WHICH ROCK COMPRESSIBILITY SHOULD BE USED IN RESERVOIR ENGINEERING

There are three volumes and three stresses used to describe rock,nine compressibilities are determined accordingly,of which only four are independent.The rock compressibility used in reservoir engineering is actually the one of pore volume of rock.Rock compressibility plus the compressibility of reservoir liquids is called the total compressibility,which can be converted to the effective compressibility by oil saturation.The comprehensive compressibility used conventionally is obscure conceptually,which is not suggested to be used any more.Formation compressibility is easily confused,which can neither be measured nor be used in engineering,so is not suggested to be lectured in school for students any more,and had better be immediately eliminated from textbooks.