A L L D R I L L I N G • A L L C O M P L E T I O N S • A L L T H E T I M E

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Dr i l l i ngC O N T R A C T O R

OFFICIAL MAGAZINE OF THE INTERNATIONAL ASSOCIATION OF DRILLING CONTRACTORS

N O V E M B E R / D E C E M B E R 2 0 1 3 W W W. D R I L L I N G C O N T R A C T O R . O R G

WELL CONTROL Expanded containment system under development for GOM; study targets better prediction of pipe shearing characteristics – p.57

THE RISING EAST Big changes, big growth on the horizon for Asia Pacific drilling landscape – p.80

DC Nov13 COVER indd 2 10/21/2013 12:51:57 PM

Completions

Reprinted from the November/December issue of D r i l l i n g contractor. © 2013 Drilling Contractor. All rights reserved. Printed in the USA.

a fter multiple cement squeezes in a well in Malaysia failed to iso-late a damaged casing section, it

appeared that abandonment was likely. As with many aging wells around the world, the decision to restore this well-

bore’s integrity was based on economics. For this offshore well, the difficulty of

achieving an effective cement job made the operation appear to be a futile effort. Other solutions, such as conventional lin-ers or straddle packers, were not feasible

because valuable hole size would be lost.To make the remediation effective, two

goals had to be achieved. First, the cost of the repair had to be balanced by long-term isolation that significantly extends the well’s life. Second, the solution had to

Economical solution can provide long-term isolation to extend

life of well, maximize injection rates while conserving hole size

By Luis Godoy, Weatherford

Figure 1: Extended recovery supports the value of casing remediation through solid expandable liners.

Expandable cased-hole liners assist integrated casing remediations

Completions

Reprinted from the November/December issue of D r i l l i n g contractor. © 2013 Drilling Contractor. All rights reserved. Printed in the USA.

maximize injection rates by conserving as much hole size as possible.

Instead of abandoning the asset, the operator collaborated with Weatherford to deploy an integrated remediation sys-tem that allowed them to find the specific issue, prepare the wellbore prior to fixing the issue and recomplete the well to con-vert it to a water-alternating-gas injec-tion well. This integrated remediation approach, which includes expandable cased-hole liners, is finding increasing favor across a range of global remedia-tion applications.

For the Malaysia well, installation of 69 ft of an expandable cased-hole liner provided a reliable, long-term means of restoring wellbore integrity with minimal loss of inside diameter. Performed on a single trip, the installa-tion conserved hole size with a 7.90-in. post-expansion ID and 7.775-in. drift. Successful isolation of the problem sec-tion was confirmed with a post-instal-lation pressure test to 3,000 psi. As a result, the injection well was restored to optimal service condition and given a new, long-term lease on life.

A globAl solution The economic and operational chal-

lenges and results from the Malaysian casing remediation are much the same as applications in others parts of the world. Onshore and offshore, in producing and injection wells, expandable liner systems

are being used to address a variety of critical remedial challenges, such as cor-roded or damaged casing, water shut-off and sealing off old perforations.

With the increasing number of mature fields and the growing risk and com-plexity of developing new oil and gas reserves, operators are looking for more effective and cost-efficient remediation solutions to maximize production from existing assets.

With an integrated remediation approach, restoring productivity often makes economic sense. The cost of reme-diation to return an asset to its optimal production is typically an easily support-ed expenditure when considering life-of-well productivity (Figure 1).

integrAted remediAtion The development and use of expand-

able liners is a significant contributor to this growing trend and is resulting in a second look at mature fields that might otherwise have been abandoned. In these wells, expandable cased-hole liners are helping to improve performance by restoring wellbore integrity and maxi-mizing reservoir output. Applied as part of an integrated remediation system, the technology is achieving significant suc-cess in restoring long-term casing integ-rity that reduces intervention costs and extends recovery.

Compared with cement squeezes or straddle packers and conventional liners,

the expandable liner can be a more reli-able and cost-effective tool for restoring casing integrity.

Single-trip installation without the shoe drillout required with a conven-tional liner significantly reduces rig time and NPT. Typically, expandable liners are installed in one to two days, allowing the operator to immediately test the well and return it to production.

Completions, production and future interventions are optimized because the expandable liner conserves hole size to provide the largest possible wellbore ID. Conventional liners and packer meth-ods are often limited or unacceptable because this valuable hole size is lost. The smaller ID constrains the comple-tion and ensuing production and reduces options in future production optimiza-tion efforts.

