Advanced theory for colloidal detachment of detrital and authigenic fines in rocks

Abstract

Hereby I present a PhD thesis by publications. The thesis includes two published journal papers, one submitted journal paper, one archived paper at Cornell University (USA), and three peer-reviewed conference papers. The journals include high-impact-factor ones: Chemical Engineering Journal, International Journal of Rock Mechanics and Mining Sciences, and Geo-mechanics and Geophysics for Geo-energy and Geo-Resources. The thesis develops a novel advanced theory for colloidal detachment of detrital and authigenic fines in natural porous reservoirs. Detrital fines are attracted to the surface by DLVO electrostatic forces, while authigenic particles form a mechanical bond with a substrate. The essence of the process is fines detachment, mobilization with further migration and recapture by the porous media. The capture of mobilized particles yields a decrease in suspension concentration and rock permeability. Significant permeability decline occurs due to straining or size exclusion. SEM images widely show open pores before the flow and image of the same pore plugged by strained particles after the flow. Regarding detrital particles, we discuss colloidal-suspension-nano transport in porous media with particle detachment and further capture by the rock. Previous works formulate particle-scale detachment conditions and porous-media scale transport equations with empirical coefficients, which are determined from the flow tests and are not predicted from the microscale. The present thesis establishes the upscaled procedure by stochastic distribution of torque and force balance on the attached particle and derivation of macro-scale equation for maximum retained concentration of attached particles as a function of velocity, PH, salinity, and temperature. Exact solution for 1D flow problem is used to determine Maximum Retention Function (MRF) from laboratory test and match it with the stochastic microscale model for detachment. High match obtained for four colloidal coreflood experiments validates the stochastic model and upscaling procedure. While micro and macro scale models for detrital fines detachment are available, and only upscaling procedure must be performed, none of models is available for authigenic particles. In this thesis, integrating the 3D version of Timoshenko and Goodier’s beam theory of elastic cylinder deformation with a CFD-based model for viscous flow around the attached particle and with strength failure criteria for particle-rock bond, we derived an explicit criterium for fines detachment by breakage at the pore scale. This leads to an explicit formula for the breakage flow velocity. Its upscaling yields a mathematical model for fines detachment by breakage, expressed in the form of the maximum retained concentration of attached fines versus flow velocity – MRF for breakage. We performed corefloods with piecewise constant increasing flow rates, measuring breakthrough concentration and pressure drop across the core. The behaviour of the measured data is consistent with two-population colloidal transport, attributed to detrital and authigenic fines migration. Indeed, the laboratory data show high match with the analytical model for two-population colloidal transport, which validates the proposed mathematical model for fines detachment by breakage. This thesis developed an advanced mathematical model for colloidal-suspension-nano transport in porous reservoirs. Forthcoming research works will apply this model in several areas of chemical, environmental, petroleum, geological, and civil engineering.