一种经济有效的水平井冲砂工艺方法

An Economical and Effective Technique for Sand Washing in Horizontal Wells

水平井与直井冲砂的主要区别在水平井段,由于重力作用,砂粒在水平井段内自由沉降方向与液流方向近乎垂直,所以水平井冲砂是否成功,冲砂液排量大小已不是主要因素,关键是冲砂液要具有很好的悬浮和携带能力。实验表明,提高冲砂液的粘度可有效降低砂粒的沉降速度,当粘度大于4mPa.s时,砂粒沉降速度已变得很慢。根据室内实验结果和对胍胶液性能测定,认为在目前设备技术条件下,胍胶液是比较理想的水平井冲砂液,它具有粘度高、冲砂效果好、易于配制、性能稳定、成本低廉等优点。通过在Z11平1井冲砂实践进一步证明:"胍胶液+反循环+出口机械除砂"是解决水平井冲砂问题的有效方法之一,具有较好的推广应用价值。

The main difference of sand washing between horizontal wells and vertical wells is mainly on their horizontal section.Due to the action of gravity,the direction of settlement of sand is nearly vertical to that of the liquid flow.Therefore,whether the sand in horizontal wells can be washed successfully depends on the suspension and carrying capacity of the applying sand washing fluid,rather than its displacement.The experiment indicates that the settling speed of the sand can be reduced effectively by enhancing the viscosity of the sand washing fluid.When the viscosity is more than 3～4 mPa·s,the settling speed will be very low.According to the experiment result and the measurement of the guar gel fluid,the guar gel fluid is quite ideal sand washing fluid for horizontal wells at the present time.It has many advantages such as high viscosity,efficiency in washing sand,easy preparation,stable performance and cheap cost etc.The practice of sand washing in a horizontal well,Well Z11H1,further proves that 'the guar gel fluid + reversal circulation + mechanical sand removal in exit' is one of the effective methods of sand washing for horizontal wells,and that it is applicable for horizontal wells.