Parameter optimization of tight reservoir porosity determination

The porosity is an important parameter to evaluate reservoir physical properties and calculate petroleum reserves. The porosity of tight reservoir is less than 10%, and that of gas shale is usually less than 5%, which is a great challenge of porosity determination apparatuses. Currently the Boyle's Law Double-Cell (Matrix Cup) Method is widely used. The porosity determination for gas shale and tight sandstone needs ultra high accuracy, and it is necessary to carry theory analysis and optimize determination parameters. The objective pressure distinction function is established and numerical simulation is carried out. To obtain higher accuracy, it is necessary to set higher reference cell primary pressure, higher sample cell primary pressure, lower standard bulk volume and lower sample bulk volume. The relative error of experimental porosity of the standard sample of 5.0% can decline as much as 14%, and the absolute error can decline by 0.7%. This study developed a theory calculation model, which will be useful for technical support for tight reservoir porosity determination.