physical property of Well MA5-1H is similar to that of MA4-H1.The horizontal well length of the former is three times as large as that of the latter, but the difference of capacity between two wells is smaller.The main reasons are that the traditional reservoir engineering methods do not take impacts on gas well productivity caused by well-bore friction and non-Darcy flow into consideration.To solve the problems above, length of horizontal wells was optimized in Hetianhe gas reservoir.Results showed that, in consideration of wellbore friction and non-Darcy flow, there is not a linear relationship between the growth of gas well production and the length of horizontal section.As the amplitude of the length of horizontal section length rises, the growth of gas well production becomes smaller and smaller.The friction within 1200m exerts less effect on horizontal well production and could be ignored.With the conclusion, we optimized the reasonable length of the horizontal well in Hetianhe gas field, and confirmed the reasonable length ranged from 500m to 800m after optimization.The new recognition could be important reference to further horizontal well design in Hetianhe gas field.