Application of degradable polymers in sand control

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.

I claim: 
     
       1. A method for gravel packing a well, comprising:
 placing a screen or liner in the well, the screen or liner having a solid hydrolytically degradable polymeric coating, the polymer comprising a polyester, the coating covering the screen or liner to initially prevent entry of particles or fluid flow into or out of the screen or liner; 
 gravel packing the well; and 
 allowing the polymer to degrade to form a material that can be displaced from the well. 
 
     
     
       2. The method of  claim 1  wherein the solid hydrolytically degradable polymer comprises polylactic acid. 
     
     
       3. The method of  claim 1  wherein the solid hydrolytically degradable polymer further comprises a solid material to increase strength of the polymer coating. 
     
     
       4. The method of  claim 3  wherein the solid material is a soluble material. 
     
     
       5. The method of  claim 1  wherein the solid hydrolytically degradable polymeric coating further comprises a chemical to be released to enter fluids around the screen or liner as the polymer degrades. 
     
     
       6. The method of  claim 1  further comprising a plurality of solid hydrolytically degradable polymers having varying degradation rates on different areas of the screen or liner. 
     
     
       7. A method for gravel packing a well, comprising:
 placing a sand control screen or liner in the well, the screen or liner having a base pipe or mandrel with apertures therein plugged with a solid hydrolytically degradable polymer, the polymer comprising a polyester. 
 
     
     
       8. The method of  claim 7  wherein the solid degradable polymer further comprises a chemical to be released to enter fluids around the screen or liner as the polymer degrades.