有了降阻工具 连续油管何止“万能”！

连续油管在石油行业有着“万能作业机”的美誉，其应用范围广，可应用于钻井、测井等多种油田作业中。随着非常规油气和深水项目的不断开发，连续油管的应用也遇到了一些难题，比如在深水井或者超深井的连续油管使用中，由于其与油、套管之间的摩擦阻力，连续油管很难到达指定深度，这已经是业内公认的一大难题。

针对这一难题，Trican Well Service公司与CT Energy Services联合研发推出一种新型降低连续油管摩阻工具——Toe Tapper。Toe Tapper作为新一代降低摩阻工具的典型代表，可增加连续油管入井深度，在利用连续油管磨铣作业中可更好地控制磨鞋上部钻压。Toe Tapper能够发射低频脉冲，压力脉冲能够长时间的作用在连续油管上，更有效、持久地降低连续油管与套管间的摩阻。

该工具通过流体流动造成负压脉冲，进而引起射流冲击效应，“打破”连续油管和套管间的摩阻力并产生液压牵引力。螺旋弯曲效应（helical buckling）会导致连续油管在井内发生锁定，而摩阻降低会削弱该效应造成的消极影响，连续油管入井深度也会增加。

Trican公司在连续油管和井下工具作业方面拥有丰富的经验，并向全球的运营公司和工具服务商提供Toe Tapper工具。此外，该公司还提供一套完备的井下磨铣钻具组合、连续油管压裂工具以及水平井多级完井工具组合。

Toe Tapper连续油管降阻工具

Toe Tapper是一款独特的连续油管降低摩阻工具，通过产生负压脉冲来削弱连续油管所受到的摩阻拖曳力。该工具在流体通道内部署了一个变量限流器，从而可向环空低频泵送流体。由于连续油管底部压力的急剧降低，便会产生周期性的射流冲击效应。这种压力脉冲会驱动连续油管下行，降低了从静态向动态转变时的摩擦系数。

该工具发射低频脉冲的特性使压力脉冲在连续油管上的作用时间会更久，同时也可提高碎屑清洁效果。射流冲击效应也会产生机械力；在旋转阀运行周期内，液压惯性力在轴向发生作用，产生的冲击能量脉冲能够促进重量转移。相关证据表明，这种压力脉冲提高了螺旋屈曲阈值，连续油管与Toe Tapper工具组合的刚度变化区间变得更加宽阔且压力峰值时的刚度较大。

Toe Tapper配备有一个旋转阀，由一款低额定转速的动力装置驱动。旋转阀通过周期性地改变流体流向来引起连续油管内的压力变化，频率变化取决于流量变化。

该装置还可以根据需要进行配置优化，比如在可以确定较快的压力变化速率可以更有效地降低摩阻的情况下，则可以增加动力装置部分的功率，更有效的降低摩擦阻力。该工具特别适用于大斜度水平井内磨铣作业，可以显著降低平均磨铣次数。

为使工具效能达到最大化，大约5%~8%泵入连续油管内的流体会通过Toe Tapper工具靠近底部的喷嘴流入环空。这种贯通设计能够产生更高效的负压脉冲，引起的射流冲击效应可以有效降低摩阻。低频负压脉冲作用在连续油管上的时间会更久，可使连续油管下行时间更长。此外，这种贯通设计还允许泵速进一步提高，进而可以更好地清理井底碎屑与井眼清洗。

应用石油圈原创www.oilsns.com

1. 单井增产措施作业，井筒干预作业；
2. 复合桥塞磨铣；
3. 断裂金属落鱼磨铣；
4. 清砂作业；
5. 生产测井，磨料射流作业。

特性石油圈原创www.oilsns.com

1. 动力装置功率可调，进而可改变压力脉冲频率；
2. 阀门系统可调，进而可增加或降低压力脉冲幅度；
3. 可与多种性质流体配合使用，例如氮气。

应用优势石油圈原创www.oilsns.com

1. 射流冲击效应产生液压拉力，能够促进重量转移；
2. Toe Tapper™能够发射低频脉冲，压力脉冲作用于连续油管的时间会更久，从而能够更有效地降低摩阻，连续油管入井深度便会更大；
3. 减小螺旋屈曲效应引起的摩阻；
4. 可减少平均磨铣次数；
5. 特别适用于水平段较长的单井；
6. 可提高井内碎屑清洗效果。

