Simulation Experiments on Sandstone Mechanical Compaction Diagenetic and its Physical Properties Evolution

Xi, Kelai; Cao, Yingchang; Wang, Jian; Yuan, Guanghui; Yang, Tian

As an important part of diagenesis event, compaction has a great impact on reservoir porosity and permeability evolution. However, current studies about compaction mainly focus on simple and qualitative description, and little work has been done through simulation experiments. In order to simulate the physical property change of sandstones during the compaction diagenetic process, a set of new equipment has been designed and applied to simulating the mechanical compaction using different modern sediments in fluvial and littoral facies in Shandong, China. The initial porosity of the modern sediments is 37%-44%, and the initial permeability is 372.9-733.72mD. Results of the experiments show that in the compaction diagenetic process the porosity and permeability are not regularly changing during compaction, but it can be divided into two sections, i.e. a sudden change section at early stage(Depth<600m) and an uniform change section at later stage(Depth>600m). 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, Moreover, the porosity and permeability also have an exponential relationship. When the sandstone only experiences mechanical compaction, for the sediments with the same source and sorting coefficient, the more coarse of grain size, the slower compaction rate is, and the final porosity and permeability will be larger, for the sediments with the similar source and grain size, the poorer sorting, the quicker compaction rate is, and the final porosity and permeability will be less. During the uniform change section, the porosity reduction of average 100 meters is also various in different sandstone lithofacies, that is the well sorted medium sandstone is the least, followed by the well sorted fine sandstone and well sorted siltstone, then the medium sorted coarse sand, and that in poorly sorted pebbly sandstone is the largest.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013