[编者注：这个故事最初出现在 2020 年 4 月版的 E&P中。在这里订阅杂志 。]

曾经有点新颖的大延伸支管现在正在北美以更快的速度进行钻探。以二叠纪盆地为例，过去5年完成的横向长度超过10,000英尺的水平井数量增加了近12倍，从2014年的63口跃升至2018年的
813口。

这些较长的支管使运营商能够完成更多阶段并实现每口井更大的储层覆盖率，从而提高每口井的产量。然而，它并非没有挑战。

挑战之一是在井趾阶段进行有效增产。在完井作业的第一阶段使用油管输送射孔时会出现作业挑战和风险。这种风险是由工具必须在井下行进的极端距离的性质造成的。尽管引入了液压驱动滑动套筒来解决这一挑战，但可靠性一直是一个问题，许多操作员被迫运行多个套筒作为预防措施。

Packers Plus 发布了一套在超长支线末端运行的工具，通过无干预操作降低风险来应对当前的挑战。将这些趾部选项与滑套完井技术相结合可以进一步加快完井时间并更快地使油井上线。

增产挑战
即插即用 (PNP) 是迄今为止最古老的完井方法之一。这种方法早于水平井，因此，部署在垂直井或小斜井中的电缆依靠重力进行井下输送。在水平井中，需要大量的水将电缆射孔枪泵送到深处，特别是在存在狗腿和狭窄区域的情况下。如果由于任何原因工具被卡住，补救机械或液压工具需要额外的液体。

PNP 工具还可以使用连续油管 (CT) 进行部署。在趾部阶段使用 CT 的优点之一是能够持续循环流体，这有助于调节油井以实现更顺畅的输送。然而，CT 的一个显着缺点是其范围。通电流体、专门的金属对金属润滑剂以及拖拉机或搅拌器可以帮助运输。然而，当将工具推入深处时，由于累积摩擦，CT 会呈螺旋状。如果 CT 推得太用力，它可能会扭结或弯曲，导致管道卡住或断裂。对于长井，这些限制可能会使脚趾阶段超出 CT 的范围。 

液压驱动套筒
液压驱动滑动套筒无需在完井计划的第一阶段进行干预，这对于大位移侧井来说是一个主要优点。这些套筒通过液压方式打开，无需干预并启动流体流入储层以启动增产。

可靠性已成为市场上一些液压驱动滑套的常见问题。由于某些套筒无法打开，操作人员已开始在井趾处运行两个或三个液压驱动的滑动套筒，以确保至少有一个套筒能够进入储层。虽然此选项确实允许无干预操作，但它不是一个具有成本效益的解决方案。

刺激选项
Packers Plus 设计了系统，通过一套液压激活脚趾接头来有效地刺激长距离侧向的脚趾阶段：Toe-XT 可测试液压脚趾套筒、Toe-AP 液压脚趾套筒、TREX 爆破片接头和 TREX 湿式接头鞋子。

Toe-XT 可测试液压套筒是一个注入/生产端口，允许套管柱在打开前进行一次压力测试。在执行套管完整性测试并且释放井中的压力后，滑动套筒准备好激活，操作员可以开始增产作业。

Toe-AP 液压趾套是用于固井衬管第一阶段的滑动套筒，可降低操作风险，同时节省第一阶段有效处理的时间和成本。通过结合用于工具激活的内部爆破片，脚趾套筒的可靠性得到增强。

TREX 爆破片短节消除了在 PNP 完井中使用 CT 运行来对第一级射孔的需要。这种液压启动接头通常作为主液压趾套的经济备用选项运行。如果需要，爆破片将在设定压力下爆裂，以与储层建立连通，并能够部署电缆工具来增产第一阶段。

TREX 湿鞋短节是一种液压驱动工具，无需 CT 运行即可在 PNP 完井的第一阶段进行射孔。着陆镖安装在浮环正上方，可取代水泥，用于启动湿靴短节并在镖周围创建一条流动路径，以与储层建立连通，并能够部署电缆工具以开始增产作业。

