Michael Stephens has been granted 8 US patents while listed as an inventor at Phillips Petroleum . The first was granted in 1990 and the most recent in January 2001. Michael Stephens ranks #600,572 of 4,157,543 US inventors in our database (top 14.4%). Patent records list Michael Stephens in Bartlesville, OK, US.
Patents per Year Patents granted per year, 1990 to 2001 Bar chart with a peak of 3 patents in 1992. peak 3 1990: 1 patents 1990 1991: 1 patents 1991 1992: 3 patents 1992 1994: 1 patents 1994 1995: 1 patents 1995 2001: 1 patents 2001
Issued Patents All Time
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Showing 1–8 of 8 patents
Patent # Title Co-Inventors Date Approx Value ⓘ
6176314 Low density well cement compositions and method of use — 2001-01-23
$73,638,000
5380705 Drilling mud comprising tetrapolymer consisting of n-vinyl-2-pyrrolidone, acrylamidopropanesulfonicacid, acrylamide, and acrylic acid Billy L. Swanson , Bharat B. Patel 1995-01-10
$22,938,000
5294651 Fluid loss additives for well cementing compositions — 1994-03-15
$27,608,000
5153240 Fluid loss additives for well cementing compositions containing a tetrapolymer — 1992-10-06
$16,984,000
5135909 Drilling mud comprising tetrapolymer consisting of N-vinyl-2-pyrrolidone, acrylamidopropanesulfonic acid, acrylamide, and acrylic acid Billy L. Swanson 1992-08-04
$6,637,000
5109042 Fluid loss additive for cement slurries containing a n-vinyl-2-pyrrolidone-.omega.-2-acrylamido-2-methylpropane sulfonate-.omega.-acrylic acid-.omega.-acrylamide polymer — 1992-04-28
$5,268,000
5041630 Well cement slurries and dispersants therefor Bharat B. Patel 1991-08-20
$7,889,000
4923516 Well cement slurries and dispersants therefor Bharat B. Patel 1990-05-08
$10,784,000