Resumen

RODRIGUEZ, Jackeline; MARTINEZ, Manuel  y  SANCHEZ, Marisela. DETERMINATION OF BASICS MECHANICAL PARAMETERS IN SHALES, CARAPITA FORMATION, WESTERN OF VENEZUELA, THROUGHT THE TSI SYSTEM (TERRATEK STRENGTH INDEX). IMME [online]. 2004, vol.42, n.2, pp.21-39. ISSN 0376-723X.

The purpose of this work was to investigate the feasibility of determining the compressive strength values on shale samples from Carapita formation using the scratch test in the Terratek Strength lndex (TSI). This method has been used successfully in sandstone, and consists in subjecting the samples of rock to a superficial cut with a cutter with horizontal movement at a constant speed and depth. The use of this method in shales has been limited, as it is necessary to preserve the samples in mineral oil to avoid the lost of properties. To achieve this objective a fluid recipient was designed and adapted to fit the frame of the TSI system. Afterwards the mineralogy of the five (5) shale samples used in this study was determined. Finally, the effect of drilling fluids on the mechanical strength of shale samples was investigated by submerging two (2) of the samples in a water based polymer fluid over different periods of time (24 hours and 48 hours). The other samples were submerged in mineral oil. It was determined that is feasible to use the TSI equipment to perform Scratch tests in shale samples. This quick and simple method reduces the cost of carrying out testing and analysis. The results indicate that the mechanical parameters estimated from the tests with the TSI system, using mineral oil as inhibitory fluids, are quite similar to the results obtained from destructives or compressive tests using load frame technology. Additionally, it was observed that the shale samples submerged in water based polymer fluid produced values of intrinsic energy and internal friction angle quite similar to the values obtained in the samples submerged in mineral oil.

Palabras clave : Carapita; Shale; Fluid Recipient Container; Mud Fluids; Internal Friction Angle; Compressive Strength; Intrinsic Specific Energy.