Applications of degradable polymers for delayed mechanical changes in wells

Abstract

Degradable polylactic or polyhydroxyalkanoate polymers may be used to viscosify aqueous fluids for use in wells, Sand control screen or liner can be coated with a solid degradable polymer during placement in a well. Mechanical changes or flow changes in a well can be caused by solid degradable polymer that changes physical properties after it is placed in a well. Parts of devices or entire devices can be made of solid degradable polymer that converts to a fluid after selected times in an aqueous environment in a well.

1 . A method for delaying a mechanical action in a well comprising placing a solid degradable polymer, the solid degradable polymer comprising a polyester, in a device in an aqueous environment such that degradation of a mechanical property of the degradable polymer after a selected range of time allows operation of the mechanical action. 
   
   
       2 . The method of  claim 1  wherein the mechanical action is the release of a spring-loaded mechanism. 
   
   
       3 . The method of  claim 1  wherein the device is attached to a tubular. 
   
   
       4 . The method of  claim 1  wherein the operation of the mechanical action is a change of position, status or operation of the device. 
   
   
       5 . The method of  claim 1  wherein the solid degradable polymer comprises PLA or PHA. 
   
   
       6 . The method of  claim 1  wherein the device includes a support. 
   
   
       7 . The method of  claim 1  wherein the mechanical property is compressive strength, tensile strength, bending strength or a combination thereof. 
   
   
       8 . A device or part of the device for use in a well comprising a solid degradable polymer, the solid degradable polymer comprising a polyester, selected to decrease in strength a selected amount in a selected range of time in an aqueous environment in the well. 
   
   
       9 . The device or part of the device of  claim 8  wherein the device is a packer, bridge plug or cement retainer. 
   
   
       10 . The device or part of the device of  claim 9  wherein the decrease in strength releases the device in the well. 
   
   
       11 . The device or part of the device of  claim 8  wherein the device is a flotation container. 
   
   
       12 . The device or part of the device of  claim 8  wherein the solid degradable polymer is PLA or PHA. 
   
   
       13 . A device to be placed in a well in an aqueous environment, the device being made of a solid degradable polymer, the solid degradable polymer comprising a polyester. 
   
   
       14 . The device of  claim 13  wherein the degradable polymer is PLA or PHA. 
   
   
       15 . The device of  claim 13  wherein the degradable polymer includes solid particles so as to form composite with the solid degradable polymer. 
   
   
       16 . The device of  claim 13  wherein the device is packer, bridge plug or cement retainer. 
   
   
       17 . The device of  claim 13  wherein the device is a nipple or pipe.