疏松砂岩油藏水平井均衡酸洗工艺

Uniform acidizing technology for horizontal wells in unconsolidated sandstone reservoirs

由于渗透率差异和跟趾效应,笼统酸洗过程中酸液将不均衡进入地层。基于水平井变质量流理论和泡沫分流特性,建立了水平井均衡酸洗数学模型。研究认为,井筒内较低的酸液流速和较高的酸液黏度,有助于酸液均匀进入地层,实现均匀酸洗。设计了均匀配液设备,通过均匀配液设备进一步均衡井筒液流,改进了水平井氮气调剖均衡酸洗施工流程,实现了酸液负压返排。该工艺能够实现酸液均匀进入地层,最大程度地解除近井地层堵塞。采用该工艺的水平井较同区块油井产能提高30%,有效期已延长230 d,且继续有效。

Due to the difference of permeability and heel-toe effect in the zone, acid will enter the formation unevenly in the general acidizing process. Based on the law of variable mass flow in the horizontal wellbore and the theory of foam diversion acidizing, an uniform acidizing mathematical model were built. It is considered that a higher viscosity and lower velocity of acid in the wellbore are conducive to uniform injection and acidizing. The uniform liquid distribution equipment was designed to further balance the wellbore fluid flow through the pressure dividing and flow obstructing device, and the nitrogen profile control and uniform acidizing operation process of horizontal wells was improved to realize acid negative pressure backflow. The process can achieve the uniform entry of acid and relieve the blockage near the bottom of the well to the greatest extent. The productivity of horizontal wells using this process is 30% higher than that of oil wells in the same block, the validity period has been extended by 230 days, and it is still effective.