BLEN-SEAL

Function

A superior, high strength cellulose fiber used to prevent/cure seepage loss, differential sticking, high torque and drag.

General Description

Micronized cellulose fibers, pre-absorbed with a low-aromatic/low toxicity lubricant.

Product Benefits

  1. Prevents and/or cures seepage loss of whole fluids.
  2. Can be used in any mud system.
  3. Is biodegradable and non-polluting.
  4. Has excellent high temperature performance.
  5. Reduces tendency for differential sticking and provides lubricity to reduce torque and drag.
  6. Neutral pH will not affect chemistry of water-based drilling fluids.
  7. Because of the unique lubricant on the fiber, water wetting is reduced.

Product Description

  • Color: tan to light brown
  • Form: Micronized cellulose fibers
  • Specific Gravity: 1.0
  • Bulk Density (Ibs./cu/ ft.):
  • Uncompacted: 15-18
  • Compacted: 28-30
  • pH in Water (10 ppb): 6.5-7.5
  • Packaging: 25 Lb. Multi-ply bag with poly-inner liner.

Typical Treatment

  1. Blen-Seal can be used effectively as either a slug type treatment (high concentration sweep) or to treat the entire system.
  2. Typical slug treatment normally contains 20-40 lbs./bbl of Blen-Seal. The pill should be large enough to cover the expected trouble zone.
  3. For treating the entire system, normally 4-8 ppb is sufficient.
  4. To reduce torque and drag, 2-4 ppb is recommended.

Recommended Uses

  1. Prevents and/or cures seepage mud loss in under-pressured formations.
  2. Prevents differential sticking in depleted low pressured sands.
  3. Reduces torque and drag.
  4. As a sweep to clean the hole and add lubricity.
  5. Effective as a high concentration pill to cure severe lost circulation.

Case History 1

On a well drilling in Chambers County, Texas, an 8 1/2½ bit was being used to drill at 11,525'. While making a connection the pipe became differentially stuck. It was necessary to back -off the pipe and begin washover operations. Three joints of heavy weight drill pipe and eight 6 ½" drill collars were left in the hole.

It was decided to utilize 10 lbs. bbl. sweeps of Blen-Seal (25 bbl. pills) during washover operations to keep the washover pipe from sticking due to the small clearances involved. All the drill string was recovered without any undue complications.

It was further decided to make a 25 bbl. sweep per tour while drilling to prevent future problems. The sweeps were run for three days and 682' were drilled with little torque and drag problems. After this period the sweeps were discontinued for a period of three days. While making a trip out of the hole on the fourth day, the pipe again became stuck at 11,782'. This time the pipe was jarred free in one hour.

The Blen-Seal sweeps were reinstated and the well was drilled to T.D. (approx. 13,000') without any further difficulties.

Case History 2

Three wells were proposed to be drilled in offshore Louisiana. These wells were to be kicked-off at 500' and drilled to 5,100' vertical depth with angle built at 4° per 100' to a total angle of 65°.

To reduce torque and drag at this high angle, the operator decided to run 3 lbs./bbl. of Blen-Seal throughout the mud system and maintain this concentration. It was planned to utilize the same mud type for all three wells.

Since Blen-Seal fibers are small enough to go through a downhole motor without plugging, while still exhibiting good hole cleaning and sand sealing properties, it was decided to run occasional sweeps consisting of 25 lbs./bbl. in 25 bbls. of fluid.

As of this writing, two of the three wells have been drilled, logged and casing set with minimal torque and drag. The operator, as a result of these operations, has decided to incorporate Blen-Seal into the mud program of all future wells as a preventive measure.

NOTE: On the last hole the production liner was run to bottom. Forty minutes elapsed while waiting for the cementing head and liner to be rigged up. It was decided to pick up the casing out of the slips to see how much drag had developed during this delay. Only 10,000 lbs. over-pull was experienced.

Case History 3

A well drilled in Chambers Country, Texas had 9 5/8" casing set at 12,000' with an 8 ½" bit drill out to 12,060'. It was determined, from two (2) reference wells in the area, that a Frio sand at 12,300' + would have a very low pore pressure. This sand had been on production for several years. It was estimated that the pore pressure in this sand was as low as 5 lbs./gal. mud weight equivalent. Additionally, a sand at 13,000' + had a calculated pore pressure of 17 lbs./gal. The drilling mud weight at 12,060' was 13.4 lbs./gal.

It was decided to drill through the depleted sand using 20 lbs./bbl. sweeps of Blen-Seal. It was hoped that this would not only prevent lost circulation, but would also enable the operator to weight up to the required 17 lbs./gal. mud weight at 13,000' without additional pipe.

One 40 bbl. sweep was pumped as soon as the sand was encountered. When the pill came to the surface, the shakers were by-passed allowing the pill to mix in the total mud system. The entire 60' sand stringer was drilled without any significant mud lost.

Another 40 bbl. pill was pumped after drilling through the sand prior to performing a leak off test. This sweep was done by pumping a pill at normal rates from surface to bit, but at a reduced rate from bit to problem area, and at normal rates back to surface.

A dynamic leak-off test to 17 ppg. equivalent was then run. Pressure and circulation was maintained for ten minutes with no loss of mud.

Normal drilling was continued. The mud was weighted up to control pore pressures encountered.