Every well comes to an end… and at a pure cost to the operator.
Thousands of wells are approaching end of life each year. An increasing number of them are costly subsea developments.
Decommissioning is an inevitable chapter in every well’s lifecycle. When production rates drop below economically sustainable rates, plug and abandonment (P&A)—unlike other stages of well life—comes at a pure cost to the operator. Removing downhole infrastructure and leaving behind a clean seabed is a costly endeavor, averaging tens of millions of dollars for a single subsea well. And global spending on P&A operations is expected to double in the next decade as a record number of wells reach end of life.
Efficient casing removal is critical to the bottom line. So is safety.
Minimizing the number of trips it takes to retrieve casing is key to reducing nonproductive time (NPT) and avoiding excessive, unnecessary costs. But cost isn’t the only concern. Extra trips also translate to increased health, safety, and environmental (HSE) exposure. So effcient operations and reliable well control during casing removal are critical to protecting people and the environment.
And the need for efficiency extends beyond well P&A operations. When you’re not ready to abandon, slot recovery can be a cost-effective means to drill for additional resources from the same surface structure.
But casing removal can be difficult because of cement stringers, scale buildup, and other unknown factors.
Accomplish your objective in one run. Safely. Efficiently.
After decades downhole—encased in cement and subjected to wellbore conditions—casing can present serious challenges during retrieval. Cement stringers, barite settling, or other unknown factors can make pulling the cut casing impossible. And when the casing is stuck, the spear has to be released, pulled out of the hole, and then run back in for another attempt. The entire operation is then repeated by cutting at points higher up in the well until a successful pull is made. In difficult wells, this process can quickly compound into a great number of wasted trips and lead to significantly more rig time, higher costs, and increased risk.
With the Harpoon cut and pull spear, multiple recovery attempts can be performed in a single trip, significantly increasing the likelihood of retrieving the casing in one run. This drastically reduces NPT, and increases the overall efficiency, safety, and economics of P&A and slot recovery operations.
When performing a cut and pull operation, the Harpoon casing spear is run to depth in a bottom hole assembly (BHA) consisting of a multistring cutter, Harpoon spear, jar, accelerator, and drill collars. The spear does not require a stop ring, so it can engage the casing directly above the cut point and transmit maximum force during cutting operations.
Once at depth, specially designed FLEX-LOCK slips engage the casing and provide 360° coverage to maximize pulling capabilities and prevent casing deformation. Applied overpull sets the retrievable packing element stack, which stays energized throughout cutting operations to control circulation paths for added safety. The pack-off feature also enables hydraulic boosting to assist with retrieval.
During cutting operations, tension is applied to the casing to enhance cutting performance. The cutters— dressed with METAL MUNCHER Advanced Milling Technology (AMT) tungsten carbide—are super durable, and can perform multiple consecutive cuts, if required. In the event that a pressurized zone is exposed during cutting, the outlet ports are closed and the well is re-balanced so operations can be safely resumed. A built-in filter prevents cuttings and other debris from collecting in the blowout preventer (BOP) stack for added reliability.
When the cut is complete, the casing can be retrieved using any combination of the following methods to apply tension and pull the fish:
Overpull
Jarring impacts
Hydraulic pressure
Once the casing is free, the Harpoon spear unsets from its position at the bottom of the casing and resets at the top of the fish to allow for easy handling of both the spear and the casing at surface. If well conditions such as cement or scale buildup make pulling the casing impossible, the Harpoon spear can be easily unset and relocated higher in the casing to perform another cut and pull attempt. The ability to set and reset within the same run eliminates a dedicated round trip to reset the spear. This helps keep costs down and reduces HSE exposure. And those benefits only compound as each extra trip is eliminated.
Applications
Slot recovery
Well plug and abandonment
Land operations
Offshore/deepwater
Where cement and scale build up are unknown
Features and benefts
Continuously resettable in-line spear
– Enables multiple cut-and-pull operations in the same trip
Works with drillpipe rotation or a motor
– Enables mechanical set andrelease independent of hydraulicactuated tools
– Provides versatility
Robust design
– Holds force in both directions, enabling jars to be recocked
360° slip coverage
– Maximizes pull capabilities
– Limits deformation to the casing
Built-in debris filter
– Prevents debris from collecting in the blowout preventer stack
Pack-off feature
– Helps control gas circulation if a gas kick occurs
– Allows pack-off and hydraulic lift assistance if needed
Cuts in tension
– Improves cutting performance
Case study
Location: Norwegian Sea
Benefts
Minimized NPT by reducing a tworun operation to a single trip
Saved 19.5 hours rig time and an estimated USD 650,000
Background and challenges
Offshore, deviated well with settled barite and solids
Slot recovery operation
Baker Hughes solution
Deployed the Harpoon cut and pull spear because of its advanced ability to perform multiple recovery attempts in a single trip
Reset the spear farther up the casing due to difficulties with the retrieval of the cut casing in its initial location
Cut the casing while applying tension, set the spear twice in different locations, and retrieved 1,134 ft of casing in a single trip in only 16.5 hours
石油圈
