Insulating or modified conductivity casing in casing string

Abstract

A casing string in a wellbore has conductive tubulars and modified conductivity (MC) or non-conductive tubulars joined to one another. A MC/non-conductive tubular may be disposed between two conductive tubulars. If there are at least two MC/non-conductive tubulars and at least three conductive tubulars, two of the MC/non-conductive tubulars may be alternately disposed between three of the conductive tubulars. The MC/non-conductive tubulars may be formed from materials such as stainless steel, fiber-reinforced thermal sets, and thermal plastics. One such thermal plastic is polyetheretherketone (PEEK) and it may be glass-reinforced. The conductive tubulars, if electrically isolated, may be used as electrodes to transmit or receive electromagnetic signals. The casing string may used for borehole to surface applications, surface to borehole applications, borehole to borehole applications, or single well applications. The casing string may also have downhole sensors, uphole sensors, and surface sensors. Those sensors may be transmitters or receivers.

1 . A casing string disposed in a wellbore, comprising:
 one or more conductive tubulars; and   one or more modified conductivity or non-conductive (MC/non-conductive) tubulars joined to the one or more conductive tubulars.   
     
     
         2 . The casing string of  claim 1 , wherein one of the one or more MC/non-conductive tubulars is disposed between two conductive tubulars. 
     
     
         3 . The casing string of  claim 1 , wherein the one or more MC/non-conductive tubulars comprise two MC/non-conductive tubulars; the one or more conductive tubulars comprise three conductive tubulars; and the two MC/non-conductive tubulars are alternately disposed between the three conductive tubulars. 
     
     
         4 . The casing string of  claim 1 , wherein the one or more MC/non-conductive tubulars are formed from materials selected from the group consisting of stainless steel, fiber-reinforced thermal sets, and thermal plastics. 
     
     
         5 . The casing string of  claim 1 , wherein the one or more MC/non-conductive tubulars are formed from polyetheretherketone (PEEK). 
     
     
         6 . The casing string of  claim 5 , wherein the polyetheretherketone (PEEK) is glass-reinforced. 
     
     
         7 . The casing string of  claim 1 , wherein one or more of the conductive tubulars is an electrode. 
     
     
         8 . The casing string of  claim 7 , wherein one or more of the electrodes is used to transmit or receive an electromagnetic signal. 
     
     
         9 . The casing string of  claim 1 , wherein the casing string is used for borehole to surface applications, surface to borehole applications, borehole to borehole applications, or single well applications. 
     
     
         10 . The casing string of  claim 1 , further comprising a downhole sensor and an uphole sensor or a downhole sensor and a surface sensor. 
     
     
         11 . The casing string of  claim 10 , wherein the downhole sensor is a transmitter and the uphole sensor is a receiver or the downhole sensor is a transmitter and the surface sensor is a receiver. 
     
     
         12 . The casing string of  claim 10 , wherein the downhole sensor is a receiver and the uphole sensor or the surface sensor is a transmitter. 
     
     
         13 . The casing string of  claim 1 , wherein the one or more MC/non-conducting tubulars have threaded metal ends. 
     
     
         14 . A logging system, comprising:
 one or more conductive tubulars;   one or more modified conductivity or non-conductive (MC/non-conductive) tubulars joined to the one or more conductive tubulars; and   a logging tool disposed in the interior region of the tubulars.   
     
     
         15 . The logging system of  claim 14 , wherein the logging tool is a transient or continuous-wave electromagnetic tool, a nuclear tool, an acoustic or sonic tool, or a nuclear magnetic resonance tool. 
     
     
         16 . A method to make formation measurements, comprising:
 providing a logging tool;   providing a casing string having one or more modified conductivity or non-conductive (MC/non-conductive) tubulars joined to the one or more conductive tubulars; and   making formation measurements using the logging tool and the casing string.   
     
     
         17 . The method of  claim 16 , wherein the logging tool is a wireline tool. 
     
     
         18 . The method of  claim 16 , wherein the logging tool is a transient or continuous-wave electromagnetic tool, a nuclear tool, an acoustic or sonic tool, or a nuclear magnetic resonance tool. 
     
     
         19 . The method of  claim 16 , wherein the formation measurements relate to one or more of electrical resistivity, a dielectric constant, radioactivity properties, acoustic properties, nuclear magnetic resonance properties, and magnetic properties. 
     
     
         20 . The method of  claim 16 , further comprising using the formation measurements for borehole to surface applications, surface to borehole applications, borehole to borehole applications, or single well applications. 
     
     
         21 . The method of  claim 16 , wherein the one or more MC/non-conducting tubulars have threaded metal ends.