Rex E Duhn

US Patent:

6543533, Apr 8, 2003

Filed:

Mar 2, 2001

Appl. No.:

09/798436

Inventors:

Robert K. Meek - Bakersfield CA
Rex E. Duhn - Bakersfield CA

Assignee:

Duhn Oil Tool, Inc. - Bakersfield CA

International Classification:

E21B 3304

US Classification:

166 781, 166104, 1662416

Abstract:

A mandrel rotator is provided is mounted in a housing for coupling to a well casing head. The mandrel rotator comprises of an annular gear having external gear teeth and an axial opening. The annular gear is coupled to a mandrel outer surface, such that rotation of the annular gear causes rotation of the mandrel. A retainer limits or prevents axial movement of gear within the housing. A second gear is coupled to the annular gear for rotating the annular gear.

US Patent:

6920925, Jul 26, 2005

Filed:

Feb 19, 2003

Appl. No.:

10/369070

Inventors:

Rex E. Duhn - Bakersfield CA, US
Robert K. Meek - Bakersfield CA, US

Assignee:

Duhn Oil Tool, Inc. - Bakersfield CA

International Classification:

E21B033/03

US Classification:

166 7513, 166 7514, 166 961, 166 931, 166379

Abstract:

A wellhead isolation tool and a wellhead assembly incorporating such a tool are provided. The wellhead assembly has an annular assembly coupled to a well. The annular assembly may include a casing head coupled to the well and a tubing head mounted over the casing head. The wellhead isolation tool is suspended in the annular assembly. The wellhead isolation tool has a first end portion extending above the annular assembly and a second end portion below the first end portion within the annular assembly. A production casing suspended in the annular assembly and is aligned with the wellhead isolation tool.

US Patent:

7322407, Jan 29, 2008

Filed:

Nov 9, 2005

Appl. No.:

11/272289

Inventors:

Rex E. Duhn - The Woodlands TX, US
Robert K. Meek - Bakersfield CA, US

Assignee:

Duhn Oil Tool, Inc. - Bakersfield CA

International Classification:

E21B 33/03

US Classification:

166 7514, 166 881, 166 971, 166 951, 2851231

Abstract:

A wellhead assembly is provided including a casing and a tubular member mounted over the casing. A flange extends from the tubular member. A generally elongated annular member is provided in the tubular member. The generally elongated annular member has a first end portion above the tubular member and second end portion below the first end portion. A seal is formed between the second end portion and the tubular member. A hanger may be suspended within the tubular member. In such case, a seal may be formed between the elongate annular member and the hanger.

US Patent:

7416020, Aug 26, 2008

Filed:

Aug 9, 2007

Appl. No.:

11/891431

Inventors:

Rex E. Duhn - The Woodlands TX, US
Robert K. Meek - Bakersfield CA, US

Assignee:

Duhn Oil Tool, Inc. - Bakersfield CA

International Classification:

E21B 33/03

US Classification:

166 7513, 166 7514, 166 961, 2851231

Abstract:

A wellhead assembly is provided including a casing and a tubular member mounted over the casing. A flange extends from the tubular member. A generally elongated annular member is provided in the tubular member. The generally elongated annular member has a first end portion above the tubular member and second end portion below the first end portion. A hanger may be suspended within the tubular member. In such case, a seal may be formed between the elongate annular member and the hanger.

US Patent:

7493944, Feb 24, 2009

Filed:

Sep 23, 2004

Appl. No.:

10/947778

Inventors:

Rex E. Duhn - The Woodlands TX, US
Robert K. Meek - Bakersfield CA, US

Assignee:

Duhn Oil Tool, Inc. - Bakersfield CA

International Classification:

E21B 33/03

US Classification:

166 7513, 2851231

Abstract:

A wellhead assembly is provided including a first tubular member, a hanger mounted within the first tubular member and an annular member coupled to the outer surface of the hanger. The assembly also includes a second tubular member mounted to the annular member and surrounding a portion of the hanger. A method is also provided for fracturing a well requiring coupling a tubing mandrel hanger to a casing, the hanger having a central bore, coupling an annular nut on a portion of the outer surface of the hanger, mounting a tubular member having a flange over the hanger and on the flange, and applying fluids though the bore formed though the hanger for fracturing the well.

US Patent:

7520322, Apr 21, 2009

Filed:

Dec 11, 2007

Appl. No.:

12/001621

Inventors:

Rex E. Duhn - The Woodlands TX, US
Robert K. Meek - Bakersfield CA, US

Assignee:

Duhn Oil Tool, Inc. - Bakersfield CA

International Classification:

E21B 33/03

US Classification:

166 7513, 166 961, 166 7514, 2851233

Abstract:

A wellhead assembly is provided including a casing and a tubular member mounted over the casing. A flange extends from the tubular member. A generally elongated annular member is provided in the tubular member. The generally elongated annular member has a first end portion above the tubular member and second end portion below the first end portion. A seal is formed between the second end portion and the tubular member. A hanger may be suspended within the tubular member. In such case, a seal may be formed between the elongate annular member and the hanger.

US Patent:

7726393, Jun 1, 2010

Filed:

May 21, 2008

Appl. No.:

12/154338

Inventors:

Rex E. Duhn - The Woodlands TX, US
Robert K. Meek - Bakersfield CA, US

Assignee:

Duhn Oil Tool, Inc. - Bakersfield CA

International Classification:

E21B 33/03

US Classification:

166 7513, 166 7514, 166 961

Abstract:

A wellhead assembly is provided including a casing and a tubular member mounted over the casing. A flange extends from the tubular member. A generally elongated annular member is provided in the tubular member. The generally elongated annular member has a first end portion above the tubular member and second end portion below the first end portion. A hanger may be suspended within the tubular member. In such case, a seal may be formed between the elongate annular member and the hanger.

US Patent:

8272433, Sep 25, 2012

Filed:

Apr 9, 2010

Appl. No.:

12/757940

Inventors:

Rex E. Duhn - The Woodlands TX, US
Robert K. Meek - Bakersfield CA, US

Assignee:

Seaboard International Inc. - Houston TX

International Classification:

E21B 33/03

US Classification:

166 7513

Abstract:

A wellhead assembly is provided including a casing and a tubular member mounted over the casing. A flange extends from the tubular member. A generally elongated annular member is provided in the tubular member. The generally elongated annular member has a first end portion above the tubular member and second end portion below the first end portion. A hanger may be suspended within the tubular member. In such case, a seal may be formed between the elongate annular member and the hanger.