Stress sensitivity consists in low permeability and middle-high permeability reservoirs

Some scholars confused two different concepts: compressibility of pore space of rock and compressibility of reservoir rock. Some mistake recognitions were opened because some experimental results were explained by one mistake derivative equation. In order to clarify the concepts compressibility concepts of pore rock under different pressure condition das expresses, different relationship between rock porosity with compressibility of pore space of rock and rock porosity with compressibility of reservoir rock was put forward. A new compressibility equation of pore space was derived based on a volume equation (total volume is equal to porous solid plus pore volume). Compressibility of pore space of rock increases as porosity decrease, and compressibility of reservoir rock increase as porosity increase. The relationship accords with the Hall curve of describing relationship of porosity and compressibility of pore space, and further prove the Hall curve is correct. The paper emphasizes the mistakes conclusions and recognitions that come from the mistake equation, calculation results of the theoretic equations have to be proved by experimental methods. Experimental study is a basic science in science research. The experimental and theory results express their reasonability and correctable under a certain condition. Research results of laboratory in the world have proved that low permeability reservoir stress sensitivity is stronger than middle-high permeability reservoir; many experimental data of researchers are reliable, but not experimental errors of system.