Halliburton used the HydraWash™ system to perforate, wash and cement wells in a single trip, eliminating milling and disposal issues in the process.

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A CAse study:

Time and expense of milling casing

When abandoning wells, Norwegian regulations call for cementing two 50-meter sections of casing above and below each hydrocarbon-bearing zone. The preferred way to do this used to be milling out casing. But each section took more than 10 days to mill and generated four tons of swarf.

Swarf damaging blow out preventer (BOP)

Milling generates swarf, which then must be removed before cementing. However, swarf removal can damage the BOP. To avoid well integrity issues with a non-functional BOP and ensure safe operation on future jobs, BOPs had to be dismantled, inspected and repaired at considerable expense.

Re-entry into well if necessary

Traditional milling destroyed the casing. This makes re-entry into the well more or less impossible if problems develop either during the operation or in the future.

Perforate casing, then wash and cement

The HydraWash system eliminates milling. It perforates, washes and then places cement into the annulus of an already set casing, all in one run. The system incorporates tubing conveyed perforating guns, cement stinger and the HydraArchimedes cementing assurance tool.

HydraWash system eliminates swarf

Because the HydraWash system generates no swarf, it eliminates removal costs, plus a source of potential damage to the BOP. Finally, it eliminates the cost of BOP disassembly, inspection and repair.

Leaving casing intact

The HydraWash system leaves casing intact so operators can re-enter the well if problems develop. They simply drill out a cement plug inside the casing.

CHALLeNGe sOLutION

Saving rig time during plugging and abandonment

In the Norwegian sector of the North Sea, environmental regulations require cementing every permeable zone before abandoning a well. Because cement must go all the way to the formation, operators used to mill out casing and remove tons of swarf before spotting the cement. In addition to being expensive and time-consuming, this operation prevented re-entry into the wellbore. The HydraWash system can perforate, wash, and cement wells in a single trip, and greatly increases displacement efficiency by placing cement in a much more controlled manner. This method allows operators to re-enter the well to verify cement integrity. It also saves time by eliminating the need for milling and removal of swarf. The HydraWash system complies with all Norwegian regulations, which are among the most stringent in the world. The system helped operators in the North Sea save 414 rigs days while plugging and abandoning 67 offshore wells.

How North Sea operators saved 414 rig days while plugging and abandoning 67 wells

Source of BoP Damage eliminateD

ON 67WELLS

SAVED

414DAYS

High Cost of Milling EliminatedOne operator’s standards for plugging and abandonment (P&A) called for setting two plugs above the reservoir and two above the overburden (total of four) to help eliminate the possibility of leakage and contamination. Milling four areas took an average of 28 days with an average rig day costing $650,000. By eliminating the need to mill casing, the HydraWash™ system saved a major operator in the North Sea $18 million per well on 50 of the 67 wells mentioned on the previous page. Compared to milling, this one operator alone saved 340 of the total 414 days.

16 Tonsof swarf EliminaTEd pEr wEll

A CAse study: Saving rig time during plugging and abandonment

Milling each 50-meter section of casing generated four tons of swarf that had to be recovered, cleaned and disposed of. The HydraWash system eliminated these costs, too.

Eliminating swarf also eliminated one of the main sources of damage to BOPs during P&A.

The versatile HydraWash system is deployed on tubing. During the first phase of the operation, the tool perforates casing. Then it cleans out the annulus, removing debris, old mud, barrite, old cuttings and traces of cement behind the casing. Finally, it pumps cement into the void behind the casing to seal off permeable zones and prevent the migration of oil and gas to other strata or the surface.

ONE TOOL, ONE RUN

Massive projects calls for new solutionOperators have been drilling in the North Sea for more than three decades. Many reservoirs are now depleted. Authorities estimated, in May 2013, that 3000 wells in the Norwegian sector alone need to be plugged and abandoned. They also estimated that if five rigs were dedicated to the job full time, it would take 20 years to plug and abandon all those wells. This made finding a more efficient alternative to traditional milling techniques a top priority.

