Method and apparatus for sampling and/or testing downhole formations

Abstract

Performing a hydraulic fracture test includes conveying a downhole sub in a borehole to a formation, the downhole sub including a first sealing member, a second sealing member, and an extendable member disposed between the first sealing member and the second sealing member. The first sealing member and the second sealing member are actuated to define a first isolated zone within the borehole. A fluid is introduced to the borehole wall via the extendable member to fracture the formation whether extended or not, and a property of the formation is estimated at least in part using an output signal from a downhole transducer.

1 . A method for performing a hydraulic fracture test comprising:
 conveying a downhole sub in a borehole to a formation, the downhole sub including a first sealing member, a second sealing member, and an extendable member disposed between the first sealing member and the second sealing member;   actuating the first sealing member and the second sealing member to establish a first isolated zone within the borehole;   introducing a fluid to the borehole wall via the extendable member to fracture the formation; and   estimating a property of the formation at least in part using an output signal from a downhole transducer.   
   
   
       2 . A method according to  claim 1 , wherein conveying the downhole sub comprises conveying using one or more of a drill string, a wireline and a slickline. 
   
   
       3 . A method according to  claim 1 , wherein estimating a property of the formation includes estimating a hydraulic pressure of the introduced fluid when the formation is initially fractured. 
   
   
       4 . A method according to  claim 1  further comprising continuing to introduce the fluid to the formation to extend the fracture. 
   
   
       5 . A method according to  claim 4 , wherein estimating a property of the formation includes estimating a hydraulic pressure of the introduced fluid during a time interval while fracture is extending. 
   
   
       6 . A method according to  claim 4  further comprising halting the introduction of fluid to the formation after the fracture is extended to allow the fracture to close. 
   
   
       7 . A method according to  claim 6 , wherein estimating a property of the formation includes estimating a hydraulic pressure of the introduced fluid during a time interval while fracture is closing. 
   
   
       8 . A method according to  claim 1  further comprising estimating a fracture treatment characteristic at least in part using the estimated property of the formation. 
   
   
       9 . A method according to  claim 8 , wherein the fracture treatment comprises a subsequent hydraulic fracture treatment. 
   
   
       10 . A method according to  claim 8 , wherein the fracture treatment comprises a hydraulic fracture treatment and the estimated fracture treatment characteristic includes a treatment fluid characteristic. 
   
   
       11 . A method according to  claim 1 , wherein the extendable member includes one or more of an extendable probe and a pair of packers, the method further comprising establishing a second isolated zone within the borehole by extending the extendable member. 
   
   
       12 . A method according to  claim 11  further comprising controlling a borehole pressure within the first isolated zone and in the second isolated zone to create a first pressure differential between the first isolated zone and a borehole annulus above the first isolated zone and a second pressure differential between the first isolated zone and the second isolated zone. 
   
   
       13 . A method according to  claim 12 , wherein the second pressure differential is less than the first pressure differential. 
   
   
       14 . An apparatus for performing a hydraulic fracture test comprising:
 a downhole sub that is conveyed in a borehole to a formation;   a first sealing member coupled to the downhole sub;   a second sealing member coupled to the downhole sub axially displaced from the first sealing member, the first sealing member and the second sealing member defining a first isolated zone;   an extendable member disposed between the first sealing member and the second sealing member, the extendable member configured to introduce a fluid to the formation for fracturing the formation; and   a downhole transducer coupled to the downhole sub that provides an output signal, the output signal being used at least in part to estimate a property of the formation.   
   
   
       15 . An apparatus according to  claim 14 , wherein a fracture treatment characteristic is estimated using at least in part the estimated property of the formation. 
   
   
       16 . An apparatus according to  claim 15 , wherein a treatment fluid characteristic is estimated using at least in part the estimated property of the formation. 
   
   
       17 . An apparatus according to  claim 14 , wherein the extendable member is extended to establish a second isolated zone within the borehole, a first pressure differential being established between the first isolated zone and a borehole annulus above and below the first isolated zone and a second pressure differential being established between the first isolated zone and the second isolated zone. 
   
   
       18 . An apparatus according to  claim 14 , wherein the downhole sub is conveyed in the borehole using one or more of a drill string, a wireline and a slickline. 
   
   
       19 . A method for performing a hydraulic fracture test comprising:
 conveying a downhole sub in a borehole to a formation, the downhole sub including a first sealing member, a second sealing member, and an extendable member disposed between the first sealing member and the second sealing member;   actuating the first sealing member and the second sealing member to define a first isolated zone within the borehole;   introducing a fluid to the borehole wall via the extendable member to fracture the formation;   estimating a hydraulic pressure of the introduced fluid when the formation is initially fractured;   extending the extendable member to a position in sealing engagement with the borehole wall;   continuing to introduce the fluid to the formation via the extendable member to extend the fracture;   estimating a hydraulic pressure of the introduced fluid during a time interval while fracture is extending;   halting the introduction of fluid to the formation after the fracture is extended to allow the fracture to close;   estimating a hydraulic pressure of the introduced fluid during a time interval while fracture is closing; and   estimating a treatment fluid characteristic at least in part using the estimated hydraulic pressures of the formation.