Discussion on the compression of reservoir rock

The stress sensitivity of rock is closely related with the compressibility of rock. In order to clarify the stress sensitivity of reservoir rock, compression of reservoir rock was deeply studied. The compression of pore volume of rock is caused by the compression of skeleton of rock. So the compressibility of pore volume is related to the porosity of rock and the property of skeleton. Due to systematic error, the abnormally-high compressibilities are usually measured by the volume method, and the compressibilities measured show the reversal logic. The method of elastic modulus removed the systematic error of measurement, and the measurements conform to the scientific logic. The compressibilities of pore, skeleton and bulk volumes of rock are defined based on different pressures, so they can not be substituted for each other. As porosity is 0, the pore compressibility is also 0, but the compressibilities of skeleton and bulk volume are all not 0, and the skeleton compressibility equals to the bulk compressibility. The stress sensitivity index of rock can be determined from pore compressibility of rock. Due to the low value of pore compressibility of tight rock, the stress sensitivity of low permeability is very weak, and can be neglected in production of reservoir.