Simulation of diagenesis and permeability variation in two-dimensional rock structure

Abstract

S U M M A R YA model is suggested to simulate the physical aspect of diagenesis in porous rocks. A bidisperse ballistic deposition model with relaxation of deposited grains is used to generate the porous structure. Sedimentation and erosion are allowed to restructure the pore space as a fluid flows through the rock. The effect of this restructuring of the pore space on permeability is studied. The Navier-Stokes equation is solved numerically by the finite difference method to determine the pressure and velocity distributions in the pore space. We find that though deposition is the dominant process in our model of diagenesis, reducing the porosity, the permeability may increase dramatically in some cases. These are when the erosion takes place at a single narrow constriction in the pore channel.

Depositional and Diagenetic Controls on Pore Structure of Tight Gas Sandstone Reservoirs: Evidence from Lower Cretaceous Bashijiqike Formation in Kelasu Thrust Belts, Kuqa Depression in Tarim Basin of West China

“…The complex diagenetic modifications during its long geological history, exert profound controls on reservoir quality, they will modify the original pore systems (Morad et al, 2000). Various type and degree of diagenetic processes distinctly reshape the pore structure (porosity and connectivity of pores) (Sadhukhan et al, 2007;Nelson, 2009;Okazaki et al, 2014). Cementation decreases permeability by filling primary porosity and pore throats, while compaction decreases porosity by establishing tighter inter-grain contacts.…”

“…The pore network characteristics modified by diagenesis are crucial factors in determining permeability (Sadhukhan et al, 2007). The pore network consists of pores connected through throats, and the HPMI analysis can provide insight into the pore structure and pore size distributions in porous sandstones (Torabi et al, 2013).…”

“…Depositional parameters such as grain size, sorting, shape, and matrix content strongly influence subsequent pore-system evolution (Ajdukiewicz & Lander, 2010). Diagenesis takes place at a molecular level (Sadhukhan et al, 2007), it exerts a strong control on the quality and heterogeneity of sandstone reservoirs (Morad et al, 2010). Diagenetic modifications influence the evolution of reservoir spaces and pore structures, pore-throat size and distribution.…”

Existence of convective threshold and its role on temperature in reactive flow through fractured rocks: a simulation study in 2D

“…An imaginary layer of grids is also added to the inlet and outlet. The fluid is assumed to enter the sample normally from one side, and after traversing the porous pathway, ejects out normally through the opposite side through these cells [25]. The tangential components of velocity are set zero in these cells.…”

“…Equations (5) and (6) are then spatially discretized before we finally employ them in our simulations [24,25]. Starting with zero velocity as the initial condition, equations (5) and (6) are iterated until the steady state is achieved.…”