|
Abstract Through systematic experiments test includes static rock dissolution experiments，dynamic rock flow experiments，triaxial mechanical tests and microstructure analysis of rocks，the mechanical strength reduction of limestone reacting with different acids were studied from the macroscopic and microcosmic perspective. Static and dynamic dissolution experiments showed that gelled acid could create many small solution caves on the rock face，while viscosity acid was mainly of surface dissolution. triaxial mechanical test indicated that the compression strength of rock was reduced by 18%，and Young?s modulus by 26% after reaction with gelled acid，which was much larger than the mechanic strength reduction that dissolved by viscosity acid. Stress-strain curve showed that the compaction densification process after reaction continued for a long time，and showing more plastic behavior. Scanning electron microscope observation indicated that there were many small dissolution holes in the rock after reacting with gelled acid，while the viscosity acid was mainly of uniform dissolution，which has little damage to the internal structure of rock. The difference of dissolution structure for different acids maybe the fundamental reason for the difference of mechanical strength. For high closure stress reservoirs，it should be care more about the mechanical strength reduction that caused by acid-rock reaction，which means to choose leak off-control acids.
|
|
Received: 05 February 2012
|
|
|
|
2013, Vol. 32 