Using straddle packers to isolate a casing problem can reduce ID even more than a conventional liner. While the straddle packers can be removed to allow work deeper in the well, they provide only temporary isolation, not a permanent solution, and they do so at the cost of severely limiting ID.

In 4 ½-in. and 5 ½-in. cased holes, expandable liners provide a permanent remediation option in smaller diame-ters where a standard liner is not a viable alternative. Further, while con-ventional liners are cost-effective over long intervals measured in thousands of

Integrated remediation by the numbers• Malaysia: 69-ft expandable cased-hole liner installation conserved hole

size with a 7.90-in. post-expansion ID and 7.775-in. drift. Successful isolation was confirmed with pressure test to 3,000 psi.

• Iraq: two 7 5/8-in. x 9 5/8-in. expandable liners were installed. a 39.3-ft lower perforation level was isolated with a 110.8-ft liner. Upper 13.1-ft interval was isolated with 35.1-ft liner.

• new Mexico: 4 ¼-in. x 5 ½-in. expandable liner with a post-expanded length of 700 ft was installed in target interval at 5,000 ft. Isolation allowed new intervals to be fractured at 5,500 psi.

Completions

Reprinted from the November/December issue of D r i l l i n g contractor. © 2013 Drilling Contractor. All rights reserved. Printed in the USA.

feet, expandable liners can be more cost-effective for shorter sections with specific casing repair and isolation problems.

The other common remediation method, a cement squeeze, can pro-duce unpredictable results and expose the formation to high-pressure risks. Ultimately, it is more of a short-term treatment that will require repeated interventions throughout the well’s remaining life.

A comparison of conventional cement squeeze and solid expandable cased-hole liner costs illustrates the relative eco-nomics. In a study of casing remediation methods, the authors found that when considering days versus cost, the total outlay of a single squeeze operation is nearly $225,000, accounting for nine total days from the time the rig is moved on location until the well is back on produc-tion (Farley, SPE 159685).

Using the same base costs from an East Texas job, it was determined that using a solid expandable liner saved an average of three days while incurring 36% less in associated costs. Another cost factor is that cement squeezes are often not successful on the first attempt. A second squeeze in the same operation could increase costs to nearly $291,000 and add two more days of rig time. The fixed cost of a solid expandable cased-hole liner could cut those costs in half.

remediAtion cycle process

The operator uses the expandable liner as part of an integrated process that locates the problem, prepares the wellbore, fixes the casing and recom-pletes the well. It requires no cement and applies no pressure to the formation dur-ing the installation process. The process has a history of success in repairing and remediating common problems.

The method first employs cased-hole wireline logs to precisely locate problems with casing, water production sources, wellbore obstructions and bypassed production zones. These logs include advanced imaging and multisensory cali-per tools used to locate internal and external defects caused by corrosion, scale, wear and failure.

Once the problem is identified, the wellbore is prepared for remediation based on the specific conditions. A vari-ety of clean-out mills, such as junk, taper or watermelon mills and other tools, may be deployed to provide a clear path for running the expandable liner. Chemical, hydraulic or other mechanical methods also can be applied prior to the liner installation.

The actual remediation step involves installation of an expandable cased-hole liner to cover the problem area. The lin-ers can be run in short and long lengths

to precisely cover target intervals. They are installed in a single trip and require no cement or shoe drill-out (Figure 2).

Once casing integrity is restored, a variety of cased-hole completion services are applied to install packers, frac plugs and artificial lift.

globAl ApplicAtions

PErforation isolation in thE MiddlE East

In northern Iraq, developing new pro-duction from an existing well first required isolation of two perforated intervals in the 9 5/8-in. casing. The remediation had to minimize the loss of inside diameter and provide good economics with long-term isolation. It was also important that planned well tests avoid inducing commu-nication across the old zones.

To meet the objectives, the wellbore was prepared using cleaning equipment, including casing scrapers and brushes, and a junk mill. Once the casing was pre-pared, two 7 5/8-in. x 9 5/8-in. expandable cased-hole liners were installed across the two sets of perforations. The lower perforation interval of 39.3 ft was iso-lated with a 110.8-ft liner, and the upper perforation interval of 13.1 ft was iso-lated with a 35.1-ft liner. Hole size was conserved with a post-expansion drift of 7.475 in. for a 7.60-in. ID.

Figure 2: Expandable cased-hole liners can be effective for shorter intervals with specific casing repair and isolation problems, while conventional liners may be better for long intervals.

