New Polymer-Based Material Can Solve Massive Lost Circulation Problems

In an attempt to solve moderate-to-severe lost circulation problems, operators have pumped a variety of substances down the wellbore to reduce the loss of drilling fluid to a thief zone. Many of these "cures" involve the use of materials that swell in the presence of water and fill the thief zone area or at least plug the flow path from the wellbore so that fluid loss ceases.

Historically, lost circulation materials (LCM) and chemical products designed to treat severe or massive fluid loss situations have included cellulose, almond hulls, black walnut hulls, dried tumbleweed, kenaf, paper, asphalt and both coarse and fine rice. Pumping a powdered bentonite-diesel oil pill and chasing it with water is another method. The pill forms a semi-solid mass that can stem a severe loss. Bentonite can also be mixed with chemical polymers to form a pliable gel in the presence of water. These solutions may provide relief in moderate fluid loss situations, but most fail to restore drilling fluid circulation in situations involving massive fluid loss.

Fortunately, massive fluid loss solutions advanced considerably with the introduction of the recently developed FUSE-IT™ system from Halliburton Fluid Systems. This new system has proven successful in situations where all other treatments have failed.

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FUSE-IT sealant is a new and important component in the Halliburton Wellbore Stress Management™ service that addresses loss prevention and remediation. These services include software for engineering analysis and several other product options from Halliburton Fluid Systems and Halliburton Cementing product service lines. This selection of products allows Halliburton wellbore stability experts to help operators plan lost circulation solutions based on rock mechanics rather than a "one fit for all" flowchart.

FUSE-IT™ System
The chrome-free FUSE-IT system is a synthetic, polymer-based material that can offer significant advantages over other options in solving severe lost circulation events. The material does not crosslink and can achieve effective formation sealing properties without the addition of clays or other inorganic materials. In fact, the FUSE-IT material can be applied when either water-based or non-aqueous (oil- or synthetic-based) fluids are in the wellbore. It can be applied unweighted, or can be weighted up to 20.0 ppg for both water-based and non-aqueous fluid applications.

The FUSE-IT material will not set up on surface. After the lost circulation pill is placed downhole, it reacts instantaneously with water, most water-based muds and sodium chloride brines to create a competent, cohesive seal. It exhibits excellent tolerance to temperatures ranging from mild to 400ºF+. The system is suitable for both onshore and offshore applications and can be pumped straight from totes by using a conventional cementing unit with a mixing tank and manifold. No cement blending unit is necessary. The material is suitable for healing losses under many types of conditions:

Highly fractured or depleted formations
Vugular or cavernous formations
Cementing and squeeze operations
Interwell communications due to induced fractures, injection or water flooding.

FUSE-IT system added to lignosulfonate mud sample in a 1:20 ratio.

Case History
While drilling the 8-1/2" hole with a 16.6 ppg oil-based mud at 12,889 ft, a South Louisiana onshore operator experienced lost returns and 10,000 units of gas. The mud weight was increased to 16.8 ppg while the operator circulated through the choke. Losses increased and no returns were recovered. The operator made several unsuccessful attempts to stop the losses using various lost circulation materials containing fibers and asphalt materials and then performed a cement squeeze. All these attempts to restore lost circulation failed.

After studying the problem, Halliburton recommended applying a FUSE-IT lost circulation treatment with the appropriate spacers. The drillstring with bottomhole assembly and bit was tripped out of the hole and an RTTS packer (bypass tool) was tripped back into the hole to 11,720 ft while the crew mixed a FUSE-IT lost circulation pill.

Halliburton injected a 220-bbl treatment volume in the following sequence: 1) 100 bbl of water-based mud; 2) plus 50 bbl of FUSE-IT lost circulation pill with spacers; and 3) 70 bbl of water-based mud that was forced into the formation behind the LCM pill. The FUSE-IT material was allowed to set for 12 hours prior to opening the RTTS packer to circulate and thereby expose the formation to the full pressure of the wellbore. Circulation was established at the drilling rate with no losses.

Drilling resumed at 12,889 ft at 20 fph with a flow rate of 246 gpm and 1,920 psi standpipe pressure. Drilling continued to total depth (TD) at 13,270 ft with normal seepage losses. The total volume lost after the treatment, including mud lost on cuttings, was approximately 100 bbl.

The successful application of the pill eliminated non-productive rig time and expense related to setting a cement plug and sidetracking the well. The solution benefited the operator by extending the drilling depth from 12,900 ft to 13,270 ft without the need to set a 7-5/8" liner, resulting in a savings of approximately $500,000 for the operator. Drilling ahead in the 8-1/2" hole to 13,270 ft enabled the operator to run 5-1/2" production casing rather than 5" casing, allowing faster production.

Summary
Loss of circulation while drilling can be costly and difficult for operators, and massive lost circulation events can be devastating. These severe lost circulation events can disrupt drilling for days or even weeks.

The fast-acting FUSE-IT system offers operators new options when severe lost circulation occurs. This synthetic polymer-based material can help seal off even the most severe loss zones to allow the operator to return to normal drilling activities in as little as 30 minutes. This system has been proven in both onshore and offshore wells where all other cures have failed and is applicable in highly fractured or depleted formations, vugular or cavernous formations, cementing and squeeze operations and for interwell communications due to induced fractures, injection or water flooding.

FUSE-IT™ lost circulation material can be squeezed into loss zones to seal fractures. (Click image to enlarge)