Completion And Workover Fluids

Completion and workover fluids are any fluids used in the completion of a well or in a workover operation. These fluids range from low-density

1.4 COMPLETION AND WORKOVER FLUIDS TABLE 1.7 Aromatic Content Standards

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Performance of

Fluids Meeting Internal Olefin

New Blended-Base

Standard

Fluid

Base fluid biodegradation Equal to or better than a 65:35 Ratio = 0.8

blend of C16 C18 internal olefin in a 275-day test. Tested once per year. Ratio of IO result compared with base fluid must be calculated at 1.0 or less.

Base fluid biodegradation Equal to or better than a 65:35 Ratio = 0.8

blend of C16 C18 internal olefin in a 275-day test. Tested once per year. Ratio of IO result compared with base fluid must be calculated at 1.0 or less.

Leptocheirus base fluid toxicity Ten-day Leptocheirus LC50 must Ratio = 0.8

be equal to or less toxic than a 65:35 blend of C16 C18 internal olefin tested at least annually. Ratio of IO result compared with base fluid must be calculated at 1.0 or less.

PAH content of base fluid High-performance liquid chro- Below 1 ppm limit of matography/UV-EPA method detection 1654 must give a PAH (as phenanthrene) content of less than 10 ppm.

Summary of permit requirements and performance of blended drilling fluid, base fluid against those permit mandated C16-18 Internal olefin standards.

From US-EPA (2001) NPDES General Permit for New and Existing Sources in the Offshore Subcategory of the Oil and Gas Extraction Category for the Western Portion of the Outer Continental Shelf of the Gulf of Mexico (GMG290000) 66 Fed. Reg. No. 243, p. 65209, December 18, 2001.

gases such as nitrogen to high-density muds and packer fluids. The application and requirements vary for each fluid.

Workover fluids are fluids used during the reworking of a well after its initial completion. They may be gases such as nitrogen or natural gas, brine waters, or muds. Workover fluids are used during operations such as well killing, cleaning out a well, drilling into a new production interval, and plugging back to complete a shallower interval.

Completion fluids are used during the process of establishing final contact between the productive formation and the wellbore. They may be a water-base mud, nitrogen, oil mud, solids-free brine, or acid-soluble system. The most significant requirement is that the fluid does not damage the producing formation and does not impair production performance.

Packer fluids are fluids placed in the annulus between the production tubing and casing. Packer fluids must provide the required hydrostatic pressure, must be nontoxic and noncorrosive, must not solidify or settle out of suspension over long periods of time, and must allow for minimal formation damage.

Various types of fluids may be used for completion and workover operations:

  1. Oil fluids a. Crude b. Diesel c. Mineral oil
  2. Clear water fluids a. Formation salt water b. Seawater c. Prepared salt water such as calcium chloride, potassium chloride or sodium chloride salt and zinc, calcium, or sodium-based bromides
  3. Conventional water-base mud
  4. Oil-base or invert emulsion muds

Completion or workover fluids may be categorized as

  1. Water-base fluids containing oil-soluble organic particles
  2. Acid-soluble and biodegradable
  3. Water base with water-soluble solids
  4. Oil-in-water emulsions
  5. Oil-base fluids

Three types of completion or workover fluids are

  1. Clear liquids (dense salt solutions)
  2. Weighted suspensions containing calcium carbonate weighting material, a bridging agent to increase the density above that of saturated solutions
  3. Water-in-oil emulsions made with emulsifiers for oil muds

Clear liquids have no suspended solids and can be referred to as solids-free fluids. Weighted suspensions are fluids with suspended solids for bridging or added density. These fluids can be referred to as solids-laden fluids.

For solids-free fluids, water may be used in conjunction with a defoamer, viscosifier, stabilized organic colloid, and usually a corrosion inhibitor. Solids-free completion and workover fluids have densities ranging from 7.0 to 19.2 pounds per gallon (ppg) (0.84 - 2.3 SG).

Solids-laden fluids may be composed of water, salt, a defoamer, suspension agent, stabilized organic colloid, pH stabilizer, and a weighting material/bridging agent.

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Responses

  • Ivano
    What are workover fluids in drilling?
    8 years ago
  • Cassandra
    What are completion and workover fluid?
    7 months ago
  • Jukka
    What are completion and work over fluid?
    7 months ago

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