液压趾头接头具有多种功能，可融入各种完井设计中，以降低水平井第一阶段增产的操作风险。

混合完井系统
在大位移侧井的下部阶段将液压驱动趾接头与滑套技术相结合，可以进一步提高第一阶段的作业效率。混合完井在大位移侧井中特别有用。

球驱动完井是较低阶段的理想选择，因为它们不需要通过 CT 或钢丝绳进行输送。Packers Plus 球激活系统为操作员提供了裸眼或固井尾管以及单点进入或有限进入应用中混合系统所需的灵活性。与传统的 PNP 方法相比，长距离支线脚趾处的球激活套筒有助于更快、更有效地开始治疗过程。

当上级的测量深度触手可及时，系统通常会交叉返回 PNP 或 CT 套筒。混合组合可根据操作员偏好和完井设计要求进行定制，从而实现利用每种技术的最佳功能的定制系统。

案例研究 
一位在二叠纪盆地工作的操作员安装了 Toe-XT 液压套筒，以简化 PNP 井第一阶段的操作。经过近八个月的井下测试，趾套的激活成功执行，没有出现任何问题。

在激活 Toe-XT 液压套筒进行刺激之前，进行了 15 分钟的 8,900 psi 套管完整性测试。套筒在下一个压力循环时打开，从而能够刺激第一阶段。该井的第二阶段包括五个 QuickPORT IV 有限进入滑动套筒，这使得作业能够继续进行，而无需在阶段之间停机。

在另一个案例中，一家在二叠纪盆地工作的操作员通过在其 PNP 完井的趾部阶段部署球驱动滑动套筒，成功解决了大位移支管的操作问题。

其中一口井包括 80 个 QuickPORT IV 限制进入滑动套筒，分为 20 级，以覆盖最深 3,900 英尺的侧井，然后恢复到 PNP 状态以用于井的其余部分。这种混合完井技术被证明是有效的，所有 20 个阶段都在不到 70 小时的泵送时间内得到了增产。

结论
液压驱动脚趾接头为在大范围支管中开始增产作业提供了一种有效且高效的方法。通过在井趾处部署这些工具，运营商能够降低与大位移支管中电缆或 CT 输送相关的操作风险，并有效增产趾部阶段，同时最大限度地减少非生产时间并加快完井时间，从而更快地使油井上线。 。

[Editor's note: This story originally appeared in the April 2020 edition of E&P. Subscribe to the magazine here.]

Once somewhat of a novelty, extended-reach laterals are now being drilled at a greater pace across North America. In the Permian Basin, for example, the number of horizontal wells completed with lateral lengths exceeding 10,000 ft has increased by nearly 12 times over the last five years, jumping from 63 in 2014 to
813 in 2018.

These longer laterals have provided operators with the ability to complete more stages and achieve greater reservoir coverage with every well, resulting in higher production per well. Yet, it has not come without challenges.

One challenge is effective stimulation at the toe stages of the well. Operational challenges and risk arise when using tubing-conveyed perforating for the first stage of completion operations. This risk is present by the nature of the extreme distance the tools must travel downhole. Although hydraulically activated sliding sleeves were introduced to solve this challenge, reliability has been an issue, and many operators have been forced to run multiple sleeves as a precautionary measure.

Packers Plus released a suite of tools to run at the toe of extended-reach laterals that address current challenges by decreasing risk with interventionless operation. Combining these toe options with sliding sleeve completion technology can further expedite completion time and bring wells online quicker.

Stimulation challenges
Plug and perf (PNP) is by far one of the oldest completion methods. This method predates horizontal wells and, as such, the wireline deployed in vertical or slightly deviated wells relied on gravity for downhole conveyance. In horizontal wells, large volumes of water are needed to pump wireline perforating guns to depth, especially if there are doglegs and tight areas. If for any reason the tools get stuck, remedial mechanical or hydraulic tools require additional fluid.

PNP tools also can be deployed using coiled tubing (CT). One advantage of using CT for the toe stages is the ability to continually circulate fluid, which helps condition the well for smoother conveyance. However, a significant disadvantage of CT is its reach. Energized fluid, specialized metal-to-metal lubricants and tractors or agitators can help with the conveyance. However, CT can spiral due to cumulative friction when pushing tools to depth. If CT is pushed too hard, it can kink or buckle, causing the tubing to become stuck or part. For long wells, these restrictions may leave the toe stages out of reach of CT. 

Hydraulically activated sleeves
Hydraulically activated sliding sleeves eliminate the need for intervention for the first stage of a completion program, which is a major benefit in extended-reach lateral wells. These sleeves are opened hydraulically, without the need for intervention and initiate fluid flow into the reservoir to initiate stimulation.