Completions

Reprinted from the November/December issue of D r i l l i n g contractor. © 2013 Drilling Contractor. All rights reserved. Printed in the USA.

Each installation was performed in a single trip, and, unlike a conventional liner, no shoe drill-out was required. The total operation, including the cleaning run to prepare the casing interior, took 29 hrs.

africa casing corrosionCorroded casing and water flow in a

shallow well offshore Congo presented multiple challenges. First, it was critical to find a remediation method that was economical in the context of the mature field. Operationally, the remediation had to contend with platform deck space and weight limitations that prevented the use of a workover rig. The presence of H2S further complicated the remedia-tion.

The corrosion and source of the water flow was first located with wireline ser-vices. Prior to installing an expandable liner system, the casing was prepared using fishing and wellbore cleaning ser-vices.

Weatherford worked with the opera-tor to develop an H2S-resistant 5 ½-in. x 7-in., 29 lb/ft expandable liner. The liner covered a corroded interval between 820 ft and 1,312 ft to provide a long-term, stable and cost-effective reme-diation that brought the well up to full integrity.

Instead of a workover rig, a jacking system and specialized equipment were used to overcome platform limitations and run the liner. The single-trip instal-lation provided a post-expansion drift of 5.265 in. to optimize the completion and production. Water production was elimi-nated, and the well was put on produc-tion at 250 bbl/day of oil.

south aMErica sEal-offIn an onshore S-type well near

Santander, Colombia, watered-out inter-vals led to installation of a 55-ft, 5 ½-in.,

17 lb/ft expandable liner in the wellbore’s existing 7–in., 29 lb/ft casing. The objec-tive was to improve production capac-ity by sealing off upper water-producing perforations and recomplete deeper in the well.

To optimize the completion and future production, it was important that the remediation minimize the loss of inter-nal diameter. The expandable cased-hole liner resulted in a reduction of only 0.79 in. The inner diameter of the expanded system was 5.39 in., allowing a drift diam-eter of 5.265 in.

Due to the tubing overpull and work-over equipment limitations, the expan-sion was performed hydraulically in stag-es using a setting tool. The pipe was suc-cessfully expanded and pressure-tested to confirm restored integrity.

us rEfracs and intEgrityAn operator in New Mexico needed to

cost effectively cover and isolate perfora-tions in 5 ½-in., 15.5-lb production casing to seal off watered-out zones and enable the stimulation of new intervals.

For this well remediation, the process included preparing the casing interior, installing the expandable liner to iso-late the perforations and supporting the completion with specialized equipment.

A 4 ¼-in. x 5 ½-in. expandable liner with a post-expanded length of 700 ft was installed in the target interval at approximately 5,000 ft. The installation covered and isolated the upper perfora-tions so that newer intervals could be fractured at 5,500 psi.

The permanent liner provided an economical solution that eliminated the need for multiple cement squeeze operations. Unlike a conventional liner, the expandable liner maximized the retained hole size for optimal produc-tion and to facilitate future well inter-vention. A unique composite frac plug

was used to allow the operator to set back inside 5.5-in. parent casing after passing through the installed expand-able liner.

In a North Dakota well, multiple cement squeezes had failed to mitigate corrosion leaks in 7-in., 26 lb/ft casing. Running conventional casing significant-ly limited the wellbore ID. To re-establish casing integrity, an integrated remedia-tion process was applied.

The wellbore was cleaned, and Weatherford’s wireline multi-sensor cali-per tool was run to identify the extent of damage and determine the best remedy. TotalView visualization software pro-cessed the caliper data to identify casing restrictions, assess drift ID and deter-mine casing damage. The analysis iden-tified severe damage across the 150-ft section, and a 5 ½-in., 17 lb/ft expandable liner was installed.

The cased-hole remediation provid-ed a long-term, cost-effective means of restoring casing integrity in the well-bore. The solution brought the well to full integrity standards in less than two weeks.

conclusionIn the midst of a fully developed

infrastructure, aging wells around the world represent a tremendous oppor-tunity for operators. These wells typi-cally face age-related casing integrity problems that are critical constraints to their ongoing operations. For many of these wells, conventional remediation techniques, such as cement squeezes, straddle packers and conventional lin-ers, present hurdles to cost-effective remediation. An integrated remediation system that includes expandable lin-ers provides an option that is return-ing wellbores to service and changing the productive outlook for thousands of wells.