Method for detecting formation pore pressure by detecting pumps-off gas downhole

a technology of pore pressure detection and pumping gas, which is applied in the direction of borehole/well accessories, survey, construction, etc., can solve the problems of insufficient weight of drilling fluid to maintain over-balance on the well, the wellbore portion of the formation can be detrimental, and the wellbore portion may be drilled slightly over-balanced
US20090159334A1Inactive Publication Date: 2009-06-25BP CORP NORTH AMERICA INC
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
BP CORP NORTH AMERICA INC
Publication Date
2009-06-25
Estimated Expiration
Not applicable · inactive patent

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Abstract

Methods and systems are described for drilling a well while distinguishing circulated gas or air from pumps-off gas in a drilling fluid at downhole pressure and temperature. A well is drilled with a drilling fluid, drill string, and drill bit. Drilling fluid is pumped through the drill string, drill bit, and into an annulus between the drill string and a wellbore. The drill string comprises one or more sensors sensing a parameter indicative of circulated gas or air in the drilling fluid flowing through the drill string, one or more sensors being behind and near the drill bit. The sensors measuring gas in the drill string may be at the same level as gas detectors in the annulus. The measurements are communicated to a human-readable interface at the surface, allowing an operator to determine if pressure of the wellbore fluid is greater than formation fluid pressure.
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Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a continuation-in-part of, and claims benefit under 35 U.S.C. § 120 from application Ser. No. 12 / 004,175, filed Dec. 19, 2007, which is incorporated herein by reference in its entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.BACKGROUND OF THE INVENTION

[0003] The present disclosure relates in general to methods of drilling wellbores, for example, but not limited to, wellbores for producing hydrocarbons from subterranean formations, and more particularly to methods of distinguishing circulated gases from connection gas or gas influx in a drilling oil or gas well.BACKGROUND ART

[0004] Drilling techniques for producing wellbores to great depths in the earth are well known and are widely used, especially in the exploration for and production of hydrocarbons. These wells are typically produced by the use of a drill bit positioned on the lower end of a drill string which is supp...

Claims

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