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.

What I claim is: 
     
       1. A sand control screen having a solid hydrolytically degradable polymeric coating, the polymer comprising a polyester, the coating covering the screen to initially prevent entry of particles or fluid flow into or out of the screen. 
     
     
       2. The sand control screen of  claim 1  wherein the solid hydrolytically degradable polymer comprises polylactic acid. 
     
     
       3. The sand control screen of  claim 1  wherein the solid hydrolytically degradable polymer further comprises a solid material to increase strength of the polymer coating. 
     
     
       4. The sand control screen of  claim 3  wherein the solid hydrolytically material is a soluble material. 
     
     
       5. The sand control screen of  claim 1  wherein the solid hydrolytically degradable polymer further comprises a chemical to be released to enter fluids around the screen as the polymer degrades. 
     
     
       6. The sand control screen or liner of  claim 1  further comprising a plurality of hydrolytically solid degradable polymers having varying degradation rates on different areas of the screen. 
     
     
       7. A sand control screen or slotted well liner having a base pipe or mandrel with apertures therein plugged with a solid hydrolytically degradable polymer, the polymer comprising a polyester. 
     
     
       8. The sand control screen or slotted well liner of  claim 7  wherein the solid hydrolytically degradable polymer comprises polylactic acid. 
     
     
       9. The sand control screen or slotted well liner of  claim 7  wherein the solid hydrolytically degradable polymer further comprises a chemical to be released to enter fluids around the screen or liner as the polymer degrades. 
     
     
       10. A slotted well liner having a solid hydrolytically degradable polymeric coating, the polymer comprising a polyester, the coating covering the slotted well liner to initially prevent entry of particles or fluid flow into or out of the slotted well liner. 
     
     
       11. Slotted liner of  claim 10  wherein the solid hydrolytically degradable polymer comprises polylactic acid. 
     
     
       12. The slotted well liner of  claim 10  wherein the solid hydrolytically degradable polymer further comprises a solid material to increase strength of the polymeric coating. 
     
     
       13. The slotted well liner of  claim 12  wherein the solid material is a soluble material. 
     
     
       14. The slotted well liner of  claim 10  wherein the solid hydrolytically degradable polymer further comprises a chemical to be released to enter fluids around the slotted well liner as the polymer degrades. 
     
     
       15. The slotted well liner of  claim 10  further comprising a plurality of solid hydrolytically degradable polymers having varying degradation rates on different areas of the slotted well. 
     
     
       16. The sand control screen of  claim 1  wherein the polyester polymer is selected so as to degrade no longer than thirty days from initial placement in the well. 
     
     
       17. The slotted well liner of  claims 10  wherein the polyester polymer is selected so as to degrade no longer than thirty days from initial placement in the well.