Patents by Inventor Stefano C. Crema

Stefano C. Crema has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5228915
    Abstract: A cementing composition useful in cementing oil, gas and water wells, comprising water, hydraulic cement and an effective amount of water soluble fluid loss additive comprised of a blend of a copolymer (i) of acrylamide/vinyl imidazole in a weight percent ratio of from about 95:5 to 5:95, said copolymer (i) having a molecular weight range of from about 100,000 to 3,000,000, and a copolymer (ii) of vinyl pyrrolidone and the sodium salt of vinyl sulfonate in a weight percent ratio of 80:20 to 20:80, said copolymer (ii) having a molecular weight range of from about 100,000 to 3,000,000. The blend is comprised of a weight percent ratio of copolymer (i) to copolymer (ii) in the range of 20:80 to 80:20. The composition can also optionally include a dispersant such as sodium or potassium salts or a sulfonated naphthalene formaldehyde condensate.
    Type: Grant
    Filed: November 23, 1992
    Date of Patent: July 20, 1993
    Assignee: BASF Corporation
    Inventors: Stefano C. Crema, Clare H. Kucera, Gerd Konrad, Heinrich Hartmann
  • Patent number: 5092935
    Abstract: A cementing composition useful in cementing oil, gas and water wells, comprising water, hydraulic cement and an effective amount of water soluble fluid loss additive comprised of a copolymer of acrylamide/vinyl formamide and derivatives thereof in a weight percent ratio of from about 95:5 to 5:95, said copolymer having a molecular weight range of from about 100,000 to 3,000,000. The composition can also optionally include a dispersant such as sodium or potassium salts or a sulfonated naphthalene formaldehyde condensate.
    Type: Grant
    Filed: February 26, 1990
    Date of Patent: March 3, 1992
    Assignee: BASF Corporation
    Inventors: Stefano C. Crema, Clare H. Kucera
  • Patent number: 5046562
    Abstract: A cementing composition useful in cementing oil, gas and water wells, comprising water, hydraulic cement and an effective amount of water soluble fluid loss additive comprised of a blend of a copolymer of acrylamide/vinyl imidazole in a weight percent ratio of from about 95:5 to 5:95, said copolymer having a molecular weight range of from about 100,000 to 3,000,000, and a terpolymer of acrylamide/acrylamidomethylpropane sulfonic acid sodium salt/vinyl imidazole in a weight percent ratio of 60:20:20, said terpolymer having a molecular weight range of from about 100,000 to 3,000.000. The blend is comprised of a weight percent ratio of copolymer to terpolymer in the range of 20:80 to 80:20. The composition can also optionally include a dispersant such as sodium or potassium salts or a sulfonated naphthalene formaldehyde condensate.
    Type: Grant
    Filed: January 22, 1991
    Date of Patent: September 10, 1991
    Assignee: BASF Corporation
    Inventors: Stefano C. Crema, Clare H. Kucera, Gerd Konrad, Heinrich Hartmann
  • Patent number: 5025040
    Abstract: A cementing composition useful in cementing oil, gas and water wells, comprising water, hydraulic cement and an effective amount of water soluble fluid loss additive comprised of a blend of a copolymer of acrylamide/vinyl imidazole in a weight percent ratio of from about 95:5 to 5:95, said copolymer having a molecular weight range of from about 100,000 to 3,000,000, and a terpolymer of acrylamide/acrylamidomethylpropane sulfonic acid sodium salt/vinyl imidazole in a weight percent ratio of 60:20:20, said terpolymer having a molecular weight range of from about 100,000 to 3,000,000. The blend is comprised of a weight percent ratio of copolymer to terpolymer in the range of 20:80 to 80:20. The composition can also optionally include a dispersant such as sodium or potassium salts or a sulfonated naphthalene formaldehyde condensate.
    Type: Grant
    Filed: June 11, 1990
    Date of Patent: June 18, 1991
    Assignee: BASF
    Inventors: Stefano C. Crema, Clare H. Kucera, Gerd Konrad, Heinrich Hartmann
  • Patent number: 4933378
    Abstract: A cementing composition useful in cementing oil, gas and water wells, comprising water, hydraulic cement and an effective amount of water soluble fluid loss additive comprised of a copolymer of acrylamide/vinyl imidazole and derivatives thereof in a weight percent ratio of from about 95:5 to 5:95, said copolymer having a molecular weight range of from about 100,000 to 3,000,000. The composition can also optionally include a dispersant such as sodium or potassium salts or a sulfonated naphthalene formaldehyde condensate.
    Type: Grant
    Filed: August 7, 1989
    Date of Patent: June 12, 1990
    Assignee: BASF Corporation
    Inventors: Clare H. Kucera, Stefano C. Crema, Michael D. Roznowski, Gerd Konrad, Heinrich Hartman
  • Patent number: 4931489
    Abstract: A cementing composition useful in cementing oil, gas and water wells, comprising water, hydraulic cement and an effective amount of water soluble fluid loss additive comprised of a copolymer of acrylamide/vinyl imidazole and derivatives thereof in a weight percent ratio of from about 95:5 to 5:95, said copolymer having a molecular weight range of from about 100,000 to 3,000,000. The composition can also optionally include a dispersant such as sodium or potassium salts or a sulfonated naphthalene formaldehyde condensate.
    Type: Grant
    Filed: August 4, 1989
    Date of Patent: June 5, 1990
    Assignee: BASF Corporation
    Inventors: Clare H. Kucera, Stefano C. Crema, Michael D. Roznowski, Gerd Konrad, Heinrich Hartmann
  • Patent number: 4676916
    Abstract: The subject invention relates to acidizing concentrates used to prepare acidizing systems for oil and gas recovery. The additives comprise:(a) a C.sub.4 -C.sub.12 aliphatic alcohol, and(b) a polyether nonionic surfactant having the following structural formula: ##STR1## wherein R is the residue of an aliphatic alcohol having 2 to 10 carbon atoms resulting from the oxyalkylation of a corresponding aliphatic alcohol having a functionality equal to n, and n has a value of 2 to 3; and wherein X and Y are numbers such that the ratio of X to Y is from 8:1 to 0.31 in the total molecular weight of the molecule is from 1,000 to 15,000.
    Type: Grant
    Filed: December 2, 1985
    Date of Patent: June 30, 1987
    Assignee: BASF Corporation
    Inventor: Stefano C. Crema
  • Patent number: 4609477
    Abstract: This invention relates to a liquid foaming additive comprising(a) a nonionic fluorochemical surfactant; and(b) a nonionic heteric polyether surfactant having at least two additive hydrogen atoms wherein components (a) and (b) are used in an effective amounts.The foaming additives are used to foam lower alkyl alcohols which are injected into oil and gas wells to break up underground formations which trap the oil and gas.
    Type: Grant
    Filed: February 5, 1985
    Date of Patent: September 2, 1986
    Assignee: BASF Corporation
    Inventor: Stefano C. Crema