Artificial Sandstone Cores Production with a Wide Range of Petrophysical Properties

Abstract

In petroleum engineering, to investigate the effect of a certain factors on rock permeability, it is more convenient to use homogenous rock samples with nearly constant initial permeability. Obtaining a sandstone rock samples with a constant initial permeability is very difficult. Also the difficulties in getting (or lack) the natural field cores let many researchers to look for a permanent source of rock samples. Adding to these circumstances, the permanent need for continuos supply of rock cores for teaching purposes encourages to look for an alternative source of rock samples.The purpose of this paper is to simulate natural sandstone rock and come-up with a homogeneous compacted rock with known properties. Many scholars investigated the effect of some sedimentation and compaction factors on rock properties, but few attempts to manufacture an artificial sandstone matrix with wide ranges of rock properties were made. In this study the main rock lithification factors were defined and their effect on rock properties were evaluated. These factors are grain size, cementing material concentration, compaction (confining) pressure, and dehydration temperature. Five groups of a grain size ranged between 45 and 300 μm were used. The cementing material was added 4 to 8 % by weight of sand grains, and a 11350 to 23500 psi compaction pressure was applied to shape the sandstone cores. By varying these factors, a wide range of rock samples with different properties were produced. The stability of these samples and their properties were evaluated. A homogeneous artificial sandstone cores samples with a permeability of 15 to 5000 md and a porosity of 20 to 33 % were obtained. The mean pore size of these core samples was between 11 and 50 μm. The results of this study were presented as graphs of simulated lithification factors versus rock properties. With the help of these graphs, a sandstone core with a certain initial permeability and mean pore size can be produced.