关于Trican Well Service石油圈原创www.oilsns.com

Trican 是一家业内领先的技术服务公司，业务服务范围覆盖全球。公司始建于1996年，经过多年的发展，积累了相当雄厚的技术团队，其中在压裂、完井和井筒干预等方面的技术在业内处于领先地位。此外，公司还提供连续油管、酸化、固井等服务。

来自/Trican Well Service     译者/姚园     编辑/Lemon

Toe Tapper works by enabling the fluid flow to generate negative pressure pulses that cause a fluid hammer effect. This breaks the friction between the coiled tubing and casing and creates hydraulic pull forces. The reduced friction decreases the effects of helical buckling, which can lead to a coiled tubing lock-up situation. As a result of this decreased friction, far greater well depths can be reached.

The tool’s unique capability of producing a low frequency pulse means more effective friction reduction through a pressure pulse that has more time to act on the coiled tubing. The Toe Tapper contains a rotary valve that is driven by a low RPM power section. The valve diverts flow to cyclically change the pressure within the coiled tubing. The frequency is driven by the flow rate. If it is determined that faster frequencies are more effective for a particular application, the power section of the tool can be adjusted to increase speed.

This tool is of particular interest to those working on extended horizontal wells, where better average milling times can be achieved. Trican has extensive knowledge in coiled tubing and downhole tool operations, and the company will offer this tool worldwide to operating companies and tool service providers alike. Trican offers a complete range of milling bottomhole assemblies, coiled tubing fracturing tools, and a comprehensive portfolio of horizontal multistage completion solutions.

Trican’s Toe Tapper™ is a unique coiled tubing friction reduction tool. The tool generates a negative pressure pulse that stimulates the coiled tubing frictional drag. By using a variable restrictor in the fluid flow, the Toe Tapper is tuned to dump fluid to the annulus at a low frequency. This generates a periodic fluid hammer effect, due to a sharp reduction in pressure at the bottom of the coiled tubing. This pressure pulse actuates the flexible coiled tubing, reducing the friction coefficient from static to dynamic.

The slower frequency of the tool gives more time for the energy of the pressure pulse to act on the coiled tubing, which also improves cuttings removal (as the coiled tubing actuates over a larger area). The fluid hammer effect also generates a mechanical force; while the valve cycles, the hydraulic inertial forces react axially and produce an impact energy pulse which improves weight transfer. Evidence has shown that this pressure pulse improves the helical buckling threshold, as the rigidity of the coiled tubing with the Toe Tapper is more dynamic, with higher rigidity at the pressure peaks.

The tool’s unique capability of producing a low frequency pulse means that the tool provides a more effective friction reduction through a pressure pulse that has more time to act on the coiled tubing. As a result of this decreased friction, far greater well depths can be reached.

To achieve maximum tool efficiency, approximately 5%-8% of the fluid being pumped down the coiled tubing is vented to the annulus through a nozzle near the bottom of the Toe Tapper. This venting generates a more efficient negative pressure pulse, which produces the fluid hammer effect responsible for breaking friction. The low frequency negative pressure pulse actuates the coiled tubing over a longer period, allowing the coiled tubing more time to move. The fluid venting also permits slightly higher pump rates, which in turn improve debris removal and well cleaning.

Features

• Power section can be tuned to change pressure pulse frequency.
• Valving system can be tuned to increase/decrease pressure pulse magnitude.
• Can be used with a variety of fluids including N2.

Benefits

• Fluid hammer effect produces hydraulic pull, improving weight transfer.
• Low frequency enables the high amplitude pressure pulse time to act on the coiled tubing effectively.
• Reduces friction caused by helical buckling.
• Improved milling times.
• Extended reach in long horizontal well sections.
• Improved debris cleaning

Applications

• Extended reach well stimulation operations.
• Extended reach well intervention procedures.
• Extended reach composite bridge plug milling.
• Extended reach fracture hardware milling.
• Extended reach toe preparation.
• Extended reach sand cleanout.
• Extended reach production logging.
• Extended reach abrasive perforating.

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