Hydraulic and mechanical noise isolation for improved formation testing

Abstract

An apparatus and method for isolating a downhole tool section from hydraulic and mechanical noise. Anchoring grippers are used in conjunction with a fluid diverter valve to anchor the tool section to a borehole wall and divert fluid flowing in the drill string away from sensitive test equipment during formation testing.

We claim:  
     
         1 . A downhole tool for acquiring a parameter of interest, the tool being conveyed into a well borehole on a drill string having a rotatable bit at a distal end thereof, the tool comprising: 
 a) an extendable gripper element disposed on the drill string, wherein the extendable gripper element forcibly engages the borehole wall to anchor at least a portion of the drill string radially, axially and circumferentially while the borehole wall is engaged by the extendable gripper element;    b) a diverter valve coupled to the drill string to divert drilling fluid into the annulus; and    c) a test device coupled to the drill string portion for determining the parameter of interest.    
     
     
         2 . The tool of  claim 1 , wherein the extendable gripper element includes a textured pad mounted on the gripper element to increase frictional force between the borehole wall and the gripper element.  
     
     
         3 . The tool of  claim 2 , wherein the pad is a single pad.  
     
     
         4 . The tool of  claim 2 , wherein the pad is a plurality of pads.  
     
     
         5 . The tool of  claim 2 , wherein the pad is a single elongated pad attached to a housing using at least one of i) a flexible member coupling the pad to the housing and ii) a member coupling the pad to the housing at a pivot point.  
     
     
         6 . The tool of  claim 2 , wherein the pad has a tapered end.  
     
     
         7 . The tool of  claim 1 , wherein the extendable gripper element further includes one or more pistons and a pad, the one or more pistons operable to extend the pad to engage the borehole wall.  
     
     
         8 . The tool of  claim 7 , wherein the pad is has a conical shape pressed into mudcake when the extendable gripper element engages the borehole wall.  
     
     
         9 . The tool of  claim 2 , wherein the textured pad includes a surface pattern selected from one or more of i) diamond; ii) raised points; iii) ridges; iv) grooves; v) dimpled; vi) cross hatch; and vi) circular.  
     
     
         10 . The tool of  claim 1  further comprising a hydraulic valve coupled between the diverter valve and the extendable gripper element for supplying hydraulic pressure to extend the gripper element.  
     
     
         11 . The tool of  claim 1  further comprising a hydraulic drive device for supplying hydraulic pressure to extend the gripper element.  
     
     
         12 . The tool of  claim 11 , wherein the hydraulic drive device comprises a motor and pump for pumping drilling fluid at high pressure to extend the gripper element.  
     
     
         13 . The tool of  claim 1 , wherein the diverter valve includes a piston and a seal axially moveable by the piston to seal a main mud stream flow path and open an aperture for allowing the mud stream to enter the annulus.  
     
     
         14 . The tool of  claim 1  further comprising an expandable packer coupled to the drill string below the diverter valve to isolate the test device from pressure variations in an annulus between the tool and borehole wall while diverter valve is diverting fluid.  
     
     
         15 . The tool of  claim 1 , wherein the test device comprises: 
 i) an extendable probe adapted to admit formation fluid into the test device; and    ii) a sensor for sensing a characteristic of the admitted fluid, the sensed characteristic being used in part to determine the parameter of interest.    
     
     
         16 . The tool of  claim 1 , wherein the drill string portion comprises a selectable nonrotating sleeve coupled to the drill string.  
     
     
         17 . The tool of  claim 16 , wherein the coupling between the nonrotating sleeve and drill string includes a spring and bearing to allow progression of the drill bit while the gripper element anchors the nonrotating sleeve.  
     
     
         18 . The tool of  claim 1 , wherein the extendable gripper element comprises a first extendable gripper element when extended anchoring a first drill string portion and a second extendable gripper element axially displaced from the first extendable gripper element, the second extendable gripper element when extended anchoring a second drill string portion.  
     
     
         19 . The tool of  claim 16 , wherein the test device is adapted to determine the parameter of interest while the drill bit progress through the formation.  
     
     
         20 . The tool of  claim 1 , wherein the test device comprises a sensor for sensing a characteristic of the admitted fluid, the sensed characteristic being used in part to determine the parameter of interest.  
     
     
         21 . The tool of  claim 1 , wherein the sensed characteristic includes one or more of i) temperature; ii) pressure; iii) formation fluid composition; iv) resistivity; v) water content; vi) mobility; and vi) nuclear properties.  
     
