新型连续冲砂工艺研究与应用

Research and Application of A New Type of Continuous Sand-flushing Technology

清水冲砂存在一些问题,如污染油层、沉砂卡钻、接冲砂单根放压时间长等,严重影响冲砂的连续性。近几年低密度泡沫冲砂工艺发展较快,解决了低压井漏失量大的问题,并通过单流阀的使用,减少了压缩气体的放压时间,但限制了反循环冲砂作业,加大了发生井下事故的风险。针对上述问题,进行了连续冲砂工艺技术的研究,研发了连续冲砂装置(即控制阀),配合现有的常规冲砂管柱和工具,实现了连续冲砂作业。该项工艺技术已在多个海上油田得到了应用,实践证明该项工艺实现了连续冲砂作业,取消了单根冲砂管柱卸扣与连接时的放压作业,保证了冲砂液的正、反循环冲砂作业,减小了井下事故风险,显著提高了冲砂作业效率。

There existed problems in fresh water sand flushing operation,such as formation damage,the accidents of sanding in and the long waiting time of making up a joint,it seriously affected continuity of sand-flushing operation.Subsequently,the sand-flushing with low density foam fluid was developed to solve the high leakage in low pressure wells.It reduces the releasing time of compressed gas pressure by using non-return valve,but it limited the operation through reverse circulation,increased the risk of drilling accidents.In consideration of the problems,the technology of continuous sand-flushing was researched.The continuous sand-flushing device(a control valve)is developed,combined with the conventional sand-flushing pipe string and tools,a continuous sand-flushing is implemented.The technology has been applied in some offshore oilfields.The applications show that the continuous sand-flushing cancelled the releasing operation of gas during making and removing ajoint and ensured the sand-flushing by normal circulation and reverse circulation,reducing the risk of downhole accident and greatly improving the sand-flushing efficiency.