The rock compressibility has always been the focus of reservoir workers; and the influence of clay characteristics on the rock compressibility gets more attention in recent years. Rock is regarded as two-component model ‘clay + matrix’

based on definition of rock compressibility and theories of elastic mechanics

two-component rock compressibility formula is derived; thus the theoretical relationship between the rock compressibility and content of clay as well as the mechanical properties of clay has been found. Clay-containing sandstone cores from Daniudi gas field are regarded as the research objects

the compressibilities of these cores are measured by triaxial compression experiment with variable internal pressures

the micro-experimental study is carried out simultaneously. Theoretical values of compressibility of these cores are obtained by using the two-component rock compressibility formula as well as the other traditional mathematical methods which do not take clay into consideration. By comparison among the theoretical values of compressibility of different mathematical methods and the measured ones

two-component rock compressibility is proved the closest to the experimental result

which indicates the rationality of theory of two-component rock compressibility

this theory develops a new ideal for predicting the reservoir compressibility.