Drilling lost circulation material

{
  "publication_number": "US9410066B2",
  "country": "US",
  "kind": "B2",
  "title": "Drilling lost circulation material",
  "abstract": "An engineered composition for reducing lost circulation in a well includes a mixture of coarse, medium and optional fine particles, and a blend of long fibers and short fibers. The long fibers are rigid and the short fibers are flexible. The long fibers form a tridimensional mat or net in the lost-circulation pathway that traps the mixture of particles and short flexible fibers to form a mud cake. The mixture of particles and blend of fibers may be added to water based and oil-based drilling fluids. The composition, size, and concentration of each component of the mixture of particles and blend of fibers may be fine-tuned for each application.",
  "claims": [
    "1. A method for reducing lost circulation in a well comprising: (i) adding to an aqueous drilling fluid a composition comprising: (1) a mixture of coarse particles having an average particle size between 300 and 1200 μm, medium particles having an average particle size between 20 and 150 μm and optionally fine particles having an average particle size between 5 and 15 μm; and (2) a blend of long fibers having an average length between 8 and 15 mm, and short fibers having an average length between 1 and 8 mm; and (ii) circulating the drilling fluid in and out of the well.",
    "2. The method of claim 1, wherein the particle mixture comprises from 0 to 15 weight percent fine particles, 20 to 40 weight percent medium particles, and 40 to 60 weight percent coarse particles.",
    "3. The method of claim 1, wherein the particles are selected from the group consisting of alkaline earth carbonates, poly-paraphenyleneterephthalamide, mica, rubber, polyethylene, polypropylene, polystyrene, poly(styrenebutadiene, fly ash, silica, mica, alumina, glass, barite, ceramic, metals and metal oxides, starch and modified starch, hematite, ilmenite, microspheres, glass microspheres, magnesium oxide, gilsonite, sand, and mixtures thereof.",
    "4. The method of claim 1, wherein the particle mixture comprises 8 to 12 weight percent fine calcium carbonate, 30 to 40 weight percent poly-paraphenyleneterephthalamide, mica or calcium carbonate, and 45 to 60 weight percent coarse calcium carbonate.",
    "5. The method of claim 1, wherein the fibers are selected from the group consisting of polyvinyl alcohol, polyamide, aramid, para-aramid, polylactic acid, polyglycolic acid, metals, painted metals, polymer-coated metals, hollow metals, hollow painted metals, hollow coated metals, polypropylene, polyethylene, polyester, polyamide, polyolefin, novoloid, phenol-aldehyde, nylon, rayon, extruded mineral wool, carbon, basalt, asbestos, and glass.",
    "6. The method of claim 1, wherein the weight ratio of long fibers to short fibers is from 1:4 to 4:1.",
    "7. The method of claim 1, wherein the length ratio of long fibers to short fibers is from 1:1 to 3:1.",
    "8. The method of claim 1, wherein at least a portion of the fibers is acid soluble.",
    "9. The method of claim 1, wherein the long fibers comprise water insoluble polyvinyl alcohol and the short fibers comprise water-soluble polyvinyl alcohol.",
    "10. The method of claim 1, wherein the short fibers comprise a mixture of fibers of two different lengths.",
    "11. The method of claim 1, wherein the short fibers comprise a mixture of two different lengths of polyvinyl alcohol fibers.",
    "12. The method of claim 1, wherein the short fibers comprise a mixture of multiple lengths of polyaramid fibers.",
    "13. The method of claim 1, wherein the particle mixture is added to the drilling fluid at a concentration between 2.85 kg/m 3 and 130 kg/m 3.",
    "14. The method of claim 1, wherein the blend of fibers is added to the drilling fluid at a concentration between 14 kg/m 3 and 42 kg/m 3.",
    "15. The method of claim 1, wherein at least a portion of the fibers is coated with a material that improves the dispersion of the fibers in the drilling fluid.",
    "16. The method of claim 1, wherein the long fibers comprise water-insoluble polyvinyl alcohol and the short fibers comprise polyaramid fibers, water soluble polyvinyl alcohol fibers, or inorganic mineral fibers.",
    "17. The method of claim 1, wherein the long fibers comprise polyaramid fibers or polyvinyl alcohol fibers.",
    "18. The method of claim 1, wherein the short fibers comprise a mixture of two different lengths or a mixture of multiple lengths of fibers.",
    "19. The method of claim 1, wherein both the long fibers and the short fibers comprise polyvinyl alcohol fibers.",
    "20. The method of claim 1, wherein at least one fiber type has a Young's modulus higher than 20 GPa."
  ],
  "description_excerpt": "The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.\n\nDrilling fluids have a number of functions, including but not limited to, lubricating the drilling tool and drill pipe which carries the tool, providing a medium for removing formation cuttings from the well to the surface, counterbalancing formation pressure to prevent the inflow to the wellbore of gas, oil, and/or water from permeable or porous formations which may be encountered at various levels as drilling progresses, preventing the loss of drilling fluids to void spaces and to permeable or porous formations, maintaining hole stability prior to setting the casing, minimizing formation damage, and holding the drill cuttings in suspension, especially in the event of a shutdown in drilling and interruption of pumping of the drilling mud.\n\nDrilling fluid additives in time can form a thin, low permeability filter cake (mud cake) that can seal openings in formations to reduce the unwanted influx of fluids or the loss of drilling fluids to permeable formations. The mud cake forms when the drilling fluid contains particles that are approximately the same size as or have diameters greater than about one third of the pore diameter (or the width of any openings such as induced fractures) in the formation being drilled. Drilling fluid additives can also increase the stability of the wellbore.\n\nThe drilling fluid must circulate in the wellbore (down the drill pipe and back up the annulus) in order to perform all of the desired functions to allow the drilling process to continue.",
  "cpc": [
    "C09K 8/035",
    "C09K 2208/08",
    "C09K 8/5045",
    "C09K 8/506",
    "C09K 8/516",
    "E21B 21/003"
  ],
  "ipc": [
    "C09K 8/035",
    "C09K 8/504",
    "C09K 8/506",
    "C09K 8/516",
    "E21B 21/00"
  ],
  "assignees": [
    "Schlumberger Technology Corp"
  ],
  "inventors": [
    "Jaleh Ghassemzadeh"
  ],
  "filing_date": "2013-07-02",
  "publication_date": "2016-08-09",
  "grant_date": "2016-08-09",
  "priority_date": "2008-12-11",
  "application_number": "US-201313934179-A",
  "family_id": "40673594",
  "cited_by_count": 95,
  "citations": [
    "US2610149A",
    "US2779417A",
    "US3574099A",
    "US4247403A",
    "US4474665A",
    "US4579668A",
    "US5004553A",
    "US5071575A",
    "US5076944A",
    "US6323158B1",
    "WO1993018111A1",
    "US5377760A",
    "US6399545B1",
    "US20030195120A1",
    "US6790812B2",
    "WO2003048266A1",
    "US20040129460A1",
    "US20040123985A1",
    "US6889780B2",
    "US20070056730A1",
    "WO2004101704A1",
    "US20050194141A1",
    "US20070034410A1",
    "US7226895B2",
    "WO2005110942A2",
    "US20080045421A1",
    "US20050269080A1",
    "WO2005121500A1"
  ]
}