DEVELOPMENT OF PETROPHYSICAL STRESS MODELS FOR CONVERSION OF CORE POROSITY AND PERMEABILITY DATA FROM AMBIENT TO RESERVOIR CONDITIONS: A NEW HYBRID APPROACH

Correction of ambient measured core data to reservoir conditions poses a major challenge in the optimal use of historical core data in reservoir description and exploitation. The use of such data in any form of reservoir evaluation without appropriate correction to reservoir conditions will result to some degree of uncertainty in reserves determination and flow performance predictions. Core data from the Ventura avenue field was used for this development. This field is structurally complex and consists of a turbidite sand sequence that is shaly, thinly bedded and laminated. Porosity and permeability values are low and variable. This paper presents a new hybrid approach that uses the numerical or error minimization techniques to approximate the non‑linear and double exponential relationship of porosity and permeability versus stress and takes into account the shaly and laminated sand variability, microscopic pore throat attributes and resultant stress patterns inherent in the Ventura Core data. This approach eliminates the use of average parameters that is more favored in homogenous reservoirs. It also examines and compares with other existing methodologies in the industry. The result is promising and shows a more improved and accurate porosity and permeability conversion stress model.