Maysam Pournik

New correlations to predict fracture conductivity based on the formation lithology

ABSTRACT Acid fracturing is one of the most important well stimulation methods. Acid fracture conductivity, which represents the available capacity of the fluid pass in fractures, is one the main parameters for designing acid fracturing process. The volume of dissolved rock, rock strength, and closure stress on the fracture are the effective parameters on the acid fracturing conductivity. In this study, regarding above parameters and formation lithology, Genetic Algorithm was used to develop a robust intelligent model to estimate the fracture conductivity by considering experimental data of different formations. Results showed that formation lithology plays a considerable role in fracture conductivity prediction.

Study of Nanoparticle Retention in Porous Media - A Perfect Sink Model

Physicochemical interaction between the nanoparticles and the pore walls can cause significant retention of nanoparticles. The objective of this paper is to study nanoparticles retention when there is no energy barrier between the nanoparticles and rock surface. In this case, the double layer repulsion doesn’t exist, that nanoparticles retention depends on the diffusion coefficient of the nanoparticles and the thickness of the DLVO layer that mainly contributed by van der Waals attractive force. Perfect sink model is adjusted to calculate the rate of deposition of nanoparticles. Deposited nanoparticles could be released from the surface by physical perturbations. The kinetics of mobilization was analyzed by torque balance applied on a nanoparticle adhered to a flat surface in a moving fluid. Surface roughness is an important parameter in initiating particle to release from rock surface by affecting the length of the torque arms. The critical velocity for release acting at the center of nanoparticle can be identified. Numerical model was used to compare the theoretically calculated rates to experimental data. The model can be used to determine the fate of nanoparticles in porous media under different conditions of temperature, ionic strength, concentration, and pH that suppress the double layer repulsion.