PORE COLLAPSE IN WEAKLY CEMENTED AND POROUS ROCKS

Withdrawal of fluids from hydrocarbon reservoirs results in a decrease in pore pressure which in turn leads to an increase in effective stre ss on rock matrix. Such a situation may lead to the occurrence of pore collapse in reservoirs having weakly cemented, porous rocks. It is co nsidered to be a potential problem in several producing reservoirs. Nu merical simulation of a compacting reservoir due to pore collapse requ ires an appropriate constitutive model. Consequently, a constitutive m odel based on the concept of elasto-plasticity using isotropic hardeni ng is developed to predict pre and post-pore collapse behavior of rese rvoir rocks. An experimental study is carried out on a high-porosity r ock susceptible to pore collapse for different stress paths. The devel oped constitutive model is tested with respect to two different materi als exhibiting such behavior. Parameters for the model are evaluated b ased on the experimental results, highlighting the procedure involved. Further, the data is used to demonstrate the strengths and the weakne sses of the constitutive model. Experimental data for the second mater ial is obtained from literature. Satisfactory agreement is achieved be tween experimental data and model predictions.