The Formulae of Rock Compressibility of Reservoirs —Reply to Dr Wang Liqiang

The rock compressibility measured by volumetric method is usually overvalued,which is caused by the interstices between cores and core sleeves during experiments.The elastic modulus method gets rid of the negative effect of interstices on rock compressibility,with which the measurements are much more reasonable.The compression of rock results from the compression of rock matrix.The decrease of rock pore pressure results in the increase of rock matrix stress,which allows the matrix to be compressed along with the pore volume.Rock matrix can not expand with the decrease of pore pressure.As rock porosity equals to 0,the pore volume disappears,the compressibility of rock pore volume equals to 0 consequently.