Abstract:

In order to simulate the physical property change of sedimentary strata in the diagenetic process, a set of new equipment was designed and applied to simulate the mechanical compaction using different modern sediments. Results of the experiments show that the porosity and permeability are not regularly changing during compaction, and it can be divided into two sections, ie. a sudden change section at early stage and a uniform change section at later stage. In the uniform change section, the porosity decreases with the increase of the depth, and they have an exponential relationship; the permeability also decreases with the increase of the depth, and they have an exponentiational relationship; the porosity and permeability also have an exponential relationship. When the sandstone only experiences mechanical compaction, for the sediments with same source and separation, the more coarse of grain size is, the slower of compaction rate is, and the porosity and permeability will be larger; for the sediments with the similar source and grain size, the poorer sorting is, the quicker compaction rate is, and the porosity and permeability will be less. During the uniform change section, the porosity reduction per 100 meters is also different for different lithofacies in sandstones. The porosity reduction per 100 meters is the least in well sorted medium sandstone, followed by that in well sorted fine sandstone and well sorted siltstone, then that in medium sorted coarse sand, and that in poorly sorted pebbly sandstone is the largest.

Key words: porosity, permeability, mechanical compaction, diagenetic simulation