Traditional solutions too costly, time consuming and limitedNorwegian regulations call for isolating all permeable zones before plugging and abandoning wells. Cement must extend a minimum of 50 meters above any source of inflow. Hydrocarbon-bearing formations require two such barriers.

Traditionally, companies complied with this regulation by milling out 50-meter sections of casing, often in multiple runs. Then they had to remove swarf. Finally, they had to use an under-reamer to create a clean section in the formation before cementing. Each 50-meter section took 10.5 days and generated four tons of metal swarf. The sharp swarf often damaged expensive BOPs, which had to be inspected and refurbished after each job at great expense.

After completion, this traditional method also prevented operators from re-entering the wellbore if a problem developed or if future technologies made it economically worthwhile to recover reserves left in the ground.

one-run Hydrawash solution cuts time by more than two-thirdsSetting one 50-meter isolation plug using the traditional method used to take an operator 10.5 days and four trips for milling, clean out, under-reaming and cementing. Using the HydraWash system, they can now achieve comparable results in less than three days and one run. But the savings are even more dramatic. The HydraWash system can handle two zones on the same run, so treating two sections takes just 3.5 days. (Note that these times do not include actually setting the plug, just preparing the well for the plug.)

in use since 2010 with a 99.3% success rateOne major operator in the North Sea began using the HydraWash system in 2010. Since then, the system has had a 99.3% success rate. The system was originally conceived as a hydraulic perforating system, but has evolved to include explosive perforating guns, washing tools, a cement stinger, and cement assurance tools. Since its introduction, the tool has also evolved from a triple- to a double- to a single-trip system. Initial findings on the tool are summarized in SPE 148640 – Novel Approach to More Effective Plug and Abandonment Cementing Techniques.

The HydraWash™ system perforated, washed and cemented wells in a single trip, eliminating milling and saving 414 rig days on 67 P&A jobs.

A CAse study: Saving rig time during plugging and abandonment

Meets all regulatory requirementsThe HydraWash system meets Norway’s environmental regulatory requirements, which are among the highest in the world. Cementing with the HydraWash system creates effective zonal isolation as good as that achieved after milling. The results are comparable, except that when using the HydraWash system, the wellbore can be re-entered. The HydraWash system also has a number of other benefits. No swarf generated‘Swarf’ is the term used to describe metal shavings generated during milling operations. Typically, milling a 50-meter section of casing generates four tons of swarf. Swarf can interfere with cementing operations – especially when it gets into the annulus, so operators must try to recover as much as possible. However, many operators only recover approximately 25 percent. By eliminating swarf, the HydraWash system also eliminates swarf damage to other tools.

No post-operation inspection of BoP due to swarf requiredSwarf can also damage the BOP when it’s being removed from the well. By eliminating milling, the HydraWash system also eliminates any potential for damage due to swarf. Typically, after P&A of wells that have been milled, BOPs must be returned to the manufacturer for disassembly, inspection, and repair before they can be reused. HydraWash system technology eliminates this cost.

No viscous milling fluid to treat and disposeOperators must capture swarf, separate it from the fluids used in milling operations and then recycle or dispose of them. The HydraWash system eliminates these costs also.

Potentially saving operators billions of dollarsWith more than 3000 wells in the Norwegian sector of the North Sea that need plugging and abandonment, savings due to HydraWash technology could total billions of dollars. One major operator in the area estimates that HydraWash technology has already saved the company more than a quarter of a billion dollars while setting just 55 barriers.

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H010885 © 2013 Halliburton. All rights reserved. HydraWash™ is a trademark of HydraWell.

The HydraWash™ system perforated, washed and cemented wells in a single trip, eliminating milling and saving 414 rig days on 67 P&A jobs.

A CAse study: Saving rig time during plugging and abandonment

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