     
         22 . A system for acquiring a downhole parameter of interest while drilling a borehole through a formation, the system comprising: 
 a) a drill string having a rotatable bit at a distal end thereof, the tool comprising:    b) an extendable gripper element disposed on the drill string, wherein the extendable gripper element forcibly engages the borehole wall to anchor at least a portion of the drill string radially, axially and circumferentially while the borehole wall is engaged by the extendable gripper element;    c) a diverter valve coupled to the drill string to divert drilling fluid into the annulus;    d) a test device coupled to the drill string portion, the test device including a sensor for measuring a desired downhole characteristic and for providing an output signal representative of the measured characteristic; and    e) a processor receiving and processing the output signal, the processed signal being indicative of the parameter of interest.    
     
     
         23 . The system of  22 , wherein the processor is coupled to the drill string at a downhole location, the system further comprising a transmitter for transmitting the processed signal to a surface location.  
     
     
         24 . The system of  22 , wherein the processor is located at a surface location the system further comprising a transmitter for transmitting the output signal to the to the processor for surface processing.  
     
     
         25 . The system of  22 , wherein the processor is coupled to the drill string at a downhole location, the system further comprising a downhole memory device for storing the processed signal.  
     
     
         26 . The system of  claim 25  further comprising a transmitter for transmitting to a surface location selected values from the stored signals.  
     
     
         27 . The system of  claim 22 , wherein the extendable gripper element includes a pad mounted on the gripper element to increase frictional force between the borehole wall and the gripper element, the pad having a conical shape pressed into mudcake when the extendable gripper element engages the borehole wall.  
     
     
         28 . The system of  claim 22 , wherein the extendable gripper element includes a textured pad mounted on the gripper element to increase frictional force between the borehole wall and the gripper element.  
     
     
         29 . The system of  claim 28 , wherein the textured pad includes a surface pattern selected from one or more of i) diamond; ii) raised points; iii) ridges; iv) grooves; v) dimpled; vi) cross hatch; and vi) circular.  
     
     
         30 . The system of  claim 28 , wherein the extendable gripper element further includes one or more pistons operable to extend the pad to engage the borehole wall.  
     
     
         31 . The system of  claim 28 , wherein the pad is a single pad.  
     
     
         32 . The system of  claim 28 , wherein the pad is a plurality of pads.  
     
     
         33 . The system of  claim 28 , wherein the pad is a single elongated pad attached to a housing using at least one of i) a flexible member coupling the pad to the housing and ii) a member coupling the pad to the housing at a pivot point.  
     
     
         34 . The system of  claim 28 , wherein the pad has a tapered end.  
     
     
         35 . The system of  claim 22  further comprising a hydraulic valve coupled between the diverter valve and the extendable gripper for supplying hydraulic pressure to extend the gripper.  
     
     
         36 . The system of  claim 22  further comprising a hydraulic drive device for supplying hydraulic pressure to extend the gripper element.  
     
     
         37 . The system of  claim 36 , wherein the hydraulic drive device comprises a motor and pump for pumping drilling fluid at high pressure to extend the gripper element.  
     
     
         38 . The system of  claim 22 , wherein the diverter valve includes a piston and a seal axially moveable by the piston to seal a main mud stream flow path and open an aperture for allowing the mud stream to enter the annulus above the gripper element.  
     
     
         39 . The system of  claim 22  further comprising an expandable packer coupled to the drill string below the diverter valve to isolate the test device from pressure variations in an annulus between the drill string and borehole wall while diverter valve is diverting fluid.  
     
     
         40 . The system of  claim 22 , wherein the test device comprises an extendable probe adapted to admit formation fluid into the test device, wherein the desired characteristic sensed by the sensor relates to the admitted fluid.  
     
     
         41 . The system of  claim 22 , wherein the drill string portion comprises a selectable nonrotating sleeve coupled to the drill string.  
     
     
         42 . The system of  claim 41 , wherein the coupling between the nonrotating sleeve and drill string includes a spring and bearing to allow progression of the drill bit while the gripper element anchors the nonrotating sleeve.  
     
     
         43 . The system of  claim 22 , wherein the extendable gripper element comprises a first extendable gripper element when extended anchoring a first drill string portion and a second extendable gripper element axially displaced from the first extendable gripper element, the second extendable gripper element when extended anchoring a second drill string portion.  
     
     
         44 . The system of  claim 41 , wherein the test device is adapted to sense desired characteristic while the drill bit progresses through the formation.  
     
     
         45 . The system of  claim 22 , wherein the sensed characteristic includes one or more of i) temperature; ii) pressure; iii) formation fluid composition; iv) resistivity; v) water content; vi) mobility; and vii) nuclear properties.  
     
