Experimental Study on the Effect of Temperature on the Mechanical Properties of Unconsolidated Silty Sandstones

Hydrocarbon reservoirs can be subjected to temperature changes due to different processes during production. Heat injection has become an advantageous method to produce heavy oils in Canada and Venezuela because it increases oil recovery. The heat reduces oil viscosity and oil flows easily. Colombia has significant heavy oil reserves in unconsolidated silty sandstones. It is important to understand the mechanical behavior of these reservoirs in thermal recovery conditions (temperature and effective stress). The reconstituted samples from a Colombian heavy oil outcrop were evaluated using a high-temperature and high-pressure triaxial cell. Twelve isotropically consolidated drained triaxial tests were conducted at three different effective stresses (0.4, 4.0, and 8.2 MPa) and a temperature range from 50 to 230 °C to represent the initial and thermal recovery conditions, and obtain parameters, such as Young’s and Bulk moduli, internal friction angle, and cohesion. The samples at higher confining stress (4.0 and 8.2 MPa) were under contraction, while samples at lower confining stress (0.4 MPa) were under dilation. The stiffness increased as the confining stress increased and decreased as temperature increased, and the strength properties significantly decreased as temperature increased. Finally, the Colombian samples exhibited low friction angles when compared to clean sandstones as Canadian sands.