﻿ 基于阿基米德双螺旋线原理的水力喷射压裂技术

1. 中国石油大学(北京)石油工程教育部重点实验室, 北京 102249;
2. 油气资源与工程国家重点实验室, 北京 102249

Hydraulic Jet Fracturing Technology Based on Archimedes Spiral Theory
TONG Shaokai1,2, GAO Deli1,2
1. MOE Key Laboratory of Petroleum Engineering, China University of Petroleum(Beijing), Beijing, 102249, China;
2. State Key Laboratory of Petroleum Resources and Engineering, Beijing, 102249, China
Abstract: The multi-stage double-cluster hydraulic jet often encounters problems such as that of relative ineffectiveness, uneven erosion between the upstream and downstream by the injector, and sanding problems caused by the easy settlement of sands.To overcome these challenges, the theory of Archimedes double helix was utilized and integrated to a mathematical model of hydro jet fracturing, which provides the basis in the design of the double-helix hydraulic fracturing tubing string and injector.Then visualizations of the sand-carrying evaluation experiments were performed to evaluate the double-helix characteristics.In addition, kinetic equations of sand migration in sand-carrying fluid through straight pipes and double-helix pipes with the same diameter under hydraulic fracturing conditions were obtained based on Newton's second law, then transformed into the calculation models of the kinetic velocity of sands.As indicated in the research, the double-helix hydraulic fracturing pipe strings and injector can generate rotational flow, which help to balance double-helix hydraulic fracturing effects, and reduce erosion unevenness between the upstream and the downstream.The movement of sands can be described in a model by the accelerated movement equation with a constant accelerated velocity and varied accelerated velocity inside straight pipes and double-helix pipes, respectively.The research demonstrated that the double-helix hydraulic fracturing pipe strings and injector can function well, which are feasible evidently in balancing the multi-stage hydraulic fracturing effects and improving sand-carrying capacity of fluid along horizontal wellbores.
Key words: hydraulic jet fracturing     Archimedes double helix     injector     fracturing tubing string     carrying sand flow

1 阿基米德双螺旋线原理

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2 双螺旋水力喷射器结构与性能 2.1 结构设计

 图 1 阿基米德双螺旋水力喷射器 Fig.1 Archimedes double helix hydraulic injector 1.双螺旋本体；2.喷嘴套；3.O形密封圈；4.铜垫片；5.喷嘴
2.2 材料优选与参数优化 2.2.1 材质优选

2.2.2 承压能力

2.2.3 喷嘴节流压差损失

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 图 2 双螺旋水力喷射器喷嘴节流压差随排量变化曲线 Fig.2 Change of throttling pressure difference of injector with pump displacement

3 双螺旋管柱室内试验及动力学机理 3.1 可视化携砂试验

 图 3 等径直管内携砂流动过程 Fig.3 Dynamic process of sand-carrying flow in straight pipe

 图 4 双螺旋管内携砂流动过程 Fig.4 Dynamic process of sand-carrying flow in double helix pipe

3.2 携砂流动动力学机理 3.2.1 砂粒运动的动力学方程

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1) 砂粒所受流体曳力

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2) 水平压力梯度力

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3) 虚拟质量力

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4) 砂粒的重力

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5) 螺旋离心力

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3.2.2 砂粒运动速度求解及分析

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4 现场试验

5 结论与建议

1) 压裂管柱及喷射器内增加双螺旋结构是可行、有效的，能够起到螺旋旋流作用，建议将该技术推广应用到国内各油田水平井的水力喷射体积压裂施工中。

2) 双螺旋管柱可以改善水平段携砂流体中砂粒的悬浮性，降低上、下游喷嘴处砂粒分布的不均匀性，使上、下游喷射器喷嘴及本体周围的冲蚀更加均匀，延长双簇水力喷射器的使用寿命。

3) 等径直管和双螺旋管内携砂流体中砂粒的运动速度分布规律为：等径直管内砂粒的运动满足恒定加速度运动方程，双螺旋管内砂粒的运动符合变加速度运动方程。这揭示了等径直管和双螺旋管内携砂流体中砂粒运动的动力学机理。

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#### 文章信息

TONG Shaokai, GAO Deli

Hydraulic Jet Fracturing Technology Based on Archimedes Spiral Theory

Petroleum Drilling Techniques, 2018, 46(1): 90-96.
http://dx.doi.org/10.11911/syztjs.2018013