     
         46 . The system of  claim 22 , wherein the extendable gripper element includes a textured pad for engaging the borehole wall.  
     
     
         47 . The system of  claim 46 , wherein the textured pad includes a surface pattern selected from one or more of i) diamond; ii) raised points; iii) ridges; iv) grooves; v) dimpled; viO cross hatch; and vi) circular.  
     
     
         48 . A method of isolating a downhole test device from noise, comprising: 
 a) conveying a drill string into a well borehole, the drill string having a rotatable bit at a distal end thereof and an inner bore for conveying drilling fluid from a surface location to the drill bit;    b) anchoring a drill string portion to the borehole wall using an extendable gripper element such that the drill string portion is anchored radially, axially and circumferentially while the borehole wall is engaged by the extendable gripper element;    c) diverting drilling fluid into an annulus surrounding the drill string portion using a diverter valve; and    d) obtaining a desired characteristic using a sensor disposed on the anchored drill string portion.    
     
     
         49 . The method of  claim 49 , wherein anchoring the drill string portion includes engaging the borehole wall with a pad mounted on the extendable gripper element to increase frictional force between the borehole wall and the gripper element, the pad having a conical shape pressed into a mudcake when the extendable gripper element engages the borehole wall.  
     
     
         50 . The method of  claim 48 , wherein anchoring the drill string portion includes engaging the borehole wall with a textured pad mounted on the extendable gripper element to increase frictional force between the borehole wall and the gripper element.  
     
     
         51 . The method of  claim 50 , wherein the textured pad surface includes a surface pattern selected from one or more of i) diamond; ii) raised points; iii) ridges; iv) grooves; v) dimpled; vi) cross hatch; and vi) circular.  
     
     
         52 . The method of  claim 50 , wherein the extendable gripper element further includes one or more pistons and a pad, the pistons operable to extend the pad to engage the borehole wall.  
     
     
         53 . The method of  claim 50 , wherein the pad is a single pad.  
     
     
         54 . The method of  claim 47 , wherein the pad is a plurality of pads.  
     
     
         55 . The method of  claim 50 , wherein the pad is a single elongated pad attached to a housing using at least one of i) a flexible member coupling the pad to the housing and ii) a member coupling the pad to the housing at a pivot point.  
     
     
         56 . The method of  claim 50 , wherein the pad has a tapered end.  
     
     
         57 . The method of  claim 48  further comprising supplying hydraulic pressure to extend the gripper element using a hydraulic valve coupled between the diverter valve and the extendable gripper element.  
     
     
         58 . The method of  claim 48  further comprising supplying hydraulic pressure to extend the gripper element using a hydraulic drive device.  
     
     
         59 . The method of  claim 58 , wherein the hydraulic drive device comprises a motor and pump, the method further comprising pumping drilling fluid at high pressure to extend the extendable gripper element.  
     
     
         60 . The method of  claim 48 , wherein diverting the drilling fluid includes sealing inner bore flow path using a piston and a seal axially moveable by the piston and opening an aperture for allowing the drilling fluid to enter the annulus.  
     
     
         61 . The method of  claim 48  further comprising isolating the test device from pressure variations in the annulus between the drill string and borehole wall while the diverter valve is diverting fluid using an expandable packer coupled to the drill string below the diverter valve.  
     
     
         62 . The method of  claim 48 , wherein the obtaining a desired characteristic includes extending a fluid admitting probe to engage the formation and wherein the characteristic related to the admitted fluid.  
     
     
         63 . The method of  claim 48 , wherein the drill string portion comprises a selectable nonrotating sleeve coupled to the drill string and wherein anchoring the drill string portion comprises anchoring the nonrotating sleeve.  
     
     
         64 . The method of  claim 63 , wherein the coupling between the nonrotating sleeve and drill string includes a spring and bearing, the method further comprising rotating the drill bit to extend the borehole while anchoring the nonrotating sleeve with the extendable gripper element.  
     
     
         65 . The method of  claim 48 , wherein anchoring the drill string portion further comprises anchoring a first drill string portion and a second drill string portion and wherein the extendable gripper element comprises a first extendable gripper element when extended anchoring the first drill string portion and a second extendable gripper element axially displaced from the first extendable gripper element, the second extendable gripper element when extended anchoring the second drill string portion.  
     
     
         66 . The method of  claim 63 , further comprising obtaining the desired characteristic while the drill bit progress through the formation.  
     
     
         67 . The method of  claim 48 , wherein the sensed characteristic includes one or more of i) temperature; ii) pressure; iii) formation fluid composition; iv) resistivity; v) water content; vi) mobility; and vii) nuclear properties.