Reliability has become a common issue regarding some hydraulically activated sliding sleeves on the market. Due to some sleeves not opening, operators have taken to running two or three hydraulically activated sliding sleeves at the toe of a well to ensure at least one sleeve will provide access to the reservoir. While this option does allow interventionless operations, it is not a cost-effective solution.

Stimulation options
Packers Plus has engineered systems to effectively stimulate the toe stages of extended-reach laterals through a suite of hydraulically activated toe subs: the Toe-XT Testable Hydraulic Toe Sleeve, Toe-AP Hydraulic Toe Sleeve, TREX Rupture Disc Sub and TREX Wet Shoe Sub.

The Toe-XT Testable Hydraulic Sleeve is an injection/production port that allows the casing string to be pressure tested a single time before opening. After the casing integrity test has been performed and pressure in the well is released, the sliding sleeve is ready for activation and the operator can begin stimulation operations.

The Toe-AP Hydraulic Toe Sleeve is a sliding sleeve for the first stage of a cemented liner that reduces operational risk, while saving time and cost in delivering an effective treatment of the first stage. The reliability of the toe sleeve is enhanced by incorporating an internal rupture disc for tool activation.

The TREX Rupture Disc Sub eliminates the need for a CT run to perforate the first stage in PNP completions. This hydraulically activated sub is typically run as an economical backup option to the primary hydraulic toe sleeve. If required, the rupture discs will burst at a set pressure to establish communication with the reservoir and enable wireline tools to be deployed to stimulate the first stage.

The TREX Wet Shoe Sub is a hydraulically activated tool that eliminates the need for a CT run to perforate the first stage in PNP completions. Assembled just above the float collar, the landing dart that displaces cement is used to activate the Wet Shoe Sub and create a flow path around the dart to establish communication with the reservoir and enables wireline tools to be deployed to commence stimulation operations.

With a range of functionalities, hydraulic toe subs can be incorporated into a variety of completion designs to reduce operational risk in stimulating the first stage of a horizontal well.

Hybrid completion systems
Combining hydraulically activated toe subs with sliding sleeve technology in the lower stages of an extended-reach lateral well can further enhance the operational efficiency experienced for the first stage. Hybrid completions have become particularly useful in extended-reach lateral wells.

Ball-activated completions are ideal for lower stages, as they do not require conveyance by CT or wireline. Packers Plus ball-activated systems give operators the flexibility needed for hybrid systems in openhole or cemented liners as well as single-point entry or limited-entry applications. Ball-activated sleeves in the toe of extended-reach laterals help start the treatment process faster and more efficiently than traditional PNP methods.

A crossover back to PNP or CT sleeves is typical for systems at the point when measured depths for upper stages are within easy reach. The hybrid combination is customizable to suit operator preferences and completion design requirements, enabling a customized system that utilizes the best features of each technology.

Case studies 
An operator working in the Permian Basin installed the Toe-XT Hydraulic Sleeve to simplify operations for the first stage of a PNP well. After nearly eight months sitting downhole, activation of the toe sleeve was successfully executed without issue.

A casing integrity test to 8,900 psi was performed for 15 minutes before the Toe-XT Hydraulic Sleeve was activated for stimulation. The sleeve opened on the next pressure cycle, enabling stimulation of the first stage. The second stage of the well included five QuickPORT IV Limited Entry Sliding Sleeves, which enabled operations to continue without downtime between stages.

In another case, an operator working in the Permian Basin successfully resolved operational issues in extended-reach laterals by deploying ball-activated sliding sleeves for the toe stages of its PNP completions.

One of the wells included 80 QuickPORT IV Limited Entry Sliding Sleeves segmented into 20 stages to cover the deepest 3,900 ft of the lateral before reverting back to PNP for the rest of the well. This hybrid completion technique proved effective, and all 20 stages were stimulated in less than 70 hours of pumping time.

Conclusion
Hydraulically activated toe subs provide an effective and efficient method for beginning stimulation operations in extended-reach laterals. By deploying these tools at the toe of a well, operators are able to reduce operational risk associated with the conveyance of wireline or CT in extended-reach laterals and effectively stimulate the toe stage while minimizing nonproductive time and expediting completion time to bring wells online faster.